Wind Energy systems Stand-Alone

Wind Energy systems Stand-Alone
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page a
Stand-Alone
Wind
Energy
systems
A Buyer’s Guide
Natural Resources
Canada
Ressources naturelles
Canada
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page b
Stand-Alone Wind Energy Systems: A Buyer’s Guide
Text prepared by Marbek Resource Consultants and SGA Consulting for the Renewable and
Electrical Energy Division, Energy Resources Branch of Natural Resources Canada (NRCan).
The text builds upon an earlier version by Mr. Marc Chappell of MSC Enterprises and
Mr. Raj Rangi of the CANMET Energy Technology Centre.
Important Note
The aim of this publication is to provide guidance to readers who wish to assess the benefits and
risks of buying and installing a small-scale wind energy system. Because the subject is complex, and
the decision to purchase or install a system depends on many variables, this guide alone does not
provide sufficient information to evaluate fully all the aspects of a potential system. The guide is
also not intended to serve as a “how to” manual for the installation, operation and maintenance
of a system. In all cases, qualified advice and assistance to supplement the information provided
here should be sought.
Prospective buyers should consult local utility and government agencies to ensure that proposed
installations will meet all relevant electrical codes, building and site regulations.
Natural Resources Canada assumes no liability for injury, property damage, or loss from using
information contained in this publication. This guide is distributed for informational purposes
only and does not reflect the views of the Government of Canada nor constitute an endorsement
of any commercial product or person.
© Her Majesty the Queen in Right of Canada, 2000
ISBN 0-662-28254-X
Cat. No. M92-175-1999E
Aussi disponible en français sous le titre de: Les systèmes éoliens autonomes : Guide de l’acheteur.
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 1
Table of
Contents
About This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1
The Power and Potential of the Wind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
How much energy is in the wind? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Harnessing the Wind’s Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2
Different Types of Wind Energy Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Non Grid-Connected Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Grid-Connected Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
3
System Components . . . . . . . . . . . . . . .
Wind Turbines . . . . . . . . . . . . . . . . . . . . . .
Towers . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Balance of System (BOS) Components . . . .
4
Using Wind Energy to Pump Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Mechanical Water Pumping Windmills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Wind-Electric Water Pumping Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
5
How to Plan a Simple Stand-Alone Electric System . .
Step 1: Assess Your Site . . . . . . . . . . . . . . . . . . . . . . . . . . .
Step 2: How much Energy do you Require? . . . . . . . . . . .
Step 3: Size a Wind Turbine and Tower . . . . . . . . . . . . . . .
Step 4: Select Balance of System (BOS) Equipment . . . . . .
6
Hybrid Wind Energy Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
7
Economics . . . . . . . . . . . . . . . . . . . . . . .
How much does the system cost? . . . . . . . .
Compare the Alternatives . . . . . . . . . . . . . .
Using Simple Payback to Evaluate a Project
8
Other Issues to Consider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
9
Buying a Wind Energy System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Experts Can Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Selecting a Supplier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
10
Installing, Operating and Maintaining Your System .
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operation and Maintenance (O&M) . . . . . . . . . . . . . . . . .
11
Need More Information? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
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6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 2
Appendices
Appendix A, Typical Power Ratings of Appliances and Equipment . . .
Appendix B, Worksheet #1. Annual Energy Consumption . . . . . . . . .
Appendix C, Worksheet #2. Selecting BOS Equipment . . . . . . . . . . . .
Appendix D, Worksheet #3. Costing Estimates . . . . . . . . . . . . . . . . . .
Appendix E, Worksheet #4. Dealer Information . . . . . . . . . . . . . . . . .
Appendix F, Using Net Present Value (NPV) to Evaluate a Project and
Comparing Unit Costs of Energy . . . . . . . . . . . . . . . . . . . . . . . . . .
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Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Reader Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
2
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 3
About
this Guide
This buyer’s guide to stand-alone
wind energy systems will help
you decide if wind energy is
a viable option for you. The
guide will:
•
give you some very basic
theory on how wind
energy works
•
give you pointers to
determine how much
power you need
•
help you do a rough assessment of whether wind energy
will fill those power needs
•
introduce you to some of
the components of a wind
energy system
•
outline how to determine if
wind energy makes economic
sense for your circumstances
•
give you some practical
examples of wind energy
systems
This guide is not intended to be
a “how-to” install a wind energy
system. Nor does it provide you
with enough information to fully
evaluate whether wind energy
is right for your circumstances.
These systems are complicated,
and require some expertise to
set up and maintain properly. A
qualified person will be required
to determine the feasibility of the
system, its design and its set up.
Before you make any buying
decision, consult your local
utility and government agencies
to ensure that your proposed
installation meets the required
electrical codes, building regulations and site regulations.
3
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 4
1. The Power and Potential of the Wind
• A very old power source is
one of the power resources
of the future
• How much energy is in the
wind and how to get it out
Wind is a very complex
process which can be described
very simply.
People have been capturing the
energy contained in the wind’s
movement for hundreds of years.
Dutch-style windmills were first
used in the 12th Century, and by
the 1700s, had become a major
source of power in Europe. In
North America, farmers adopted
windmill technology to pump
water about a hundred years ago.
Today, the turning rotors of a
wind energy system can still be
used to run pumps, and to run a
generator to generate electricity.
The wind is a renewable energy
source, continuously generated
or replenished by the forces of
nature. Renewable energy technologies, such as wind energy
systems and solar photovoltaic
(PV) systems, which use sunlight,
convert renewable resources
into usable forms of energy
that can complement or replace
conventional energy sources.
4
▼
The sun heats the earth at different rates depending on whether
an area is below clouds, in direct
sunlight, or covered with water.
The air above the warmer areas
heats up, becomes less dense, and
rises. The rising air creates a low
pressure area. Cooler air from
adjacent higher pressure areas
moves to the low pressure areas.
This air movement is wind.
Figure 1. Wind is caused by movement of air.
Canada is a large country with
a huge wind energy potential.
Tapping into this potential
will help decrease the amount
of greenhouse gases emitted by
conventional sources of energy.
Modern large wind energy installations are popping up across
the Canadian landscape. These
“wind farms” use an array of
wind turbines, each generating
around 600 kilowatts, and are
hooked to the main electrical
grid. While this is a promising
technology, it would still take
1,500 of these large turbines to
match the output of one CANDU
reactor. On the other hand, if
replacing an oil or coal generator,
just one of these turbines could
eliminate over 1,000 tonnes of
carbon emissions per year.
This guide is aimed at those
who are considering a wind
energy system to supply energy
to their homes, farms, cottages
or businesses. In most cases, such
small systems have capacities in
the 100 watt to 25 kilowatt range.
At the low end of this scale,
enough electricity is generated
to run a few lights, a communications radio or entertainment
equipment. At the higher end,
many of the electrical needs of
farm operations or institutional
buildings could be met. Somewhat
larger systems could also supplement municipal needs and supply
power to remote communities.
While the tested technology of
direct mechanical work, such as
pumping water, will be touched
upon in this guide, we will focus
on electrical generation.
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 5
Measuring Wind Speed
Wind speed is measured by an instrument called an anemometer (Figure 2) which
turns faster as the wind blows harder on it. A data logger can be used to record
instantaneous observations of wind speed, or to store a long term record for later
analysis. A wind vane indicates the direction of the wind.
Wind speed is generally reported in kilometres per hour (km/h) or in metres
per second (m/s): 1 m/s = 3.6 km/h. Direction is indicated in degrees azimuth
or compass points.
Figure 2. An anemometer.
▼
How much energy
is in the wind?
One of the first steps in determining if a wind energy system
is feasible is finding out how
much wind energy is available.
To do this, wind speeds are
measured over a period of time,
making note of the amount of
time the wind blows at various
speeds. From this, an average
annual wind speed is calculated.
A wind energy system usually
needs an average annual wind
speed of at least 15 km/h to
be practical.
chart of the number of hours
the wind blows at various speeds
(Figure 3). The wind blows most
often at the speed corresponding
to the highest point on the curve.
Features on the ground will
impact the speed of the wind.
Hills, ridges and valleys can block
the wind or create undesirable
turbulence for a wind energy system. Air movement is also slowed
by friction close to the ground.
As you move higher, wind speed
increases. For most open spaces,
wind speed increases 12 percent
each time the height is doubled.
Locating a wind energy system
on a hill, and on a tower will
A small increase in wind speed
leads to a large increase in the
amount of energy available
(because volumes of air are being
moved, the energy available in
the wind is proportional to the
cube of the wind speed).
Harnessing the
Wind’s Energy
A wind energy system is simply a
method of extracting the energy
from the wind and converting it
into useful energy. This conversion
can be to mechanical energy, where
2 Vave
Hours per Year
It is also important to know
the variation in wind speed.
Vave
.75 Vave
0
50
75
100
150
200
250
Percentage of Average Wind Speed
▼
As it turns out, the wind is almost
never calm, and rarely exceeds
twice the annual average speed,
and then only briefly. The most
frequent wind speed is about
75 percent of the average annual
wind speed. If you call in an
expert to assess the amount of
wind energy at your site, one
assessment tool will be in the
form of a Rayleigh wind speed
distribution curve. This is just a
increase the amount of wind
energy available.
Figure 3. Annual Average Wind Speed (Vave)
The high point of the curve is the speed at which the wind blows most often.
Such a graph is called a Rayleigh wind speed distribution curve.
5
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 6
Wind Speed
Conversions
Wind speeds are often measured in
metres per second but, for simplicity,
we will refer to wind speeds in
kilometres per hour.
m/s
km/h
4
14.4
6
21.6
8
28.8
10
36.0
12
43.2
14
50.4
16
57.6
You cannot rely on the wind, so
some applications will require a
battery system to store electricity,
while some will be supplemented
with a diesel, gas or propane
powered generator which operates
when the wind is not blowing.
the wind turns a rotor which drives
a mechanical device such as a gear
or lever system running a water
pump. The conversion can also be
to electrical energy, where the rotor
runs a generator.
Swept
Area of
Blades
A basic wind energy system consists of a turbine (a propeller-like
rotor, a gear box and a generator),
a tower, and a Balance of System
(BOS) package. Components of
a BOS package vary, and will be
discussed further in Chapter 3.
Typically, wind speeds greater
than 15 km/h are needed before
a wind energy system can begin
to generate electricity. This is
known as the “cut-in” speed.
The “cut-out” speed, usually
around 70 km/h, is where the
system stalls to protect itself
from damage.
The precise amount of energy
that can be extracted from the
wind depends on many factors,
which are reflected in standard
formulae. The formulae are
complicated and depend on
such factors as the variability
and distribution of wind speed,
the height of the rotor and the
density of the air.
The diameter of the area swept
by the rotor is also important
(see box below and Figure 4).
About Wind Energy Theory
Energy production from the wind depends on several key factors:
The diameter of the area swept by the rotor blades (known as the “swept
area”). The rotor blades of a wind turbine sweep through a circular area. Because
we are dealing with circular area, increasing the rotor diameter, greatly increases
power output. For example, doubling the rotor diameter quadruples power output.
Rotor
Diameter
The speed of wind. To start with, the length of time the wind is blowing above
the cut-in speed is a critical factor. It is also important to remember that small
increases in wind speed lead to large increases in available power. A 10 percent
increase in wind speed can cause an increase in power of about 30 percent.
The variability of wind speed over time at the site. The total energy produced by a wind energy system over a period of time depends on the distribution
and variability of wind speeds over time. Not surprisingly, the annual average wind
speed at a site is more important than the speed at any given moment.
The density of the air. Wind power is directly related to air density, which
increases as the temperature drops (warm air rises). About 16 percent more
energy could be available at minus 20°C than at plus 20°C.
▼
6
Figure 4. The “Swept Area” is
the area through which the rotor
blades travel.
The Betz Limit
When energy is extracted from the wind, its speed decreases. In theory, if you
took all the energy out of the wind, the wind would stop completely! In reality,
however, you cannot remove all the energy from the wind. The most energy that
an ideal wind energy system can extract is approximately 59 percent. This value
is known as the Betz limit.
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 7
2. Different
• You need different
types of systems to
fill different needs
• Systems range from very
small to grid-connected
This guide deals mainly with non
grid-connected systems. That is,
the wind energy system does not
connect to the main electrical grid
(such as a municipal electrical
system). Changes in the way
electrical utilities operate, however,
are leading to some innovations
which we will touch on briefly
at the end of this section.
Terminology Issues
Wind energy systems that generate
electricity are often referred to as
wind turbine generators (WTGs).
For the purposes of this guide, all
systems that recover and convert
wind energy will be referred to
as wind energy systems.
Non GridConnected
Systems
Small, non grid-connected systems
can be stand-alone systems, which
provide power solely from the
wind, or hybrid systems, which use
a combination of wind and another
source of energy when the wind is
insufficient to meet demand.
Stand-alone systems can generate
electrical or mechanical energy and
often have a method for storing
energy when wind conditions are
not good. A generator driven by
a wind energy system can produce
electricity which can be stored
in batteries. Batteries are not
necessary if the owner is willing
to live with an uncertain supply.
Types
of Wind Energy Systems
Mechanical systems are relatively
simple. They can be used to
aerate ponds, pump water for
livestock, irrigation or drainage,
and to supply water to remote
households, farms and small
communities. You can think of a
water tank as storage in a mechanical system. More than a million
mechanical systems are said to
be in use today, mostly on farms.
Hybrid systems are used in
locations where the wind may
fluctuate or where users might
not want to be totally dependent
on the wind. Hybrid systems can
include solar energy or diesel
generation. These systems can
provide a reliable supply of energy
regardless of wind conditions, but
can also be costly and complex.
system may also be an option if
the cost of storage (i.e. batteries)
is high due to large loads.
Wind energy systems all have a
power rating known as the rated
output. This is the maximum
power output of the system in a
strong wind under ideal conditions.
For purposes of this guide,
we will group systems into
the following categories:
Micro Systems:
100 watts or less
They are useful for:
•
portable systems for lighting
and communications radios
at hunting and fishing camps
•
small appliances on yachts,
recreational vehicles, in
cabins and cottages
Hybrid Systems for
Remote Communities
•
electric fences
•
remote area lighting
Many remote communities depend
on diesel generators to provide electricity. If the site has good winds, a
wind turbine can also be installed
to help supply electricity for light
industry, water treatment, municipal
services, and other applications.
Whenever the wind speed is within
the turbine's operating range, the
wind-generated electricity flows to
the users and the diesel generator
has to supply less, reducing the
consumption of expensive fuel.
•
emergency lighting
•
trickle charging
•
pond aeration
•
navigational beacons
and lights
•
communications systems
•
educational programs
and displays
Wind-diesel hybrid systems are operating in several remote Canadian
communities, including Kuujjuaq
(Quebec), Fort Severn (Ontario) and
Cambridge Bay and Igloolik (NWT).
Hybrid systems are especially useful
where an existing energy technology, such as a generator, is already in
use and fuel is expensive. A hybrid
Mini Systems:
100 watts to 10 kilowatts
They are useful for
•
small gas or diesel generator
set back-up
•
pumping water for cattle
or for irrigation
•
cottage and domestic
water pumping
•
navigational aids
7
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 8
Another force at work is concern
for the environment. Climate
change and Canadian international commitments to reduce greenhouse gas emissions have brought
attention to the carbon emissions
from fossil fuel generation. Future
attempts to reduce these emissions
may encourage the use of “green”
or non-polluting electricity.
Natural Resources Canada and
Environment Canada are setting
an example by purchasing green
power for their facilities in Alberta.
Students of Assiniboine College in Manitoba install an 850 watt turbine.
(Photo courtesy of Nor’wester Energy Systems Ltd.)
▼
•
telecommunications systems
•
area and emergency lighting
•
refrigeration and ice making
for retaining quality of fish
at remote locations
•
water and waste treatment
•
waste water pumping
•
trash rack cleaners
(in irrigation systems)
•
cathodic protection
•
alarm systems
Small Systems:
10 kilowatts to 50 kilowatts
These are large enough to supply
the electrical needs of a farm
or business, and could serve as
an energy supply for remote
communities or camps.
8
Grid-Connected
Systems
Canada is entering an era of
change with the way in which its
utilities are regulated and how
they obtain or purchase electrical
power from others. New regulations will make electricity more
of a tradable commodity. Power
markets are now opening up to
private suppliers. This means
that wind energy will have the
opportunity to compete with
conventional carbon-emitting
fossil fuel and expensive nuclear
alternatives. Utilities in various
provinces, for example Alberta
and Ontario, are already moving
in this direction.
Large wind turbines that feed
electricity directly into the utility
grid are commercially available in
sizes ranging from 300 kilowatts
(kW) to 1.5 megawatt (MW).
These turbines are typically
installed in arrays known as wind
farms, although installations
of single large turbines are not
uncommon. Wind farms usually
become economically viable
only at the megawatt scale.
Standards
The Canadian Standards Association
(CSA) Standard CSA-F418-M91 Wind
energy systems – Interconnection to
the Electric Utility deals with these
issues, as well as related topics such
as requirements for installation and
operating specifications.
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 9
It is also technically possible
to connect small-scale systems
to a utility grid. This allows for
“net billing”. In most cases, however, it is uneconomical to do
so. Certain local or provincial
utilities, Ontario Hydro Services
Company for example, are now
working to make grid-connection
more attractive to owners of
smaller systems. (See the box
Grid-Connect Special Programs.)
Grid-Connect Special Programs
Ontario Hydro Services Company’s Net Billing Option pilot program is designed
for small renewable energy generators (less than 50 kW) that are connected to
the grid. Under the program, a small wind generator can supply electricity to the
grid, balancing out the electricity that the owner of the system purchases from
the grid. In effect, Ontario Hydro Services Company purchases electricity from
the owner at the same rate at which they sell it to the household. This net billing
arrangement is also referred to as “energy banking”. Up to 20 renewable energy
systems were to be tested in the pilot before the end of 1997.
For more information, contact Ontario Hydro Services Company toll-free
at 1-877-647-3783 or visit their web site at http://www.ohsc.com.
A utility’s key requirements for
grid-connected wind energy
systems are safety and the quality
of the power. The utility will
require that the system meets
certain standards and that it poses
no risk to their personnel or equipment. Quality defines the need
for the electricity generated by
the wind energy system to match
the characteristics of the grid
electricity. This will avoid damage
to sensitive electronic equipment.
For small grid-connected wind
energy systems, power quality
problems are rarely a cause for
real concern. Other issues to
consider are of a legal and
contractual nature, and require
specialized attention.
▼
As each utility has a different
policy for grid connections,
those interested should contact
the customer relations or business
office at the local utility for
further information.
Profile of a 25 kW Wenvor-Vergnet wind turbine.
(Photo courtesy of Wenvor Technologies Inc.)
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3. System Components
• The components you need
depend on the job you
are doing
the tower either has to come
down, or the service technician
has to go up.
• Help in reading technical
specifications
The generating equipment in
a VAWT is at ground level, but
VAWTs require a lot more space
to be cleared for guy wires.
Wind Turbines
Because any wind turbine may be
exposed to high winds, rain, snow,
sun, ice, and even salty air, its parts
should be made of tough, durable
and corrosion-resistant materials.
A well-built and well-maintained
turbine should have a life
expectancy of 20 years or more.
The wind turbine rotor is one of
the most visible parts of a wind
energy system, but there’s more
to the turbine than just the rotor.
The most familiar turbine is the
horizontal axis wind turbine,
known as a HAWT. The main
propeller-like rotor has an axis
that is parallel to the ground,
and therefore horizontal to the
wind. A vertical axis wind turbine,
VAWT, has an axis perpendicular
to the flow of the wind.
Rotor
The rotor consists of blades with
specially shaped, aerodynamic surfaces. When the wind blows over
the blades, the rotor turns, causing
the rotation of the drive train and
generator. The blades should be
AC/DC?
Gear
box
Rotor
height
(H)
Rotor
Generator
Hub
height
Tower
Hub
height
Tower
Guy Wire
Gear box
Generator
(HAWT)
▼
10
Generators and alternators produce electricity from the rotation
of the turbine motor. A generator
produces Direct Current (DC)
power or, as an alternator, it
produces Alternating Current
(AC) power. Most small wind turbines used for battery charging
systems use alternators generating
AC power which is converted to
DC for the batteries.
Rotor
Diameter
(D)
Rotor
Rotor
Diameter
(D)
The diameter of the rotor blades
determines how much power is
generated by the system. There
are usually two or three blades.
Three blades reduces the mechanical stresses on the system, but
increases the cost of the rotor.
Generator/Alternator
Turbines consist of several
sub-components (Figure 5):
HAWTs are most common in small
applications, and can be placed
on a tower which does not require
a large area. If servicing has to
be done to a HAWT, however,
light-weight, strong and durable
to withstand the elements. They
are usually constructed of composites of fibreglass, reinforced
plastic or wood. The turbine
should also be designed to prevent
the rotor from turning too fast
during strong winds.
(VAWT)
Figure 5. HAWT’s and VAWT’s: Horizontal and Vertical Axis Wind Turbines.
Direct Current (DC) is a flow of electricity in one direction. Alternating
Current (AC) flows first in one direction, then in the other. Alternating
Current is used in household electricity because of AC’s ability to be transmitted over long distances with minimum loss. DC, however, loses energy
the greater the distance transmitted.
You do not need to know the physics,
suffice it to say that the current coming from a battery is DC, while the
current coming from a wall outlet is
AC. Typically, DC-powered appliances
run at lower voltages than AC.
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 11
Gearbox
Rotor with
Blades
Generator/Alternator
Optional BOS
(Balance of System)
Equipment
Tailvane
(Yaw Mechanism)
DC to AC Inverter
Nacelle
Battery
Disconnect
Lead/Acid Batteries
Gasoline/Diesel
Generator
Wind Turbine
Disconnect
Tower
Figure 6. Wind energy system components.
▼
Gearbox
Tailvane (Yaw System)
Many turbines, particularly those
above 10 kW, use a gearbox to
match the rotor speed to that of
the generator. Most micro and
mini systems have the generator/
alternator rotating at the same
speed as the rotor and do not
need a gearbox.
A yaw system aligns the HAWT
with the wind. Most micro
and mini systems use a simple
tail vane that directs the rotor
into the wind. In some systems,
the rotor is downwind of the
generator, so it naturally aligns
with the wind. Some yaw systems
can be offset from the vertical
axis to regulate rotor power and
speed. Special release mechanisms
can use the yaw system to turn
HAWTs out of dangerously
high winds.
Nacelle
This is an enclosure which
protects the gearbox, generator
and other components from
the elements. It is removable
to allow for maintenance.
Control and
Protection Systems
Control systems vary from
simple switches, fuses and battery
charge regulators to computerized
systems for control of yaw systems
and brakes. The sophistication of
the control and protection system
varies depending on the application of the wind turbine and the
energy system it supports.
It is important to know some key
terms used in descriptions and
specifications of wind turbines.
On a chart on the next page, we
have outlined terms for a typical
mini DC generating turbine
that might be found in a manufacturer’s literature.
11
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 12
Specification Sample
Data
Importance
Units
Rated Output
600 W
Maximum power output (usually rated at about
12 to 15 m/s or 40–50 km/h), used to size
wiring and controls for maximum current.
Watts or kW
Rated Wind Speed
40 km/h
Speed at which rated output is produced.
kilometres/hour (km/h) or
metres/second (m/s)
Output Voltage
12 or 24
Volts DC
Determines what type of equipment
can be used or operated.
may be AC or DC
Cut-in Speed
11 km/h
Wind speed at which the turbine
starts to generate power.
kilometres/hour (km/h)
or metres/second (m/s)
Cut-out Speed
45 km/h
Wind speed at which the turbine turns away
from the wind or stalls to protect itself from
damage and stops producing power.
kilometres/hour (km/h)
or metres/second (m/s)
Blade Diameter
2.5 m
Overall diameter of rotating blade, one of the
main factors in determining power generated.
metres (m)
Number of Blades
3
Most common is three, but sometimes
two or four are used.
System Weight
20 kg
Weight of blades and generator/alternator,
to be lifted to top of tower.
kilograms (kg)
Power Curve
n/a
A graph of power output vs. wind speed;
required for an estimate of energy production.
Watts at wind speeds in
metres/second (m/s)
Warranty Period
2 years
Typically one to three years.
year
Towers
The tower holds the turbine in the
path of the wind and is therefore
an integral part of a wind energy
system. Make sure the tower is
properly engineered to handle
the system. Towers should be able
to withstand lightning strikes,
extreme winds, hail and icing.
Only towers approved by turbine
manufacturers should be used.
Otherwise, the warranty on
the turbine may be invalid.
Several types of towers are
available:
Guyed towers are economical
and very strong when properly
installed. The guy wires require
space around the base of the
tower so they can be properly
12
The Importance
of Tower Height
Because winds increase and become
less turbulent with height above the
ground, and power output increases
substantially with wind speed, increasing tower height from 10 to
50 metres can double the wind
energy available.
anchored. The tower’s concrete
foundation must have its own
secure anchor to withstand the
maximum pull on the wires.
Foundations should be placed
below the frost line; sandy and
poorly drained areas can be a
problem. Buildings, trees, and
even the lay of the land may
not permit guy wires.
Tilt up towers are often used for
smaller systems because they provide for safe maintenance of the
turbine. Tilt up towers allow assembly of the wind turbine while the
system lies on the ground. The
tower is then erected by a winch or
heavy vehicle. Tilt up towers can be
lowered for maintenance (Figure 7).
Self supporting towers tend to
be more expensive because of
the heavier materials necessary in
their construction. They do not
have guy wires, so the foundation
needs to be more substantial.
Certain micro system turbines,
such as those for recreational
purposes and cottages, can be
mounted on a simple rigid pole.
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 13
batteries have low-voltage cut-offs
to prevent a excessive DOD.
There are many kinds of suitable
batteries for wind energy systems.
Deep discharge lead acid batteries
are usually the most economical for
wind energy systems. Car batteries
(lead acid SLI – starting, lighting
and ignition – batteries) do not
have a high DOD and will fail prematurely if used in a wind system.
For suitable batteries, check
the box below.
Figure 7. Tilt-up towers tilt down to ground level, where the wind generator
can be easily installed and serviced.
▼
Balance of
System (BOS)
Components
Depending on your application,
you will need additional equipment and materials to provide
electricity at the required voltage
and current. This equipment
is referred to as the Balance of
System (BOS). The major BOS
components are batteries, the
inverter and, if you are using
one, a fossil fuel generator
(see Figure 6 on page 11).
Other BOS equipment and
materials include cables, switches,
circuit breakers, metres and other
apparatus not necessarily supplied
by the manufacturer. You should
have easy access to the BOS
equipment to do battery maintenance, repairs and to collect data
such as the number of kilowatt
hours generated. You may want
to dedicate an area in a workshop, shed or home to house
all the BOS equipment.
Batteries
Many wind energy systems use
batteries to generate electricity
when the wind is not adequate.
A system without batteries
will only provide power when
sufficient wind is blowing to
meet the demand.
Not all batteries are created equal,
and terminology for batteries can be
confusing. One of the most important specifications for wind energy
systems is Depth of Discharge
(DOD). This is the amount of power
you can drain from a battery and
still have it charge up again.
If you drain 100 percent of a
battery’s power, you will radically
shorten the life of your battery,
but batteries used for wind energy
systems are designed to have
a fairly deep discharge and
still allow recharging. Usually
a 50 percent discharge is used,
although some batteries offer up
to 80 percent DOD. This means
you can safely discharge 80 percent of the battery’s power without shortening battery life. Many
Deep Discharge
Batteries for Wind
Energy Systems
Flooded cells are the most common type of battery; they have
removable caps for adding distilled
water, are low cost, have long life,
and will withstand overcharging.
Sealed flooded cells are maintenance-free; they do not require
water; they can be damaged by
overcharging.
Recombinant flooded cells do
not require water; they are more
expensive, and can be damaged by
overcharging, but will not spill acid.
Gelled electrolyte cells do not
require water, are more expensive,
can be damaged by overcharging,
can be mounted in various positions, and will not spill acid.
The size of your battery system is
also important. It may be tempting to buy a small battery capacity
to save money, but this will likely
lead to a deep discharge and early
battery replacement. If batteries
are sized correctly for the system,
they should last three to five years.
Some very high quality large cells
can last up to 15 years.
13
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 14
It is recommended that batteries
be connected in series. Connections in parallel may cause
damage because of different
states of charge among the
individual battery cells.
Typical specifications on batteries
are explained in the chart below.
Inverters
Energy stored in batteries is
available as DC power. Some
appliances and equipment are
designed and built to run on
DC power. Camping, boating
and recreational vehicle equipment and lights are usually
designed to be run from DC
power, because they are designed
to be run from a battery.
Any electrical appliance in your
home, however, must use AC power.
An inverter converts the DC
power in the battery to AC power.
In the conversion process, about
10 percent of energy is lost.
Watt?
You do not have to know the definitions of the electrical units used in the text,
nor do you need to know how they relate to each other mathematically, but
it is helpful to know what each represents:
Amp: A short form for “ampere.” It is a measure of electrical current. Think
of it as speed, i.e. the rate of electrical flow. Wiring is rated according to how
many amps it can carry.
Volt: If an ampere is speed, a volt can be thought of as pressure. Electricity can
not move through a wire without something pushing it. That push is measured
in volts.
Watt: When you are looking at how much capacity you need for your wind
energy system, this is the number that is really important. Wattage is power.
The three measurements are related, and if you need to know the math, the
number of Watts available in a circuit can be found by multiplying the Volts by
the Amps. For example, a typical household circuit may be 15 Amps. Since your
house is supplied at 115 Volts, the circuit has a little more than 1,700 Watts of
power available. If you plug in appliances that draw more than 1,700 Watts,
you’ll blow a fuse or trip the circuit breaker.
There are different kinds of
inverters. Light duty inverters
(100 – 1,000 watts) are typically
powered by 12 volts DC and
are suitable for lights and
small appliances such as
televisions, radios and small
hand tools. Heavy duty inverters
(400 – 10,000 watts) can be
powered by a range of voltages,
12, 24 or 48 volts DC, and
can be used to run just about
Specification Sample
Importance
Cell Type
flooded
Specifies the operating characteristics,
charging voltages, and maintenance requirements.
Voltage
12 VDC
(Volts DC)
Specifies how many batteries in series are
needed to reach system voltage.
Volts DC (usually 2,
6, 12, 24 or 48)
Capacity
115 Ah
(20 hr rate)
Indicates how much energy is contained in the
battery, usually for a specific rated temperature
and an 8 or 20 hour discharge period; determines
how long the load can be maintained.
Amp-hours.
The number of amps load
multiplied by the number
of hours the load is applied.
(See explanation of Amps,
Volts, Watts, top of page)
Cycle Life
750 @
50% DOD
Specifies the number of battery cycles
(i.e. discharged, then recharged) before
capacity becomes inadequate.
Size
0.3 x 0.175
x 0.200
Indicates storage space required.
Length, width and height
(m3)
Weight
(including acid)
24 kg
A strong floor or sturdy racks will be necessary
for multiple batteries; weight determines if
one or two people can move the battery.
kg
14
Description
6126 NRCan Wind-Energy Bklet 3/14/00 9:30 AM Page 15
anything found in a home
or small business.
There is also the question of the
quality of power coming out of
the inverter. If inverter literature
starts talking about “true sine
wave” or “modified sine wave,” it
means the power is high quality,
and able to safely power sensitive
electronic equipment such as
computers and laser printers.
Inverters are sophisticated pieces
of equipment and often provide
a range of other features beyond
just converting DC to AC. Many,
for example, feature an automatic
starter for a gas or diesel back
up generator.
Generator Set (Genset) –
for Hybrid Systems
During extended periods of low
wind, a back-up generator is
required if continuous power
is needed. This generator may
be fuelled with gasoline, diesel
oil or propane. The electricity
generated is used directly where
required, or indirectly after first
charging the batteries.
An uninterrupted supply of
power may require a “remote
start” generator which will kick
in automatically before battery
power is exhausted. The start
signal is typically provided by
the system inverter. Not all
generators can be remotely
started, and not all inverters
support remote start.
Other BOS Components
The following components may be used with a wind energy system to fulfill
requirements for safety and specialized functions.
Battery Charger
Certain generators can be used to charge lead acid batteries. If the generator
does not have a battery charging output, a special battery charger is required.
Some inverters can act as battery chargers.
Rectifier
A rectifier converts AC power to DC power. Rectifiers are often used for battery
back ups in wind energy systems which have AC generators. The AC power the
generator produces has to be converted to DC power to charge the back up
batteries in times of strong winds.
Disconnect Switch
Disconnect switches, circuit breakers, fuses and other protective equipment
as recommended by the manufacturer and required by the electrical code are
important for the safe operation of the system. They electrically isolate the wind
turbine from the batteries and the batteries from the inverter and load. They
can also protect the system from damage caused by any number of things. A
disconnect switch allows maintenance or system modifications to be made safely.
Monitoring Equipment
Even the most basic BOS should include a method for monitoring the equipment’s operation. Standard monitoring equipment usually includes a voltmeter
for measuring battery voltage and depth of discharge, and an ammeter to
monitor energy production or use. More sophisticated monitoring equipment
includes alarms for system problems such as low or high voltage conditions.
Generators require not only up
front capital expenditure, they
also require fuel, periodic maintenance, rebuilding and even
replacement. While they can be
an important source of power,
generators are also noisy, create
pollution and require storage
of flammable fuels.
15
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 16
4. Using Wind Energy to Pump
Wind
Electric
Wind energy was used to pump
water long before the discovery
of electricity. Many different
approaches to wind energy water
pumping are still in use around the
world today. Large wind powered
pumps can provide significant
quantities of water for irrigation
and the watering of livestock.
Much smaller systems are adequate
to supply household water.
Mechanical
Water Pumping
Windmills
Traditional water pumping windmills use a crank mounted on the
rotor shaft. They typically have
many blades on a relatively slow
turning rotor. The equipment
changes the crank’s rotary motion
to an up-and-down motion which
drives a piston pump mounted in
a well or pond at the base of the
windmill. This series of actions
lifts the water.
Mechanical water pumping windmills have their advantages and
disadvantages. They tend to be
reliable, easy to maintain (they
require no BOS components) and
reasonably priced. But they may
be limited in their applications
because they must be located
directly above the well or pond,
even if the water may be required
some distance away.
16
Wind
Mechanical
Nacelle
Rotor
Powerhead
Tower
Pump Rod
Transmission
Line
Controller and Pump
Intake
Water
Source
Sucker Rod
Well Casing
Pump Cylinder
▼
Two technologies used for pumping water are mechanical water
pumping windmills and windelectric water pumpers. Both
are used mostly in rural or
agricultural applications.
Tail Vane
Figure 8. Mechanical and Wind-Electric Water Pumping Wind Energy Systems.
Courtesy of CANWEA.
Wind-Electric
Water Pumping
Systems
Unlike a mechanical system, a
wind-electric system does not have
to be located near the source of
the water. A wind energy system
powers an electric pump, which
moves water from its source (a
well or pond) to where it is needed
(a livestock watering trough, pond
or irrigation system). The power
consumed by the electric pump
can be matched to the power
output of the turbine so the
wind energy is used efficiently.
Electric water pumping systems
do not require elaborate BOS
components, mainly because
batteries are not required.
A reservoir tank for the water
serves as the energy storage
device.
▼
• An age-old technology
is simple and effective
Water
Mechanical water pumping
system.
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 17
5. How to Plan a Simple Stand-Alone Electric System
• Once you have completed
the steps, you can move
to the next phase – a
preliminary system design
Step 1: Assess
Your Site
You will need wind. A methodical
and well-reasoned assessment
of the amount of wind power
available is extremely important.
Over- or under-estimating the
wind resources at a site can be
costly. There are several ways
to go about estimating how
much energy is available.
In general, an annual average
wind speed greater than15 km/h
is needed to consider a wind
energy system. Speeds higher
than that are desirable.
The Atmospheric Environment
Service (AES) of Environment
Canada has measured wind
speeds for hundreds of locations
in Canada. From these measurements (always taken at 10 metres
above the ground), they have
calculated the annual average
wind speed for each site and
produced a “wind map” of
Canada (Figure 10).
From the map, it is apparent that
the windiest areas in Canada are
along the east and west coasts,
some parts of the far North and
the southern Prairies.
AES has also published a set of
wind data reports for Canada.
These reports contain extensive
information on speed direction
and variation of winds for six
different regions. A local weather
station can provide information
about a narrower area and may
even have detailed regional
wind maps.
These resources are a good place
to start your assessment, but you
will need more information. For
example, by convention, wind
speeds are taken at 10 metres
above the ground. The AES data
does not tell you about speeds
above 10 metres. It also does
not tell you about the microconditions that may occur at the
specific location you have in mind.
In general, wind turbines should
be installed in unobstructed, open
areas with clear exposure to prevailing winds. If possible, find a
How Much Wind is Enough?
A wind energy system needs an average annual wind speed of at least 4 metres
per second (m/s) to be able to operate with any degree of efficiency.
Average Wind Speed
Wind Regime
Up to 4 m/s (about 15 km/h)
No good
5 m/s (18 km/h)
Poor
6 m/s (22 km/h)
Moderate
7 m/s (25 km/h)
Good
8 m/s (29 km/h)
Excellent
▼
• Following straightforward
steps, determine if it is
feasible to proceed with
a wind energy system
Figure 9. A small 25kW WenvorVergnet wind energy system in
Collingwood, Ontario, supplies
electricity to a rural residence.
(Photo courtesy of Wenvor
Technologies Inc.)
site near the top of a hill or ridge,
because wind speeds increase with
height above the ground. Siting a
wind energy system on the windy
side of a hill will provide better
access to prevailing winds than
siting it on the sheltered side of
the same hill (Figure 11).
Consider more than just the
wind when considering a site.
For example, the distance of the
turbine from where the electricity
will be used is important. The
farther you have to transmit the
electricity, the more expensive
the system will become.
17
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 18
10
Mean Wind speed
15
20
15 20
10
km/h
Period 1967-1976
Elevation 10m
10
10
15
20
25
30
10
20
15
30
20
25
20
10
15
25
30
5
2025
20
20
25
20
15
10
15
20
10
20
The analysis is not valid at higher
elevations in mountainous areas
15
20
25
15
Figure 10. Annual average wind speed map of Canada. Courtesy of Environment Canada.
▼
Wind Energy
Resource Maps
for Canada
Copies of the Environment Canada
report Wind Energy Resource Maps
for Canada (ARD-92-003-E) are
available from:
Gary Beaney
Climate Service Specialist
Canadian Climate Centre
4905 Dufferin Avenue
Downsview, Ontario
M3H 5T4
Telephone (416) 739-4328
Fax (416) 739-4446
18
10
Once you have a tentative site,
monitor wind speed for several
months. This is especially important if your preliminary information shows annual average
wind speeds near the minimum
15 km/h. On-site monitoring
will provide information about
periods of calm and low wind.
Monthly or even spot readings
can be compared with the
monthly data from AES.
Wind monitoring is worth the
effort. It will help you determine
the size of turbine and the
amount of battery storage
capacity you’ll need for your
energy requirements.
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 19
10 m
100 m
Figure 11. Siting a wind energy system.
▼
To review, answer these questions:
1. What is the annual average
wind speed for your site at a
set height above the ground?
2. How does the average wind
speed vary with height?
3. What is the frequency and
duration of wind speeds,
particularly those periods
below cut-in speed and
above cut-out speed?
4. Is it worth proceeding?
Note:
This step is a “go” – “no-go”
decision point.
Step 2:
How much
Energy do
You Require?
When you determine how much
energy you require, you are really
asking two questions. First, how
much total energy do you require
over a year to operate all the
appliances and equipment your
system will run? Second, what
is the peak power requirement?
What is it you want to run?
You have to determine what it is
you expect to run with the electricity generated by your smallscale wind energy system. Some
household appliances such as
water heaters, clothes dryers,
stoves and electric heaters can
draw a large amount of power,
but do so only intermittently.
Other appliances, such as refrigerators and freezers draw a large
amount of electricity, and the
supply must be reliable.
Lighting, on the other hand, does
not require that much power,
and the draw is fairly consistent.
Even so, it is best to look for the
most efficient lamps and fixtures.
Remember that fluorescent lamps
use far electricity than incandescents, last ten times longer, and
give the same amount of light.
Screw-in compact flourescent are
widely available. DC flourescent
are also available.
Remember always that saving
a kW of energy is more costeffective than producing one.
If you plan to use wind energy
to run systems on a farm,
remember to distinguish between
equipment required to operate
the farm, and the energy requirements of the home. Power needs
for farming equipment vary
widely, especially when it comes
to livestock watering, and should
be accounted for separately.
19
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 20
A Note About
Energy Efficiency
Worksheet #1.
Annual Energy Consumption (sample)
The more power you need, the
larger and more expensive the system will have to be. Try to minimize
power requirements as much as possible, because saving a kW usually
proves more cost-effective than
producing one. Where possible, use
the most energy efficient appliances
available. Natural Resources Canada
manages the Energuide appliance
labelling program that collects
energy consumption ratings for
major home appliances available
in Canada. To obtain information
on Energuide please contact
Canada Communications Group
at 1-800-387-2000.
Appliance/
Equipment
AC
4 – 24 watt
fluorescent
lamps
Estimating Annual
Electrical Energy
Requirements
You will need two pieces of information for this estimate. First,
you need to know how long, in
hours, each of your appliances
will run. Second, you need to
know how much power each
appliance draws.
Power is measured in watts. We
are all familiar with wattage of
light bulbs, but every piece of
electronic equipment will have
an indication of how much power
it draws. Look on the back of
your television set, for example,
and you will find specifications
inscribed on a plate at the back.
A typical power draw might
be 90 watts.
If you have the television
set on for two hours a day,
every day of the year, that’s
(365 days x 2 hours) 730 hours.
20
Rated
Wattage
(W)
Hours
per day
Hours
per
year
Annual Wh
yes
96
5
1825
175,200
water pump
yes
400
1
365
146,000
colour
television (14")
yes
90
2
730
65,700
250
3
1,095
273,750
high efficiency
refrigerator
DC
yes
Total – Annual
Energy Consumption
The TV draws 90 watts of power
for 730 hours for a total annual
energy consumption of (90 watts
x 730 hours) 65,700 watt hours.
In the standard measurement of
kilowatt hours, this is 65.7 kWh.
In the back of this guide,
Appendix A, Typical Power Ratings
of Appliances and Equipment, will
be helpful in estimating annual
electrical energy requirements.
There is also a sample worksheet
at the top of this page.
660,650 Wh
(661 kWh)
Look to the future and changing
energy requirements when doing
your estimate as well. Will your
household be expanding or
shrinking in size? How will
this affect energy consumption?
(Keep in mind that you can take
your wind energy system with
you if you relocate!)
Peak Power Consumption for a Home
Wind Energy System – an Example
Appliance/Equipment
Power (watts)
4 x 24 watt lamps
96 W
small colour TV
90 W
portable phone
6W
clock
3W
iron
1,100 W
water pump (automatic)
350 W
high efficiency refrigerator
150 W
Total
1,795 W
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 21
Check Appendix A, Typical Power
Ratings of Appliances and Equipment, at the end of this guide
to note the most power hungry
appliances which may be operating simultaneously. Add up the
wattage to obtain the peak load.
Portable Remote Power system,
Canada Olympic Park, Alberta.
While not all systems are this
portable, you can take your
system with you when you
move. (Photo courtesy of
Nor’wester Energy Systems Ltd.)
▼
Estimating Peak
Power Requirements
To ensure you have the right size
of wind energy system, you need
to know more than just annual
electrical energy consumption.
Many appliances, such as refrigerators, do not run constantly,
but cycle on and off. Similarly,
lighting is not in constant use,
nor is an electric iron, electric
space heater or many other
pieces of equipment.
To properly size your system,
you must estimate peak power
consumption. Even though it
is unlikely all your equipment
and appliances will be turned on
at once, a peak power estimate
should be an extreme example.
Consider, for example, that you
might be watching television
with the lights on while you do
a few minutes of ironing and
that your water pump and high
efficiency refrigerator also turn
on automatically. This could be
your peak load. An example of
this scenario is given in the table
on the previous page.
Step 3:
Size a Wind
Turbine
and Tower
You should now have an estimate
of the wind energy available at
your site, and an estimate of how
much energy you need. Sizing
the turbine is a matter of trying
to match the two.
Helpful Hints
To obtain smooth airflow, the
tower should position the turbine
of a mini or a small system at 100
metres horizontally from the nearest
obstacle at turbine height (such
as larger trees or buildings), and
10 metres above any obstructions
which are closer.
Look at the manufacturer’s specifications for turbines to get an idea of
approximately how much energy
will be available given your site’s
average annual wind speed. A
more precise estimate will depend
on the variability of the wind
speed over time.
This is also the time to think
about towers. A higher tower
will be more expensive, but could
give your turbine access to greater
wind energy. A shorter tower
will require a larger turbine to
generate the same amount of
energy as a higher tower with a
smaller, less expensive turbine.
The type of tower you need will
depend on your site. Is there
room for the tower guy wire
anchors? Is a stand-alone tower
a more viable option? Does the
tower height allow the turbine
to operate 10 metres above
nearby obstructions?
Step 4: Select
Balance of
System (BOS)
Equipment
BOS equipment depends entirely
on the answer to the earlier
question, “What is it you want to
run?” Will it require power every
day, on demand? Will it require
AC power? Is the power absolutely
required 24 hours per day, every
day, all year? Let us look at each
of these questions in turn:
Do you need power
every day on demand?
If “yes,” you will require batteries. You will need to know what
size of battery best fits your system. You should have an experienced wind equipment dealer
help you calculate the amount
of battery storage you need
because the estimate is based
on several factors.
For example, what is the longest
period you can expect to be without adequate wind? You will need
enough battery capacity to run
your appliances during this period.
An example of this calculation is
shown in the box on the next page.
Remember also that when the
wind is blowing, your wind energy system must not only run your
appliance and equipment, it must
generate enough excess power
to recharge your batteries.
21
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 22
You also should determine how
much time you want to spend
maintaining the batteries. If
maintenance will be regular,
flooded cell batteries are appropriate. If not, a maintenance-free
battery would be a better choice.
If the answer to the question is
“no,” your BOS requirements
will be minor because the turbine
will provide the required power.
Will AC power be required?
Any home, business or factory
hooked to the electrical grid
needs AC power. However, DC
appliances, equipment and lighting are readily available, designed
for use in cottages, recreational
vehicles, and boats. Cottages,
for example, could have both AC
and DC power, with DC running
the lights and a small water
pump. In these cases, the system
will have separate DC and AC
wiring circuits and fuses or
circuit breakers.
If, however, the wind energy
system will be running equipment or appliances designed
to take AC power, you will need
an inverter. An inverter converts
stored DC power (from a battery)
into AC. Many systems actually
use two identical inverters to
increase reliability and improve
operating efficiency.
If you will not require AC power,
you will not need an inverter.
22
Calculating Battery Storage Capacity
Battery capacity is measured in amp hours. Here is how you calculate how
many amp hours of battery capacity you will need.
From your earlier calculations on electrical requirements, you should have
an estimate, likely in watt hours, of how much energy you require each day.
Let us say it is 1,300 watt hours (1.3 kWh). Assume three days is the maximum
amount of time without adequate wind. You will require (1,300 watt hours x 3)
3,900 watt hours.
A typical battery supply would provide 24 volts. The battery specifications tell
you that this battery supply will allow for a 50 percent depth of discharge
(DOD). That means only one-half the total capacity is available without draining
the battery too far.
To find the number of amp hours needed, simply divide the watt hours
by the voltage. In this case, 3,900 watt-hours divided by 24 volts gives us
162.5 amp hours.
But remember, your battery capacity has to be twice this because you do
not want to draw more than 50% of the total capacity (i.e. the DOD is 50%).
Therefore, you need a battery supply rated at a minimum of 325 amp hours
(162.5 x 2) capacity. In fact, it is best to round this number up, say to
400 amp hours.
Is power absolutely required
24 hours per day, every day,
all year?
If the answer is “yes,” you should
be planning a hybrid system which
has a back-up, fossil-fuelled generator. Find out more about hybrid
systems in the next chapter.
The generator could be started
manually by the operator, or, if
uninterrupted power is required,
a remote start generator would
be necessary. This works automatically when the battery
voltage reaches a pre-set lower
limit. Remote start generator
systems are more expensive.
If the answer is “no,” the combination of wind turbine and back
up batteries will be sufficient.
We have included Worksheet #2.
Selecting BOS Equipment (at the
back of the guide) to help you
check off the BOS equipment for
a proposed system. (If necessary,
refer to Chapter 3 for descriptions
of the components.)
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 23
Wind Energy in Use
A small stand-alone system installed in southern Alberta allows a farm
to operate independently of the grid. The farm had been connected
to the grid, but the owner wished to have autonomous power and
to reduce the environmental impact of his farm and home energy
use. The farm’s wind energy system supplies power to a residence
for a family of four, a machine shop, a water well and yard lights.
The peak load is about 5 kW. The wind map of Canada shows that
the region has a 18 km/h (5 m/s) annual average wind speed at
10 metres height.
▼
Power is generated by a 10 kW wind turbine on an extra-tall
33 metre tower. Power from the turbine is rectified (i.e. converted
from AC to DC power) to 48 volts DC for storage in high quality
low maintenance gelled electrolyte cell deep discharge batteries
of 1000 Ah capacity. A 5 kW inverter then supplies 120 and
240 volts AC to the farm and house. To reduce peak loads and
electricity consumption, major energy consuming appliances – the
stove, clothes dryer, furnace and water heater – are fuelled by natural
gas. Additional equipment required to control the power safely
includes a transfer switch, battery charging controls, system monitor
and circuit protection. If the wind turbine has charged the batteries
and is still producing power, a dump load controller “dumps” (or
“shunts”) excess power to pre-heat water for the water heater.
A small stand-alone wind energy system can
supply power to both the farm and residence.
(Information and photo courtesy of Nor’wester
Energy Systems Ltd.)
This system is larger than a non-farming home would require as it provides power for both the home and farm.
The installed cost of the wind turbine, the tower, premium batteries and other BOS equipment was $60,000 (1997).
The farm is now free of utility cost increases and the power being consumed has little environmental impact.
23
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 24
6. Hybrid Wind Energy Systems
• Hybrid systems provide a
reliable source of electricity
• Some pointers to help you
assess whether a hybrid system might be your answer
If the preliminary assessment in
the last chapter shows that you
need reliable power 24 hours a
day every day, a hybrid system
should be considered. Hybrid systems draw on more than a single
source of energy, resulting in a
reliable supply of electricity. A
number of power sources can be
used in combination with wind
energy: solar, gas or diesel generators, and even hydro power.
ment (such as at a remote homestead or for telecommunications
sites), to small applications (such
as for remote community grids).
It is likely not possible to buy an
off-the-shelf hybrid system that
is right for your application, and,
just as with stand-alone systems,
a careful assessment of requirements should be made before
you start shopping.
The rules for assessment of a
hybrid system are similar to
those for stand-alone systems,
but consider the cost and availability of the other source of
energy that makes up the hybrid:
•
•
This remote radio repeater in
Kananaskis, Alberta uses solar
energy to produce electricity in
addition to wind. (Photo courtesy
of Nor’wester Energy Systems Ltd.)
▼
Hybrid systems are far more complex than stand-alone systems
and entail more elaborate design
features. But, depending on your
situation, a hybrid system can be an
attractive option. They are dependable, more environmentally friendly
than fossil-fuelled generators and,
often, are more economical.
Hybrid systems are as varied as
the needs of wind users, from
micro and mini applications,
where dependability is a require24
•
you still have to know the
availability of wind energy at
your site, just as with a standalone system. For a hybrid,
you should also look at the
availability of other renewable
resources, such as solar.
consider the cost of fossil fuel
to power the generator; how
dependable is the supply of
fossil fuel, and how difficult
is it to get the fuel to the site?
you still have to know what
your power requirements are.
Use the same guidelines as
were set out in the stand-alone
assessment in the last chapter –
look at occurrence of peak
loads, daily demand, the
requirement for dependable
power. Keep in mind as well
the quality of power required.
Sophisticated equipment, such
as computers or telecommunications equipment, requires
high quality electricity which
does not fluctuate.
Here is where the assessment
becomes more difficult than for
stand-alone systems. Hybrid systems should be designed for technical reliability and cost effectiveness.
If the generator is to start itself
when wind energy production
drops below a certain point, for
example, sophisticated control
systems will have to be installed.
Even with these controls, the
generator may not start the
instant it is needed. If the generator is running below its design
capacity, it may not be very efficient, driving up operating costs.
Batteries may still be desired
to accommodate excess power
during periods of high wind,
but if the system is providing a
large amount of power, the cost
of battery storage will be high.
To recap, some of the difficulties
in planning a hybrid system are:
•
The variable nature of the
wind and the load make it
difficult to predict how to
match these reliably.
•
Large generator sets used for
back-up do not always start
the instant they are needed.
•
Running a generator set
below its design capacity
is very inefficient.
•
Battery storage can be used
to provide continuous power
in the face of wind variations
and the stop-start operation
of generator sets, but batteries
are expensive, especially for
large loads.
To ensure that your hybrid system
provides dependable power and
is cost effective, you should seek
professional help to assist with
the required analysis and to
consider the design options.
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 25
7. Economics
• Compare costs over the
long term to determine
the real value of a wind
energy system
A wind energy system is a
serious investment, and should
be assessed like an investment. It
is likely wind energy will be cost
competitive, and may even be less
expensive over the long term. But
there is also a chance that a wind
system is just not economically
right for your application. This
section will provide you with
an overview of some of the key
issues in determining whether
a wind energy system is a viable
economic option.
How much does
the system cost?
There are two costs to consider:
initial costs and annual costs.
Initial costs are those that occur
at the beginning of the project
before any electricity is generated.
Annual costs, or operating and
maintenance (O & M) costs, recur
on a regular basis to keep the
wind energy system in running
order. Generally, wind energy
systems have high initial costs,
but relatively low annual costs
compared to, say, a generator
set which requires re-fuelling.
Initial Costs
If you have done the assessment
in Chapter 5, you should have an
idea of the basic configuration for
your system. It is possible now to
obtain a complete system price
for the installation. Alternatively,
you could list the components
and obtain a quote by calling
equipment suppliers and checking
catalogues and price lists.
Helpful Hints
Suppliers should indicate what spare
parts are important for a system so
they can be purchased right away.
The after-purchase price will often
be significantly higher.
Remember to include the costs
for BOS components such as
batteries and inverters, and
other associated costs such as
tower foundations, buildings
for controls or battery storage,
electrical distribution and connection equipment and the
costs of installing all of that.
Once you have added up all this,
you still do not have the initial
cost of the system. There are
also “soft” costs to consider and,
depending on the size and complexity of the project, they can
add considerably to initial costs.
Here are some examples:
Prefeasibility Study: Just going
through the quick assessment
guideline in Chapter 5 will not
be sufficient for larger systems or
hybrid systems. You may want to
call in an expert to take a quick
look at potential, before moving
to higher cost engineering designs
and feasibility studies. A prefeasibility study may be completed
without a site visit, using resource
and demand estimates from other
sources. (Calculate up to 2 percent of the total initial costs).
NRCan has developed a prefeasibility software tool called
RETScreen™ to assist you.
RETScreen™ is a standardized
renewable energy project analysis
software that could help you
determine whether a wind energy
system is a good investment for
you. Please refer to Chapter11,
Need More Information? to
find out how to get your copy
of RETScreen™.
Feasibility Study: This is the design
phase, and the analysis of the
design. It is useful for small and
some micro and mini systems.
Costs will vary depending on
access to the site and the availability of wind data. For a small
hybrid wind energy system, a
wind resource assessment will
be required if no there is no data.
This will involve at least one year
of readings from a tower-mounted
anemometer. A site investigation
will be required for all feasibility
studies. This will try to match the
site with an appropriate design.
An environmental assessment
of the project may be required,
especially if access roads to the
site are needed or there is a possibility of visual impact from a
tall tower. (Calculate up to 7 percent of the total initial costs).
Project Development: For small
wind energy systems and systems
which may be community-based,
project development often requires time and expense. These
costs may include permits and
approvals for construction, land
rights and surveys, project financing, legal and accounting costs,
and project management. (Costs
vary depending on the project).
Engineering: All but the smallest
micro systems will require
mechanical, electrical or civil
engineering services. These
requirements increase as the
systems increase in size and
complexity. (Calculate up to
7 percent of total initial costs).
Transportation: This is often overlooked, but the cost of transporting
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6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 26
equipment to the site can be significant, particularly for remote locations. (Costs vary depending on
the location and application).
Access Road Construction: For
small systems, this is not an issue,
but for larger community- based
systems, year-round access by
road may be important, and roads
may have to be built for drainage
and snow clearance. (Costs vary
depending on the location and
application).
Erection and Installation: The
equipment supplier may install
the system and erect the tower,
otherwise, outside services may be
required. For larger systems especially, special equipment such as
cranes or heavy vehicles, winches
or gin poles may be required.
These can be rented, but might be
costly. Skilled labour may also be
required for mechanical and electrical work. (Costs vary depending
on the application).
Annual Costs
The most important annual
costs are parts and labour for
system maintenance, but,
depending on your specific
application, they may also
include land leasing, property
taxes and insurance premiums.
O&M Costs
The annual Operating and
Maintenance cost for a wind turbine
may be estimated as a percent of the
initial capital cost of the installed
equipment. Values typically range
around 3 percent for a well-designed
and well-built wind turbine.
overhauled after two or three
years of continuous use.
We have summarized some
of these expenses in the chart
below and there is a worksheet
in the Appendix D.
Compare the
alternatives
maintenance costs run in the
range of 3 percent of the initial
capital cost per year. As with
all mechanical and electrical
equipment, maintenance costs
are low when the unit is new,
and increase over time. A good
quality, properly maintained
wind turbine can be expected
to last up to 20 years.
All this information on the cost
of your wind energy system over
time tells you nothing unless
you look at the cost of other
methods of generating electricity.
A thorough analysis is likely not
necessary for some mini and
most micro systems, but as the
systems get larger, a full economic
analysis is valuable.
If you are making a total cost
calculation of a wind system,
use 15 or 20 years for the life
of the project.
Depending on the size and cost
of the system, you may want to
call in an experienced professional to do this analysis. It may
involve such specialized issues
as tax savings, the time value
of money and life cycle costing.
Other equipment may have to
be replaced during the lifetime of
the wind turbine. Include in your
estimate the cost of replacing batteries every five to ten years. For a
hybrid system, a small generator
would need to be replaced or
Life cycle costing is all the costs
incurred over the lifetime of
the project. From the previous
section, we have determined the
Annual Maintenance Cost Components
of a Wind Energy System
Wind turbines require maintenance once or twice a year.
Mechanically-inclined owners
may choose to do their own
maintenance, and that will be
cheaper than paying a technician
to travel to the site and check
the turbine.
Component
Operation Costs
Replacement
Schedule (Approx.)
Wind turbine
Monitoring, routine lubrication
and adjustments; snow,
ice and dirt removal
20 years
Batteries
Monitoring for failure and low state
of charge after recharge, hydrogen
build-up, water levels; terminal cleaning
5 to 10 years
Maintenance costs for most wind
turbines are well-established and
should be available from the
manufacturer. Typically, annual
Gasoline/diesel
generator
Lubrication and servicing; fuel
2 to 15 years
Distribution
lines
Tree clearing and damaged
parts replacement.
As required
26
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 27
approximate cost of a wind energy
system over 15 or 20 years. Now,
we must compare that to the cost
of alternate methods of generating
electricity. For example, if the
alternative is a diesel generator,
you will have to determine the
costs of running a diesel generator
with the same power capacity
over 15 or 20 years. This will
include the cost of the generator,
the cost of replacing or overhauling the generator (since it is
not likely to last as long as the
wind turbine), and, of course,
the cost of fuel needed to run
the generator.
The table below gives an example
of life cycle costing comparisons.
Table 1. Cost Streams
500 W Wind Energy
System with Batteries
Year
0
1 kW Diesel Genset
with Batteries
Initial Cost
Ongoing and Annual Costs Initial Cost
Equipment
Material &
Services
5 Year
Annual
Battery O&M (3% of)
Replacement
system cost
$7480
Equipment
Material &
Services
Ongoing and Annual Costs
3 year
Generator
Replacement
5 Year
Battery
Replacement
Annual
O&M (3% of
system cost)
Annual
Fuel
and Oil
$2280
1
0
$194
0
0
$68
$380
2
0
$200
0
0
$70
$391
3
0
$206
$874
0
$73
$403
4
0
$212
0
0
$75
$415
5
$580
$219
0
$580
$77
$428
6
0
$225
$955
0
$79
$441
7
0
$232
0
0
$82
$454
8
0
$239
0
0
$84
$467
9
0
$246
$1044
0
$87
$481
10
$672
$254
0
$672
$89
$496
11
0
$261
0
0
$92
$511
12
0
$269
$1141
0
$95
$526
13
0
$277
0
0
$98
$542
14
0
$285
0
0
$100
$558
15
$779
$294
$1246
$779
$103
$575
16
0
$303
0
0
$107
$592
17
0
$312
0
0
$110
$610
18
0
$321
$1362
0
$113
$628
19
0
$331
0
0
$116
$647
20
0
$341
0
0
$120
$666
27
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Using Simple
Payback to
Evaluate a
Project
In smaller systems, where the
recurring annual costs are relatively low, you can determine
if a project is viable by using a
simple payback approach. Simple
payback is a straightforward
measure of the number of years
it would take to have your annual
energy savings pay for the initial
and annual costs of operating the
wind energy system. This method
does not account for inflation or
how the value of money may
change over time.
While this approach can be useful
under certain circumstances, it is
not suitable if the annual costs or
the annual savings are large or if
they occur in irregular amounts.
The formula for calculating
simple payback is:
simple payback (in years) = net
installed cost/net annual savings
An example is shown in the
box below.
28
Simple Payback
Energy requirements in a remote cabin are about 2kWh per day. A 500 W wind
turbine with a 20 metre tower and 220 Ah of batteries will cost about $7,500.
Operation and Maintenance (annual costs) and battery replacement every five
years will amount to about 5 percent of the capital costs or ($7,500 x 5%) $375.
The alternative is a small diesel generator which will cost about
$2,500 and $1.56/kWh to run, including fuel and maintenance.
The net installed cost is the initial cost of the wind energy system,
less the original cost of the generator: $7,500 – $2,500 = $5,000
The net annual savings are the annual cost of the generator:
$1.56 per kWh x 2 kWh/day x 365 days = $1,139
minus the annual cost of operating the wind energy system
(which we said was $375):
$1,139 – $375 = $764
Simple Payback = $5,000 ÷ 764 = 6.54, or about 6-1/2 years.
More in-depth
economic analysis
There are other ways to compare
more accurately the cost of
various energy alternatives over
time. Some of these are fairly
complex. If you are interested
in this analysis see Appendix F,
Using Net Present Value (NPV) to
Evaluate a Project and Comparing
Unit Costs of Energy.
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 29
8. Other
Issues
• You may have your own
reasons for choosing
renewable wind energy,
and these are just as important to consider as cost
to consider
Environment. Wind energy is non polluting, reduces the demand on the grid,
and reduces the use of fossil fuels, the construction of hydroelectric dams or
nuclear generators. Buyers of wind energy equipment need to decide whether
and how to put a price on the environmental advantages of wind power use,
and what role the environment should play in the decision-making process.
Chances are you had several
good reasons to consider wind
energy that had nothing to
do with economics. There are
also other considerations to
think about that have nothing
to do with technical issues.
Most of these are difficult to
quantify, but this does not
mean that they do not
have technical or economic
implications, or that they are
less important than those
which can be costed out.
Safety. In cold regions, ice can accumulate on wind turbine blades. This can
cause severe vibrations; the ice may be thrown great distances. Hydrogen venting
from batteries is another potential safety issue. Climbing of towers by the owner
or maintenance persons is a potential liability. Special safety precautions are
required if children have access to the system.
There are also other issues
which cannot be quantified,
but which might impact
your wind energy system.
Noise. With a hybrid system, generator noise may be a problem. It would
be a good idea to listen to the generator to see how much noise it makes
when operating. The turbines themselves are relatively quiet.
The chart below lists a number
of issues to consider when
deciding if wind energy is
right for your situation.
Extreme weather. In some parts of the country, the environment is very hard
on equipment and can cause operational and durability problems for the wind
energy system and batteries.
Neighbours. The proximity of a wind turbine to a neighbour's property should
be discussed with the neighbour before proceeding with a wind energy system
purchase. Neighbours could be concerned about the size of the system and the
noise a system’s generator might make.
Aesthetics. The wind energy system can affect a view, or that of your
neighbours’, and it might block or change an historic landscape.
Corrosion. Corrosion of system parts at locations close to the ocean can be
a problem.
Zoning restrictions and other potential legal obstacles. Local municipal
offices should have information about restrictions on elements such as noise
and permissible tower height.
Local bird life. Birds can be injured or killed if they collide with the blades or
the tower; and their breeding, nesting and feeding habits could be disturbed.
To minimize these potential problems, avoid siting a wind energy system on
a migration route or where many birds nest and feed. The system should be
designed to reduce perching and nesting opportunities. This is typically not
a problem with smaller systems.
Electromagnetic interference. Systems sometimes produce electromagnetic
interference that can affect television or radio reception. The interference can
usually be traced to the generator, alternator, or metal blades. This problem
can be avoided if the parts are shielded, filtered or made of wood, plastic or
fibreglass.
Technical know-how. Some small wind energy system can be maintained
by the owner. This may require basic technical skills. It will save money, but
will require time and the inclination to do what is necessary.
Access. The existence of an access road for remote systems will simplify
construction, maintenance and fuel delivery, and will likely bring with it
associated cost benefits.
Insurance, construction standards, private property deed restrictions
should also be considered.
29
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 30
9. Buying a Wind Energy System
• This chapter provide you
with a guide to shopping
for wind energy system
Experts
Can Help
Finding an expert
To find an expert, contact one of
the organizations or associations
identified in Chapter 11 Need
More Information?
Even if you have diligently followed every step in this guide, it
is very important to consult an
independent expert or a supplier
or manufacturer to ensure that
any system you buy and install is
as efficient, cost effective and safe
as possible. Before approaching
an expert, you should have the
details of your preliminary assessment, and some ideas about
your basic design. Even if you
are a do-it-yourselfer, you should
discuss your project with an
expert before committing to
a particular system.
Some areas where experts can
be of assistance:
Preliminary assessment: They can
review your preliminary assessment and confirm the accuracy
of the energy and wind resource
estimates, and give you some
advice on your preliminary design.
Detailed assessment: They can
visit the site, identify appropriate
applications and do a more
detailed resource assessment, and
an in-depth economic assessment.
System design: They will help you
determine the optimal capacity
of the wind energy system, and
the size and configuration of the
system components, based on
the results of the assessments.
Expert assistance becomes more
important as a system becomes
more complex.
Equipment selection and costing:
Based on their experience, they
can find the best equipment for
your system design.
Cost estimates and financing
arrangements: The economic
assessment and the cost of the
final design will lead to accurate
cost estimates – then you will
know if you need financing
and if so, how much.
Installation, servicing, routine
maintenance: For larger and
more complex systems, outside
expertise in these areas becomes
more important.
Selecting
a supplier
Manufacturers or dealers in wind
energy systems can be a valuable
resource for information.
Different suppliers specialize
in different types of systems.
A supplier should have proven
experience in design and installation of the type of system
you require. Suppliers differ
in terms of the level of service
they provide. Some offer turnkey
(i.e. ready-to-operate) installation.
Others offer the option of direct
purchase from the factory for
self-installation.
Request and review equipment
catalogues and price lists. Many
30
Dealers vs.
Manufacturers
Local dealers may be more familiar
with local conditions, and are in a
better position to provide service
than a more “remote” manufacturer.
Also, dealers may have access to
a choice of systems from a variety
of manufacturers.
catalogues offer useful information about system design.
Do not hesitate about asking
suppliers to see equipment manuals for BOS or wind turbines
you are especially interested in.
Manufacturer’s typically charge
for the manual, but the price
can usually be applied toward
the purchase price of the unit
should a purchase be made.
The manual should describe,
in clearly understood terms,
the assembly and installation
procedure for the unit and
the subsequent operation and
maintenance requirements.
Do not buy from a manufacturer
who does not provide the
required product literature.
Read all the manuals carefully
and look for details that will
answer these questions:
•
What type of equipment
is the inverter capable of
operating?
•
What quality of AC power
does the inverter produce?
•
Does the generator have
remote start capability?
•
What is included in the
BOS package?
•
Are the wiring and smaller
parts supplied?
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 31
Reading Equipment
Manuals
Important Questions
when Choosing a Dealer:
Standard items to review
in the literature provided
by the manufacturer:
•
Years in business?
•
Background or qualifications?
•
Familiarity with local electrical requirements, codes, zoning regulations?
•
Installation and operating
instructions
•
Technical and pricing details available?
•
Maintenance requirements
•
List of customers available for reference?
•
Warranty details
•
Copy of installation and maintenance manual available?
•
CSA verification
•
Independent test reports of equipment available?
•
Other certifications,
e.g. ISO 9000
•
Operational experience satisfactory? Able to service systems
in remote locations? Under various, possibly harsh, conditions?
•
Services offered? Installation? Warranty support? Maintenance?
•
Price and payment options? Purchase the system outright or
lease on a term arrangement? Performance contracting?
•
Member of the Canadian Wind Energy Association?
Think also about local availability.
Replacement parts will be easier
to get if there is a local dealer.
The equipment should have been
on the market for a few years,
and been proven to be able to
operate effectively in a range
of environments.
Ask for designs at different prices
and get a written estimate from
each dealer approached. Finally,
study the warranty agreement
to ensure it covers a reasonable
period and that it includes parts
and labour. Confirm that the
products advertised in brochures
are available, and that they have
a good performance record.
Before committing to a purchase,
shop around. In addition to differing in the range of products
they have to officer, suppliers
may differ in other ways. We
have provided a worksheet in
the Appendix E Worksheet #4.
Dealer Information to help you.
Make sure the final sale is accompanied by a written contract.
The contract should detail exactly
what your responsibilities are
and those of the dealer, including
details about follow-up service
and service contracts.
31
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 32
10. Installing, Operating and Maintaining Your System
• Considerations when
installing your wind
energy system
• Commissioning procedures
• Regular maintenance
Some micro systems are relatively
simple and easy to install and
maintain, but, as systems increase
in size, more expertise is required.
Installation and maintenance
of a hybrid system of virtually
any size requires a fair degree
of knowledge.
Even if you are a do-it-yourselfer,
chances are you should be looking for some expert help in both
the planning and installation
of the system.
If you are involved in the installation, however, chances are
you will have a much better
understanding of how the
system works, and may be
able to do maintenance when
it is not possible to reach a
service representative.
Safety...
Safety...Safety
This cannot be emphasized enough
when working in the field, and wind
turbine installations are no exception. Many potential hazards can
injure you when you are installing
a wind turbine: you can fall off a
tower, you can get struck by falling
tools or parts, you can get struck by
a blade, you can get electrocuted...
the list goes on and on. The only
sure way to avoid getting hurt, or
worse, is to recognize the potential
hazards, and avoid them.
32
Doing it yourself can also save
you money. However, it becomes
your responsibility to ensure
that you have all the required
building and electrical permits
and approvals, and that you follow all the necessary electrical
codes. Read and follow all instructions carefully to ensure safety.
When in doubt, ask for advice!
Installation
Installation requires excellent
mechanical and electrical skills as
well as experience working with
heavy objects and high voltages.
This information is not intended
to serve as a “how to,” it is merely to set out some very basic rules
about installation.
Specifics of installing a wind
turbine vary according to the
size, design and application.
If you are looking for more
detailed information, check the
turbine’s manual, consult the
Canadian Standards Association
Standard CAN/CSA-F429-M90,
Recommended Practice for the
Installation of Wind Energy
Conversion Systems, and ask
about publications available
from the Canadian Wind Energy
Association. We have also listed
other resources in Chapter 11
of this guide.
The basic
installation rules
•
If you do not have the
experience or confidence
to do it yourself, use an
experienced subcontractor.
•
Make sure proper climbing
and tool securing equipment
is used when working with
the tower.
Helpful Hints
Discussing the requirements of
the application with the electrical
inspector and the electrical contractor before you commence the installation will prove to be a valuable
investment in time and dollars.
•
Ensure nobody stands below
the tower since falling objects
can cause severe injury.
•
If the system is using more
than 24 volts, use a qualified
electrician, and seek the local
utility’s approval for hook-up.
•
Planning is key to successful
and inexpensive installation.
Realizing that you forgot to
pick up the cable clips when
you were in town yesterday
is an expensive exercise if
you have a crane holding
the tower in place!
•
Tower foundation requirements are going to depend on
turbine design, tower design
and size and soil conditions at
the site. Before you start, consult a local engineer or contractor to determine whether
the soil at the site requires
special consideration for the
foundation type proposed
by the manufacturer.
•
An installation must conform
to local electrical codes and
regulations. For mini and
small systems in the multi
kilowatt power range, voltages
and current are high enough
to cause problems if they are
not handled correctly. Hire
an electrician.
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 33
•
•
Make sure you have enough
space to assemble the turbine.
Make sure you understand
each step in the installation
and have the right tools at
the right time.
For micro units, turbine erection can be done by hand.
Small unites may need a
tower mounted gin pole and,
if the turbine is larger than
about 10 kilowatts, you may
need a crane or base mounted
gin pole. A small mistake
during the erection phase
can destroy your turbine or
case injury. Fully understand
all the loads and distances
involved in this step.
Commissioning
Once the wind turbine is erected,
it must be commissioned. This
means that tests are performed
on the unit to ensure each of its
systems and subsystems performs
as they are supposed to. The commissioning process will check, for
example, that not only does the
brake work, but it will reliably
engage during an emergency
condition, such as high winds.
Once again, the commissioning
procedure becomes more complex
as the wind energy system
becomes more complex.
The commissioning procedure
should be fully outlined in the
owner’s manual. If the turbine
is not commissioned properly,
the manufacturer may not
honour warranty claims if
problems arise later. It may
also be necessary to have a
manufacturer’s representative
present during each step of
the commissioning procedure,
depending on the size of
the project.
Helpful Hints
You have to be careful during
commissioning, and each step
in the procedure should be
well documented (with notes
describing tests conducted
and results obtained including,
where practical, photos).
Batteries should be kept at the
proper operating temperature;
freezing will damage the cells.
Operation and
Maintenance
(O&M)
Lead-acid batteries that are not
sealed require regular maintenance,
topping up of water and verifying
state of charge.
Most wind energy systems that
are commercially available require
little owner intervention during
operation. For simpler turbines,
such as those used as battery
chargers or water pumpers,
the control systems to ensure
safe and reliable operations
are quite simple.
Unsealed batteries may give off
hydrogen and should be housed
in ventilated enclosures.
Charge and discharge rates should
not be exceeded.
Special switches, fuses and circuit
breakers will help ensure the safe
operation of battery systems.
More complex designs may
change maintenance demands.
Many manufacturers offer maintenance service for the wind
turbines they install. The manufacturer should at least have
detailed information on maintenance procedures and when
they should be carried out.
Most turbines can operate for
long periods of time without
troubleshooting or repair. Minor
maintenance is usually done on
a quarterly basis or twice a year.
More comprehensive maintenance is required annually.
Maintenance can range from
simple checking of oil levels,
which just about anyone can
do, to intricate checking of
gear backlash or blade pitch
settings, which may require
a high degree of expertise.
33
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 34
11. Need More
Information?
Natural Resources Canada
Renewable and Electrical
Energy Division
Energy Resources Branch
580 Booth Street, 17th Floor
Ottawa, Ontario
K1A 0E4
Fax.: (613) 995-0087
Web Site:
http://www.nrcan.gc.ca/es/erb/reed
CANMET Energy Technology
Centre
Natural Resources Canada
580 Booth Street, 13th Floor
Ottawa, Ontario
K1A 0E4
Fax.: (613) 996-9418
Web Site:
http://www.nrcan.gc.ca/es/etb
Canadian Wind Energy
Association (CANWEA)
100, 3553 - 31 St., NW
Calgary, Alberta
T2L 2K7
Toll Free: 1-800-9-CANWEA
Outside of Canada: 403-289-7713
Fax.: (403) 282-1238
Web Site: http://www.canwea.ca
34
Free software
available to assist
you in your decision.
Renewable energy technologies,
such as a wind energy system,
can be a smart investment.
RETScreen™ just made it easier.
RETScreen™ is a standardized
renewable energy project analysis
software that will help you determine whether a wind energy
system is a good investment
for you. The software uses
Microsoft® Excel spreadsheets,
and a comprehensive user
manual and supporting databases
to help your evaluation.
The RETScreen™ software and
user manual can be downloaded
Free from the following web site
at: http://retscreen.gc.ca or by
contacting NRCan by phone
at 1-450-652-4621 or by fax
at 1-450-652-5177.
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 35
Appendix A
Typical Power
Ratings of Appliances
and Equipment
Typical annual energy consumption levels in the following charts
are approximate values, based on
an estimated number of hours use
per small household. Individual
habits and the number of family
members will have a large impact
on overall energy usage. You can
estimate your household hours
of television viewing, vacuuming,
tool usage, and other activities to
determine your annual electricity
consumption. Check the reverse
side and nameplates of your
appliances for watts energy
consumption, and use those
values if they are different from
the information in the table.
Large appliance energy consumption is based on Energuide data
for the standard major appliances
listed. Manufacturer data was
used for the high efficiency
appliances.
Electric hot water heaters and
furnaces are not listed because
it is generally not economical
to use wind energy for these
energy hungry loads.
Typical Daily Energy Consumption of Appliances
(annual kWh includes automatic on/off cycling)
115 VAC Loads
Appliance/Equipment
Power Rating (watts)
Annual kWh
Refrigerator:
450 litres (16 ft3) standard
440
450 litres (16 ft3) hi efficiency
200
113 litres (4 ft ) standard
350
3
113 litres (4 ft ) high efficiency
60
3
Freezer:
540 litres (19 ft3) standard
500
540 litres (19 ft ) high efficiency
440
113 litres (4 ft ) standard
250
113 litres (4 ft3) high efficiency
120
3
3
Dishwasher, excluding hot water
1300
292
Clothes Dryer
4000
500
Stove
800
Block Heater
500
180
2
18
Wringer
300
75
Automatic
500
100
900
100
200
200
Laptop
15
16
Printer
10-300
2-100
Clock
Clothes Washer: excl. hot water
Coffee Maker
Computer:
Portable desk top
35
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 36
Typical Daily Energy Consumption of Appliances
(annual kWh includes automatic on/off cycling)
115 VAC Loads
Appliance/Equipment
Power Rating (watts)
Annual kWh
Drill
300
3
Fan, portable
120
70
Furnace fan
350
1100
Hair dryer
1000
20
Iron
1000
140
60 watt incandescent bulb
60
110
24 watt compact fluorescent
(75 watt incandescent equiv.)
24
44
9
17
1000
100
5
10
400 – 1000
5
12
50
100
2
4
12
30
22
Telephone, portable
3
26
Telephone, answering machine
6
52
14" b&w
40
29
14" colour
90
65
1100
40
800
40
30
10
400
150
Lighting:
fluorescent 15 cm single ended
Oven, microwave
Radio, transistor
Saw, circular
Radiotelephone: idle
Radiotelephone: transmitting
Single side band radio (idle)
Stereo, portable
Television:
Toaster
Vacuum cleaner, portable
VCR
Water Pump
DC Livestock pumps:
36
250 litre/hour @ 6 m head
15
400 litre/hour @ 25 m head
60
180 litre/hour @ 70 m head
72
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 37
Typical Daily Energy Consumption of Appliances
12 VDC Loads
Appliance/Equipment
Power Rating (watts)
Annual kWh
60
5
Auto Stereo
6
7
Clock, digital
5
44
144
5
25 watt incandescent bulb
25
46
25 watt equivalent fluorescent
25
46
200 – 1000
5
b&w (2 hr/day)
20
15
colour (2 hr/day)
60
45
1100
40
24
5
13 l/min automatic demand
90
70
11.6 l/min
36
26
7.5 l/min
18
13
Air Compressor
Drill
Circular saw
Television:
Toaster
Ventilation Fan (15 cm blade)
Water Pump:
37
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 38
Appendix B
Worksheet #1. Annual Energy Consumption
Appliance/Equipment
AC
Total Annual Energy Consumption
38
DC
Rated
Wattage
(W)
Hours
per
day
Hours
per
year
Annual Wh
Wh
(kWh)
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 39
Appendix C
Worksheet #2. Selecting BOS Equipment
BOS Component
Description
Specification
Required
(yes/no)
Batteries
DC to AC Inverter with:
Remote Start Signal
“true sine wave”
Back-up Generator Set:
Manual Start
Remote Start
Other BOS Equipment:
Battery Charger
Disconnect Switch
Yes
Monitoring Equipment
Wiring, Miscellaneous
Yes
Other Equipment (e.g. rectifier)
39
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 40
Appendix D
Worksheet #3. Costing Estimates
Initial Costs
No. of Units
Cost/Unit
Total Cost
Annual Costs
Frequency (yrs)
Total Replace
Cost
Total Annual
Cost
O&M – WTG
annual
O&M – Batteries
annual
Equipment and Materials
Wind Turbine
Tower
Tower Foundation
Batteries
Inverter
Disconnect Switch
Transfer Switch
Distribution Box
Control Building
System Monitor
Circuit Protection
Wiring, Conduit, Misc
Scheduled Spare Parts
Generator Set
Total Equipment/Material Cost
Planning Service Costs (for larger mini and small systems)
Prefeasibility Study
Feasibility Study
Project Development
Engineering
Transportation
Access Road Construction
Erection and Installation
Contingency
Total Planning/Installation Service Cost
Total Initial Costs
O&M – Generator set (including rebuild)
annual
Generator Fuel and Lubricant
annual
Battery Replacement
Gen-Set Replacement
Other Part Replacement
Miscellaneous
Total Annual Costs
40
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 41
Appendix E
Worksheet #4. Dealer Information
Dealer 1
Dealer 2
Dealer 3
Dealer Name:
Address:
Phone:
Fax:
Contact:
Years in Business
Qualifications/Background
Familiar with local electrical requirements, etc.
Technical/pricing details available?
References
System manual available?
Test reports of equipment available?
Experience satisfactory?
Services offered:
Installation?
Warranty support?
Maintenance?
Price
Payment options
Member of CanWEA
General comments/
Observations
41
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 42
Appendix F
Using Net Present Value
(NPV) to Evaluate a
Project and Comparing
Unit Costs of Energy
This section on Net Present Value
and the one following on Unit
Costs of Energy are not intended
to serve as a “how-to,” they are
intended only to give you an
indication of what a professional
will consider when doing a full
economic analysis.
Using Net
Present Value
(NPV) to
Evaluate
a Project
Larger, more costly projects
require a very accurate analysis to
see it they make economic sense.
This is done using a calculation
known as Net Present Value.
Net Present Value determines how
much money you would have to
put aside today to pay for the
start up and operating costs of the
project over its lifetime – keeping
in mind that if you put money
aside today, it would earn interest
over the course of the project.
For example, a Net Present Value
calculation can tell you how
much money you would have to
put in the bank today in order
to have $1,000 in the bank five
years from now at an interest
rate of 5 percent.
For purposes of the Net Present
Value calculation, the rate of
interest is referred to as the
“discount rate.” Today’s dollars
will also be worth more in the
future because of inflation.
42
Most computer spreadsheet
programs have a function to find
Net Present Value, if you want
to try the calculation yourself.
By comparing the costs of
different energy options
in today’s dollars, the true
economic value of any one
option can easily be seen.
Table 2 shows how Net Present
Value has been applied to four
possible energy alternatives: a wind
energy system with batteries; a
photo-voltaic system with batteries;
an extension to the grid; and, a
diesel generator set with batteries.
The calculation shows that despite
the fact the wind energy system
does not have the lowest initial
cost, over time, its cost is the
lowest of the four options.
It makes a number of assumptions which are detailed in the
table caption.
Comparing Unit
Costs of Energy
When alternate approaches produce different amounts of energy,
often the best way to make a
comparison is by calculating the
unit cost of the energy, usually
expressed in dollars per kilowatt
hour ($/kWh). In these situations,
it is important to compare projects based on the present value
of their unit costs of energy, to
make sure they are being evaluated based on a common variable.
Let us consider the example
of a wind energy system as an
alternative to extending a line
to the grid. In our example,
we will consider establishing
a 2 kilometre line from the
grid, as compared to a 500 W
wind energy system.
In the wind energy system, design
considerations do not permit an
increase in the amount of energy
the system can provide. The grid,
on the other hand, can accommodate an almost unlimited growth
in demand. To compare them
fairly, we have to look at the unit
cost of energy generated by the
wind energy system over its lifetime with the unit cost of the
energy generated by the grid.
It is also best to compare the
net present value of the cost
of a kilowatt hour of energy.
We set out the sample
calculations on page 44.
In this case, the wind energy
option is not the preferred choice.
Extending a line to the grid
will cost $1.71 per kilowatt
hour while wind generation
will cost $1.82 per kilowatt hour,
in today’s dollars.
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 43
Table 2. An Economic Comparison of Costs
500 W Wind
Energy System
with Batteries
Year
Initial
Cost and
5 yr. battery
repl.
Annual
O&M Cost
(3% of
system cost)
750 W PV System
with Batteries
Initial
Cost and
5 yr. battery
replacement
$10095
Annual
O&M Cost
($16/month
+ $0.08/kWh)
Annual Fuel,
Oil and
O&M Cost
(3% of
system cost)
1
0
$194
0
$100
$225
0
$448
2
0
$200
0
$103
$233
0
$462
3
0
$206
0
$106
$241
$874
$476
4
0
$212
0
$109
$249
0
$490
5
$580
$219
$580
$113
$258
$580
$505
6
0
$225
0
$116
$267
$955
$520
7
0
$232
0
$119
$276
0
$535
8
0
$239
0
$123
$286
0
$551
9
0
$246
0
$127
$296
$1044
$568
10
$672
$254
$672
$130
$306
$672
$585
11
0
$261
0
$134
$317
0
$603
12
0
$269
0
$138
$328
$1141
$621
13
0
$277
0
$143
$340
0
$639
14
0
$285
0
$147
$352
0
$658
15
$779
$294
$779
$151
$365
$2025
$678
16
0
$303
0
$156
$378
0
$699
17
0
$312
0
$160
$392
0
$720
18
0
$321
0
$165
$406
$1362
$741
19
0
$331
0
$170
$421
0
$763
20
0
$341
0
$175
$436
0
$786
$8613
$2831
$11228
$1456
$3416
$7003
$6529
For the diesel genset system:
The equipment and material
$2280
$10000
$12684
$13416
•
For the grid extension project: The
cost for the extension to the grid is
$5,000 per kilometre; O&M costs
are $0; the annual costs assume
a 6% annual increase in the grid
kWh charge; a $16/month service
$13532
charge to connect to the grid;
and a cost of $0.08/kWh charged
by the utility for electricity.
costs include the cost of replacing
the genset every three years.
Assumptions for Table 2
For systems with batteries: The
equipment and material costs
include the initial hardware
costs plus the cost of replacing
batteries every five years.
$10000
Initial
Cost and 5 yr.
battery repl.
3 yr. gen-set
repl.
$7480
Total
$11444
(Initial, Equipment Replacement and Annual Costs)
•
Initial Cost
(2 km grid
extension)
1 kW Diesel
Genset
with Batteries
0
NPV
•
Annual
O&M Cost
(1% of
system cost)
2 km Extension
to the Grid
•
For all systems: The annual inflation rate for maintenance, battery
costs, and hydro connect fee is 3%;
the discount rate for the calculation of NPV is 6%.
43
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 44
Comparing the Costs of a Unit of Energy
500 W Wind Energy System
with Batteries
2 km Extension to the Grid
Energy Supply
Energy supply remains constant at
1.5 kWh/day, 548 kWh/year over
the 20-year life of the system
Energy supply increases by
3 percent each year for 20 years,
starting at 548 kWh in the first year,
based on 1.5 kWh/day for that year
Total energy supplied after 20 years
6,280 kWh (with no load growth
and after NPV calculation)
7,980 kWh (with 3 percent load
growth and after NPV calculation)
Total NPV of the system
costs after 20 years
$11,445
$13,629 (includes 3 percent increase
in total annual cost of electricity due
to increased load)
Present Value of unit cost of electricity
$1.82/kWh
$1.71/kWh
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6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 45
Glossary
Terminology
Amp (A) is a measure of electric
current; one A of current represents one coulomb of electrical
charge moving past a specific
point in one second (1 C/s = 1 A).
Amp-hours (Ah) is used to
express the storage capacity of a
battery (that is, 100 Ah battery
can provide 1 A over a period
of 100 hours or 100 A over
a period of 1 hour).
Anemometer is a device used
to measure wind speed.
Annual average wind speed
(AWS) is the average of all
instantaneous wind speeds for a
location over the course of a year.
Annual energy output (AEO)
is the total energy produced
by a wind turbine over the
course of a year.
BOS is the Balance of System
or the equipment beyond the
standard wind turbine and tower
required to install a complete
wind system.
Commissioning is the procedure of inspection, installing
and monitoring of a new wind
energy system to confirm proper
operation at startup.
Control system is a sub-system
that receives information about
the condition of the wind turbine
and/or its environment, and
adjusts the turbine to maintain
operation within prescribed
limits.
Current is the rate at which
electricity flows through
a conductor; measured
in amps (A).
Cut-in wind speed is the
lowest wind speed (at hub height)
at which the turbine starts to
produce power.
Cut-out wind speed is the
maximum wind speed (at
hub height) at which the
wind turbine is designed
to stop producing power.
Discount Rate is the assumed
interest rate that is applied to calculate the time value of a future
cash flow. It should account for
the principal and interest that
could have been earned had the
money used for the system been
invested in some other way.
Downwind wind energy
system is a turbine whose
rotor operates downwind of
the tower, that is, in the main
wind direction.
Energy is that which can
accomplish work; usually
measured in Watt-hours (Wh)
or kilowatt- hours (kWh).
Free standing tower is a
tower that does not use external
supports, such as guy wires.
Generator set (genset) a
machine using an internal
combustion engine (gasoline
or diesel) and generator to
produce AC or DC electricity.
Guy anchor is a foundation
designed for guy wire connection.
Guy cable is a cable or wire used
as a tension support between a
guy anchor and a tower.
Hub is the fixture for attaching
the blades or blade assembly of
a HAWT to the rotor shaft.
Hub height is the height of the
centre of the wind turbine rotor
above the ground. For a vertical
axis wind turbine the hub height
is the mid-height of the rotor.
Maximum power (wind
turbines) is the highest sustained
level of net electrical power
delivered by a wind turbine in
normal operation (approximately
the same as Rated Power).
Mean wind speed is the statistical mean of the instantaneous
value of the wind speed averaged
over a given time period which
can vary from a few seconds to
many years.
Nacelle is the housing which
contains the drive-train and other
elements on top of a horizontal
axis wind turbine tower.
Net present value (NPV) is
the value of a system’s lifecycle
costs in today’s dollars.
Photovoltaics (PV) is the
direct conversion of sunlight
into electricity.
Power is the expression of
the rate of doing work. It is
usually measured in watts (W)
or kilowatts (kW).
Power curve is a graph that
depicts the power output of a
wind turbine as a function of
wind speed.
Guyed tower is a tower that
uses external guy supports.
Power output is the amount
of power produced by a wind
turbine at a given speed.
Horizontal axis wind turbine
(HAWT) is a wind turbine whose
rotor axis is horizontal or parallel
to the ground.
Rated power is the power produced by a wind turbine at the
rated wind speed (approximately
the same as Maximum Power).
45
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 46
Rated wind speed is the specified wind speed at which a wind
turbine's rated power is achieved.
Rayleigh wind speed distribution is a statistical curve whose
shape approximates the actual
shape of a wind speed distribution curve. It is used as a standardized distribution curve to
estimate the energy production
performance of a wind turbine.
Rotor is the set of blades of the
wind turbine including the hub.
Rotor speed is the rate of
rotation of a wind turbine rotor
about its axis.
Voltage is a measure of the
electric potential difference
between two points; usually
expressed as volts (V).
Watts is the unit to measure
the rate at which work is done
(power) or energy is consumed;
usually expressed as Watts (W)
or kilowatts (kW). Note that
W = V x A.
Yaw is the rotation of a HAWT
about its vertical axis to align it
with the wind.
Symbols
AC
=
alternate current
Simple payback is the length
of time required to recover the
cost of an investment from the
cash flow produced by the investment. It does not account for
the discount rate.
D
=
rotor diameter
(for HAWTS) m
DC
=
direct current
DOD
=
Depth of discharge
kW
=
kilowatt
Swept area is the area through
which the rotor blades rotate.
It is the area of the disk formed
by the blade rotation.
kWh
=
kilowatt hours
PV
=
Photovoltaic
W
=
Watt
Tower is the structure of a wind
energy system that supports the
rotor and power train, etc., above
the ground.
Upwind wind energy system
has a rotor which operates upwind of the tower. These systems
use yaw mechanisms to keep
them pointed into the wind.
Vertical Axis Wind Turbine
(VAWT) is a wind turbine whose
rotor axis is vertical to the ground.
These turbines do not have to be
yawed into the wind. They will
accept wind from any direction.
46
6126 NRCan Wind-Energy Bklet 3/14/00 9:31 AM Page 47
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