Recent technical advances
Modern wind turbines stand 400 feet tall and capture premium wind resources higher above the ground than earlier models, according to AWEA’s Anthony. The average turbine installed in 2007 was rated at 1.6 MW of capacity — twice as powerful as turbines installed in 2005. The largest land-based turbines today are rated at 3 MW, and offshore projects use even larger machines with 5-MW turbines planned for installation within the next two years.
"Improved turbine design has led to a 70% reduction in capital costs since the early 1980s, according to Lawrence Berkeley National Laboratory (LBNL)," Anthony said. "Recently, however, the cost of raw materials and other factors have caused capital costs to go up as they have for all power technologies. LBNL also finds a 35% drop in operations and maintenance costs over the last 10 years. Also important is the continuing increase in wind turbine capacity factors: a 15% increase in capacity factor over the last 10 years, according to LBNL. State-of-the-art turbines achieve 36% capacity factors, compared with an average 22% capacity factor achieved by turbines operating commercially before 1998, and those factors continue to improve."
Lowe provided information about his company’s technical advances in the wind power arena. Since 2002, GE has invested over $750 million in promoting reliable and efficient wind technology, to improve performance and increase customer value. The company has continued to expand its wind energy operations, increasing its wind engineering team threefold and applying experience and expertise from its gas turbine, steam turbine, and controls business units, in addition to GE Aircraft Engines and GE Transportation, to advance its wind turbine technology.
"GE continues to improve performance and reliability of its 1.5-MW wind turbine through GE designed technology (pitch system, blades, and gearboxes), improved component robustness, and better diagnostic capabilities," he said. "The result is continuous improvement in overall fleet availability — from 96%+ for units commissioned in 2005 to 98%+ for units commissioned in 2007 — even as the 1.5-MW installed base has grown from only 1,000 units in 2002 to over 9,000 units today."
Future technical goals
CH2M HILL’s Bartholf pointed out that there are still a number of new design concepts that may work their way into the mainstream in the future, including a redundant generator, a self-erecting turbine, and a vertical axis. Other possible new technologies include electrical innovations, such as system load-shaping and mechanical advances in gearbox reliability.
According to Anthony, the DOE’s 20% Wind Energy by 2030 report finds that wind can meet the 20% goal using existing technology. The report, however, does note that continued capital cost reductions (10%) and capacity factor improvements (15%) over the next few decades will help make the use of wind power even more cost-effective. The DOE identifies several areas where continued research and development would help reduce costs and improve performance even more:
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Improved reliability of towers, blades, power electronics, and gearboxes.
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Developing lighter-weight drive trains, taller towers, and enhanced rotor technologies.
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Developing new materials and more aerodynamic designs to further improve blade performance.
"GE’s wind product strategy is focused on creating more value for our customer in the areas of reliability, efficiency, and advanced logistics," Lowe said. "Since 2002, we have increased the reliability and capacity factor of our 1.5-MW wind turbine by 12 and 9 points, respectively. We are also using more robust materials, employing the more sophisticated electronics already being used in our other power generation products, and shaping turbine blades to better capture the wind."
Looking ahead, according to Lowe, GE is exploring the addition of carbon composite to turbine blades. Although it is more expensive than fiberglass, carbon is lighter — allowing the blade length to be increased by 16 feet. This would translate into a significant boost of energy and flexibility — allowing the blades to operate at higher wind speeds.
Additionally, the company is working on electronics controls to optimize performance and the sound level of entire wind farms. One of GE’s research teams is developing software for modeling how to best place turbines in a wind farm, while another is working on the electronic controls to get wind power fed into the grid most effectively.
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