26 February 2008
Wind Energy Among Fastest-Growing Ways of Generating Electricity
Industry strives to meet financial, technical challenges for greater success
Washington -- Engineering advances have made wind energy one of the world’s fastest-growing methods of generating electricity, and multimegawatt wind turbines produce electricity today at costs that are starting to compete with conventional energy sources. But challenges to the industry remain.
In the United States -- the best market for wind power with 5.2 gigawatts (1 gigawatt equals 1 billion watts) of new wind-energy capacity installed in 2007, followed by Spain (3.5 gigawatts) and China (3.4 gigawatts) -- barriers to growth are economic, geographic and industrial.
In economic terms, “the key to maintaining the industry’s momentum is to extend the wind-production tax credit,” Randall Swisher, executive director of the American Wind Energy Association (AWEA), told America.gov. “That has to happen and I’m confident it will, but until we get that done it will be hard for us to focus on a range of other things that are going to be important long term.”
The production tax credit is a federal tax credit created in 1992 to encourage large-scale wind-energy production. Congress has let the credit expire three times over 10 years, Swisher said, creating a disincentive for U.S. and international companies to invest in the U.S. wind-power manufacturing sector.
AWEA, he added, “is seeking as long an extension as possible for the tax credit, but at least five years and ideally 10 or longer.”
A more stable tax credit would augment the growing movement of wind turbine and component manufacturers in Europe and elsewhere into the booming U.S. market. At 56.5 gigawatts, Europe has the most installed wind power of any continent, but since 2005, the United States has been the world’s largest wind turbine market.
“European manufacturers see that if they want to continue growing their business, they need to participate in the U.S. market,” Swisher said, and “to be cost-competitive with a company like General Electric, they need to manufacture here and not be importing their equipment from Europe.”
WIND-POWER TECHNOLOGY
At utility-scale levels, wind energy is produced mainly by massive three-bladed wind turbines that sit atop tall towers and work like fans in reverse. Rather than using electricity to make wind, turbines use wind to make electricity.
Wind turns the blades and the blades spin a shaft that is connected to a generator; the spinning produces electricity. Industry-scale turbines for utilities can generate up to 2.5 megawatts. Homes, telecommunications dishes and water pumps use single small turbines that generate less than 50 kilowatts.
In the 1980s, rotor (blades and hub) diameter averaged 20 meters. Today, a rotor can be 90 meters wide.
“That’s important,” Mike Robinson, Research and Development Group manager at the National Renewable Energy Laboratory’s (NREL) National Wind Technology Center, told America.gov, “because if you make the blade twice as large, you capture four times the energy.”
Technology advances and increased machine size have made wind power competitive with new coal-fired or gas-fired electricity generation if the wind-production tax credit is in place.
“We were looking at [wind] technology 20 years ago that was on the order of 30 to 40 cents per kilowatt hour,” Robinson said. “Now it’s easily down to 5 to 6 cents per kilowatt hour.”
MOVING MEGAWATTS
In wind plants or wind farms, groups of turbines are linked together to generate electricity that is sent to utilities through transmission lines, and such lines are one of the wind industry’s greatest challenges.
In the United States, Robinson said, 70 percent to 80 percent of electricity demand lies within 161 kilometers of the East and West coasts and the Great Lakes.
“That’s where all the big cities are, he added, “so you generate clean electrons [energy] in the middle of the country but you have to push them to both coasts. It becomes a transmission issue and that’s going to be a tough one to solve.”
Building new transmission lines is expensive and, Robinson said, instituting a transcontinental system of such lines would require the complex process of gathering authorizations from each affected state.
RESEARCH PRIORITIES
At NREL, the Department of Energy’s laboratory for renewable energy and energy efficiency research, priorities include making wind turbines more reliable.
“We want to make wind turbines like refrigerators,” Robinson said. “You buy one, put it in your house, use it for 15 or 20 years, and don’t think about it. A lot of our technology development is focused on improving [turbine] drive trains, power electronics, blades, controls -- all the things that go into making a very robust technology.”
Most machines are operational about 98 percent of the time, he added. That means operation and maintenance costs are one quarter to one half a cent of the 5-cent-per-kilowatt-hour price of wind power.
“It’s not a tremendous amount,” Robinson said, “but it’s an operational cost that we think we can continue to improve upon.”
The other priority is to reduce a machine’s overall capital costs -- “make it cheap,” he said, “and that is a bit more of a challenge.” Making a turbine cheaper means making it lighter and, unavoidably, more dynamically active.
“If you make something really strong and stiff and hit it with a strong wind, it doesn’t care,” Robinson explained. “But if it’s more flexible because it weighs less, it’s going to bend and flex, so then you need advanced controls and engineering methods to reduce” the effects of the wind. The solution is to balance weight and advanced controls to arrive at the lowest cost.
In all their wind work, the engineers at NREL collaborate with scientists around the world -- Denmark, Germany, the Netherlands and Spain.
“Wind technology has a very international development focus,” Robinson said. “Scientists and engineers collaborate in terms of equations and technology, and all of us are collaborating to do what we can to improve the technology and bring the costs down.”
More information about wind technology research is available on the NREL Web site.
Additional information about wind energy is available on the DOE Energy Efficiency and Renewable Energy program Web site.
More information about the American Wind Energy Association is available on that organization’s Web site.
