NREL — Keeping Up with the Rapidly Growing Wind Industry
Wind energy — it's the fastest growing electricity-generating technology in the world. And thanks to the successful research and development partnerships between industry and DOE's Wind Program at NREL and Sandia National Laboratories, it's breaking U.S. records as well.
In the past 10 years, global installations of wind energy systems have grown at least tenfold—from a total capacity of 2.8 gigawatts (GW) in 1993 to almost 40 GW at the close of 2003. In the United States, wind energy installations tripled in only 5 years. Totaling less than 2000 MW in 1998, the capacity of wind energy installations added up to more than 6000 MW in late 2003.
Robert Thresher, director of the National Wind Technology Center, stands at the base of a new Clipper wind turbine drive train that as researchers prepare the machine for fatigue testing on the center's 2.5-MW dynamometer test bed.
"Wind energy is real, it's no longer a dream," said Bob Thresher, director of the National Wind Technology Center (NWTC) at NREL. According to the American Wind Energy Association (AWEA), businesses around the world invested $9 billion in wind energy technologies in 2003.
Explaining why wind energy is growing faster than other electricity sources, Thresher said, "With the current fuel prices, wind is the most cost-effective energy source out there, and it's a clean, domestic, renewable resource that can wean the United States from its dependence on foreign fuel sources. There's enough wind energy resources on- and offshore to more than meet the electrical energy needs of the country."
This great progress in wind energy is largely the result of the research and development activities conducted under the U.S. Department of Energy's (DOE's) Wind Energy Program by NREL and Sandia National Laboratories with their wind industry partners.
"From watts to megawatts, from design to integration, NREL has worked by the wind industry's side for more than 20 years to advance the technology and make wind energy cost effective," said Thresher. During that time, the cost of wind energy dropped from 80¢ (in current dollars) per kilowatt-hour (kWh) to about 4.5¢/kWh for utility-scale production.
Although 4.5¢/kWh comes close to competing with conventional fuels, the cost of wind energy must fall further to be truly competitive. One major goal of the Wind Program, therefore, is to reduce the cost of utility-scale wind energy to 3¢/kWh onshore and 5¢/kWh offshore by 2012.
Another important goal for the year 2007 is to produce electricity from small, distributed wind systems in Class 3 wind resource areas—areas with average annual wind speeds of 5.6 meters per second (m/s) at a height of 10 m above ground—at a cost of 10¢ to 15¢/kWh. Today, that's the cost of producing electricity in Class 5 wind resource areas, with average wind speeds of 6.4 m/s at 10 m.
NREL's New System Cuts Blade Testing Time in Half
As wind turbine blades become longer and more flexible, they also become more difficult to test for endurance. At the same time, test methods developed for smaller blades have become more expensive and less effective.
To test the new, larger blades, NREL's researchers have developed a novel hydraulic resonance blade test system to replace a conventional system that uses a hydraulic actuator to push the blade up and down in millions of cycles for up to 4 months. The new system contains a 317.5- to 453.5-kg (700- to 1000-lb), hydraulically actuated weight housed in a fixture attached to the end of the blade. The exact weight used depends on the size of the blade, and the weight is precisely controlled to oscillate up and down and excite the blade at its natural flap frequency.
The new test system uses one-third as much energy as the conventional one does, and the blade oscillates at more than twice the conventional rate. It now takes less than 2 months to apply 3 million cycles to fatigue test a blade. The new system, which will test blades manufactured for giant multimegawatt turbines, will be the only one of its kind in the world.
Testing Industry's Giants
To achieve these goals, NREL and its industry partners are taking on some difficult technological challenges. These include finding ways to increase production, reduce construction costs, and design utility-scale machines that can operate cost effectively in areas with lower average wind speeds—for example, Class 4 wind resource areas where wind speeds are from 7 to 7.5 m/s at 50 m. For wind systems to be cost effective in these areas, larger turbines will be needed.
In 1997, the average turbine was about 60 m tall and produced enough electricity (600 to 750 kW) to power about 200 to 300 average homes. Today's turbines are almost as tall as the Statue of Liberty (93 m), with rotor diameters larger than the wingspan of a jumbo jet (64 m), and they produce enough electricity to power more than 500 homes. Some turbines on the drawing board are even larger.
As our industry partners develop these multimegawatt giants, NREL plans to accommodate them by upgrading its test facilities at the NWTC, which are just south of Boulder, Colorado. Dedicated in 1996, NWTC facilities were designed to test turbines rated at up to 1.5 MW. But in less than 10 years, the wind industry has nearly outgrown this world-class research center. In September 2004, for example, TPI Composites sent the NWTC a wind turbine blade 45 m long—a good 13 m longer than the test facility. To meet TPI's immediate needs, NREL is building a temporary 50-m blade test stand.
NREL's future plans for expansion will allow researchers to test wind turbines rated up to 8 MW as well as related turbine components. If a new, 70-m structural blade test facility and an 8-MW dynamometer test bed are approved, NREL will begin constructing them in 2006.
Partnering to Harvest More Wind
According to NREL's wind energy technology manager, Brian Smith, DOE's Wind Energy Program is the only government program in the world that has a comprehensive plan for developing turbines that take advantage of wind resources at lower average wind speeds. "Our plan is centered on strong technology partnerships with industry. We believe combining NREL's research expertise with industry know-how is the best way to bring competitive wind technology to commercial markets," Smith said.
The NWTC prepares to test Clipper's innovative, 8-generator, 1.5-MW drivetrain on their 2.5-MW dynamometer test bed.
Most wind farms developed to date take advantage of our country's best wind resources—areas that have an annual average wind speeds between 8 and 9 m/s at a height of 50 m. As the wind industry continues to grow, excellent wind resources will be developed closer to load centers, which is more economical, leaving only hard-to-access sites and those with lower wind speeds.
DOE launched efforts to develop low wind speed technologies in 2001 with a request for proposals from industry to participate in the program in any of these three areas: (1) concept studies, (2) component development, and (3) full-scale prototype development. In 2004, DOE launched the second phase of this effort with a solicitation to develop advanced systems, components, and concepts.
The second solicitation identified 21 public-private partnerships to be negotiated by NREL and Sandia National Laboratories. They represent a DOE investment of $30 million over 4 years and will include an additional investment of $30 million from industry.
NREL has formed partnerships with such companies as Advanced Energy Systems, AWS Scientific, Berger/ABAM Engineers, Inc., BEW Inc., Clipper Windpower, Concept Marine, GE Energy, Global Energy Concepts, NA Technology, New Generation Motors, Northern Power Systems, Peregrine Power, and TPI Composites. The partnerships have generated prototype turbines, advanced drive trains, new blade designs, novel blade manufacturing composites, advanced control systems, and new tower designs. GE Energy alone has produced more than 2,500 1.5-MW wind turbines—the descendents of proof-of-concept turbines developed in partnership with DOE.
Southwest Windpower's Storm wind turbine is designed to operate quietly in areas with low wind speeds, and it can be marketed to consumers like household appliances.
Developing Advanced Small Wind Turbines
NREL also works with turbine manufacturers to develop advanced small wind systems for agricultural, residential, and business applications. Small distributed wind systems can make a significant contribution to our nation's energy needs. The industry estimates that 60% of the United States has enough wind resources to make small turbines a good option. They also know that 24% of the population still live in rural areas.
The ranchers, business owners, and homeowners of rural America can use small wind turbines to reduce their utility bills and stabilize their electricity supplies. In addition, they will be displacing carbon emissions from conventional fuel sources and helping to reduce our dependence on foreign energy by feeding their excess generation into the utility grid.
To help increase the use of small turbines, NREL researchers work with manufacturers to make the machines more efficient, less noisy, and more aesthetically appealing. An Arizona company, Southwest Windpower, has worked with NREL since 2000 on a small turbine that can be marketed to consumers like a household appliance. And Oklahoma-based Bergey Windpower has worked with NREL since 1997. This partnership is perfecting a 50-kW wind turbine suitable for agricultural and small business applications.
Overcoming Barriers
In addition to rising to the technological challenges, researchers are tackling barriers that block the widespread development of both onshore and offshore wind installations. Regional transmission constraints, operational policies, and misunderstandings about the impact of wind energy on a utility grid are three barriers to future development. To better understand utility grid integration issues, NREL works with rural electric cooperatives and utilities to collect much-needed data on fluctuations in wind farm power output and effects on utilities. This helps researchers evaluate the interconnection and system impacts of both current and proposed wind farms.
NREL and DOE also cosponsored a Wind Integration and Interconnection Workshop with AWEA, the Utility Wind Interest Group, and the International Council on Large Electric Systems in May 2004. The event drew more than 160 participants and provided detailed information on analysis methods used in operating impact studies, capacity credit valuations, interconnection issues, and worldwide grid code efforts.
To further address deployment barriers, NREL participated in a National Wind Coordinating Committee meeting in June 2004 to discuss relevant transmission and wind development siting issues in the Southwest Power Pool region. The meeting drew more than 40 participants representing utilities, the wind industry, environmental groups, regulatory bodies, and state and federal government groups.
At the state and regional levels, NREL's Wind Powering America (WPA) team makes use of state-, utility-, and Native American-based strategies to identify and address barriers to wind energy development. WPA's goal is ensure that at least 30 U.S. states have at least 100 MW of wind capacity by 2010.
State-Based Strategies. At the state level, WPA team members help coordinate meetings that provide local landowners and businesses, utilities, developers, and other interested parties with information about the technology and the economic impacts of wind energy development in rural areas. They also provide area wind resource maps and information about anemometer loan programs and local policies and incentives. The key outcome of these meetings is the formation of a wind working group in each state to encourage wind development.
To help developers identify areas with the best wind resources, WPA facilitates a cooperative mapping and wind measurement effort. This effort supports a public/private-sector mix of wind resource analysts and meteorological consultants who update state wind resource maps. Identifying the wind resource in an area is the first step in evaluating and installing both large and small wind systems.
Utility-Based Strategies. During the past three years, WPA has worked closely with national consumer-owned and public power utilities and others to present up-to-date information to their membership and customers nationwide. These cost-shared efforts include co-sponsorship of wind-specific meetings, conferences, and workshops as well as joint development and distribution of material containing technical and market-specific information and wind project success stories. WPA also provides real-time technical assistance for everything from the state of wind technology and economics to information on barriers, benefits, and how to get a wind project started.
Native American-Based Strategies. The WPA team helps Native Americans on the mainland, in Alaska, and in Hawaii as they explore the development of their wind power resources. The United States is home to more than 700 Native American groups and corporations that control 38.8 million hectares (96 million acres) in the United States. Many of these groups have excellent wind resources that could be commercially developed either as an export or to meet local needs.
To encourage the development of these resources, WPA works with tribal leaders and groups to address key issues that include adequate wind resource data; community and local utility authorities and policies; developer risks, both real and perceived; limited loads; and needs for investment capital, technical expertise, and transmission to markets. To address these issues, WPA offers a Native American anemometer loan program, provides outreach materials, and conducts workshops on the wind development process and options available to Native Americans.
Ensuring Future Growth
Although the growth of the wind industry has been constant in each year of the past decade, there is much more to be done. To achieve program and industry goals and enable the technology to achieve its full potential in the future, researchers at NREL today are exploring several innovative applications.
These new applications include offshore deep-water development, the use of wind power to clean and move water, and the development of new technologies that will allow wind energy to work in synergy with other clean energy systems, such as hydropower and hydrogen. As this work continues, the promise we are hearing in the winds all around us will most assuredly be fulfilled.
Home Page Photo: The Northern Power Systems North Wind 100-kW turbine installed at the NWTC is the only small-to-moderate size turbine available that has the ability to operate in extremely cold environments.
—Contributed by Kathy O'DellDecember 2004
