Strategic Sustainable Development for the Stationary Power Sector:

Strategic Sustainable Development for the Stationary Power Sector:
Strategic Sustainable Development for the
Stationary Power Sector:
Is Carbon Capture and Storage a Strategic
Investment for the Future?
Lisa Chacón, Benjamin Hornblow,
Daniel Johnson and Chris Walker
School of Engineering
Blekinge Institute of Technology, Karlskrona, Sweden,
2006
Thesis submitted for completion of Master of Strategic Leadership towards
Sustainability, Blekinge Institute of Technology, Karlskrona, Sweden.
Abstract:
An examination of the stationary power sector is performed using The
Natural Step framework and Sustainability Principles (SP), in order to aid
decision makers in developing policy to balance energy needs while
reducing carbon dioxide (CO2) emissions in order to address climate change.
Carbon capture and storage (CCS) is evaluated for its sustainability
aspects, and is found to be a potentially sustainable approach which can be a
bridging technology to a more sustainable energy mix, as well as a
remediation technology which can remove CO2 from the atmosphere when
utilized in combination with biomass fuel.
Initial actions for restructuring the stationary power sector should
emphasise demand reduction and efficiency efforts, followed by switching
to renewable energy sources. If the first two strategies can not provide
sufficient CO2 reductions, then investments in CCS technology may be an
appropriate choice. CCS with coal-fired power can be a means to decouple
CO2 emissions from fossil fuel use, but other SP violations associated with
coal use must also be fully addressed before this strategy can be considered
a truly sustainable option.
Keywords:
Carbon sequestration, Carbon capture and storage, Stationary power, Policy,
Strategic sustainable development, Sustainability principles
Acknowledgements
This thesis is the product of not only the authors’ work, but also the help of
many additional people, without whom this report would not have been
possible. We would therefore like to acknowledge:
Karl-Henrik Robèrt and Roya Khaleeli, our thesis advisors.
Kate Maddigan, Kyle White, and César Levy, members of our peer-review
group.
Dag Christensen, Director of New Energy technologies, Oil & Energy
Division, Norsk Hydro and Frederik Hedenus (Ph.D. student at Chalmers
University) for reviewing our proposal and providing direction.
Klaus Lackner of Columbia University, David Bayless of Ohio University,
Martin Goldblatt of GreenFuel Technologies, and Geoffrey Coates, of
Cornell University for interviews on CO2 sequestration and storage
technologies.
ii
Executive Summary
The purpose of this report is to first understand society’s interaction with
the biogeochemical carbon cycle as a result of energy consumption, and
then to consider the potential role of fossil fuels in the transition to a
sustainable energy future, utilizing The Natural Step’s sustainability
principles and backcasting methodology. Carbon Capture and Storage
(CCS) is analyzed in detail to determine the extent to which it might be
successful strategy. Finally, the intent is to create a framework or mental
model for policy makers in government to utilize to analyse the wide range
of energy and CCS options which can meet the energy needs of a growing,
industrializing population. Policy options are outlined, but generalized
decisions are not recommended due to the need for local and/or regional
input, which can vary considerably The following research questions
provide the basis for the investigation:
•
Can point source carbon, notwithstanding fuel source, be
sequestered in a sustainable manner?
•
Will investments in fossil fuel based CCS be a strategic step
towards a sustainable stationary power sector?
•
What should governmental policy-makers take into consideration in
order to develop sustainable strategies within the stationary power
sector?
Methods include literature review, expert interviews, system dynamics, and
mathematical modeling. The results of this study indicate that point source
carbon can be captured and stored in a sustainable manner. The preferred
CCS technologies are gas separating membranes and sub-ocean geological
reservoirs.
This report shows that CCS is a flexible platform, because if biomass fuel is
used rather than coal, it enables for the first time, an effective approach to
removing CO2 from the atmosphere. This is possible because the biomass
incorporated CO2 from the atmosphere during its growth through
photosynthesis, and when CCS is implemented in conjunction with
biomass, the CO2 that is re-released through combustion will be
permanently stored underground. The importance of such a weapon in our
arsenal to combat CO2 emissions and climate change cannot be overstated.
iii
Governmental policy-makers should utilize a systems perspective which
can explore the trade-offs and complexity of the power sector. Prioritization
of the strategies will be region specific; there is no single answer to the
question of which energy technology option to choose. The strategy should
also be dynamic and change over time such that initial investments in
energy efficiency can provide savings for future investments in a mix of
renewable technologies and CCS with fossil fuels during the transition. In
order to make meaningful comparisons between technology options,
sustainability violations should be quantified by including the externalities
to show the overall cost to society in other sectors. This transition will be
greatly facilitated by sensible policy which makes CCS the least cost option
when penalties such as carbon taxes or caps are in place.
Investments in fossil fuel based CCS can be a strategic step towards a
sustainable stationary power sector. It is important to implement this
technology because of the large and growing base of coal-fired power
plants, and the plentiful supply of coal worldwide.
iv
List of Abbreviations
CCS
Carbon Capture and Storage
CO2
Carbon Dioxide
GWP
Gross World Product
H2O
Water
IGCC
Integrated Combined Cycle Gasification
LHV
Lower Heating Value
N2
Nitrogen
NGCC
Natural Gas Combined Cycle
NOx
Nitrogen Oxides
PCC
Pulverized Coal Combustion
PV
Photovoltaic
SOx
Sulphur Oxides
SSD
Strategic Sustainable Development
TNS
The Natural Step
ZET
near-Zero Emissions Technologies
v
Table of Contents
Acknowledgements ..................................................................................... ii
Executive Summary................................................................................... iii
List of Abbreviations .................................................................................. v
Table of Contents ....................................................................................... vi
List of Figures and Tables......................................................................... ix
1
Introduction ..................................................................................... 1
1.1
Climate Change............................................................................. 3
1.1.1 Biogeochemical Carbon Cycle ............................................. 3
1.2
Fossil Energy ................................................................................ 5
1.2.1 Carbon Capture and Storage ................................................. 6
1.3
Research Questions....................................................................... 7
2
Methods .......................................................................................... 10
2.1
Overview..................................................................................... 10
2.2
Strategic Sustainable Development ............................................ 10
2.2.1 Five Level Framework........................................................ 11
2.2.2 Backcasting......................................................................... 12
2.2.3 Sustainability Principles ..................................................... 12
2.2.4 ABCD Analysis .................................................................. 13
2.3
Applied ABCD Analysis ............................................................ 14
2.3.1 A Step – Defining the System and Success ........................ 15
2.3.2 B Step – Current Technology Score Card .......................... 15
2.3.3 C Step – Vision, Measures and Solutions........................... 16
2.3.4 D Step – Prioritization ........................................................ 17
3
Results of ABCD Analysis............................................................. 18
3.1
The System (A Step)................................................................... 18
3.1.1 Defining the System............................................................ 18
3.1.2 Defining Success................................................................. 24
3.2
Current Reality – Power Generation (B Step) ............................ 24
3.2.1 Pulverized Coal Combustion .............................................. 27
vi
3.3
3.4
3.5
3.6
4
4.1
4.2
3.2.2 Integrated Combined Cycle Gasification ............................ 27
3.2.3 Natural Gas.......................................................................... 30
3.2.4 Nuclear ................................................................................ 31
3.2.5 Photovoltaic Solar ............................................................... 32
3.2.6 Wind .................................................................................... 34
3.2.7 Hydroelectric....................................................................... 35
3.2.8 Ocean – Tides, Waves, Currents ......................................... 37
3.2.9 Biomass ............................................................................... 39
3.2.10
Geothermal ...................................................................... 40
Current reality – Carbon Capture (B Step).................................. 42
3.3.1 Separation with Sorbents..................................................... 42
3.3.2 Separation with Membranes................................................ 43
3.3.3 Separation by Cryogenic Distillation .................................. 43
3.3.4 Capture Systems Emissions ................................................ 44
Current Reality - Carbon Storage (B step) .................................. 45
3.4.1 Geological Storage .............................................................. 46
3.4.2 Ocean Storage ..................................................................... 50
3.4.3 Mineral Carbonation ........................................................... 52
3.4.4 Industrial Uses..................................................................... 53
Desired Future (C1 Step) ............................................................ 54
Strategies for Success (C2 Step) ................................................. 58
3.6.1 Demand Reduction.............................................................. 58
3.6.2 Renewable Energy............................................................... 60
3.6.3 Carbon Capture and Storage ............................................... 60
Discussion ....................................................................................... 63
Overview ..................................................................................... 63
D Step.......................................................................................... 65
4.2.1 Demand Reduction.............................................................. 65
4.2.2 Renewable Power................................................................ 68
4.2.3 Fossil Fuel Power with CCS ............................................... 69
4.2.4 Primary research question ................................................... 70
4.2.5 Second Research
Question……..…………………..71
vii
4.2.6 Third Research Question .................................................... 73
5
Conclusions .................................................................................... 80
5.1
Further Research ......................................................................... 81
References.................................................................................................. 83
Appendix A: Field Experts Consulted .................................................... 90
Appendix B: Computer Model Method .................................................. 91
Appendix C: Computer Model Parameters and Assumptions............. 93
United States Power Sector Projections .......................................... 93
Power Network Characteristics ....................................................... 93
Power Plant Parameters................................................................... 93
Experience Curves........................................................................... 94
Economic Assumptions:.................................................................. 95
Carbon Dioxide Emission Assumptions:......................................... 95
Power Supply Assumptions:............................................................ 95
Appendix D: Computer Model Results................................................... 97
BAU Scenario.................................................................................. 97
Demand Reduction Scenario ........................................................... 98
Non-fossil Fuel Power Scenario...................................................... 99
Carbon Capture and Storage Scenario........................................... 100
Strategic Sustainable Scenario ...................................................... 101
Appendix E: Author Contributions ...................................................... 103
viii
List of Figures and Tables
Figures:
Figure 1.1. World total primary energy supply (IEA 2005a, 8).................... 1
Figure 1.2. 2003 world electricity generation by fuel (IEA 2005a, 26)........ 2
Figure 1.3. The EPICA ice core (Brook 2005) ............................................. 4
Figure 2.1. The Five Level Framework....................................................... 11
Figure 3.1. Causal loop diagram of the stationary power sector................. 20
Figure 3.2. The IGCC process (GTC, 2005) ............................................... 29
Figure 3.3. Stationary power sector “Desired Future” (adapted from
Greenpeace 2006, 21).................................................................................. 57
Figure 4.1. Decision-making process flow chart......................................... 79
Tables:
Table 2.1. Sustainability rating system ....................................................... 16
Table 3.1. Sustainability assessment for PCC power generation................ 27
Table 3.2. Sustainability assessment for IGCC power generation.............. 29
Table 3.3. Sustainability assessment for NGCC power generation ............ 30
Table 3.4. Sustainability assessment for nuclear power generation............ 32
Table 3.5. Sustainability assessment for PV power generation .................. 34
Table 3.6. Sustainability assessment for wind power generation ............... 35
Table 3.7. Sustainability assessment for hydroelectric power generation .. 37
Table 3.8. Sustainability assessment for ocean power generation ……..39
ix
Table 3.9. Sustainability assessment for biomass power generation.......... 40
Table 3.10. Sustainability assessment for geothermal power generation ... 42
Table 3.11. Sustainability assessment of CO2 capture technologies .......... 44
Table 3.12. Geologic CO2 storage capacity and retention time (Grimston et.
al. 2001, 161) .............................................................................................. 48
Table 3.13. Sustainability assessment for geologic CO2 storage................ 49
Table 3.14. Sustainability assessment for ocean CO2 storage .................... 51
Table 3.15. Sustainability assessment for mineral carbonation CO2 storage
.................................................................................................................... 53
Table 3.16. Sustainability assessment for industrial uses of CO2 ............... 54
Table 3.17. Geologic storage options comparison...................................... 62
Table 4.1. Comparison of some examples of demand reduction actions ... 66
Table 4.2. Strategies for a sustainable stationary power sector .................. 67
x
1
Introduction
Viewing the history of human progress over the past two centuries from
the perspective of energy is a fascinating and compelling study. It has been
a period of dramatic advances in technology and quality of life, much to
the benefit of industrialized societies. With each advance came an
increasing reliance on fossil fuels as a primary energy source, and an
overall increase in energy intensity of lifestyle. Energy intensity is defined
as the amount of energy required to produce one unit of gross domestic
product. There are many lifestyle factors that influence energy intensity,
including the energy efficiency of buildings and appliances, fuel efficiency
of vehicles, distance traveled in vehicles, mass transportation availability,
cold or warm climate requiring heating or cooling, and many other factors.
About 80% of the world’s primary energy supply is from fossil fuels
(Figure 1.1Error! Reference source not found.) and stationary electric
power production is responsible for 37% of the world’s CO2 emissions.
RE
11%
Other
1%
Coal
24%
Oil
34%
Gas
21%
Hydro
2%
Nuclear
7%
Figure 1.1. World total primary energy supply (IEA 2005a, 8)
The predominant stationary electric power technologies are shown in
Figure 1.2. Since coal is responsible for 40% of electricity generation
worldwide, it is a large target for reductions in CO2.
1
Oil
7%
Other
2%
Nuclear
16%
Coal
40%
Hydro
16%
Gas
19%
Figure 1.2. 2003 world electricity generation by fuel (IEA 2005a, 26)
While three quarters of the anthropogenic CO2 released into the atmosphere
over the last century has been emitted by the industrialized world, the
developing world is now rapidly increasing its fossil fuel consumption as it
endeavours to acquire the benefits of a more technologically-advanced
society. Countries which have had historically low energy intensities, but
with ambitions for rapid development and industrialization in this century
include China, with its large population, and India, which is large and
growing. The effect of the industrialization of these large “economies in
transition” upon both energy consumption and greenhouse gas emissions is
significant. Given the strong historical correlation between increasing gross
domestic product and higher energy intensities, fossil fuel use and CO2
emissions are projected to rise significantly unless a commitment is made to
sustainable development (WRI 2002).
In some societies, positive change is occurring however, as a result of two
key mega-trends that are driving policy shifts: climate change and declining
fossil fuel availability (which will ultimately have the effect of increasing
energy prices). These mega-trend drivers will be elaborated upon in the
following sections.
2
1.1 Climate Change
Within the past two years in particular, significant environmental changes
have been observed, with a rapidity and magnitude which have exceeded
the predictions of climate models. Polar ice caps and arctic sea ice are
thinning. The melt zone in Greenland is expanding, which, in addition to
contributing to rising sea levels, decreases salinity in the ocean which could
potentially cause the Gulf Stream current to collapse, creating significant
cooling on both sides of the Atlantic (Gagosian 2003). Forest composition
is shifting radically, with warm climate species such as oak expanding into
coniferous zones. Since the 1970s, the number of category four and five
hurricanes has increased dramatically, as sea temperatures have raised.
Though it is difficult to make a direct causal link between specific weather
events such as Hurricane Katrina and the long-term trend of climate
change, simply examining economic losses due to extreme weather events
argues for applying the precautionary principle in allocating resources to
address this problem, as costs are likely to continue rising. From the 1950’s
through the 1970’s, economic losses due to extreme weather events rarely
exceeded $10 billion US dollars (USD) per annum (IPCC 2001a). Since the
1980’s there has been a steep increase in losses, and in the past four years
alone, extreme weather related annual losses have climbed from $50 billion
to nearly $200 billion USD (UNEP 2005). The Stern review on the
economics of climate change estimated that the cost of stabilization of CO2
at 550 ppm by 2050 will cost 1% of global GDP annually. This is
significant but the cost of inaction will be even greater, as GDP will be
reduced by up to 20% than otherwise expected if no action is taken (Stern
2006).
1.1.1 Biogeochemical Carbon Cycle
3
At the beginning of the Industrial Revolution, CO2 was present in the
atmosphere at 280 parts per million by volume (ppmv). Since then, more
than 3,900 gigatons (Gt) of carbon dioxide have been released into the
atmosphere through fossil fuel and biomass combustion, and the depletion
of soils (Socolow 2005). In addition to this, the biosphere’s ability to
naturally absorb carbon has been systematically undermined through
physical degradation of natural terrestrial sinks, such as forests and
vegetation. Anthropogenic emissions of CO2 are 6.6 Gt per year, which
exceeds absorptive capacity of natural sinks by 3.3 Gt per year (IPCC 2005,
12). As a result, the atmospheric CO2 concentration was 375 ppmv in 2003
(Blasing and Jones 2005), one-third higher than it has been in the past
650,000 years (Figure 1.3) (Brook 2005).
Figure 1.3. The EPICA ice core (Brook 2005)
Carbon dioxide is acknowledged as the primary greenhouse gas (GHG),
and there is strong consensus within the scientific community that higher
4
atmospheric CO2 concentrations are causing increasing climate instability
and increasing global mean temperature at a rate faster than the adaptive
capacity of the biosphere. Increasing atmospheric CO2 concentrations are
linked to the Greenhouse Effect, which gives rise to increasing global land,
air and ocean temperatures. One consequence is a higher level of water
vapour in the atmosphere, which when coupled with higher ocean
temperatures, gives rise to more violent storms.
Over the past 150 years, there has been an increase in mean global
temperature of approximately 0.6°C (IPCC 2001b, 105). Numerous climate
models have predicted global mean temperature increases of between 1.5
and 6 °C over the next 100 years (Ibid, 555).
1.2 Fossil Energy
With growing dependence on coal for electricity generation worldwide, it is
essential that CO2 emissions from this source be addressed. Action must be
taken to first stabilize, and then ultimately reduce, atmospheric CO2 levels
within an acceptable time frame. Despite concerted actions such as the
Kyoto Protocol on climate change, the International Energy Agency
predicts that electric power-related CO2 emissions will increase by 52% by
the year 2030 (IEA, 2005b, 79). Electricity generation and heat account for
most of the “addressable” CO2 emissions, comprising about 32% of US
GHG emissions (WRI 2005). Because CO2 emissions from stationary
power plants are relatively concentrated (e.g. flue gas is 15% CO2 by
volume, vs. 375 parts per million in the atmosphere), these sources are
obvious candidates for abatement efforts, where emissions can be mitigated
“upstream” of the atmosphere. Other sources of CO2, such as most forms
transportation are less compatible with abatement technologies, and
therefore fuel switching to sustainable fuels must be considered instead.
Even as demand rises for fossil fuels, production rates from key reserves of
oil and natural gas are diminishing. Global production of “conventional” or
crude oil is expected to peak in 2005 at 1900 billion barrels, while
“unconventional” oil sources (heavy, deepwater and polar oil, and gas
liquids) are predicted to peak in 2010 (ASPO 2006, 2). Natural gas
production has been in decline in North America, which is a strong driver
for developing liquefied natural gas imports from the Middle East (EIA
5
2006a). The cost of natural gas in North America increased by 50% during
2005, which is encouraging fuel switching to cheap coal for stationary
power production.
Coal is the most plentiful of the fossil fuels, with an estimated 200 years of
supply at current consumption levels1 (EIA 2004a). In addition, new uses of
coal are being commercialized more widely, since it can be converted into
diesel or synthetic natural gas through a chemical process known as the
“Fischer-Tropsch” process.
These fundamental supply constraints make questionable any large capital
investments in rapidly depleting (and increasingly economically
unfavourable) primary energy sources. However, short-term energy needs
and economic goals are winning out over strategic, long-range planning. To
ensure a sustainable energy future, governmental policy makers should
consider technology options that will be viable beyond the expiration date
of our current suite of fossil fuels.
1.2.1 Carbon Capture and Storage
Since the 1970’s, the oil industry has developed methods for separating
CO2 from natural gas and from combustion gases and also developed the
capability to inject CO2 back into underground geological reservoirs. These
technologies are collectively known as ‘carbon capture and storage’ (CCS).
CCS encompasses a number of physical and chemical approaches to
separate CO2 from other gases and then store it permanently, securely and
in an environmentally benign form. There are multiple chemical, biological
and physical approaches from which to choose. From an economic,
engineering and scientific perspective, each method has its own set of risks,
assumptions, and impacts on biological and economic systems, all of which
will be explored in the Results section (Chapter 3). The term ‘carbon
sequestration’ is also widely used, but it is quite broad and encompasses
1
Coal is only estimated to last 200 years at current consumption levels. Energy (and coal)
consumption continues to grow annually. A 2% annual increase could exhaust this supply
in 50 years. (Weisz 2004, 50)
6
both natural sinks (e.g. forests, soil) and the chemical transformation of
CO2 to inert, stable compounds. We have limited the scope of this paper to
technologies which can be coupled with large point source emissions within
the context of the power generation sector, as a method of decoupling the
use fossil fuels from increasing CO2 concentrations in the atmosphere.
1.3 Research Questions
Given the complexity of the global energy system, it is likely that a
combination of approaches and technologies will be required to address the
CO2 challenge. To avoid further catastrophic climate impacts, it will be
necessary to stabilize atmospheric CO2 levels by cutting emissions, even
while energy demand increases, and ultimately bring CO2 levels back
towards historical norms. Clearly, significant investments in energy
efficiency, renewable energy and alternatives such as nuclear must be
carefully considered to balance supply and demand, environment and
economy, and meet human needs worldwide. The many stakeholders and
interests must be weighed against each other, but the final answers must
preserve the earth’s ability to support the biosphere and human society. The
strategic challenge for decision- and policy-makers is to critically prioritize
investments over a short- to mid-term timeframe (5-15 years), in order to
mitigate the long-term (20 – 100 years) risks to our planet’s climate, and
the security and the stability of global society. The solutions must be
timely, in order to address the urgency of the situation, and also balance
current and future economic repercussions.
To inform policies for a strategic transition towards sustainability within
the power sector requires a creation of robust tools and concepts for
decision-making. In order to make sustainable choices in such a complex
system, it is necessary to take a rigorous and systematic approach. In this
thesis, a systems dynamics perspective of society’s impact upon the carbon
cycle is used to help determine the key relationships and leverage points for
impacting the system, and develop a strategic plan for a dynamic energy
infrastructure transition.
7
Utilizing a framework for Strategic Sustainable Development2 (SSD), the
specific purpose of this report is to first understand society’s interaction
with the biogeochemical carbon cycle, and then to consider the potential
role of fossil fuels in the transition to a sustainable energy future. Carbon
capture and storage is analyzed in detail to determine the extent to which it
might be successful strategy. Finally, the intent is to frame the energy
sustainability challenge for policy makers so that they take the appropriate
factors into considering in their selection of potential energy generation and
CCS technologies that can meet the energy needs of a growing,
industrializing population.
The following research questions will provide the basis for the
investigation:
1. Can point source carbon, notwithstanding fuel source, be
sequestered in a sustainable manner?
2. What should governmental policy-makers take into consideration in
order to develop sustainable strategies within the stationary power
sector?
3. Will investments in fossil fuel based CCS be a strategic step
towards a sustainable stationary power sector?
In addition, several hypotheses were articulated:
- Hypothesis 1: that the current major point source power generators are
not sustainable
- Hypothesis 2: that CCS could play an important role as a sustainable
emissions reduction and/or mitigation technology
- Hypothesis 3: Renewable power generation technologies have a
possibility of being sustainable options
- Hypothesis 4: Fossil fuels are firmly entrenched in the power
generation sector. Coal especially, is gaining momentum as the cost of
natural gas is causing a shift towards dirtier, more CO2 electrical power
2
Also known as The Natural Step Framework, further elaborated in Section 2.2
8
production. It will require decades to phase coal out of the power supply
mix.
- Hypothesis 5: Efficiency is a more successful strategy than increasing
power supply, even renewable power supply
The methodology for answering these questions will be described in
Chapter 2 (Methods). The various energy technologies and CCS options
will be analyzed in detail and presented in the Chapter 3 (Results). The
preferred options and actions will be presented in Chapter 4 (Discussion).
Lastly, the key findings of this study will be presented in Chapter 5
(Conclusion).
9
2
Methods
This section outlines the methodology undertaken for the thesis. A brief
overview of the process is first presented. Background information on the
main tools, concepts and definitions used in the analysis are then provided,
followed by an in-depth description of how they were applied to the
stationary power sector.
2.1 Overview
Given the complexity of the stationary power sector, care was taken to
properly understand the system through an extensive literature review of
peer-reviewed journals and reports, attendance at two conferences3 and a
number of interviews with relevant experts in the fields of energy
generation, CO2 emissions and carbon capture and storage. A
comprehensive list of the field experts consulted is provided in Appendix
A. The stationary power sector was then analysed using a comprehensive
approach for strategic planning in complex systems. The results from both
the research and analysis form the supporting information from which we
base our answers to the research questions.
2.2 Strategic Sustainable Development
This paper uses a framework for strategic sustainable development, widely
known by business leaders as The Natural Step Framework. It is named
after its founding organization, The Natural Step (TNS), an international
NGO. The framework is a methodology for strategic sustainable
development and consists of a Five Level Framework for planning in
complex systems, a set of Sustainability Principles to set the minimum
constraints for sustainability, the concept of backcasting for strategic
planning, and an ABCD analysis tool to aid in the backcasting process. A
description of each of these components is provided below.
3
Point Carbon’s Carbon Markets Conference, Copenhagen, February 2006, and the World
BioEnergy Conference in Jonkoping, May 2006
10
2.2.1 Five Level Framework
The Five Level Framework (Robèrt, et. al. 2005, xx) is a generic tool for
comprehensive planning in complex systems. Each level of the planning
process is distinct and hierarchical as well as interconnected such that
feedback occurs between adjacent levels. The five levels and their
connections are illustrated in Figure 2.1.
Figure 2.1. The Five Level Framework
1. Systems Level. At this level, the fundamental characteristics of the
complex system are described. To avoid reductionism, all of the major
components, interrelationships, and essential aspects of the system must be
included.
2. Success Level. At this level, the objectives or desirable results that must
be achieved within the systems are described.
3. Strategy Level. Strategic guidelines for achieving the goals defined at the
Success Level are stated.
4. Action Level. Tangible events occur at this level in agreement with
strategic principles identified at the Strategy Level.
11
5. Tools Level. There are three main types of tools at this level: systems,
capacity and strategic. Systems tools make direct measurements on the
Systems Level in order to learn more about the current status of the system.
Capacity tools help communicate and clearly define the goals at the Success
Level. Strategic tools are designed to ensure that events at the Action Level
agree with strategic principles at the Strategy Level.
2.2.2 Backcasting
Backcasting is a concept that is essential for strategic planning in complex
systems (Holmberg and Robèrt 2000). Unlike forecasting where future
predictions are based on past trends, backcasting is a planning procedure in
which first a successful outcome is imagined and then strategies that lead
towards that outcome are determined. By looking backwards from that
future and asking the question “what do we need to do today to achieve a
successful outcome?” actions that can strategically progress towards the
goal can systematically be undertaken.
2.2.3 Sustainability Principles
The word ‘sustainability’ is frequently used, but often without a clear
indication of what that entails. In this thesis, sustainability is defined by
adhering to four separate socio-ecological sustainability principles (SP´s)
that were developed through a process of scientific consensus. These
principles are:
In a sustainable society, nature is not subject to systematically increasing…
1. concentrations of substances extracted from the Earth’s crust,
2. concentrations of substances produced by society,
3. degradation by physical means
and, in that society…
4. people are not subject to conditions that systematically undermine
their capacity to meet their needs.
12
Collectively these principles are referred to as the sustainability principles,
(also known in the business community as the TNS ‘system conditions’).
and are considered to be the minimum requirement for which a sustainable
society must comply (Holmberg et al. 1996 and Ny et al. 2006)4.
2.2.4 ABCD Analysis
The ABCD Analysis (Robèrt 2000, 246-7) is a strategic tool belonging to
the Tools Level of the Five Level Framework. It is called the ABCD
Analysis after its four logical steps. It explicitly explains Levels 1, 2 and 3
of the Five Level Framework and provides a systematic approach to
backcasting from objectives defined at the Success Level. Below is a
description of each step of the analysis:
A Step. At this step, a shared understanding of both the Systems and
Success Levels of the Five Level Framework is developed among the
participants of the planning process. It is essential that these levels are
defined as clearly as possible as they create the foundation from which all
subsequent steps are based.
B Step. This is where backcasting is first applied. Here the participants
scrutinize the current activities occurring at the Systems Level from the
future perspective defined by the Success Level. In this manner, an
understanding of how the system is not meeting the objectives stated at the
Success Level is determined.
C Step. At this step, visions and solutions are brainstormed by the
participants of the planning process. This is done again from a backcasting
perspective in order to ensure that suggestions are aligned with Success
Level objectives. The measures generated from this process correspond to
the Strategies Level of the Five Level Framework. Conducting the C step
often gives a clearer view of the current conditions in the B step, as
carrying out the B step helps create the C step’s sustainable vision of the
4
The initial phrasing of the principles was first published by Holmberg and Robèrt in
1996. Since that time the wording has been revised as reflected in Ny et al. 2006.
13
future. Thus, it is often helpful to conduct the B-C steps as an iterative
process instead of a linear one.
D step. This is where prioritization of the brainstormed measures occurs.
Each measure is examined individually in order to determine whether the
answer is ‘yes’ to the following three questions:
1. Does this measure proceed in the right direction with respect to all of
the sustainability principles?
2. Does this measure provide a flexible platform for further
development?
3. Is this measure likely to produce a sufficient return on investment?
Based on these results, the best strategies can be determined and actions
taken that will strategically lead the system towards the desired objectives.
2.3 Applied ABCD Analysis
The ABCD Analysis becomes a strategic tool for sustainable development
when compliance with the sustainability principles is stated as a
requirement at the Success Level of the Five Level Framework. This
approach to planning in complex systems formed the backbone of our
methodology, and was applied specifically to the stationary power sector.
Additional tools such as a causal loop diagram (CLD) and a computer
model were used at various stages during the analysis in order to develop a
deeper understanding at the Systems Level as well as to help illustrate the
effects of measures at the Strategies Level. An outline of how specifically
the ABCD Analysis was applied to the stationary power sector is provided
in the following sections. Although presented in a linear order here,
feedback and iteration took place between steps, in a similar fashion as
described for the Five Level Framework. The first three steps (A,B and C)
are presented in the Results section. The prioritization questions of step D
integrated well with our research questions, and for this reason step D was
incorporated into the Discussion section.
14
2.3.1 A Step – Defining the System and Success
Defining the System. The scope of this thesis was determined to be the
stationary power sector within society within the biosphere. From this
starting point, the power generation technologies of a typical distributed
power network and its interactions with society and the biosphere were
analyzed. Additionally, emerging CCS technologies and their potential role
in the stationary power sector were also considered.
A CLD was created in order to develop a shared mental model of the
system. The function of a CLD is to map out the structure and causal
relationships of a system in order to understand its feedback mechanisms.
Feedback is responsible for changes within systems – action causing
reaction. It is any action that causes an effect back to the starting point of
the action, and is therefore both the cause and the effect. CLD´s are used to
understand how a behaviour has been manifesting itself in a system so we
can develop strategies to work with, or counteract that behaviour. A brief
description on how to interpret CLD’s is provided in the Results section.
To supplement our knowledge of how the system could be strategically
changed over time, a bottom-up computer model of a stationary power
network was developed. The model developed was not intended to be
predictive with respect to reality, but rather to provide relative comparisons
between scenarios and to illustrate the potential for specific actions to lead
towards success, all within the context of the model and its assumptions.
Comprehensive information on the computer model methodology,
parameters and assumptions, and results are provided in Appendices B, C
and D respectively.
Defining Success. In addition to compliance with the sustainability
principles, goals specific to atmospheric CO2 levels were also included.
2.3.2 B Step – Current Technology Score Card
The power generation and CCS technologies identified in the system were
thoroughly researched in order to understand their characteristics. A rating
system was developed that ranked each technology in terms of how well
they currently complied with each sustainability principle. A sustainability
15
‘score card’ was then given to each technology and the results collated into
a summary table.
Table 2.1. Sustainability rating system
++
+
0
--
An excellent performer in this category. No major issues.
Only minor SP violations, that can be addressed easily.
Tradeoffs exist. SP violations may be difficult to avoid or compensate
for. Exercise caution in allowing this option.
SP violations exist that make this option a bad choice in all but
temporary, transitional options, when accompanied by a phase-out plan.
Serious SP violations. Avoid at all costs.
2.3.3 C Step – Vision, Measures and Solutions
Envisioned Future. Characteristics of a sustainable stationary power sector
were brainstormed. These ideas were then incorporated into a graphic
representation of a future stationary power sector which was then referred
to as the “desired future”.
Measures and Solutions. Through the application of backcasting, measures
were listed that would strategically move the system towards the desired
future. Measures that appeared to have similar results on the system were
then clustered into groups and referred to as a strategy. Each strategy was
then correlated to causal relationships in the system CLD and named in
accordance with the actors that leveraged the system. Three strategies for
strengthening the balancing loops were identified through this process. The
first two strategies were essentially equivalent to the strategies of
substitution and dematerialization identified in a review of the major
methodologies for achieving sustainability (Robèrt et. al. 2002). We added
a third strategy - abatement, defined as to nullify or diminish. Pollution
abatement can be accomplished through any technology which chemically
transforms harmful emissions into inert or more easily controlled
substances. For example, pollution abatement technologies include exhaust
scrubbers implemented in manufacturing facilities to neutralize acidcontaining gases and convert them into solids, and catalytic converters on
automobiles which reduce nitrogen oxides, which cause acid rain, into
harmless nitrogen and oxygen.
16
2.3.4 D Step – Prioritization
In addition to the three prioritization questions used at the D Step, research
relating to stationary power sector examples where measures were
strategically implemented was also used to support our recommendations.
The following two sections provide an overview to our approach at
prioritization.
Prioritization Questions. Each measure was evaluated with respect to the
three prioritization questions.
1. Does this measure proceed in the right direction with respect to
success?
In addition to the sustainability principles, additional goals were included in
our definition of success. For this reason, question 1 has been reworded to
encompass all of the requirements outlined in our definition of success. The
sustainability scorecards developed at the B step were used as the primary
source of information for answering this question.
2. Does this measure provide a flexible platform for further
development?
Each strategy was examined to determine if investments in these directions
might lead down blind alleys. A flexible platform for further development
would provide a technology basis for extending the state of the art with new
advances, or would be compatible with alternate fuels, for instance.
3. Is this measure likely to produce a sufficient return on investment?
Each strategy was examined to determine what economical and
environmental benefits they provided.
Prioritization Research. Specific research efforts focused on identifying
existing prioritization methodologies which are currently employed in the
stationary power sector was undertaken.
17
3
Results of ABCD Analysis
This section describes the results of the ABCD analysis of ‘the stationary
power sector within society within the biosphere,’ including possible
actions and their prioritization the project in the following sections:
•
•
•
•
•
A – The System: A description of the stationary power sector within
society within the biosphere, including major actors within the
system and the interaction between them
B – Current Reality: An analysis of SP violations today, as well as
assets currently available for potentially addressing the problems.
C1 – Envisioned Future: A potential future which is in compliance
with the SP’s is envisioned, and becomes the perspective from
which backcasting is performed.
C2 - Strategies: A brainstorm of the policies and power generation
strategies and technologies to help us reach our envisioned future is
described.
D step - Prioritization of Strategies, is developed in Chapter 4, the
Discussion section.
3.1 The System (A Step)
The A step in the ABCD process involves developing an understanding of
the system. Here, we have broken it up into two parts:
• Defining the System - setting the boundaries of our study and
describing how it works.
• Defining Success – what we would consider to be a successful
outcome to backcast from.
3.1.1 Defining the System
This section provides an overview of the system we are studying: the
stationary power sector within society within the biosphere. This
corresponds to Level 1 of the 5-Level Framework.
18
We look at the various types of power generation in use today—fossil fuel,
nuclear, and renewable—that are connected to a common grid from large
point sources to produce electricity for commercial, residential, and
industrial applications. Currently, power sources are predominately fossil
fuel based. There is a significant amount of fossil fuel infrastructure in
place, and the burning of fossil fuels produces CO2 which is released into
the atmosphere. Current trends indicate a continued reliance on fossil fuel
power with continually growing energy demands. CCS is in the early
demonstration phase and being considered for use with fossil fuel power
plants to reduce CO2 emissions.
A causal loop diagram was developed for the stationary power sector within
society within the biosphere and is shown below in Figure 3.1. This
diagram illustrates the main actors, major causal relationships and defines
the boundary of the system being studied.
The grey circles represent variables (also known as actors) in the system.
Each variable is labelled according to the action, event, or component that it
is describing. The arrows show a causality, where a variable at the tail of
the arrow causes a change to the variable at the head of the arrow. A plus
sign near the head of the arrow indicates a change in the same direction
while a minus sign indicates a change in the opposite direction. Loops are
formed by connecting actors together with arrows pointing in the same
direction (either clockwise or counter clockwise) that ultimately lead back
to the actor where they started from. The letter “R” indicates that feedback
in a loop is reinforcing behaviour in the same direction (also known as a
reinforcing loop). The letter “B” indicates that feedback in a loop is
balancing behaviour in the opposite direction (also known as a balancing
loop). For simplicity, relative strengths and delays in causal relationships
are not shown in the diagram and are instead discussed in the supporting
text where appropriate.
19
Figure 3.1. Causal loop diagram of the stationary power sector
20
Central to the diagram is the reinforcing loop between ‘Economic Growth,’
‘Power Demand,’ and ‘Fossil Fuel Power Consumed’ (loop R1 – a,b,c,a).
This has been the driving force of the global economic engine since the
Industrial Revolution, and continues to be for the majority of the
industrialized world. Two similar reinforcing loops exist in parallel to loop
R1, R2 (a,b,d,a) and loop R3 (a,b,e,a). These loops operate in the same
manner as loop R1, the only difference being the type of technology
providing the power consumed. The relative strengths between loops R1,
R2 and R3 are determined by the characteristics of the stationary power
network being studied.
A major repercussion of loop R1 is the production of ‘CO2 Emissions’ from
‘Fossil Fuel Power Consumed.’ These emissions have contributed to an
increase in ‘Atmospheric CO2 Levels,’ and as CO2 is a primary greenhouse
gas, it is directly responsible for an increase in ‘Climate Change Impacts.’
These impacts are now being recognized on a global scale which has
created an increase in ‘Stakeholder Awareness’ (in this context,
stakeholders refers to society at large). In a functioning democratic society,
an increase in ‘Stakeholder Awareness’ should translate into an increase in
‘Sustainable Governance’ (a sustainability-focused governmental body
intent on transitioning society towards sustainability). ‘Sustainable
Governance’ in turn feeds back to ‘Stakeholder Awareness’ (through
undistorted communication of relevant information for example) as well as
being responsible for creating ‘Strategic Sustainable Policy.’ Through
‘Stakeholder Awareness’ and ‘Strategic Sustainable Policy,’ balancing
loops have been put in place to address the ‘CO2 Emissions’ associated with
‘Fossil Fuel Power Consumed.’ Three key actors in the system are integral
to these balancing loops: ‘Demand Reduction,’ ‘Renewable Power’ and
‘Carbon Capture and Storage.’
Demand Reduction. The electrical power needs of the individual consumer
are reduced, or in other words, the energy intensity of lifestyle is reduced.
An increase in ‘Demand Reduction’ causes a decrease in ‘Power Demand.’
This weakens or slows loops R1, R2 and R3 and consequently reduces the
‘CO2 Emissions’ associated with loop R1. The consumer (or Stakeholder)
can have a great influence on ‘Demand Reduction.’ Actions such as turning
lights off when not being used and installing solar hot water heating
systems can greatly reduce electricity needs. This balancing loop is shown
21
as B1 (b,c,g,h,i,j,m,b). ‘Strategic Sustainable Policy’ can also play an
important role in increasing ‘Demand Reduction.’ Requirements for
appliance power consumption and standards for building insulation are two
examples of how this might be achieved. This balancing loop is shown as
B2 (b,c,g,h,i,j,k,l,m,b).
Renewable Power. The development, deployment and utilization of
renewable power generating technologies is considered here. An increase in
the availability of ‘Renewable Power’ will increase the ‘Renewable Power
Consumed’ (providing that renewable power supply utilization is
prioritized over fossil fuel and nuclear). This will bias the mix of supply in
favour of renewable power generation which strengthens loop R3 while
weakening loops R1 and R2. In doing so, reducing the ‘CO2 Emissions’
associated with loop R1. The consumer can have a direct influence on
‘Renewable Power.’ Net metering of installed solar panels or requesting
renewable power from regional power supply companies are two ways of
how this can be done. This balancing loop is shown as B3 (c,g,h,i,j,n,c).
‘Strategic Sustainable Policy’ can have a great influence on ‘Renewable
Power.’ Grants for renewable power research and development, subsidies
for increasing installed capacity, and taxes on fossil fuel are just a few of
the ways that policy can do this. This balancing loop is shown as B4
(c,g,h,i,j,k,l,n,c).
As well as reducing fossil fuel power CO2 emissions, there are a number of
other benefits associated with increasing reliance on renewable power
generation. This is represented by ‘Benefits of Renewable Power.’ These
benefits include: reduced health impacts associated with the combustion of
fossil fuel, enhanced power supply stability through source diversification,
and improved energy security from reduced geopolitical tensions over fuel
supply. This provides a feedback connection to ‘Stakeholder Awareness’
and creates two reinforcing loops [R4 (f,j,n,e,f) and R5 (f,j,k,l,n,e,f )], that
further strengthen loop R3.
Carbon Capture and Storage. The development, deployment and utilization
of CCS technologies in conjunction with power generation technologies is
conducted. An increase in ‘Carbon Capture and Storage’ will result in a
decrease of ‘CO2 Emissions.’ ‘Strategic Sustainable Policy’ is the only
actor in the system with the power to increase ‘Carbon Capture and
Storage.’ This can be achieved by either implementing financial penalties
22
on CO2 emissions or by providing financial rewards for the sequestering of
atmospheric CO2. The Kyoto Protocol cap and trade system is one example
of how this is currently being legislated. This balancing loop is shown as
B5 (g,h,i,j,k,l,o,g). If CCS is applied to fossil fuel power generation
technologies then a second causal connection is necessarily created. An
increase in ‘Carbon Capture and Storage’ will increase ‘Fossil Fuel Power
Consumed’ for two reasons. Efficiency losses from the capture and storage
process, requires more fossil fuel to be consumed in order to produce the
same amount of electrical power. Continued consumption of fossil fuels
will also further promote development and deployment of fossil fuel power
generation technologies – perpetuating our dependence on ‘Fossil Fuel
Power Consumed.’ This creates a reinforcing loop R6 (o,c,g,h,i,j,k,l,o) that
opposes the balancing effects created by ‘Demand Reduction’ and
‘Renewable Power.’
Leverage Points. In the context of complex systems, the term ‘leverage
point’ refers to a place of intervention where a small shift can produce big
changes everywhere else (Meadows D, 1999). All of the balancing loops
created by ‘Demand Reduction’, ‘Renewable Power’ and ‘Carbon Capture
and Storage’ pass through ‘Stakeholder Awareness.’ This is an important
actor in the system as it can directly affect all of the balancing loops
identified for reducing CO2 emissions. For this reason, we have identified
‘Stakeholder Awareness’ as a leverage point in the system, and have
labelled it as L1. A sub-set of the balancing loops also passes through
‘Sustainable Governance’. This actor also plays an important role in
determining the effectiveness of these loops. Unlike ‘Demand Reduction’
and ‘Renewable Power’, where there is a causal relationship coming
directly from ‘Stakeholder Awareness’, ‘Carbon Capture and Storage’ can
only be influenced directly by ‘Sustainable Governance’. Furthermore,
‘Sustainable Governance’ can increase ‘Stakeholder Awareness’ and
indirectly affect the other balancing loops as well. For these reasons, we
have identified Sustainable Governance as a leverage point in the system,
and have labelled it L2. This thesis: Strategic Sustainable Development
(SSD) for the Stationary Power Sector is intended to ‘leverage’ L2 by
assisting policy-makers to make strategic decisions that will reduce and
ultimately eliminate CO2 emissions from the stationary power sector.
23
3.1.2 Defining Success
The second part of the B step in the ABCD process, Defining Success,
corresponds to Level 2 of the 5 level Framework for Strategic Sustainable
Development. As a bare minimum for sustainability, this success must
include compliance with the 4 Sustainability Principles.
As discussed in the introduction, anthropogenic CO2 emissions have
increased atmospheric CO2 levels to well above that of previously recorded
natural variations. In addition to reducing CO2 emissions to within the
carrying capacity of the bio-sphere, it is the shared view of the authors that
atmospheric CO2 levels must be restored back to within natural variations.
Thus, for the purposes of this study, we have defined ‘Success’ to mean
both compliance with the sustainability principles and that atmospheric CO2
levels have stabilized below 500 ppm, and are trending down towards 280
ppm. The threshold of 500 ppm CO2 was selected as this is a level which is
generally believed to be accessible with currently identified technologies
within a time frame of fifty years (albeit with monumental effort and
investment) (Pacala and Socolow 2004, 968). The ultimate target of 280
ppm represents the upper limit of the natural variation of CO2
concentration, which was originally reported in the Vostok ice core study,
and has been confirmed by the EPICA ice core study (Petit et al. 1999). In
order to reach these targets and restore atmospheric CO2 concentrations
within a reasonable time frame, we hypothesize that CCS technologies may
be required.
3.2 Current Reality – Power Generation (B
Step)
The B step includes an analysis of current reality from the perspective of
sustainability principle violations within the stationary power sector and the
assets currently at our disposal to address the problems. This section
surveys the stationary power generation landscape to assess the
sustainability aspects of the current supply mix and evaluate our future
options.
The following are some of the major Sustainability Principle (SP)
violations that were identified by examining the stationary power sector
24
described in the A-step. They will be explored in more detail in the
individual sections.
•
•
SP I
•
•
SP II
•
•
•
•
SP III
•
•
•
•
•
•
SP IV
•
•
CO2 emissions from fossil fuel power plants
Mercury, lead, and sulphur emissions from fossil fuel
power plants
Uranium and other isotopes from uranium mining for
nuclear power plants
SOx, NOx, and particulate emissions from fossil fuel
burning
Aerosols
Radioactive waste from nuclear power facilities
Habitat and biodiversity loss from fossil fuel extraction
River interference and flooding from hydroelectric
dams
Infrastructure (pipelines, power lines)
Fossil fuel extraction waste products (tailings, ponds)
Depleted aquifers from fossil fuel extraction (e.g. tar
sands) and nuclear power plants
Resource exploitation of underdeveloped fossil fuelrich countries, which supports oppressive regimes
Re-location of people and villages because of valley
flooding from hydro-electric
Further use of fossil fuels as well as nuclear power
leads to decrease of national security due to possible
targets for terrorist attacks, reduced self-reliance at
regional level and geopolitical tensions linked to such
problems.
Linkage between nuclear power and nuclear arms.
Competition for diminishing fossil- and nuclear- fuel
leads to increased risks for war
Each technology or group of technologies is evaluated for compliance with
the Sustainability Principles and given a scorecard according to the rating
system presented in the Methods section (Section 2.3.2).
25
Fossil Fuels. The major fossil fuels explored in the B step are coal and
natural gas technologies. Oil is not used to a great extent in electricity
generation. Coal is the most abundant fossil resource and is used to produce
40% of the world’s electrical power (IEA 2005a). Around 90% of coalfired power plants utilize pulverized coal combustion (PCC) technology,
with one of three variations: sub-critical, supercritical and ultrasupercritical (depending on the pressure level of the steam system). There
are several emerging power generation strategies with an emphasis on
“clean” coal, or near-zero emissions technologies (ZETs), which
prominently feature integrated combined cycle gasification (IGCC) due to
its high efficiency and amenability to CCS and mitigation of other
pollutants, though it is currently a small part of the mix (<10%). Natural gas
combined cycle (NGCC) is also evaluated, as the main competitor to coal
powered electricity generation.
Renewable Energy Technologies. When sustainable electricity alternatives
are proposed they are usually referred to as ‘renewable energy;’ however,
as with ‘sustainability’ there are a variety of definitions of ‘renewable.’ A
brief survey of definitions reveals common characteristics:
1. Natural replenishment, within a reasonable time frame (at most one
generation to one lifetime). (BCH 2002a)
2. Exploitation of the resource occurs at a rate that does not lead to
depletion (i.e. systematic degradation of the resource) (CRS 2001a)
3. The focus is on the characteristics of the energy source, rather than
the technology employed (NAAG, 14-15)
We assess the sustainability aspects of renewable energy technologies
involved in the stationary power generation sector. That includes options
such as wind, solar, hydroelectric, and biomass. Options such as ethanol are
not considered, as they are not widely used for electricity generation due to
the much higher efficiencies from burning biomass directly without first
converting it to a liquid fuel. It should be noted that ‘renewable energy’
does not implicitly mean that the technology is sustainable, it just means
that the fuel supply is renewable. We will define Renewable Energy as
energy forms derived directly or indirectly from solar radiation, from tides
and from the heat of the Earth’s core. (B.C. Hydro 2002).
26
3.2.1 Pulverized Coal Combustion
Finely powdered coal is burned in air within a large combustion boiler, and
the heat produced is used to raise steam which drives a steam turbine. A
range of efficiencies can be obtained for this process, depending mainly
upon the steam pressure. At pressures above the supercritical point of water
(22.1 MPa), greater thermal efficiencies can be achieved, on the order of 42
– 47% for the most advanced new technologies. Supercritical unit sizes up
to 1000 MW are routinely operated worldwide. Efficiencies up to 50% can
be achieved with even higher pressures (35 MPa) with the
‘ultrasupercritical’ process currently under development The postcombustion effluent is known as ‘flue gas,’ and is composed of N2 (70%),
CO2 (15-25%), and H2O, and also contains SOx, NOx, particulates and
heavy metals such as mercury which are removed by various scrubbing
technologies before the flue gas is released to the atmosphere. Due to the
use of air for combustion, the CO2 in the flue gas is diluted by a large
volume of nitrogen, which has implications for appropriate sizing and cost
of the CO2 separation system, when CCS is considered. One possibility for
enabling the compatibility of PCC with CCS is ‘oxy-fuel’ combustion,
where oxygen is used in place of air in the combustion boiler and produces
an effluent which is more highly concentrated in CO2.
Table 3.1. Sustainability assessment for PCC power generation
Right Direction
SP I
--
SP II
-
SP III
-
SP IV
-
Emissions of CO2, heavy metals and particulates.
Emissions of SOx and NOx (abatement required by
law in OECD, but not in developing countries.
Land disturbance (especially with “mountain-top
removal”). Surface and groundwater contamination.
Methane emissions.
Adverse health impacts due to particulates, mercury
and acid gases where they are not mitigated.
Safety hazards for miners.
3.2.2 Integrated Combined Cycle Gasification
IGCC technology can convert a wide range of carbon-containing feedstocks
(high and low quality coal, oil, biomass, or waste) into a ‘synthesis gas’
which is a mixture of carbon monoxide and hydrogen. This synthesis gas
27
(or ‘syngas’) can be used in a number of ways – as a fuel to generate
electricity or steam, or as a chemical feedstock for the production of a range
of industrially important chemicals. These chemical products include
ammonia, methanol and hydrocarbons ranging in length from methane
(CH4) up to diesel (chains longer than C16H34) via the Fischer-Tropsch
chemical process.
Combined-cycle technology utilizes two turbines: a combustion turbine,
where the syngas is burned in air, and a second steam turbine which utilizes
steam raised by the waste heat of the combustion turbine. Because waste
heat is utilized, combined cycle efficiencies are around 60%, compared to
~35% for a combustion turbine alone.
Because oxygen is used rather than air in the gasification process, the
effluent gases are highly concentrated in CO2, making IGCC very amenable
to CCS. Pollutants such as sulphur, and mercury are converted to their
elemental or reduced forms and are readily captured as sulphur, ammonia
and metallic mercury. Particulates are also removed before further
processing. IGCC is clearly a favoured zero-emissions technology, and is
currently receiving significant levels of government funding for research,
development and deployment in the US and in Europe (Henderson 2003,
34).
28
Figure 3.2. The IGCC process (GTC, 2005)
There are 385 IGCC units in operation worldwide. Of these, only four of
are used for power generation while the others produce chemicals. Key
barriers to more widespread adoption include higher cost and lower
reliability than PCC technology.
Table 3.2. Sustainability assessment for IGCC power generation
Right Direction
SP I
+
SP II
+
SP III
-
SP IV
+
Emissions of CO2, (Heavy metals and particulates
greatly diminished relative to PCC)
Emissions of SOx and NOx are mitigated by
scrubbing technology
Land disturbance (esp. with “mountain-top
removal”). Surface and groundwater contamination.
Methane emissions
Safety hazards for miners
29
3.2.3 Natural Gas
Most power plants built in the US in the 1990’s utilized NGCC technology,
in a drive to meet tougher air standards by moving away from dirty,
polluting coal. The advantages of natural gas (also methane or CH4) over
coal are that particulate matter is not produced in the combustion, SOx and
NOx are minimal, and there are no heavy metals. Natural gas combustion is
more exothermic than coal, resulting in higher temperatures, and thus
higher efficiency in energy conversion. When burned, natural gas produces
less CO2 per unit energy than coal. However, despite these advantages,
limited supply of natural gas (particularly in North America) has caused the
cost of the fuel to nearly triple over the past three years, making this an
economically unfavourable option. In the 1990’s, natural gas wellhead
prices were in the range of $1.50 - $2.00/MMBtu, but today they are highly
volatile, and have ranged from $6.00 to $14.00/MMBtu in the past twelve
months. Gas production from the Gulf Coast region is particularly
vulnerable to disruption during the hurricane season, as Hurricane Katrina
demonstrated in 2005. This supply constraint is the motivation behind
developing liquefied natural gas (LNG) infrastructure, which is imported
from areas where it is plentiful, such as the Middle East or Russia. Higher
natural gas prices are a key driver for reverting to coal-fired power
generation for new installations. Currently, natural gas fuels 19% of the
world’s electricity production.
Table 3.3. Sustainability assessment for NGCC power generation
Right Direction
SP I
-
SP II
0
SP III
-
SP IV
0
Emission of CO2 to the atmosphere
(however, it is less than that of coal)
Emissions are inherently cleaner than when
coal is burned
Disturbance of the environment due to
natural gas extraction, and LNG terminals
are potentially damaging to sensitive coastal
areas
Risk of LNG terminal catastrophic explosion
30
3.2.4 Nuclear
All commercial nuclear reactors operate on the principles of nuclear fission.
During this process, the atoms of certain isotopes of uranium and plutonium
are split and energy is released. 438 commercial nuclear reactors were
operating at the end of 2000 with a net generating capacity of about 360
GW. The annual amount of uranium required to fuel this capacity is
estimated to be 64,014 tonnes (Nuclear Energy Agency 2001, 10).
Reactors can be divided into two main categories; thermal slow reactors
and fast neutron reactors. Thermal slow reactors use enriched or natural
uranium for fuel, while fast neutron reactors require highly enriched fuel
(sometimes weapons grade) or plutonium to sustain the fission process. In
both cases, the energy released is in the form of heat, which is typically
converted to electricity by means of a steam turbine. Considerable
infrastructure is required to support a controlled nuclear reaction,
particularly with respect to safety and cooling systems. For this reason,
nuclear power generating facilities are best suited for medium and largescale power generation in which electricity is supplied on a continuous
basis.
Uranium is a radioactive metal that occurs throughout the earth’s crust. In
certain locations, concentrations are sufficiently high enough that extraction
of it for use as nuclear fuel is economically feasible. At end of 2000 there
was approximately 3,933,000 tonnes of uranium (≤USD130/kgU) in known
reserves, which based on the current level of consumption, is expected to
last just over 50 years. The total undiscovered conventional resources,
however, are estimated to be approximately three times this amount
(Nuclear Energy Agency 2001, 9). Advanced fast reactors use plutonium
(created from uranium during the reaction) as part of the fuel source,
allowing 60 times more energy to be generated from the original uranium.
These reactors are expensive to build when compared to thermal slow
reactors, and currently there is only one in operation. As significantly less
fuel is required for there operation they may become cost competitive if and
when natural uranium resources run scarce (World Nuclear Association
2005).
There are many steps involved in the nuclear fuel cycle. These include;
mining, processing, enriching, storage, reprocessing and disposal.
31
Throughout this process the fuel becomes more and more radioactive, and
consequently safety measures become more stringent. High-level waste
accounts for 95% of the radioactivity produced, and a typical large 1000
MWe reactor will produce 25-30 tonnes of this material per year (World
Nuclear Association 2001). This material will remain highly radioactive for
thousands of years, and even after 50 years of commercial operation of
nuclear power, no country has successfully developed a means for
disposing of nuclear waste safely over the time period during which it will
remain hazardous. This is a serious concern from both an environmental
and economic perspective as the long term effects of systematically
accumulating high-level nuclear waste in the bio-sphere are yet to be
realized.
Table 3.4. Sustainability assessment for nuclear power generation
Right Direction
SP I
0
SP II
--
SP III
-
SP IV
--
CO2 emissions from uranium ore mining and processing
heavy metals and low concentration radioactive materials
in tailings.
High-level nuclear waste (plutonium and other fission
products) created during normal operation. Reactor core
failure and nuclear waste has the potential to release
radioactivity to the air and ground water.
Large scale mining operations to obtain fissionable
materials can degrade natural systems.
Fear of nuclear weapon proliferation. Severe health effects
in the event of release of radioactivity.
3.2.5 Photovoltaic Solar
Photovoltaic (PV) cells convert sunlight directly into electricity.
Technology advancements in this industry are rapid, with new materials
being introduced all the time. The sustainability aspects of each new
material need to be weighed individually. There are two major categories of
PV cells: crystalline silicon and thin-film.
Silicon crystal cells are the most common. Thin wafers of silicon are
created in the same process used to create microchips, requiring much
energy to produce—hence, the high cost. Within this technology,
monocrystalline cells have the highest efficiencies, but require the most
32
energy to produce. Polycrystalline and ribbon cells are easier to produce,
but are less efficient. Silicon solar cells are often mounted in aluminum
frames, which also require a significant energy investment to manufacture.
A common misconception is that PV cells require more energy to
manufacture than they will produce in their lifetime. This is not true. While
energy payback times will vary depending on latitude and available
sunlight in a given location, the energy payback time of present-day
systems may be 2-3 years in a sunny climate and 4-6 years under less
favourable conditions. Currently-produced PV cells have a lifespan of at
least 25-30 years. (Alsema and Nieuwlaar 2000, 1003)
Thin film technologies are the third generation of PV, and require
significantly less materials and energy to produce than silicon crystal cells.
The films can be applied to a variety of materials, including flexible plastic,
and even used as window glazing. There are a number of thin film
technologies, produced from a variety of materials. Some of those materials
are rare, leading to potential SP II problems. The most common materials at
this time are copper indium gallium selenide (CIGS), chalcogenide (CIS),
and cadmium telluride (CdTe). Gallium arsenide (GaAs) multijunction cells
are another very efficient (up to 40%), but very expensive (US$40 per cm2)
technology. They have an advantage of working well at higher temperatures
and can be combined with solar concentration using mirrors or Fresnel
lenses. Other emerging technologies exist as well. Germanium is being
researched to generate electricity directly from the infrared spectrum.
Organic semiconductors and light-absorbing dyes are being developed for
thin film PV. (Chopra, Paulson and Dutta 2004)
The fuel for solar energy is sunlight, which is free. Availability varies by
latitude as well as cloud and vegetation cover. One major advantage PV
has over other renewable energy sources is that peak power usually
corresponds with peak demand – in the middle of the day, when businesses
are running, and air conditioning is in maximum use in warmer climates.
Grid-connected solar PV has increased from 0.16GW in 2000 to 1.8 GW in
2004, a 60% growth rate (REN21 2005, 6). Along with the rapid increase of
PV deployment, costs have been dropping accordingly over the past few
decades. Costs will likely continue to drop in the future as the technology
matures and efficiency improves.
33
Solar photovoltaics can be an effective method for reducing CO2 emissions.
Accounting for all the production costs, the CO2 emissions due to a PV
power plant over its entire lifespan is similar to the first 4 years of operation
of a coal plant (Tahara et al., S619).
Table 3.5. Sustainability assessment for PV power generation
Right Direction
+
SP I
-
SP II
++
SP III
+
SP IV
+
Silicon crystal solar technologies are relatively
benign.
Thin film technologies may include elements such as
gallium, arsenic, and cadmium.
No major violations not already covered by SP I.
Mining operations. Solar power facilities could take up
large areas of land if not installed on existing rooftops
or barren areas.
Mining conditions and developing world
manufacturing plants may involve human rights
violations.
Silicon crystal photovoltaics are in compliance with all the Sustainability
Principles. Current thin film PV technologies contain rare, toxic mined
elements which violate the SP’s. There are several different types of thin
film materials still in the early research phases, however, which may be
suitable from a sustainability perspective.
3.2.6 Wind
Wind is an indirect form of solar energy created by regional air pressure
differences caused by unequal solar heating effects, most often between
land masses and oceans. ‘Wind power’ refers to the technology of
converting the kinetic energy in the wind into electrical energy.
Wind is available all over the Earth, however strong, consistent winds are
not common and often not close to power grid connections. The
‘practicable’ global wind resource is very difficult to estimate given the
lack of comprehensive wind data for all areas but the European Wind
Energy Association estimate that it would be practicable for wind to supply
more than 20% of the world’s electricity by 2040. (EWEA/Greenpeace
Wind Force Report 2005)
34
As with PV technologies, there is sometimes a misconception that wind
turbines require more energy to manufacture and install than are generated
over the turbine’s lifespan. Numerous studies have shown this to be a
fallacy. For example, one recent study calculated an ‘energy payback ratio’
(calculated by dividing the total amount of energy produced by a plant by
the total energy consumed by the plant) of 23 for wind. (White et. al. 1999).
Wind supplies over 500 billion kWh of electricity which is just 0.3% of
global electricity production. However in some power grids, for example in
Northern Germany, wind provides in excess of 20% of the power used and
installed generating capacity has been growing by an average cumulative
rate of 28% 2001 to 2005 (EWEA/Greenpeace Wind Force Report 2005)
Table 3.6. Sustainability assessment for wind power generation
Right Direction
SP I
++
SP II
+
SP III
++
SP IV
++
Turbine generators require the use of common metals
like iron, copper and aluminium. Once installed wind
turbines do not violate SP1.
Once installed wind turbines do not violate SP2.
Physical impacts are small and there is good
opportunity for multiple uses of lands where turbines
are installed.
Small numbers of turbine-related bird deaths did occur
in the past with smaller, inappropriately-sited turbines.
With modern turbines the observed bird mortality is
extremely low. (AWEA 2006, 1)
Visual impact can be perceived negatively or
positively.
Noise was an issue with earlier machines but is no
longer a problem with today’s larger, slower-moving
blades. (Boyle 2004, 270)
3.2.7 Hydroelectric
Hydroelectric power uses water and gravity to create electricity. It can be
divided into a few different categories, depending on the size of the
installation. Definitions vary, but the following categories are common:
35
•
Large Scale – Generally, hydro power plants over 10 MW in size.
Large dams are constructed to create an artificial lake behind the
dam. Water is directed through turbines in the dam to the river
below.
•
Small Scale – Hydro power plants under 10 MW in size, still usually
involving dams. Sometimes, turbines can be retrofitted to existing
dams to generate power.
•
Micro Scale – Hydro plants 100kW or smaller in size, usually run of
the river, which does not require construction of dams.
Hydroelectric power was once hailed as the cleanest and most
environmentally-friendly of all energy sources. Although operational
emissions of CO2 are negligible, hydroelectric power is not free from
environmental effects.
Traditional large-scale hydroelectric plants involve the construction of large
dams, which require massive quantities of concrete to construct, and cause
flooding above the dam. This flooding displaces wildlife and sometimes
human populations, and causes methane (another greenhouse gas) to be
released as former dry-land vegetation decomposes underwater. In some
cases, the damming can also interfere with salmon migration. Even when
fish ladders are constructed to allow most of the fish to navigate back
upstream to spawn, many smolts cannot survive the trip downstream
through the turbines—8 to 10% are killed in the turbines at each dam
(Montaigne 2001, 25). As with other forms of renewable energy, the fuel is
free. Availability of hydropower is limited to the amount of flowing water
in a region.
Construction of a 10MW hydroelectric dam will contribute the same
amount of CO2 emissions as running a 10MW coal plant for 0.41 years.
(Tahara, et al., S619)
36
Table 3.7. Sustainability assessment for hydroelectric power generation
Right Direction
++
SP I
0
SP II
SP III
++
++
-
SP IV
++
-
Micro: No significant problems specific to micro
hydro.
Small & large: A large amount of cement is used in
the construction, releasing CO2. Upstream vegetation
flooding releases CH4 and reduces terrestrial sink
capacity.
No significant problems related to hydro power.
Micro: Minimal impact on natural systems.
Small & Large: Upstream habitat flooding,
disruptive to fish populations, affects erosion and
sedimentation patterns.
Micro & small: Minimal impact on human needs.
Large: Upstream flooding has sometimes displaced
people living in the area
3.2.8 Ocean – Tides, Waves, Currents
Ocean power refers to power derived from tides, waves and currents.
Waves are created by wind passing over open water, and therefore can be
considered a form of solar energy. Tides result from the gravitational pull
of the moon as it orbits the Earth. Currents can result from wind, tides, solar
heating or Earth rotational effects.
Tides, currents and waves represent huge movements of water and thus
huge energy flows. Attempts to tap into these flows for the purposes of
power generation have begun only recently. These technologies have
significant potential but as of yet contribute only a very small percentage to
the global power supply (tidal) or are still only experimental (currents and
waves). Nonetheless, we have chosen to include them because they hold
promise of being a useful part of a diversified renewable energy generation
system. Compared with wind and solar power ocean power has two
important advantages: high power density and a high number of full load
hours / year. (Leijon 2006)
Tidal Power –Barrage-type tidal power involves building barriers across a
tide-flooded estuary and channelling flood (upstream) and ebb
(downstream) tide waters through turbines to generate power. Since
appropriate estuaries and tidal ranges are very site-specific tidal power is a
37
limited generation option. In countries with suitable sites however, tidal
power can make a significant contribution; in the U.K. tidal power has an
estimated commercial potential of 14%. (Boyle 2004, 223)
Tidal stream technology involves the installation of turbines where there is
a strong current or tidal stream, without building a barrier and thus avoiding
potential large-scale environmental interference.
Wave Power – A variety of strategies are currently under development
with several operational demonstration installations currently generating
power but no plans yet for large-scale commercial projects.
The technical available resource of wave power is difficult to assess given
the early level of exploration and development. Assessments of countries
with long coastlines and frequent stormy conditions, like Chile and the
U.K., have identified practicable annual production of 40TWh (Leijon,
2006) and 50TWh (U.K. Department of Trade and Industry, 166). These
quantities represent potential for significant ocean power contributions.
Current Power – This technology is in a similar state of development as
wave power.
As of the end of 2004 global installed capacity of ocean power was 0.3GW,
or less than one tenth of one percent. Table 3.8 assesses ocean power
technologies for their sustainability aspects:
38
Table 3.8. Sustainability assessment for ocean power generation
Right Direction
+
SP I
SP II
+
++
SP III
++
SP IV
Turbine generators require the use of common metals
like iron, copper and aluminium. Once installed wind
turbines do not violate SP1.
Once installed wind turbines do not violate SP2.
The installation of seabed-mounted or floating
generating machinery and cabling can have a small to
neutral effect on the local seabed.
- Rotating turbine blades can physically damage
marine fauna, if poorly designed and located.
- Large-scale diversion structures can affect estuary
ecosystems by altering salinity, turbidity and
chemistry of the sea-water which changes the
species mix, while not necessarily leading to a net
reduction in biodiversity. (Boyle 2004, 211)
Large scale alterations to tidal and current flows and
large arrays of offshore wave generators could effect
habitats that people rely upon for food, employment,
and transportation.
3.2.9 Biomass
Biomass refers to a variety of plant-based materials which can either be
combusted for power generation, or alternatively, converted into liquid
fuels such as ethanol, methanol, and biodiesel. The latter are typically
produced from food crops, such as corn, sugar cane and oilseeds. These are
primarily viewed as substitutes for petroleum-derived gasoline and diesel in
the transportation sector, and are not generally considered as fuels for
power generation. It is more efficient to burn biomass directly than to
convert it to liquid fuel before burning in a power plant. Biomass can be
utilized through combustion or gasification, analogous to coal. The source
of biomass for power generation can be different waste streams, such as
agricultural wastes (stalks, leaves, straw, sugarcane bagasse) or wood waste
(woodchips, sawdust, pulp). Rapidly-growing “energy crops” are also being
evaluated as a fuel source, including trees (e.g. poplar, maple, sycamore),
grasses (e.g. switchgrass) and algae. Up to 5-15% biomass fuel can be
readily co-fired with coal without changing operating conditions, while
39
yielding significant reductions in NOx, SOx and CO2 (Singh and Fehrs
2001).
Assuming that the biomass is replanted, the combustion of biomass fuel for
power generation is considered to be ‘carbon neutral,’ since CO2 is taken up
from the atmosphere through photosynthesis in order for the plants to grow.
Of course, any fossil fuel inputs required for harvesting, transportation and
processing must also be considered, as well as changes in land use.
The global potential for biomass energy production in 2020 will be ~7,000
Mtoe, including crop residues, wood, energy crops, animal waste and
municipal waste (Fischer and Schrattenholzer 2001). Biomass is widely
available and widely utilized, and there is potential to produce bio-energy
crops on marginal land, thus minimizing competition for prime agricultural
land. It is a proven commercial power generation option - in the US, 61,265
megawatts (MW) were produced from biomass combustion in 2003 (EIA
2006b, 24).
Table 3.9. Sustainability assessment for biomass power generation
Right Direction
SP I
+
SP II
++
SP III
+
SP IV
0
3.2.10
Biomass combustion is theoretically carbon neutral,
however, some fossil inputs are required for
harvesting and transport.
No NOx, SOx or particulates. No violations.
Land management is a concern, especially if land is
cleared specifically for bio-energy crops, or if forests
are not harvested in a sustainable manner (e.g.
harvesting the “interest” while leaving the “capital” in
place). Potential violation.
Land use competition with food crops is a concern, if
prime agricultural lands are required for bio-energy
crops.
Geothermal
Geothermal energy is defined as heat from the earth. This thermal energy
continuously flows from the mantle to the surface of the earth and is
expected to do so for billions of years. As this heat source is essentially
limitless, geothermal energy is considered to be renewable. The flow of
thermal energy is more intense at tectonic plate boundaries, the most
40
obvious manifestations of which are active volcanoes and high temperature
geothermal fields. The world potential of known geothermal resources
suitable for electricity generation is estimated to be 240 GW. Theoretical
estimates suggest that the potential of hidden resources could be 5-10 times
larger than this amount (Stefansson 2005, 1). Currently 24 countries
generate power from geothermal resources, the total combined installed
capacity of which is 8.9 GW (Bertani 2005, 1)
Below the earths crust, magma (molten rock) heats water contained in rock
pores and fractures, creating pockets of hot water and steam known as
geothermal reservoirs. Wells are drilled into these reservoirs and the water
and or steam is extracted to the surface and used to generate electricity.
Geothermal reservoirs vary greatly in terms of size, depth, pressure,
temperature and composition and therefore require different electrical
generation technologies to optimize the energy conversion.
There are three basic types of geothermal electrical generation systems:
binary, dry steam (or ‘steam’), and flash steam (or ‘flash’). All three use a
turbine for electricity generation but differ in operation with respect to the
working fluid(s). Recent improvements in the binary system have made it
economically possible to generate electricity from lower reservoir
temperatures of 100 to 150 °C. This has significantly expanded the global
potential for geothermal electricity generation as lower grade thermal
reservoirs can now be competitively utilized. As geothermal energy is
continuous, power plants can be designed to operate with capacity factors
up to 95% (Kagel 2005, 4-8).
Geothermal reservoirs can contain non-condensable gases such as CO2 and
hydrogen sulphide. Depending on the electrical generation system, these
gases can pass through the turbine and vent to the atmosphere. A power
weighted average for 85 geothermal facilities calculated the CO2 emissions
to be 0.122 kg/kWh. In most cases, the process of natural CO2 generation is
independent of geothermal exploitation (Bertani 2002).
Geothermal heat pumps use geothermal energy for heating or cooling
purposes, but do not themselves generate electricity. As such, they are not
addressed directly in this report, but are considered an important way of
reducing electrical consumption for heating in buildings.
41
Table 3.10. Sustainability assessment for geothermal power generation
Right Direction
SP I
+
SP II
SP III
++
++
SP IV
++
Geothermal exploitation can release carbon dioxide
and hydrogen sulphide to the atmosphere that
otherwise would have remained in the lithosphere
None
None
Visual impact produced by large quantities of steam
could be perceived negatively
3.3 Current reality – Carbon Capture (B Step)
Among our assets in dealing with current violations of sustainability
problems, is CCS. These technologies are still in the experimental stages
and are being tested in combination with fossil fuel burning and extraction.
CCS has the potential to reduce the CO2 emissions from fossil fuel
consumption in the short term, and help remove previous anthropogenic
emissions when combined with biomass in the long term.
Carbon capture from power plant exhaust is the first phase in CCS where
the CO2 is separated from the exhaust gases to be stored. This section
explains the three main carbon dioxide separation technologies considered
for commercial applications: sorbents (solvents), membrane, and cryogenic
distillation. Mineral carbonation, which combines the capture and storage
phases, is discussed later along with carbon storage options.
Sorbents/solvents and membrane separation can be applied to either pre- or
post-combustion technologies, while cryogenic separation is specific to
oxyfuel combustion. The preferred option for commercial applications is
currently sorbent separation with post combustion gas streams.
3.3.1 Separation with Sorbents
In this process, the CO2-containing gas stream is passed through an
‘absorber’, a vessel containing an aqueous alkaline solvent (usually an
amine) that is capable of selectively capturing the CO2. The gas stream
exits the vessel and is released to the atmosphere while the CO2 ‘rich’
42
solvent is circulated to a second vessel known as a ‘stripper’. Heat and/or
pressure is used in the stripper to liberate the CO2 which can then be further
compressed and transported. The ‘lean’ solvent is then pumped back to the
absorber to complete the cycle. The size of this system must be matched to
the flue gas stream being purified, which for power plant faculties, is quite
large. This translates into significant additional equipment and energy
requirements which tend to lead to an important efficiency penalty and
added cost. The amount of CO2 removed from the flue gas stream is
typically between 80% and 95% (Metz et. al. 2005, 115). The exact value
of which is determined by the trade-off between additional operating costs
and the amount of CO2 removed.
3.3.2 Separation with Membranes
Membranes are specially engineered materials that allow for selective
permeation of a fluid through them. Fluid pressure, specifically the partial
pressure of the fluid to be separated, is the motive force behind the
separation process. In flue gases, the CO2 partial pressure is low which
results in a low percentage of CO2 removed. To increase the effectiveness
of separation, the flue gas pressure can be boosted, but this will result in
higher energy penalties than that of sorbent separation. Membrane
separation is currently used in many high pressure industrial applications;
however, they have yet to be demonstrated in the large-scale demanding
conditions of stationary power generation.
3.3.3 Separation by Cryogenic Distillation
Instead of separating CO2 from the flue gas stream, O2 is separated from the
air before combustion occurs. This produces a CO2 rich stream which
requires little purification before compression and transport. This process is
referred to as oxyfuel combustion, and the overall CO2 capture efficiency is
typically close to 100% (Metz et. al. 2005, 122). Cryogenic distillation is
the most economical method of producing the large quantities of O2
required for large scale power plant operations. In this process O2 is
removed as a liquid from the other constituents of air in a process by which
the air is compressed, cooled and separated in a distillation column.
Significant amounts of electrical energy are required for this process as the
pressures needed for separation are high and the volume fraction of O2 in
air is quite low.
43
3.3.4 Capture Systems Emissions
Analysis of both current and emerging capture technologies suggest that
they can reduce the power sector’s CO2 emissions by 90% or more (Metz
et. al. 2005, 143). However, in addition to producing concentrated CO2 for
storage, capture systems in most cases will also produce solid and/or liquid
wastes as well as emitting a flue gas to the atmosphere. The solid and liquid
wastes vary depending on the feed stock and separation processes, and will
generally be incinerated, in some cases this waste may be classified as
hazardous. Concentrations of harmful substances in the depleted flue gas,
primarily SOx and NOx will be similar or lower to that of a flue gas from a
power plant without carbon capture. If additional trace substances such as
HCl and Hg are captured along with the CO2 then their emissions to the
atmosphere will be reduced but health and safety as well as environmental
impacts may occur at the storage site. As solid and liquid wastes are
specific to the separation technology and feed stock used, and recognizing
that large scale CO2 applications are still being developed, further details on
environmental implications were not investigated.
Retrofit. CO2 capture can be retrofitted to existing power plants providing
that adequate site space is available and that there is sufficient plant life
remaining to justify the large capital expenditure. Older power plants that
operate at low energy efficiencies will suffer proportionality more from the
auxiliary requirements of carbon capture than those more recently built.
This could lead to early retirement of some power plants if CO2 capture was
introduced rapidly into the power sector.
Table 3.11. Sustainability assessment of CO2 capture technologies
Option
Sorbents
Membranes
Cryogenic
SP Compliance
I
II
III
+
+
+
+
+
+
+
IV
+
+
+
This table summarizes the Sustainability Principle compliance of the carbon
separation technologies. Sorbents are not recommended due to the potential
for leakage of substances, both man-made, and mined materials into the
environment. Separation with membranes and cryogenic distillation are in
44
compliance with the principles, although the former is preferred due to the
large amount of energy required for cryogenic distillation.
3.4 Current Reality - Carbon Storage (B step)
The following CO2 storage options are explored in this section:
•
•
•
Geological Storage
- Saline
- Sub-ocean
- Depleted fossil fuel reservoirs
- Enhanced oil recovery
- Enhanced coal bed methane recovery
- Other geological storage options
Ocean Storage
Combined capture and storage
- Mineral carbonation
- Industrial uses
Risk of leakage is a serious concern for CCS. Geologic storage is not
expected to leak significantly over time; storage times are expected to be
greater than 100,000 years. Any leakage that occurs would likely be
through fissures in the cap rock or through abandoned wells.
Small leakages lead to less-effective sequestration and more climate
change. Slow leaks can also work their way through the water table on the
way to the surface, which can decrease its pH, causing environmental
problems (Metz et al 2005, 34). At the surface, leaked CO2 could
accumulate in basements and cellars, causing asphyxiation.
A catastrophic release of CO2 through a fissure or well could cause CO2 to
accumulate at the surface in concentrations high enough to kill humans and
other animal life in the vicinity. An example of catastrophic CO2 release,
not related to human activity, is the Cameroon disaster of 1986. A cloud of
CO2 gas was released from the volcanic Lake Nyos, killing all animal life
within a 25km radius, including more than 1,700 people. While this event
was unrelated to CCS, it illustrates the seriousness of avoiding leakage.
Asphyxiation can happen quickly, and without any major signs of danger.
45
To avert harmful leakages, monitoring, measurement, and verification
processes will need to be implemented. Current technologies used involve
3D and 4D reflection seismology. Data are expensive to collect, and require
highly-specialized, skilled workers, and months between iterations. Other
monitoring techniques include tilt meters, passive source microseismic
mapping, electrical resistance tomography (ERT), chemical tracers, soil
chemistry studies, and deployment of atmospheric eddy correlation towers
(Friedmann 2003, 6).
There are a few risk assessment tools that are being developed throughout
the world. One is GEODISC from the CO2 Capture Project in Australia. It
has developed an ESSCI rating (Environmentally Sustainable Site for
Carbon Dioxide Injection) that takes into account a number of factors. It
warns, however, about using single number rating systems for two reasons.
First, it is impossible to arrive at one number that is universally valid
because of the diversity of subsurface conditions. Second, “if such a
number is arrived at, people are likely to misuse it.” (Bradshaw 2001, 1713)
3.4.1 Geological Storage
Geological storage involves injecting compressed CO2 into rock formations
below the earth’s surface. Usually, the sites proposed are at depths below
800m, where the pressures will keep CO2 in a liquid or supercritical state.
The cap rock above the storage formation (shale and clay rock) forms an
impermeable layer. Capillary forces can provide additional physical
trapping within pores. If there are open sides to the formation, additional
trapping mechanisms are necessary to ensure long-term storage of the CO2.
Geochemical trapping is the reaction of CO2 with the in situ fluids and host
rock. CO2 dissolves in the water. Then, over time, the dense CO2 rich
water sinks into the formation. The CO2 reacts with the rock and forms
solid carbonate minerals, over millions of years (Metz et. al. 2005, 31-32).
Saline. Saline storage occurs when CO2 is injected into subterranean
saltwater formations. The result is CO2 saturated brine and liquid CO2,
which is less dense and will float above the solution. Saline storage
reservoirs are prevalent, and the water is not suitable for agriculture or
46
human consumption. The injection of CO2 to displace the brine and extract
geothermal energy has been considered, but most areas high in geothermal
energy have more fissures in the rock, making them unsuitable for
sequestration purposes (ibid. 2005, 217).
CO2 at proposed storage depths of 800m will have a density 50% - 80% of
that of water, so it will tend to float above the water. This makes a wellsealed cap rock very important. In oil and gas reservoirs, CO2 can fill most
of the space the displaced fluid took up. In saline reservoirs, however, CO2
can only make use of up to 30% of the total rock volume. (ibid. 2005, 31)
Sub-Ocean. Geologic storage can also take place beneath the oceans. It has
an advantage in the oceans’ capability of absorbing small leaks over time
and further delaying the release of CO2 back into the atmosphere.
Catastrophic release of CO2 carries the same risks to local ecosystems as
terrestrial storage, and only shifts the risk to marine ecosystems.
Depleted Fossil Fuel Reservoirs. Storage in depleted fossil fuel reservoirs
refers to depleted natural gas and oil reservoirs.
Enhanced Oil Recovery. Enhanced oil recovery uses injected CO2 to
displace oil and force it out of wells. Once the oil has been recovered, the
CO2 can be sealed within the rock instead of vented to the atmosphere. This
is being done in Texas, and is planned for the Weyburn project (ibid. 2005,
203-4 and 43).
Enhanced Coal Bed Methane Recovery. Enhanced Coal Bed Methane
Recovery refers to the storage of CO2 in coal beds to displace the methane
that is already stored there. Coal deposits have fractures, called cleats.
Between those cleats, solid coal has a lot of micropores, where gas
molecules, that enter from the cleats, can be adsorbed. Coal can adsorb up
to 25 normal m3 (1 atm @ 0 ºC) of CH4 per tonne at coal seam pressures.
Coal has a higher affinity for CO2 than CH4 so injecting CO2 can replace
the methane and allow it to be recovered, while storing the CO2. (ibid.,
217)
The coal or organic-rich shales provide additional trapping of CO2 as it is
preferentially adsorbed onto the coal, replacing methane. The CO2 will
remain trapped as long as pressures and temperatures are stable. The coal
47
bed methane storage is shallower than hydrocarbon and saline formations
(ibid, 32).
Other Geological Storage Options. There are other geological formations
that could potentially store CO2 that have not been thoroughly studied yet.
Some ideas include basalts, oil or gas shales, salt caverns, and abandoned
mines. (ibid., 219). Mineral carbonation is another well-studied option that
is covered later in this chapter.
Geologic Storage Potential and Status
Table 3.12. Geologic CO2 storage capacity and retention time (Grimston et.
al. 2001, 161)
Sink
Enhanced Oil Recovery
Coal Bed Methane
Depleted Oil/Gas
Deep Aquifers (Saline)
Capacity (Gt C)
20-65
80-260
130-500
Up to 14,000
Retention (years)
10s
>100,000
>100,000
>100,000
New experimental carbon sequestration fields are being created all the time.
Following are some examples of the largest and most well-known fields
being used to store carbon.
Sleipner Example:
Sub-ocean saline geologic storage is currently being demonstrated by the
Sleipner project in Norway to rid excess CO2 from natural gas being mined
before it could be sold in Europe. The project started in 1996, and has been
storing about 1MtC per year. that is extracted from the natural gas it
extracts nearby. 20MtCO2 expected to be stored over the lifetime. It has a
very large storage capacity (1-10 Gt CO2) (Metz et. al. 2005, 202).
Note that it would take 3,500 Sleipner projects to constitute a single
stabilization wedge in Pacala and Socolow’s strategy for stabilizing
greenhouse gas emissions. (Pacala and Socolow 2004, 970).
48
Weyburn Example:
CCS is being used for enhanced oil recovery in the Weyburn project,
straddling the United States-Canadian border in the Williston Basin. It is
expected to inject 23 MtCO2 and extend the life of the oil field by 25 years.
(Metz et. al. 2005, 203-204).
The CO2 comes from a coal gasification plant in North Dakota (325 km
away). Weyburn should accept 3,000-5,000 tonnes per day for the next 15
years. (ibid., 204).
Salah, Algeria Example (Enhanced Natural Gas recovery):
An enhanced natural gas project by Sonatrach, BP, and Statoil is being
demonstrated in Salah, Algeria. It was created to use the extra CO2
contained in the mined natural gas from the site (up to 10%) and re-inject it
into the reservoir, aiding in the recovery of more natural gas (ibid., 203).
1.2 MtCO2 will be stored annually in the reservoir, with a total of 17
MtCO2 stored over the project’s lifetime (ibid., 203).
All geologic storage options are in compliance with the sustainability
principles. They all help to reduce an existing SPI violation, and will be
storing significantly more CO2 than that which is emitted in the storage
process. Enhanced oil recovery and coal bed methane storage receive a
lower score because they are implemented to gain access to more fossil
fuels, which further contributes to CO2 emissions.
Table 3.13. Sustainability assessment for geologic CO2 storage
Option
Saline
Sub-ocean
Depleted
FF
EOR
ECBM
SP Compliance
I
II
III
++
++
++
++
++
++
++
++
++
IV
++
++
++
0
0
++
++
++
++
49
++
++
3.4.2 Ocean Storage
The oceans cover 70% of the earth’s surface and total more than 1.37x1021
liters. Each day they absorb an estimated 20Mt of CO2, or a total over more
than 7 GtCO2 (2GtC)/yr. (ibid., 282)
Oceans are estimated to contain fifty times the amount of carbon present in
the atmosphere and roughly twenty times the amount of carbon contained in
plants and soils. Since the start of the industrial revolution the oceans are
estimated to have absorbed in excess of 500 GtCO2 (out a total
anthropogenic emissions of 1300 Gt). (ibid., 281)
The alkaline chemical capacity of the oceans will eventually absorb up to
85% of all fossil fuel CO2 emissions to the atmosphere, or the equivalent of
4,500 billion tons of CO2 could be accommodated with a pH change of
about 0.3.(U.S DOE, 2001)
Thus oceans are more than capable of absorbing all anthropogenic carbon
emissions for maximum forecast values for the next 100 years (reference)
however, the potential effects on ocean chemistry are unknown and it
seems unlikely that all species would be able to adapt to such short-term
changes.
“About one-third of the carbon dioxide we emit (2 of 6 PC/yr) is being
absorbed by ocean surface waters and mixed to the deep ocean, with
unknown long-term effects.” (Caldeira et al, U.S. DOE, 2001)
The two most frequently proposed methods for ocean sequestration are:
•
fixed pipeline to sub-3000m ocean bottoms; and
•
dispersal in the sub-1000m water column via a towed pipe attached
to a moving ship.
It should be noted that for countries with poor geologic storage options and
close proximity to deep oceans, like Japan, ocean storage presents a
convenient sequestration option and it is thus not surprising that they
continue to explore ocean sequestration potential.
50
Current experimental efforts: most recently two attempts at experimental
releases of pure liquefied CO2 (60 tons off Hawaii in 2001 and 5 tons off
Norway in 2002) at 800m depths have been cancelled by governments
because of stiff opposition from environmental groups and the public.
(Metz et. al. 2005, 285)
Small-scale releases (less than 10L) have been performed at 1000 – 3000m
depths to explore behaviour of CO2 in situ.
The 1972 Convention on the Prevention of Marine Pollution by Dumping of
Waters and Other Matters (usually known as ‘the London Convention’)
prohibits dumping of industrial waste in the water column. At this point the
status of CO2 as an ‘industrial waste’ is unclear, however, given the current
propensity for some states to flaunt international agreements if it is
perceived to be in their economic interests, it is questionable how much
deterrent effect the London Convention will have in the future.
“Adding CO2 to the ocean or forming pools of liquid CO2 in the ocean floor
at an industrial scale will alter the local chemical environment. Experiments
have shown that sustained high concentrations of CO2 would cause
mortality of ocean organisms. CO2 effects on marine organisms will have
ecosystem consequences. The chronic effects of direct CO2 injection into
the ocean on ecosystems over large ocean areas and long time scales have
not yet been studied.” (Metz et. al. 2005, 22)
Given that oceans are poorly understood (both in CO2 chemistry and effects
on marine organisms), especially over centuries, it would seem to suggest a
very cautious approach to any serious changes to ocean CO2 concentrations.
Table 3.14. Sustainability assessment for ocean CO2 storage
Right Direction
SP I
--
SP II
+
SP III
-
SP IV
+
Directly leads to systematic increase of
carbon in oceans.
CO2 becomes carbonic acid when dissolved
in water.
Pipelines and infrastructure. Local highly
acidic regions.
No significant violations.
51
3.4.3 Mineral Carbonation
Mineral carbonation is a special case as a carbon storage option, because it
also includes the carbon capture phase. Carbon dioxide reacts to form stable
mineral compounds that do not have to be stored in a confined space to
avoid leakage back to the atmosphere.
Mineral carbonation occurs naturally in nature on a geological time scale
and is known as silicate weathering. In this process CO2 is sequestered from
the atmosphere through the reaction of CO2 with metal oxide bearing
materials to form insoluble carbonates. Once this process has occurred there
is virtually no leaking of CO2 back into the atmosphere. This reaction can
also be performed in a chemical processing plant in which either silicate
rock or industrial wastes, such as fly ash, are combined with a CO2 feed
stock. The main components of this process are:
1. Preparation of the solid reactants, including mining, transport,
grinding;
2. Processing of the carbonates, under controlled reaction parameters;
and,
3. Disposal of the carbonates and by-products.
When CO2 is combined with a metal oxide (indicated here as MO, where M
is a divalent metal such as magnesium or calcium) a carbonate is formed
according to the following exothermic reaction:
MO + CO2 Æ MCO3 + heat
In general a large fraction of heat is released, however, with present
technology there is always a net demand for high grade energy when the
entire mineral carbonation process is considered.
The carbonate formed is between 50 and 100% by volume greater than that
which was originally mined. As it is not cost effective to ship the bulk of
these materials over great distances, processing plants would need to be
located close to metal oxide sources. Mine reclamation would then also
provide for a suitable disposal means. CO2 feed stock and power would
then need to be supplied to the process plant.
52
Silicate rocks are mainly found in geological zones where there has been a
lifting of the earths crust. Estimates have indicated that there are sufficient
Magnesium silicates alone to neutralize the CO2 from all world wide coal
resources. The mining of which would not differ substantially from other
minerals with similar properties such as copper.
Table 3.15. Sustainability assessment for mineral carbonation CO2 storage
Right Direction
SP I
0
SP II
SP III
SP IV
++
++
Silicate rocks contain chrysotile, a natural
form of asbestos.
No significant violations.
Large Scale Mining required
No significant violations
3.4.4 Industrial Uses
This section refers to reusing captured CO2 in industrial processes that
currently require CO2.
CO2 currently has a large number of industrial uses which include the
production of chemicals (urea), refrigeration systems, horticulture and
beverage carbonation. New process routes for the production of organic
chemicals, primarily polyurethane and polycarbonates, are currently being
investigated. In this application CO2 is used in place of other carbon feed
stocks such as methane or methanol.
In order to properly understand CO2 sequestration in an industrial process,
the system boundary must include all materials, fossil fuels, energy flows,
emissions and products. To determine the overall effect on atmospheric
mitigation the following three factors need to be considered.
1. Product lifetime
2. Source of CO2 feedstock
3. Scale of operation
The product lifetime determines the duration CO2 sequestration. This spans
a broad range from several days in the case of beverage carbonation to
centuries for polyurethanes. Most of the CO2 used commercially is
recovered from synthetic fertilizer and hydrogen plants. This is CO2 that
53
would otherwise be released to the atmosphere, so by replacing it with that
captured from power generation plants will have no net effect on reducing
atmospheric levels. A total of about 0.12 Gt CO2 /yr are currently used for
industrial purposes. This is equivalent to approximately 0.5% of all
anthropogenic CO2 emissions. A substantial expansion of the current
chemical industry would need to be required in order for this to be
considered a climate change mitigation strategy.
Table 3.16. Sustainability assessment for industrial uses of CO2
Right Direction
SP I
++
SP II
-
SP III
SP IV
++
++
No significant violations.
Organic chemicals and polymers
(polyurethane and polycarbonate)
No significant violations
No significant violations
3.5 Desired Future (C1 Step)
This section covers the first part of the C step in the ABCD process:
creating a vision for the future. The second part of the C step, developing
strategies for success, is covered in subsequent sections.
Ideas for a sustainable stationary power sector within society within the
biosphere were generated during brainstorming sessions as well as from the
research performed during the course of this thesis. These ideas were
grouped together and refined in order to help develop a shared mental
model of a desired future. This desired future represents just one possible
vision of a stationary power sector that complies with the sustainability
principles, the main characteristics of which are listed below:
1. Energy efficiency is a primary design consideration throughout the
stationary power sector and all processes are designed to minimise
power consumption.
2. A diversified blend of renewable power technologies determined by
local natural resources, is connected to a common power network.
3. Urban centers are internally linked as well as connected to
neighbouring networks to help ensure power supply resilience.
54
4. Electricity generated from stored energy sources such as hydrogen
or water from high reservoirs, is used to help compensate for
shortages caused by peak demand and renewable power supply
fluctuations.
5. Energy security and local economic development are enhanced by
encouraging locally-owned and locally-operated power
technologies.
6. Biomass and geothermal power stations where possible, are located
close to communities in order to provide heating services as well as
electricity (cogeneration).
7. Biomass power stations are equipped with CCS in order to help
restore atmospheric CO2 concentrations to within pre-industrial
variations.
8. Power generation does not produce highly persistent toxins that
cannot be broken down by biological processes (current nuclear
technologies are not acceptable).
9. Community residents have a systems perspective of the stationary
power sector and act responsibly in order to preserve its integrity.
Figure 2 illustrates how these ideas could be incorporated into a stationary
power sector. This graphic helped strengthen our shared understanding of
the desired future and provided a clear point from which to backcast.
In this desired future community, there are power supply contributions from
a variety of different natural resources (wind, solar, biomass, etc). These
contributions are all networked together and joined with the neighbouring
community. Residents in this community play an active role in both
reducing the amount of electricity they consume (ground source heat
pumps, passive solar design, etc) and in increasing the amount of electricity
they supply (photovoltaics and micro wind power generation).
Cogeneration is used at the nearby geothermal power station in order to
supply the community with both power and district heating (heating for
radiators and hot water tanks). The biomass power station is implementing
carbon capture technologies and is actively reducing atmospheric CO2
concentrations.
Overall, the stationary power network is designed to be resilient and
flexible such that advances in technology and changes in demand can easily
be incorporated. This community also enjoys a more peaceful and healthy
55
lifestyle as there is no more geo-political tension or pollutants in the air and
ground water from the use of fossil fuels.
56
57
Figure 3.3. Stationary power sector “Desired Future” (adapted from Greenpeace 2006, 21)
3.6 Strategies for Success (C2 Step)
The second part of the C Step involves developing strategies for success. It
coincides with Level 3 of the 5-Level framework for Strategic Sustainable
Development. Measures from the B step are clustered together into three
main groups:
1. Total supply reduction through demand reduction
(dematerialization)
2. Change the mix of supply towards renewable energy (substitution)
3. Carbon capture and storage of CO2 emissions (abatement)
3.6.1 Demand Reduction
Demand reduction is represented by actor ‘m’ on the CLD (Figure 3.1), and
is a key leverage point because it strengthens balancing loop B2 by
reducing power consumption. Stakeholder awareness and sustainable policy
are required to engage this leverage point.
Traditional thinking on power generation has focussed on increasing supply
to match increasing demand, which was assumed to be an essential
contributor to increasing prosperity. More recently it has become apparent
that improving energy efficiency (or “demand reduction”) can maintain the
same or improved levels of energy services while using less energy per unit
of goods and services. Explorations of the full potential for efficiency
measures have just begun and already there is strong evidence that
efficiency improvements could be the single most important strategy for the
reduction of power-related CO2 emissions (IEA 2004, 35).
A full appreciation of the potential for reducing CO2 emissions with
efficiency requires systems thinking – in this case one action towards
sustainability can have one or more additional positive spin-offs that
multiply progress towards success. For example, improving lighting
efficiency combined with enhanced natural daylight usage reduces
electricity consumption, which reduces CO2 emissions and reduces
operating costs. However, there is more; lighting-related heating now
declines, which reduces the amount of air-conditioning equipment required,
which reduces CO2 emissions and the capital and operating costs. In
58
addition, natural daylighting has also been shown to improve employee
productivity and employee satisfaction which reduces labour costs and
labour turnover (Kats 2003, 6). There are also employment benefits
associated with demand reduction over increasing supply; saving electricity
produces more local employment at a broad range of skill levels spread
across a variety of small businesses.
A second factor relevant to the success of efficiency measures in reducing
CO2 emissions is the relative contribution of fossil fuel generation in the
supply mix; the higher the fossil fuel contribution, the greater the reduction
in emissions from a reduction in end usage. This is not to say that areas
with low fossil fuel power generation (for example, Norway or Quebec
with large hydroelectric generation) cannot benefit from efficiency; their
renewable power can be exported to their neighbours.
Compared with other strategies mentioned in this study efficiency measures
are more varied and complex and subsequently more difficult to assess in
terms of their potential. An additional challenge is that efficiency has often
been overlooked as a method for increasing electricity service provision.
Instead, utilities and governments tend to focus predominantly on
increasing supply.
Experience seems to indicate that efficiency measures can produce rapid
and significant reductions in end-use power consumption when there is a
clear and compelling need coupled with determined government policies.
In 2001 California experienced average electricity prices of $0.35/KWh – a
ten-fold increase over six months. In response the state was able to reduce
average electricity consumption by 8% in one year. One-third of residential
customers reduced their demand by more than 20 percent; meanwhile the
economy grew by 2.3%. These efficiencies were achieved at an average
cost of $0.03/KWh (Bachrach et al 2003, 5). “Thanks to energy efficiency
standards that California has imposed on its own power industry, buildings,
and appliances over the last 30 years – and its increasing reliance on
renewable energy sources – California today consumes a little more than
half as many kilo-watt-hours of energy per capita each year as the rest of
America.” (Friedman 2006)
59
Examining energy intensity change over time Rosenfeld et al from the
California Climate Commission have noted: “world energy intensity
(E/GWP) is spontaneously dropping 1.3% per year” (Rosenfeld et al, 2004,
373).
This decline has occurred during a time when large fossil fuel generation
and nuclear were subsidised and efficiency encouragement was minimal. If
a levelised price, that reflected the true cost to society and the environment,
was charged for electricity and efficiency was actively encouraged it seems
reasonable to expect that energy intensity reductions could be maintained at
a level below that of primary energy consumption growth. In doing so we
could experience a growing economy at the same time as our net energy
consumption declines.
3.6.2 Renewable Energy
Society will always have energy needs. In a sustainable society, it is
important that that energy production does not violate the Sustainability
Principles, and that the energy comes from renewable sources.
Thus, only the power generation options from the B step that fit those
criteria are considered here. Fossil fuels fail the test due to their CO2
emissions. Nuclear is also not considered due to the radioactive waste.
Large scale hydroelectric power is left out of consideration because of the
effects it has on fish populations and the flooding it causes.
The technologies that are still being considered in this category are wind,
PV solar, small- and medium-scale hydro power, ocean power (waves,
tides, and currents), and biomass.
This strategy is represented by actor ‘n’ in the causal loop diagram (Figure
3.1), and is a leverage point because it strengthens balancing loop B3 by
reducing fossil fuel power consumed. Sustainable policy and stakeholder
awareness will be required to engage this leverage point.
3.6.3 Carbon Capture and Storage
This section evaluates the third set of measures from Section 3.5: Carbon
Capture and Storage (CCS) technologies.
60
Carbon capture and storage helps reduce the impact of CO2 emissions from
fossil fuel consumption. It corresponds to actor ‘O’ in the CLD (Figure
3.1). Sustainable policy measures are required to engage this leverage point.
Only those measures that passed the sustainability assessment in the B step
are considered within this strategy. For carbon capture, that means
membranes and cryogenics are acceptable, but not amines. For the storage
phase, geologic storage methods are considered, but not ocean storage.
Storage Potential
Geologic storage space is more than sufficient for any amount of CCS we
choose to implement. The greatest amount of storage is in deep saline
aquifers. Pacala & Socolow (2004, 969) estimate the total anthropogenic
carbon emissions over the next 50 years (from 2004 until 2054) in a
business as usual scenario. The scenario starts with 7 GtC of emissions and
ends with 21 GtC. The total emitted carbon in this scenario is 550 Gt. From
Table 3.17, below, we can see that deep aquifers can hold that amount of
carbon 25 times over. Not all emitted carbon would need to be stored, as
there are other carbon sinks, such as the oceans. With that in mind, depleted
oil and gas reservoirs could even store all excess anthropogenic CO2 for the
next 50 years.
Enhanced Oil Recovery (EOR) and Enhanced Coal Bed Methane (ECBM)
have lower capacities, and are used to extract extra fossil fuels for burning
– leading to more carbon emitted to the atmosphere. This makes them a
step in the wrong direction and not a flexible platform for future
development. These two methods initially appear very appealing
financially, as the recovered fossil fuels can be sold and the operation will
generate income rather than cost money.
61
Table 3.17. Geologic storage options comparison
Sink
Enhanced Oil
Recovery (EOR)
Coal Bed Methane
(ECBM)
Depleted Oil/Gas
Deep Saline Aquifers,
including sub-ocean
Capacity
(Gt C)5
20-65
Retention
(years)6
10s
Flexible
platform
No
Cost of storage
$ per tonne.7
(10-16)
80-260
>100,000
No
(10-16)
130-500
Up to
14,000
>100,000
>100,000
Yes
Yes
0.1-0.3
0.1-0.3
5
(Grimston et. al. 2001, 161)
6
Ibid.
7
(Metz et al. 2005, 345). EOR and ECBM indicate a profit of $10-16 per ton of CO2
stored.
62
4 Discussion
4.1 Overview
As a starting point in this analysis, it was assumed that the energy supply
mix will necessarily change over the long term due to the need to address
climate change and price pressures associated with fossil fuel availability.
Furthermore, ‘success’ was defined as 1) compliance with SSD
sustainability principles I-IV, and 2) that CO2 concentrations would peak
around 500 ppm then trend back towards 280 ppm as a result of specific
actions taken to reduce emissions.
The energy generation and CCS technologies presented in the Results
section were analyzed on the basis of the sustainability principles and other
key metrics. Technology options that did not conform to the sustainability
principles were eliminated from consideration in the C step of the ABCD
analysis. In this section, the D step of the ABCD analysis will be presented,
and selected actions will be prioritised by answering three key questions:
1. Does this measure proceed in the right direction with respect to all of
the sustainability principles?
2. Does this measure provide a flexible platform for further
development?
3. Is this measure likely to produce a sufficient return on investment?
In addition, two other prioritisation schemes for energy supply transition
were identified through a literature search, and are presented in this section.
The traditional approach to meeting increasing power demand has been to
increase power generation capacity. More recently it has become apparent
that improving energy efficiency (or “demand reduction”) can maintain the
same or improved levels of energy services while using less energy per unit
of goods and services. Explorations of the full potential for efficiency
measures have just begun and already there is strong evidence that
efficiency improvements could be the single most important strategy for the
reduction of power-related CO2 emissions (IEA 2004, 35).
63
The optimal strategy may first require a shift in thinking to acknowledge
that what people want from the power industry is the services power
provides, not the vector for that power (electricity). On a unit of energy
basis, decreasing power demand is equivalent to increasing power
generation supply. Even when including the full costs and benefits of a
power supply, demand reduction is more economical and can have
numerous additional positive results that reduce or eliminate sustainability
principle violations. Some of the benefits of a decentralised, sustainable
power system include: increased employment, reduced pollution emissions,
improved local air quality, improved energy security and enhanced local
economic activity.
Current power prices do not reflect the full costs because they do not
include the cost to the environment and society of Sustainability Principle
violations. Current prices also appear to be artificially low because of the
wide variety and scale of financial and regulatory subsidies for
unsustainable power options. Although there has been some subsidisation
of more sustainable power sectors, fossil fuels and nuclear power have been
the beneficiaries of signification subsidies. Building the full costs into the
retail power price is an excellent monetary method to communicate the
relative costs of power to end-users. Of course significant increases in
power costs will be greeted unfavourably by society unless governments
package the policies with clear and simultaneous offsetting benefits, for
example investing fossil fuel tax money in improved and affordable public
transit.
Even taking the most pessimistic cost projections for reaching success,
business as usual is very likely to cost far more in the long run. Although it
is very difficult to clearly establish cause and effect between CO2 emissions
and climatic disasters, economic losses due to extreme weather events have
run into hundreds of billions of dollars. In light of our research we contend
that the cost of achieving success over the next century reduces global
income by a negligible fraction while conferring significant non-monetary
benefits (Azar and Schneider 2002).
Once the three main strategies are analyzed, further discussion of the results
is placed in the context of the research questions at the end of this section.
64
4.2 D Step
The final step of the ABCD process entails a comparison of potential
measures to determine whether they are moving in the right direction with
respect to sustainability principles, whether they are likely to be flexible
platforms for future development, and whether investments are likely to
produce a sufficient return on investment. Table 4.1 shows a comparison of
the three strategies identified by the CLD analysis, which have the effect of
reducing CO2 emissions produced by fossil fuels. The results are organized
according to demand reduction, power generation technologies and the
addition of CCS to fossil fuel power generation.
4.2.1 Demand Reduction
Demand reduction is a powerful strategy for assisting society to move in
the direction of a sustainable power sector (illustrated in Appendix D:
Computer Model Results – Demand Reduction Scenario). In fact, demand
reduction does more than take society in the right direction; it takes us to
our destination because the most sustainable power is power we did not
need to generate. The process of reducing demand also has multiple
associated sustainability benefits like improved building habitability and
enhanced local economic resilience. Demand reduction is a highly flexible
platform because: firstly, it can be performed incrementally, over time, as
budgets permit. Secondly, it can be actions on a very small scale (changing
a light bulb) to very large (installing co-generation on a power plant) and
thirdly, it can be enacted by anyone, anytime, in any region. Efficiency
measures are of particular value in the developing world, where
electrification infrastructure investments are being made on a large scale,
often for the first time. It is much more economic for developing nations to
invest in the most efficient end-use designs and equipment available
because it greatly reduces their need to invest in expensive generating
capacity and the accompanying locked-in fuel requirements. Amory Lovins
states: “highly efficient use of electricity, far from being a luxury of the
rich, is a necessity especially of the poor.” (Lovins and Gadgil, 1991)
Assessing the return on investment for demand reduction is made very
difficult since this strategy involves a wide variety of actions, often applied
in concert, in complex systems like factories or buildings.
65
Table 4.1. Comparison of some examples of demand reduction actions
Energy Efficiency Improvements
High Efficiency Industrial Motors
High Efficiency lighting
Daylighting
Heating, Ventilation and Air
Conditioning (HVAC)
Solar Hot Water Heaters
Heat Pumps
Building Insulation
High Efficiency Appliances
SP
I
+
+
++
+
SP
II
+
+
++
+
SP
III
++
++
++
++
SP
IV
++
++
++
++
Flex.
Plat
Yes
Yes
Yes
Yes
ROI
++
+
+
++
+
++
++
++
++
++
++
++
Yes
Yes
Yes
+
+
++
++
No
Medium
Long
Short to long
(goals, retrofit vs.
new build)
Short to medium
Very short
Short
Short to long
Short
In this table we offer some examples of efficiency activities, recognising
that there are a wide range of appropriate actions that are available to each
sector in each location. Estimating the cost of efficiency on a $/KWh basis
is not a comprehensively-studied science and developing individual life
cycle analyses for the strategies listed is beyond the scope of this paper
however, previously-mentioned research indicates efficiency costs of 0.03 –
0.05/kWh are not uncommon.
66
67
+
+
PV
Wind
+
+
++
+
0
0
Ocean
Biomass
Biomass w/CCS
Geothermal
IGCC w/CCS
PCC w/CCS
Hydroelectric (micro) ++
++
0
0
++
++
++
+
++
+
+
++
0
0
++
+
+
++
++
++
+
++
0
0
++
+
+
++
++
++
+
++
SPI SPII SPIII SPIV
Improved Efficiency
Sustainable
Power
Strategy
S/M/L
Y
Y
Y
Y
Y
Y
Y
M/L
M/L
M
M/L
M/L
M
M/L
Renewable Power
Y
Y
Y
Y
Y
L
L
Fossil Fuel Power with CCS
Y
Y
Y
Y
Y
Y
Y
Y
H
H
L/M
M/H
L/M
M/H
L/M
M
H
L/M/H
10-15
10-15
0
5-10
0
5-10
0
0
0
0
ROI
ROI Cost Time to
Payback
of CO2 Commerci
Time
Abetment alization
(short, (low, med, (years)
med, long)
high)
Demand Reduction
Right
Flexible
Direction Platform
Table 4.2. Strategies for a sustainable stationary power sector
Not widely available
Possibility of atmospheric
CO2 removal.
Carbon neutral
Large opportunities already
exploited
Applicable to non-grid
connected societies
Applicable to non-grid
connected societies
Applicable anywhere, often
low-tech
Notes
We would like to close this section with a quote from the David Suzuki
foundation: “The energy productivity resource is purely renewable, and its
size is limited only by human ingenuity.” (Suzuki Foundation, 2002)
4.2.2 Renewable Power
Based on the definition of ‘success’ created for this study, it is clear that
wind, photovoltaic, hydroelectric, ocean (wave/tide), biomass and
geothermal are steps in the right direction, according to the sustainability
principles, and also have the effect of decarbonising the energy supply
(illustrated in Appendix D: Computer Model Results – Non-fossil Fuel
Scenario). They are flexible platforms for future development though they
generally have a medium to long term payback period. One important
factor is that the bulk of the investment in these technologies is front-loaded
as a capital investment. Once the infrastructure is operational, there are no
operating costs associated with fuel, with the exception of biomass, which
would require harvesting and transport of biomass to the power generating
facility.
The cost of decarbonising the power supply mix varies depending on the
total amount and type of fossil fuel currently used. It also depends on the
renewable energy technology selected, and the locally available renewable
resources. Solar is more expensive than wind or hydroelectric for a given
energy production capacity, for example.
Timing to commercialization also varies. Wind, PV, and hydroelectric have
been commercialized and are widely deployed around the world.
Geothermal power is not as widely available simply due to limited
availability of high quality heat sources that are geographically accessible.
Ocean power is a relatively new frontier, with a few pilot scale plants in
operation worldwide.
Biomass power generation is also deployed at a moderate level, but a great
deal of effort in this area is currently resulting in capacity growth,
particularly in Europe. Many existing coal-fired power plants can be
operated with biomass exclusively, or mixed with coal, which enables the
existing infrastructure to be a flexible platform. The combination of
68
biomass with CCS is another exciting prospect for utilizing infrastructure
designed for fossil fuels, but substituting a renewable fuel. In this particular
case however, something entirely new is possible – the ability to remove
net CO2 from the atmosphere (Azar et al. 2006). This is possible because as
the biomass grows, it takes up CO2 via photosynthesis and converts it into
plant matter. When it is burned for power, the CO2 which would be rereleased to the atmosphere is instead captured and stored underground.
4.2.3 Fossil Fuel Power with CCS
Economically, the CCS options are less favourable, and this underscores
the role that sustainable policy-making can have in levelling the playing
field and allowing theses technologies to become competitive by removing
subsidies and implementing penalties for carbon emissions.
Carbon Capture. Of the three carbon capture technologies assessed,
membrane separation appears to be the most promising method. This is an
emerging technology which has been demonstrated successfully at pilot and
small scale operations, and the specific details with regards to the materials
of construction and lifetime of operation are yet to be determined.
Although there were no major sustainability principle violation noted for
cryogenic distillation, it is significantly energy intensive. This technology
has the potential to operate at near 100% capture efficiencies, however, the
energy requirement is a major strike against choosing cryogenic distillation
for wide deployment.
Separation with sorbents was the least sustainable option. This is primarily
because sorbents used for separation, notably amines, have known harmful
effects on the biosphere, and due to the large quantities required there is a
potential for accumulation.
Transportation and Storage. The common methods for transportation of
CO2 are tanker ship, rail or road tanker and pipeline. Of these options,
pipeline was the lowest cost option, the least energy intensive and had the
lowest risk of catastrophic leakage.
Our research on carbon storage revealed several main approaches currently
being considered for the stationary power sector. In addition to the
69
sustainability principles, both the quantity of CO2 stored and duration of
storage was considered for each approach.
Geological storage, in which the CO2 is injected back into depleted gas
reservoirs, was the most sustainable option. Experience with current
geologic injection sites in Weyburn, Saskatchewan and the Sleipner field
off the coast of Norway indicate that CO2 can be stored safely and that there
is no leakage. However, the leakage monitoring data from these sites is still
less than a decade old and close monitoring over time should continue in
order to build confidence in this option for the long-term. No additional
sustainability violations were indicated for this method. Geological survey
information suggests that there is a sufficient amount of suitable storage
reservoirs for 50 years of stationary power emissions at our current rate of
generation (IEA 2001).
All forms of ocean storage were unacceptable given the toxicity of localised
high levels of CO2 that ocean dumping would entail and the uncertainties
regarding the long term stability and solubility of CO2 at the pressures and
temperatures anticipated in the ocean storage option.
Mineral carbonation is an attractive option in terms of ‘locking’ the CO2
almost indefinitely, but there would be sustainability principle violations
associated with large scale mining. Therefore this storage option is not
proposed as part of a sustainable scenario.
4.2.4 Primary research question
In order to answer the primary research question, “can point source carbon,
notwithstanding fuel source, be sequestered in a sustainable manner?,”
both carbon capture and storage were assessed independently of one
another through the lens of the sustainability principles.
Our research supports our hypothesis that CCS can theoretically be
operated sustainably, and that it can serve as a flexible platform for
mitigating CO2 emissions during the transition from a fossil fuel-based
power sector to a sustainable power sector, with the following preferences
for technology selection:
70
•
•
•
Gas separation: Membranes are the preferred separations technology
rather than amines or cryogenic distillation. Both have a high energy
requirement, and disposal of amines represents a difficult challenge.
Transportation: Pipeline is the preferred method over truck, rail or
ship, due to fossil fuel consumption.
Storage: Geological storage in saline reservoirs has acceptably low
risks of leakage and is preferred over other variations of geological
storage ocean or chemical storage.
4.2.5 Second Research Question
Now having shown that CCS can theoretically operate without
Sustainability Principle violations, the second research question asks “will
investments in fossil fuel-based CCS be a strategic step towards a
sustainable stationary power sector?”
Adding CCS to power large scale fossil-fuel power generation adds
significantly to the cost of constructing and operating a power plant.
Installing CCS at a significant percentage of power plants around the world
would require investments in the order of hundreds of billions of dollars.
Given that such investments would automatically mean less resources
available for investments in the parallel strategies of demand reduction and
renewable power generation (and vice versa) it is essential to conduct a
careful analysis on the basis of cost effectiveness and a sound long-term
strategy in order to determine whether or not significant investments in
CCS will be the most efficient and sensible way to achieve ‘success.’
We will begin by examining the results of SSD prioritisation analysis for
this technology. Referring to Error! Reference source not found. we see
that fossil fuel-based CCS does help us move in the direction of our goal of
reducing power generation-related CO2 emissions in that it reduces CO2
emissions per kWh by up to 90%.
CCS can serve as a flexible platform for mitigating CO2 emissions during
the transition from a fossil fuel-based power sector to a sustainable power
sector, because it first decouples CO2 emissions from coal-burning, and
secondly it offers the potential of using existing infrastructure to both
generate power and remove net CO2 from the atmosphere if the fuel is
switched to biomass. CCS technology can also be considered flexible in
71
that it can be applied to other large point-source CO2 emitters such as
smelters and cement plants, sources of CO2 emissions which are currently
otherwise impossible to address. In doing so, CCS could prove to be an
effective tool in the pursuit of decreasing atmospheric CO2 levels to preindustrial levels.
If the power plant in question were to continue burning coal with CCS,
there may be some acceptable trade-offs over the short term with other
violations of sustainability principles, such as mining damage to local
environments, given the global need to stabilize the climate and meet
energy needs simultaneously. Technologies exist today which can remove
mercury from coal plant exhaust gases, and improved technologies are in
the research and development stages. Requiring coal-fired power producers
to utilize mercury abatement technology is a policy issue that should be
addressed with some urgency everywhere coal is currently in use today.
Fuel switching from coal to biomass requires a separate analysis of the
biomass potential at the regional and local level in conjunction with the
other assessments. The source and harvest rate of the biomass must also
conform to sustainability principles in order for this to be a sustainable
option.
However, for CCS to be economically competitive there would need to be
appropriate financial penalties for large point source CO2 emissions such as
a carbon tax or cap and trade system (illustrated in Appendix D: Computer
Model Results – CCS Scenario).
Ideally, societies could phase out fossil fuel-generated power while
successfully meeting demand through the development of sustainable
renewable power generation and demand reduction. However, given
society’s dependence on the significant installed base of fossil fuel-fired
(especially coal) stationary power and the enormous sunk investment that
this infrastructure represents, it is understandable that they will be unwilling
to abandon these investments prematurely. For some societies, CCS may
represent a less expensive bridging technology than large-scale short-term
adoption of other identified sustainable options.
Investments in fossil fuel-based CCS could be a strategic step towards a
sustainable stationary power sector under the following circumstances:
72
1. After a society has already invested in demand reduction and is
operating at high efficiency
2. When said society has large reserves of coal and a large existing
investment in, and dependence upon, coal-fired power plants
3. When developing local renewable power, or importing renewable
power from neighbours, is significantly more expensive than
installing CCS technology. If all three of these conditions apply then
it would appear that investments in CCS technology would be a
strategic step towards a sustainable stationary power sector.
4. We cannot ignore the very real possibility that runaway climate
change may force societies to invest in all means at our disposal in
order to reduce CO2 emissions, even if these investments are not
necessarily the optimal strategies for a sustainable stationary power
sector.
4.2.6 Third Research Question
Our final research question was: “What should governmental policy-makers
take into consideration in order to develop sustainable strategies within the
stationary power sector?”
Our findings indicate that there is no single correct answer to the question
of, what society should do to move towards sustainable stationary power
future. The power system is complex and each location will have unique
resources, usage patterns, levels of development, needs, challenges and
distribution networks that will need to be taken into account in order to
select the optimal mix of power generation and/or CO2 abatement
technologies that will lead to success.
The information summarised in Error! Reference source not found.
supports our hypothesis that the first strategy to be implemented should be
demand reduction. These measures generally have a good return on
investment in a short- to medium-term time frame. The renewable options
are in alignment with the sustainability principles, and have varying return
on investment. The fossil fuels with CCS do present some tradeoffs related
to mining, and heavy metals which must be recognized. It is possible that in
73
the short term, these trade-offs may be tolerated, but in order to be
sustainable in the long term, these issues would have to be addressed
through abatement technology, or fuel switching to biomass to avoid the
violations. Further, these options are all flexible platforms, but they have
varying ROIs.
Making further prioritizations is difficult, particularly when ranking the
importance of ROI relative to other success factors, such as sustainability
principle ranking and amount of CO2 which can be eliminated. These
priorities will necessarily have to be defined for the specific region and
application to address the goals of the stakeholders and policy-makers.
Our research has identified two prioritisation schemes that are specific to
developing strategies and making decisions about power sector
infrastructure. Despite the difficult of balancing the tradeoffs, these ranking
schemes constitute a sensible “order of operations” for making any changes
to the system.
The first scheme is California’s “loading order.” California’s Energy
Action Plan (State of California) strongly supports the loading order that
sets the priority for actions to meet increasing energy needs. (State of
California 2005, 3)
1) Cost effective efficiency and demand response.
2) Renewable sources of power and distributed generation, such as
combined heat and power applications.
3) Clean and efficient fossil fuel fired generation.
Another plan for approaching the problem has been developed by the
Energy Research Centre of the Netherlands’ Energy Efficiency in Industry
(EEI) research unit. It has a 3-step prioritization plan it calls the Trias
Energetica:
1) Efficiency: reduce demand to an intelligent minimum, by increasing
efficiencies.
2) Renewables: apply renewables to the extent possible;
3) Clean fossils: for the remainder: use fossil fuels as clean as possible.
(UNDP 2004, 13)
74
In both prioritisation schemes, demand reduction is the first action, an
upstream solution to emissions problems. This can be a combination of
efficiency targets, which could include incentives to purchase efficient
appliances, or subsidies for home insulation, for example. The second
action in the prioritisation schemes has the effect of decarbonising the
power mix by replacing fossil fuels with renewable sources of energy.
Finally, once the first two options have been considered, the last action is to
make investments in using fossil fuels as efficiently and cleanly as possible.
Improving the efficiency of the power plant or adding CCS technology to
fossil-generated power are examples of this. This is not to say that all three
strategic actions should not be examined and applied in parallel; indeed,
given the magnitude of the challenge humanity now faces it is likely that all
three will need to be applied at a large scale and in a short period of time if
we are to meet our goals for success (illustrated in Appendix D: Computer
Model Results – SSD Scenario). However, we should point out that
improving fossil fuel technologies does not bring them into compliance
with the sustainability principles or address their finite nature, and therefore
CCS should be considered a bridging technology while society shifts to
renewable, non-polluting sources of energy.
Policy Approaches. From our CLD we identified “sustainable governance”
as the major leverage point, which is policy, public awareness and
sustainable power policy. Power sector policy is a huge area of research and
far beyond the scope of this study to fully examine the options in any detail.
We have presented examples of government policy when describing our
strategies for achieving our desired future in our results section. We will
now briefly describe two policies identified through our research for
encouraging demand reduction and sustainable power supply encountered
in our literature review. In this discourse we are necessarily assuming that
decision-makers are competent, and committed to a sustainable power
sector and are able to communicate their commitment to all stakeholders
(Robèrt et. al. 2005, 197).
Public Awareness
•
Actively providing information underlining the connection between
power usage choices and climate change and why involvement in
international agreements is necessary. Actively engaging the public in a
75
transparent, high profile, national and international multi-stakeholder
dialogue. Mobilising public commitment to rise to the challenge.
•
Clear information on the climate change issue, costs, benefits of
transitioning.
•
Mandatory labelling of fuel consumption and emissions for products
(power efficiency of appliances, embodied CO2).
•
Encouraging educational institutions to include climate change studies
into their curriculum.
General Policies for Sustainable Power (including demand reduction,
generation and CCS):
•
•
Introducing price mechanisms to increase energy prices
–
Removing subsidies and/or incorporate environmental externalities
(violations of sustainability principles) so that fuel costs more
accurately reflect the full costs. Passing costs on to the end-user and
transparently redistributing tax proceeds towards sustainable
alternatives.
–
Implementing revenue-neutral tax on power sector carbon fuels
appropriate to the carbon content, with the proceeds being
transparently applied to carbon-free generation options and demand
reduction.
–
Alternatively, introducing a cap and trade system for large-scale
emitters. Setting clear, binding emission reduction targets for all
large CO2 emitters with a locked-in timetable for future lower
targets
R&D for next generation technologies
–
Supporting proven sustainable technologies on the widest
appropriate scale
76
–
•
Supporting the development of new breakthrough technologies,
accelerating deployment
Establishing power consumption standards that encourage innovation
towards efficiency for appliances, electrical goods and buildings
–
Establishing and enforcing legal standards for equipment and
building codes
–
Encouraging dematerialisation
–
Promoting a “rethink, reduce, reuse, recycle” strategy to reduce
overall energy consumption.
General Considerations for effectiveness:
1) Focus – Given the importance of reducing carbon emissions, policies
should be measured in terms of their effects on CO2 reduction and
mitigation
2) Time - Policies must be phased in over an appropriate time frame so
that society can adapt in an orderly fashion with minimal economic
dislocation.
3) Transparency – Policies should be fully explained as to their intent,
costs and where and how any generated revenue will be allocated.
4) Revenue Neutrality – policies should avoid resulting in an increase in
electricity price for a given level of electricity services.
5) Subsidies - should be short-term (so as to avoid building dependency)
and as available to a broad range actions that have a demonstrated
ability, or high probability, of achieving success (so as to avoid
accusations of favouritism).
6) Monitoring – suitable measurement tools must be employed to
monitor the effectiveness of policies for achieving power sector
sustainability. (Robèrt et. al. 2005, 196)
77
We recommend that decision-makers follow the generic methodology
presented in the following flow diagram (Figure 4.1) to develop an
individual strategic plan for moving their society towards a sustainable
stationary power sector.
78
Start
Step A: Describe system boundaries, mental model, SSD
framework, assumptions, constraints
Step B: Overview of current power generation and use
(SP violations)
Step C1: Create a future sustainable power scenario
Step C2: Create a list of strategies and actions for bridging
the gap between current reality and the desired future
Primary Strategy:
Reduce Demand
Analyze
• Energy Demand
• Demand Growth
Projections
• Demand
Reduction
Secondary Strategy:
Renewable Energy
Analyze
Local renewable
resource potential
Tertiary Strategy:
Fossil fuels
with CCS
Analyze
• CCS potential
(geological
reservoirs)
• Biomass
potential
Step D: Develop locally appropriate
prioritisation that achieves success at
least cost.
Prioritised Policy List
Figure 4.1. Decision-making process flow chart
79
5
Conclusions
In conclusion, this study has shown that point source carbon can be
captured and stored in a sustainable manner. The preferred technology for
separation of CO2 from the effluent gas stream is gas separating
membranes. In the short term, amine separation is the most economical
approach, but the large quantities of amines present health hazards and
disposal issues. The industry should transition to membrane separation
technology for the long-term, in order to meet sustainability principles for
the separation stage of the CCS process. Research suggests that geological
storage of CO2 can be done sustainably, particularly if sub-ocean geological
reservoirs are used, because in the event of leakage, the escaped CO2 will
exist in the form of solids which are stable at the high pressures and low
temperatures found on the ocean floor. Recognizing that it will not always
be possible to utilize sub-ocean geological storage, terrestrial geological
storage is the next best option. Mineral storage may be required ultimately,
if there is not enough space in geological reservoirs, but in the near term, it
is costly and cumbersome, requiring the transport of large quantities of
mined minerals.
Carbon capture and storage is a flexible platform, because if the fuel is
switched to biomass rather than coal, it enables for the first time, an
effective approach to removing CO2 from the atmosphere. This is possible
because the biomass acquired CO2 from the atmosphere during its growth
through photosynthesis, and when CCS is implemented in conjunction with
biomass, the CO2 that is re-released through combustion will be
permanently stored underground. The importance of such a weapon in our
arsenal against increasing CO2 and climate change cannot be overstated.
The cost of CCS technologies are of the same order of magnitude as
renewable energy technologies such as wind and biomass, (about 30%
more), but much less than PV. However, this estimate does not include all
of the sustainability principle violations associated with coal. If these were
included as part of the economic analysis, then fossil fuels with CCS would
be even more expensive.
Governmental policy-makers should recognize that the complexity of the
power sector requires a systems perspective and a mental framework which
can be used to explore trade-offs between options. Prioritization of the
80
strategies will be region-specific, there is no one answer to the question of
which energy technology option to choose. The other key aspect is that the
strategy should be as flexible and as adaptable as possible so as to
incorporate changing circumstances in order to maximise society’s chances
of success. Initial investments in energy efficiency will provide savings
which can be reinvested in a mix of renewable technologies and CCS. In
order to make meaningful comparisons between technology options,
sustainability violations should be quantified by including the externalities
to show the overall cost to society in other sectors.
Finally, investments in fossil fuel based CCS can be a strategic step towards
a sustainable stationary power sector. It should be considered a bridging
technology to cope with CO2 emissions we emit until we can successfully
transition to renewable, non-polluting sources of energy. It is important to
implement this technology because of the significant base of already
operating coal-fired power plants, and a significant supply of coal
worldwide. This transition will be greatly facilitated by sensible policy
which makes CCS the least cost option when penalties such as carbon taxes
or caps are in place. This is particularly important because of the possibility
to “scrub” the atmosphere if biomass fuel replaces coal for power
generation.
5.1 Further Research
This thesis has laid out the basic framework for analyzing energy options
and consolidated the considerations that should be taken into account by
policy makers to work towards meeting energy needs sustainably. This
approach is generalised and cannot give an unqualified answer about the
best way to achieve these goals in every situation. There are many possible
paths to a sustainable energy future. Therefore, we have identified the
following areas for potential further research:
•
Analysis of renewable energy options in various climates and latitudes.
•
Development of a predictive model for evaluating the impact of
changes in demand and energy supply mix upon the CO2 emissions of
an actual energy infrastructure system. This model would be similar to
81
the one presented in Appendices A-C, but more comprehensive and
specific to the power sector being studied. This model could include:
–
Capability to perform full-cost accounting of renewable energy vs.
CCS for a given supply mix/scenario.
–
Analysis of the effectiveness of various policy options (e.g. taxes vs.
subsidies) to achieve a given supply mix
–
Consideration of peak loading (daily and seasonal variations in
power demand) as well as supply variations caused by renewable
power utilization fluctuations.
82
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89
Appendix A: Field Experts Consulted
Name
Dag Christensen
Fredrik Hedenius
Klaus Lackner
David Bayless
Martin Goldblatt
Geoffrey Coates
Position
Director of New Energy
Technologies
Ph.D. Candidate, studying
under Christian Azar
Mineral Carbonation
Algal CO2 Mitigation
Systems
GreenFuel Technologies
Professor of Organic
Chemistry
90
Organisation
Norsk Hydro, Oil &
Energy Division
Chalmers University
Columbia University
Ohio University
MIT
Cornell University
Appendix B: Computer Model Method
The model is based on the United States stationary power sector and was
chosen because it is an excellent example of a large diversified power
network in which fossil fuel generation is the main source of electrical
supply. Based on historical data, the model generates a future Business As
Usual (BAU) scenario. Power demand, mix of supply (power contribution
by source), and total carbon dioxide emissions were predicted for each year
between 2005 and 2104 (100 years in total). This scenario is used as a
baseline for assessing our proposed strategies for strategically changing the
system.
A stationary power network is inherently complex. Many simplifications
and assumptions were required in order to produce a model that was
manageable within the timeframe of this thesis. The major assumptions for
the model are listed below:
•
•
•
•
•
All power plants have equal power generating capacity, lifetime of
operation, and power factors (utilization)
The power network is an unregulated, free enterprise market in which
the type of new power plant built is determined by the best financial
return on investment over the lifetime of that plant
All fossil fuel plants in the model switch over to CCS operation when
and if this becomes economically viable
Fossil fuel costs are fixed, and do not increase with resource scarcity
All power plants operate until the end of their lifetime regardless of
economic conditions
In reality, these assumptions could have a significant impact on how the
system changes over time; however, we believe that the results generated
by the model are qualitatively in alignment with the recommendations and
conclusions presented in this thesis. A complete list of model assumptions
can be found in appendix C.
A measure listed under each strategy from the C Step was incorporated as
an input variable into the model. These were: power demand reduction
(through energy efficiency improvements), subsidies for building new non91
fossil fuel power plants, and tax on carbon dioxide emissions. These
measures were not proposed as optimal or preferred choices, but were
chosen specifically because they could be integrated easily into the
computer model and because they represent dematerialization, substitution
and abatement strategies respectively. The input variables were then
adjusted independently in order to generate a scenario specific to the
implementation of each strategy. Power demand, mix of supply, and total
carbon dioxide emissions (both emitted and captured) were then recalculated by the model. These results were then compared to the BAU
model scenario in order to determine the relative effects of each strategy
upon the model system.
A model scenario was developed to apply the three strategies in accordance
with our prioritization research results. Both the magnitude and time of
implementation were adjusted for each input variable. This scenario was
referred to as the Strategic Sustainable Development (SSD) scenario. As
with the assessment of the individual strategies, the power demand, mix of
supply and total CO2 emissions were re-calculated and compared to the
BAU model scenario. This demonstrated how affective the three strategies
might be when they are strategically prioritized and used in combination
with one another in the context of the model system.
92
Appendix C: Computer Model
Parameters and Assumptions
United States Power Sector Projections
Population and power supply historical data from 1950 to 2004 were used
to predict the United States energy intensity (consumer electricity needs)
per capita from 2005 to 2104 (EIA 2004, 228, 373). This data was also used
to project the rate of deployment of renewable power in the stationary
power sector over the same timeframe. Population data and projections
from 2000 to 2050 were used to predict the population of the United States
from 2005 to 2104 (U.S. Census Bureau, 2004). Energy intensity per capita
and population were then multiplied together to project the total power
demand requirements over a 100 year period.
Power Network Characteristics
The power network in the model is comprised of many individual power
plants. Three types of power plants are represented in the model: fossil fuel,
fossil fuel with CCS, and non-fossil fuel (renewable and nuclear). Power
plants are dispatched to the power network overtime in order to meet power
demand as well as to replace older plants being retired. The overall mix of
supply and total carbon dioxide emissions of the power network are
determined by the accumulative sum of the individual power plant
contributions.
Power Plant Parameters
All three types of power plants have the following attributes:
•
•
•
Lifetime of operation 30 years
Maximum power capacity 1 GW
Power utilization 75%
The capital cost of expenditure and CO2 emissions produced per kWh are
specific to each type of power plant. Table A.1 lists the CO2 emitted to the
atmosphere, CO2 captured and stored, and the initial cost of electricity
93
(COE) for each type of power plant used in the model. For both types of
fossil fuel power plants, these values were determined based on a weighted
average of the amount of NGCC, PC and IGCC power supply currently
used in the United States (EIA 2004, 3). The initial COE for non-fossil fuel
plants was chosen such that it was greater than the average COE for
renewable and nuclear technologies.
Table A.1. Power plant CO2 emissions and initial COE8
Plant Type
Initial COE (USD/kWh)
CO2 Emitted to
Atmosphere (kg/kWh)
CO2 Captured and Stored
(kg/kWh)
Fossil Fuel
Fossil Fuel with
CCS
Alternative
Energy
0.045
0.070
0.090
0.7
0.09
0
0
0.775
0
The initial capital cost of expenditure for each power plant is calculated
based on the lifetime of operation, maximum power capacity, power
utilization and initial COE.
Experience Curves
Two experience curves (or ‘learning by doing’ curves) are used to adjust
the capital cost of expenditure over the duration of a scenario. One is for
fossil fuel power plants (both with and without CCS) and the other is for
non-fossil fuel power plants. Based on these curves, the capital cost of
expenditure for each new power plant decreases relative to the total number
of power plants of that type that have been previously built.
8
Adapted from (Rubin 2005, 4)
94
Economic Assumptions:
•
•
•
•
•
•
•
•
The power network is an unregulated, free enterprise market
The type of new power plant built is determined by the best financial
return on investment over the lifetime of that plant
Fossil fuel costs are included in the capital cost of expenditure for fossil
fuel power plants
Fossil fuel costs are fixed, and do not increase with resource scarcity
Economic inflation is not included
‘learning by doing’ curves are endogenous to the model, and any
additional cost reductions from outside manufacturing or industry
related research and development have not been considered
The cost of energy efficiency improvements is incurred by the end user
and is not represented in the model
The non-fossil fuel subsidies are derived from sources outside of the
model
Carbon Dioxide Emission Assumptions:
•
•
•
•
•
All fossil fuel plants in the model switch over to CCS operation when
and if this becomes economically viable
Both new and existing fossil fuel plants are retrofit ready for CCS.
The amount of carbon dioxide emitted and carbon dioxide stored for
both types of fossil fuel plants (with and without CCS) is a fixed value.
The capital cost of expenditure for fossil fuel plants with CCS was
based on amine separation, pipeline transportation and geological
storage technologies.
Fossil fuel power plants with CCS separate 90% of the CO2 emissions
from the flue gas stream.
Power Supply Assumptions:
•
All power plants have equal power generating capacity, lifetime of
operation, and power factors (utilization)
95
•
•
•
All power plants operate until the end of their lifetime regardless of
economic conditions
In an over supplied energy market, power plants are prioritized in order
to have the maximum affect on emission reduction. Non-fossil fuel
power plants are utilized to their maximum potential first, followed by
fossil fuel with CCS power plants and then fossil fuel power plants.
Power supply and demand is constant each year (no peak loading or
season variations)
96
Appendix D: Computer Model Results
BAU Scenario
Figure A.1 shows the BAU scenario model results for both the mix of
supply and power demand for the United States power sector from 2105 to
2104. Population growth and increasing energy intensity (consumer
electricity needs) are responsible for the steady rise observed in power
demand. The mix of supply also changed over the duration of the model,
increasing from 72 to 82 percent fossil fuel power supply.
Figure A.1. BAU scenario, power
demand and mix of Supply
Figure A.2. BAU scenario, CO2
emissions
Figure A.2 shows the associated carbon dioxide emissions produced by the
power network. The emissions increased proportionally with fossil fuel
power supply more than quadrupling over the 100 year timeframe.
To supplement our research and to understand how each strategy might
affect the system, the computer model was used to illustrate the relative
changes produced by each strategy in the on the model system over time.
A computer generated scenario was then developed based on our findings
in order to illustrate how the system could change when all three measures
are implemented strategically together.
97
Demand Reduction Scenario
In this scenario the dynamic response of the system caused by
strengthening the Demand Reduction balancing loops was explored.
Model input variable: 25% reduction of projected power demand by 2010
and 50% by the end of 2104
Figure A.3 shows the model results for both the mix of supply and power
demand from 2005 to 2104. As intended, power demand dropped
significantly compared to the BAU scenario. The mix of supply was also
affected, and changed in favour of non-fossil fuel power. This is primarily
because the BAU rate of deployment for non-fossil fuel power plants
remained unchanged. The initial drastic reduction in power demand created
a temporary surplus of power supply in the power network. In this situation,
non-fossil fuel power is completely utilized before fossil fuel power. This
contributed to the favouring of non-fossil fuel power in the mix of supply.
Figure A.4 shows the carbon dioxide emission results. By the end of 2104,
the emissions were 60% less than the BAU scenario. This was 10% greater
than the amount of demand reduction, the difference of which was
produced by the change in mix of supply.
Figure A.3. Demand reduction
scenario, power demand and mix of
supply
98
Figure A.4. Demand reduction
scenario, CO2 emissions
Non-fossil Fuel Power Scenario
For simplicity, the model combines renewable power and nuclear power
together into non-fossil fuel power and makes non distinction between
which type of technology is developed. In this context, the dynamic
response of the system caused by increasing non-fossil fuel power is
equivalent to strengthening the Renewable Power balancing loops.
Model input variable: 150 billion USD non-fossil fuel power capital
expenditure subsidies available per year with a 1% growth rate
commencing in 2005
Figure A.5. Non-fossil fuel scenario, Figure A.6. Non-fossil fuel scenario,
power demand and mix of supply
CO2 emissions
Figure A.5 shows the model results for both the mix of supply and power
demand from 2005 to 2104. In this scenario, the power demand was
unaffected by the input variable and follows the BAU scenario. The mix of
supply gradually transitioned towards complete non-fossil fuel power, as
capital cost reductions from both subsidies and development of non-fossil
fuel technologies (experience curves) prevented fossil fuel power from
being economically competitive. By the end of the scenario the capital cost
of expenditure for non-fossil fuel power plants had become less than that of
fossil fuel power plants. Subsidies were therefore no longer required to
make non-fossil power plants cost effective. Figure A.6 shows the carbon
dioxide emissions compared to the BAU scenario. They immediately level-
99
off and transition to zero in accordance with the phasing out of fossil fuel
power plants.
Carbon Capture and Storage Scenario
In this scenario the dynamic response of the system caused by
strengthening the Carbon Capture and Storage balancing and reinforcing
loops was explored. The amount of carbon tax was intentionally set so that
fossil fuel plants with CCS would remain economically viable throughout
the duration of the scenario.
Model input variable: 40 USD/tCO2 carbon tax commencing in 2005
Figure A.7 shows the model results for both the mix of supply and power
demand from 2005 to 2104. Both the power demand and non-fossil fuel
contribution to mix of supply was unaffected by the input variable. The
fossil fuel mix of supply changed quite rapidly over to CCS as plants
implemented this technology to reduce their operating costs. Figure A.8
shows both the carbon dioxide emissions emitted to the atmosphere and
captured and stored. The emissions were reduced considerably compared to
the BAU scenario, but still continue to increase at rate proportional to the
increasing fossil fuel power supply. The carbon dioxide captured and stored
is shown to exceed the emissions generated in the BAU scenario. As
described previously, this is because fossil fuel plants with CCS operate
less efficiently and require greater amounts of fossil fuel to produce the
same amount of electrical power.
100
Figure A.7. CCS scenario, power
demand and mix of supply
Figure A.8. CCS scenario, CO2
emissions
Strategic Sustainable Scenario
In this scenario the dynamic response of the system caused by strategically
implementing all three strategies together was explored. The magnitude and
time of implementation of the input variables were adjusted in conjunction
with one another. This was done in a manner that produced a scenario that
minimized both the carbon dioxide emissions and magnitude of each input
variable. This scenario is referred to as the Strategic Sustainable
Development (SSD) scenario.
Model input variables: 15% reduction of projected power demand by 2010
and 30% by the end of 2104, 25 billion USD non-fossil fuel power
development subsidies available per year with a 1% growth rate
commencing in 2005, 30 USD/tCO2 carbon tax commencing in 2010
Figure A.9 shows the model results for both the mix of supply and power
demand from 2005 to 2104. As expected, power demand drops noticeably
compared to the BAU scenario. The mix of supply distinctly changed twice
over the 100 year timeframe. The first major change occurred when all of
the fossil fuel power plants switched over to CCS. This was caused by the
carbon tax on emissions. The second major change occurred when all of the
fossil fuel power plants with CCS were replaced by non-fossil fuel power
plants. Capital cost reductions from subsidies and development of nonfossil fuel power plants was responsible for this change. Figure A.10 shows
101
the carbon dioxide emissions associated with this scenario. The emissions
were reduced dramatically compared to the BAU scenario and rapidly
approach zero in the first half of the 100 year timeframe. The amount of
carbon dioxide captured and stored is relatively little compared with the
BAU emissions and also approaches zero in accordance with the phasing
out of fossil-fuel power generation.
Figure A.9. SSD scenario, power
demand and mix of supply
Figure A.10. SSD scenario, CO2
emissions
102
Appendix E: Author Contributions
This thesis is a collaborative work of Lisa Chacón, Benjamin Hornblow,
Daniel Johnson, and Christopher Walker as a requirement for Masters’
degrees in Strategic Leadership towards Sustainability in the Spring of
2006.
All group members contributed equally to the research, synthesis, report
writing, the shared mental model of the System represented by the CLD and
presentations.
Lisa was responsible for research on coal, natural gas and biomass. She
wrote the abstract, executive summary, and significant portions of the
introduction, discussion and conclusion sections.
Benjamin was responsible for research on geothermal, nuclear and CO2
separation technologies. He wrote significant portions of the Method and
Results step A and step C1 sections. He created the computer model,
analyzed the results, and wrote Appendices B, C and D. He also drafted the
first CLD which was further developed by all members of the group.
Chris researched wind and ocean power, demand reduction, renewable
power analysis and policy options, as well as ocean carbon storage. He
wrote significant portions of the discussion section.
Daniel researched photovoltaic and hydroelectric power and geologic
carbon storage options. He was responsible for compiling and editing the
results and references sections, organizing group documents and
maintaining consistency in the final thesis.
103
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