TEAM PROBLEM – CONTESTANT SCENARIO
Situation
Montanans have been hearing a great deal about wind energy resources within
the state, and are interested in learning more. The Governor has organized a
committee to investigate the feasibility of wind power development in Montana.
Your team represents this committee, and includes representatives from
Montana Alternative Power, Basics Inc., and the Montana Department of Natural
Resources. Basics Inc. is one of the largest wind energy equipment dealers in
the United States. You have been asked to look into this innovative technology
and find out if it is practical for Montanans to consider.
You are to submit a preliminary report of your findings to two members of the
Governor’s staff this afternoon. You should include the following in your report:
1.) Should Montana utilize wind power as an energy source?
2.) Where would the best place(s) be to establish a wind farm? Why?
a. Include costs, benefits, incentives, potential difficulties that may
be encountered with the specific location(s), and the resources
necessary to set up and maintain the wind farm.
General Info
WIND POWER
 Wind is caused by the sun’s uneven heating of the Earth’s surface.
 Wind patterns are affected by weather patterns, terrain, and the Earth’s
spin.
 As wind speed increases, wind energy potential increases rapidly.
o (Wind speed doubles=energy content increased by factor of 8)
 California lead the United States in wind development, even though it has
little wind resource.
 Texas and Minnesota are quickly increasing wind power investments.
 Europe is leaving the United States way behind in wind power
development.
HOW WIND ENERGY WORKS
Turbines are placed on high towers and blades that are modeled after
airplane wings rotate when the wind blows. The wind causes a pressure
differential on the turbine blades as it moves over their surfaces. The blades then
cause a rotor to turn which drives an electrical generator. The whole system
works to convert kinetic energy into electrical energy.
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A FEW SPECIFICS
Turbine blades are always oriented to face the wind either by computer
control or naturally by the wind. Turbines are designed to operate at either a
constant speed or at variable speeds. Although the variable speed design is more
complex, it is more efficient at converting wind power into electricity. Most wind
turbines are made to utilize wind blowing anywhere from 9 mph to 65 mph.
Turbine sizes range from 500 kW to 750 kW.
BENEFITS
Wind energy systems provide a cushion against the increasing prices of
electric power. They also help decrease the dependence of the Unites States on
foreign countries for fossil fuels. For people living in remote locations, wind
energy systems can help avoid high costs of bringing utility lines to the site.
These systems are quite competitive with other energy sources over a lifetime of
use through reduced and possibly avoided utility costs.
Unlike fossil fuels, wind power does not create any emissions that lead to
greenhouse gases, particulates, or acid rain precursors. Wind power can have a
negative effect on the environment, however, if not sited or managed correctly.
It is projected that wind energy projects provide three times as many jobs
as the same amount of spending on fossil fuels. Also estimated is that a 240 MW
natural gas plant pulls $28-55 million from the regional economy for annual fuel
imports. By using wind energy systems, more money can be reserved in local
companies and the possibility of extra income going to property owners in the
form of power sales or royalty payments is much greater.
DISADVANTAGES
Wind systems are associated with a high initial investment. Payback
periods, the time before the savings equal the cost of the system, depend on the
chosen system, wind resources, area electricity costs, and management of the
system.
DECIDING IF A SITE IS RIGHT
Although Department of Energy (DOE) maps showing the average wind
speeds and resources are available, each site in question will vary depending on
a variety of factors. It is important to understand the wind resource at the
location in question. If you don’t have site specific data, it is a good idea to
measure the wind speeds at your site for a year to acquire a more accurate and
predictable idea of the wind resource available. (The costs of doing this are not
really worth it when looking to install a wind turbine in a small residential area.
For that situation, the DOE maps are generally sufficient.) One way to do this is
through the use of a recoding anemometer. The best height for recordings is at
the elevation at the top of the tower, where the wind turbine would be
positioned, which is also called “hub height”. The Department of Energy uses a
standard of 33 feet (10 meters) to obtain data. The anemometer has to be
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TEAM PROBLEM – CONTESTANT SCENARIO
placed high enough to not be affected by trees, buildings, or other obstructions
that may change the data. The cost of a recording anemometer can range from
$500 to $1500.
It’s important to consider the terrain when choosing an installation site.
Considering both current and future obstacles, including buildings and trees, is
wise. Also important to realize is that the available power increases exponentially
as wind speed increases. A site with 12.6 mph average wind speed would
produce twice as much energy as a site with an average wind speed of 10 mph.
Before spending much time or money, it’s a good idea to check into the
potential environmental and legal obstacles to installing a wind system. There
are some jurisdictions that limit the height of structures permitted in residentially
zoned areas. It’s usually easy to get a variance, however, thought the neighbors
might not appreciate an obstacle in their view or might be worried about noise.
When interested in connecting the wind energy generation system to the local
utility company’s grid, find out its requirements for interconnection. Obtaining
costs and performance data from manufacturers is also very beneficial along with
understanding the basics of a wind system.
PRICING A SYSTEM
To better define what size of turbine is needed, an energy budget should
be formed. Keep in mind that energy production is often more expensive than
energy efficiency, meaning that it’s wise to make a house (or anything else)
more energy efficient and therefore requiring less energy. Have your financial
advisor conduct a thorough analysis before deciding on a wind energy system.
After deciding that a wind energy system can be used legally and without
any major problems, start pricing various systems. Make sure to research
whether the manufacturer is recognized as a wind energy business and that
parts and services will be available when needed. Check out the warranty: it’s
time frame and what is included. Another good idea is to ask for the names of
customers with similar wind energy systems to the one you are considering.
Those people can give you a better idea about the performance, reliability,
maintenance and repair, and if the system is satisfactory.
LARGE WIND TURBINES
 They are huge machines and used mostly in wind farms.
 They require large amounts of wind because they must compete with
conventional energy generation, such as coal, natural gas, oil, and
nuclear.
 They are not often used for “off-grid” applications.
 They can produce electricity less expensively than power from coal or
nuclear plants.
 There are many subsides available for them.
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SMALL WIND SYSTEMS
 They are used principally for individual homes, businesses, or facilities.
 They can be used “on-grid” or “off-grid”.
 “On-grid”, also called grid-connected systems, are used along with an
electricity transmission and distribution system. If there isn’t enough wind
and the turbine can’t deliver the energy required, the utility provides the
difference.
 “Off-grid”, also called stand-alone systems, are used alone.
 They generally cost more than large turbines.
 They can be used in areas with less wind resources and can compete at
the retail level.
 Not many subsides are currently available.
SITUATION FOR A STAND-ALONE / OFF-GRID SYSTEM
 Area with annual wind speeds of 9 mph or greater
 No available grid connection or only made with an expensive extension
 High cost of running power lines ($15,000-$50,000 per mile depending on
terrain)
 Interest in gaining independence from the utility
 Concern about environmental impact of electricity production
 Understand the intermittent characteristic of wind power and have a plan
to deal with the irregular power resource available to meet needs
SITUATION FOR A GRID-CONNECTED / ON-GRID SYSTEM
 Area with annual wind speeds of at least 10 mph
 Expensive utility-supplied power in the area (10-15 cents per kilowatt hr)
 Economical requirements for connecting wind system to the local utility’s
grid
 Building codes & land covenants allow legal installations of a wind turbine
 Feel at ease with long-term investments
 Available net metering
RESIDENTIAL WIND TURBINES
For a typical residential purpose, a home is served by both the local utility
and the wind turbine (on-grid/grid-connected systems). The cut-out wind speed,
under which no output is received from the turbine, is generally 7-10mph. If a
system produces more power than the house needs, the extra electricity is
usually sold to the utility.
In a residential application, a wind turbine will typically lower an electricity
bill by 50%-90%. Of course this depends on many factors, including the location
of the residence and the cost of electricity in that area. The amount of money
saved in the long run by installing a wind energy system depends on those same
factors as well as the system’s cost, the average wind speed at the particular
site, and many other aspects.
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Homes use 9,400 kilowatt-hours (kWh) of electricity per year on average,
which calculates out as about 780kWh per month. A wind turbine rated in the
area of 5 to 15 kilowatts would be needed to make a significant impact on the
demand of the residence, once again depending on average area wind speeds.
If economics are a concern, use this rule of thumb: a small wind turbine
owner should have at least a 10mph average wind speed and should be paying
at least 10 cents/kWh for electricity to make the system worthwhile. Many times
a wind system will recover its investment through utility savings within six to 15
years. After that time, electricity produced from the wind-energy system is in
effect free. A residential wind-energy system investment is like any other
improvement and increases property value, assuming it’s well-sited. Currently in
the United States, people purchasing residential wind-energy systems are often
doing so in preparation for retirement. They don’t want to be subjected to the
ever-changing utility rates and see this as an economical avenue to guard
against that.
ESTIMATED SYSTEM COSTS
These are some general estimates of system costs, including installation. Price
variances are due to actual size, application, service agreement, warranty details,
shipping, and grid hook-up costs.
Small wind turbine system
$6,000-$22,000
Mid-sized wind turbine system
$13,000-$42,000
Large wind turbine system
$28,000-$68,000
Industrial wind-turbine systems
$45,000-$95,000
FINANCIAL INCENTIVES
Many states provide financial incentives for the installation of wind energy
systems. There are also federal incentives. In Montana, a personal tax credit is
offered for residential, industrial, and commercial users. A 35% tax credit for an
individual, partnership, or corporation is permitted for those investing $5,000 or
more in a wind electricity generation system, or facilities used to manufacture
wind energy equipment. Property eligible for tax deductions include those
containing wind energy equipment, transmission lines, and equipment used to
manufacture wind energy devices.
WHAT ABOUT MONTANA?
When considering Montana, Washington, Oregon, and Idaho, Montana
has the greatest potential wind energy by far. Washington comes in with the
least at 3,700aMW and Oregon follows not far ahead with 4,900aMW. Idaho has
a slightly greater potential with 8,300aMW. But Montana outdoes them all with a
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potential wind energy rating of 116,000aMW. Montana has the potential to
provide enough wind energy for 15 percent of the US electricity demand; Oregon
and Idaho could supply all of their power requirements through wind energy;
Washington could supply power for approximately 3 million homes by tapping
their wind energy resources.
The great wind energy resources in Montana are a result of being located
in the zone of prevailing westerlies. Winds blowing from the poleward side of the
subtropical high pressure belts are repelled toward the east as the transition into
higher latitudes. These winds, extending from 35-60 degrees (north and south)
latitude, are labeled prevailing westerlies.
There are many factors that play a role in determining the circulation of
air, including insolation, gravitation, condensation, and rotation. The interaction
of these forces produces more specific forces which establish the motion of air in
a particular area. These more specific factors include:
Pressure gradient force-- the force that drives air from areas of high
pressure to those of low pressure
Coriolis force—deflects air to the right in the northern hemisphere due to
the earth’s rotation.
Centripetal force—comes into play when air is moving in a curved instead
of straight path along the earth’s surface
Frictional forces—includes friction between earth’s surface and the
atmosphere as well as atmospheric internal friction
When determining the wind aspects at a certain location, frictional forces
are the most important. Mountain passes, high-elevation plateaus, long valleys
coming down from mountain ranges, mountain rides and summits, and the
leeward slopes of mountain ranges perpendicular to the prevailing wind are all
surface features linked with high wind speeds. Features associated with low wind
speeds are sheltered basins, valleys perpendicular to prevailing winds, and areas
of high surface roughness. In Montana, four different wind areas are recognized:
western valley floors, eastern slopes, east and northeast plains, and exposed
mountain crests.
WESTERN VALLEY FLOORS
The western third of Montana is quite mountainous. This region has many
parallel mountain ranges containing deep valleys, usually running north-south or
northwest-southeast, between them. Since these valleys are parallel to the
prevailing wind direction and because of their depth and narrowness, average
winds speeds are low. Periods of stagnation (no wind movement) are common,
although some specific areas occasionally see high winds because of airflow
through mountain gaps.
--Montana valleys include: the Flathead, Bitterroot, and Deer Lodge
valleys in western Montana; the upper Missouri River, Shields River, and
Smith River valleys in west central Montana; and the Big Hole and
Jefferson River valleys in the southwestern part of the state.
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--Areas with occasional high winds include: the Kalispell-Columbia Falls
area and the Hellgate Canyon east of Missoula.
--Data collection sites include: the Missoula Hoerner-Waldorf site, the
Ronan Nine-Pipes site, and the Kalispell Airport site.
--Data results:
o Average annual wind speeds vary from 5-10 mph.
o Average annual wind power density ranges from 20-80
watts per
square meter (watts/m^2).
EASTERN SLOPES
Downslope areas, found along the eastern front of mountain ranges
adjacent to broad valleys, see quite strong winds. This happens when air flowing
over the mountains is compressed and accelerated as it flows down the
mountain slopes. Often a strong pressure gradient is present, causing wind
speeds to be quite high. Winds are even stronger when channeled through eastwest oriented valleys.
--Eastern slopes include: the Anaconda area, the lower Jefferson River
valley near Whitehall, and the whole Rocky Mountain front as the
mountains meet the plains.
--Areas with stronger winds resulting from east-west mountain valleys
include: the upper Yellowstone River valley from Livingston to Big Timber,
the Browning-East Glacier-Cut Bank area, the Musselshell River valley
around Harlowton and Judith Gap, the Jefferson River valley near
Whitehall, and the Missouri River valley from Cascade to Great Falls.
--Data collection sites include: the Livingston Candidate Wind Turbine site,
the Bureau of Reclamation’s Judith Gap and Cut Bank sites, and the
Whitehall Airport site.
--Data results:
o High seasonal variation in wind speed and power density.
o Highest seasonal wind speeds occur during the winter and range
from 12-25 mph while lowest seasonal wind speeds are found in
the summer and vary from 8-12 mph.
o Average annual wind speeds range from 10-16 mph.
o Average winter wind power density varies from 600-2000
watts/m^2 and during the summer it ranges from 100-500
watts/m^2.
o Average annual wind power density is between 150 and 500
watts/m^2.
EAST AND NORTHEAST PLAINS
As the eastern slopes of the Rocky Mountains turn into the east and
northeast plains, the surface roughness and low to moderate relief of the land
cause wind movement to be dominated by pressure gradient forces. Prevailing
winds come from the northwest and southeast.
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--These plains include: the corner of Montana east of a Malta-Baker line.
--Data collection sites include: the Scobey Hanrahan site, the Glendive
Microwave site, and the Glasgow Airport site.
--Data results:
o Highest average seasonal wind speeds are seen during the spring
and are generally from 12-16 mph and lowest seasonal wind
speeds are in the fall and range from 4-10mph.
o Average annual wind speeds range from 10-13 mph.
o Average annual wind power density ranges from 100-300
watts/m^2 in the spring and from 50-150 watts/m^2 during the
fall.
EXPOSED MOUNTAIN CRESTS
All Montana mountain ranges have exposed ridges and crests where wind
speeds are high. Air flowing over a mountain range is compressed and
accelerated, but total effects depend on mountain orientation in respect of
prevailing wind directions, slope and elevation of the range, and the location and
height of close mountain ranges. Not much data has been collected from these
areas, but what has been shows high wind speeds and wind power levels.
Data collection: received primarily from the US Forest Service and some
from Oregon State University researchers.
Data results:
o Average wind speeds range from 14-20 mph.
o Average wind power densities vary from 200 to greater than 500
watts/m^2.
AVERAGE ANNUAL WIND SPEEDS FOR MAJOR MONTANA CITIES
Billings
11.65 mph
Cut Bank
12.60 mph
Dillon
9.10 mph
Great Falls
12.40 mph
Havre
10.40 mph
Helena
7.90 mph
Kalispell
6.90 mph
Lewistown
10.10 mph
Livingston
14.10 mph
Miles City
10.80 mph
Missoula
6.50 mph
Sources: Renewable Northwest Project, Bergey Wind Power Company,
Residential Wind Energy, Solar Plexus, Pine Ridge Products, Windustry, “Wind
Energy Potential” newspaper article, Montana Green Power, MSU Ag Econ Dept.
MONTANA STATE AG SALES & SERVICE CDE 2004