Wind Energy: Power from the Prairie
By Ron Rebenitsch
Serious investment in wind production could yield
cheap energy.
It is one of those rare times when the North Dakota prairie is silent.
All is quiet, except for the call of a bird and the yip of a coyote in the
distance. In this part of the country, such stillness does not last long and
soon the air begins to stir. A breeze begins to flow across the land,
reaching the blades of the giant wind turbinesalert
sentinels on the prairie quietly waiting for the wind to bring them to life.
The breeze
reaches a gentle 3 mph and slowly begins rotating the wind turbine's three
giant white fiberglass blades, each 120 feet long and weighing 16,000
pounds. The breeze must then increase to 8 mph before the turbines can begin
to produce electricity. At that point, the wind turbine only generates 25
kilowatts of electricityjust enough for a few homes. However, as the wind
picks up more speed, the amount of power generated by the turbine increases
rapidly. It is going to be another windy day on the Dakota prairie, and
electricity generated from the wind begins to flow from the prairie to the
cities and towns of the region.
Wind energy from the Great Plains has the
potential to develop into a significant energy source for the United States,
and wind energy projects are beginning to appear in areas that have seen
little economic activity since the Depression of the 1930s.
North Dakota has
often been called the "Saudi Arabia of Wind" because of the steady and
consistent winds sweeping across the prairie. A study sponsored by the
Department of Energy ranked North Dakota as the top U.S. state for its
potential to produce wind energy. Until recently, California generated
the most wind energy of any state due to its early and widespread
development of wind projects; however, California's total potential is
far behind most of the Plains states, which contain good to excellent
wind resources and promise to be a growing source of energy in years to
come. Just recently, Texas surpassed California in wind generation and
is continuing to add wind projects at a hurricane pace.
Wind energy is unique in that the amount of
energy available increases dramatically as the wind's speed
increases. This means high and steady winds are critical to the development
of wind-energy projects. As a result, the Great Plainsespecially the
Dakotasare a prime location for the development of farms to harvest wind
energy for driving electrical generators. Throughout the year, the wind in
the Great Plains is blowing most of the time (as any local resident will
tell you). The vast prairies allow the wind to flow smoothly and faster
without causing the turbulence found in mountainous or wooded regions. At
the same time, the rolling landscape provides gently sloping ridges ideally
suited for wind turbines. This combination makes for an excellent wind-energy resource.
Despite these advantages, Plains wind-energy producers face
the challenges of transferring the power from turbines to the electricity
market and then competing in that market. Although tax credits and benefits
reduce the actual cost of the wind-generated electricity to levels below
that of many conventional resources, two hurdles remain:
the lack of
electrical transmission lines and the intermittent nature of wind energy.
The
Dakotas and surrounding states are eager to develop this vast resource but
lack the large electrical transmission lines needed to export the power from
the rural windy regions to the energy-hungry cities often located far away
from the wind. The electrical grid needed for that task has been described
as "the biggest machine on the planet." Hundreds of power plants,
interconnected by thousands of miles of transmission lines across many
states, are all running in precise synchronization with each other. At any
given instant, the power grid must have power plants generating exactly the
same amount of power that customers are using.
Most regions of the Great
Plains have a very low population density, so the number of electrical lines
in the region is limited. These lines are already used to export power from
existing generationfossil-fueled power plants and hydropower from the
large federal dams on the Missouri River. Most of the transmission lines in
the regional grid are 20 to 50 years old and were designed and built for the
generation projects and consumer loads that either already existed or were
planned at that time. To move additional energy from sparsely populated
windy regions to the areas where the power is needed, this electrical grid
urgently needs to be upgraded and expanded.
Unfortunately, when the cost of
upgrading the transmission system is added to the cost of wind-generated
power, the economics of building a wind project becomes difficult.
The
second hurdle faced by wind energyits intermittencyarises from the fact
that, no matter how efficient the giant wind turbines have become, they can
only generate power when the wind is blowing. Even then, constant changes in
the speed of the wind means the output can vary dramatically and frequently.
This intermittency reduces wind energy 's value because it cannot be easily
scheduled to meet the demanding needs of the electric market. As one
engineer put it, "We have a 'flip-the-switch ' power system. Every time
consumers flip the light switch, they expect the lights to go on." Not only
must the electrical grid supply power to those consumers instantly, it must
also meet very exacting electrical requirements as it does so.
Given the
need for a constant and reliable source of electricity, an intermittently
generating wind turbine cannot replace the existing generators. However,
when the wind blows, the power from the wind turbines is fed into the grid,
allowing the existing generators to work a little less hardand consume
less fuel. Wind energy is thus a "fuel displacer," conserving the fuel that
would have been burned in conventional power plants. In addition to
conserving fuel, wind energy helps reduce the emissions that
would have otherwise resulted from the burning of that fuel.
The windas a
fuelis free, but it costs money to build the wind turbines and
interconnect them to the grid system. And the cost of wind-generated
electricity must be competitive with the fuel it displaces in order to
succeed in the electricity market. Right now, coal is more competitive
because it's a cheap fuel. Coal is used to generate more than half of the
electricity in the United States and is expected to continue to be a major
fuel source for the foreseeable future.
In other areas, however, wind energy
as a fuel-displacer can be very competitive with natural gas. The high
prices for natural gas now exceed the cost of energy from advanced wind
technology, even without considering some current federal tax benefits. That
is a change from the 1980s and 1990s, when generous supplies of natural gas
were available at reasonable prices.
The high price of natural gas, combined
with a strong desire to minimize environmental impact of power generation
has resulted in the wind energy industry seeing record growth in the United
States. This growth is important not only because of the environmental
benefits, but also because the generation, of wind energy means reducing the
consumption of natural gas. Just as we all select less-expensive products
when shopping, the electric industry is eager to reduce its use of
expensive natural gas when the wind is blowing.
In August 2006, a major
milestone was reached when the amount of utility-scale wind power installed
in the United States reached 10,000 Megawatts, according to the American
Wind Energy Association. That amount of generation is enough to provide for
the average energy needs of about 1.6 million households. That wind energy
displaces and conserves natural gas for other needs, such as home
heating.
Despite advances in technology, continued growth of the wind
industry is limited by the uncertainties of the production tax credits,
which Congress has allowed to expire several times over the last 10 years.
The Energy Policy Act of 2006 extended the credit again, but for only a
brief period. These "on again, off again" tax policies have caused the
wind-generation industry to experience several boom and bust cycles, as the
credit has been extended, then allowed to expire. This uncertainty makes it
difficult for industry to build the expensive production facilities to lower
the cost of producing wind-energy equipment. Building large efficient
factories requires long-range planningand the uncertain support of the
federal government makes it difficult to make the necessary large
investments. As a result, wind energy is far more advanced outside the
United States, especially in places like Germany, Spain, and Denmark, where
the market is seen as more stable.
Compounding the market uncertainty for
wind energy in the United States is the inadequate transmission
infrastructure, which poses a serious threat to the entire economy. Over the
years, the once-strong electric transmission infrastructure has grown
increasingly congested and stressed. Local opposition and muddled government
policies have made it difficult to build the transmission lines necessary to
move the power from the generating plants to the population centers.
Wind
energy is here to stay and will grow, offering one more piece of the puzzle
that the United States needs in order to assemble a sound overall energy
portfolio that is not dependent on just one fuel or one technology. In
short, boosting wind power in the United States will require:
- Extending the production tax credit long enough to allow the
construction of the factories to produce the wind turbines in high
volume to bring down their cost.
- Supporting research into storage technologies to mitigate the
intermittency of wind generation.
- Upgrading the
national energy transmission system, which would also improve energy
security by providing better management of regional electrical grids
About the Author
Ron Rebenitsch is a registered professional engineer and manager at
the Basin Electric Power Cooperative, a large regional power supply
cooperative. E-mail rebenitsch@bis.midco.net.
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