Wind electricity generation is already a mature technology and approximately cost competitive in many areas of the country and the world, especially with electricity generated from natural gas. The installed capacity for electricity generated from wind at the end of 2009 was approximately 159 GW, or about 2 percent of worldwide energy usage (WWEA, 2010). Wind turbine size has been increasing as technology has developed, and offshore wind farms are being constructed and proposed worldwide. As with solar power, wind energy alone could theoretically meet the world's energy needs (Archer and Jacobson, 2005), but a number of barriers prevent it from doing so, including dependence on location, intermittency, and efficiency. Other estimates of the resource base are not as large, but also indicate the United States has significant wind energy resources. Elliott et al. (1991) estimate that the total electrical energy potential for the continental U.S. wind resource in class 3 and higher wind-speed areas is 11 million GWh per year. As noted in NRC (2009d), this resource estimate is uncertain, however, and the actual wind resource could be higher due to the low altitude this estimate was developed at, or lower due to the inaccuracy of point estimates for assessing large-scale wind-power extractions (Roy et al., 2004). Assuming an estimated upper limit of 20 percent extraction from this base, an upper value for the extractable wind electric potential would be about 2.2 million GWh/yr, equal to more than half of the total electricity generated in 2007. This estimate does not incorporate the substantial offshore wind resource base. Development of offshore wind power plants has already begun in Europe, but progress has been slower in the United States. Though offshore wind power poses additional technical challenges, these challenges are being addressed by other countries. However, political, organizational, social, and economic obstacles may continue to inhibit investment in offshore wind power development in the United States, given the higher risk compared to onshore wind energy development (Williams and Zhang, 2008).
The key technological issues for wind power focus on continuing to develop better turbine components and to improve the integration of wind power into the electricity system, including operations and maintenance, evaluation, and forecasting. Goals appear relatively straightforward: taller towers, larger rotors, power electronics, reducing the weight of equipment at the top and cables coming from top to bottom, and ongoing progress through the design and manufacturing learning curve (DOE, 2008a; Thresher et al., 2007). Basic research in materials and composites is expected to lead to improved and more efficient wind energy systems, for example by improving the efficiency of turbines for use in low-windspeed areas (DOE, 2009c). Research on materials reliability and stabilizing control systems could help reduce maintenance requirements and further enable wind machines to survive extreme weather events. Continued research on forecasting techniques, operational and system design, and optimal siting requirements would improve the integration of wind power into the electricity system. As with solar energy technologies, modifications to the electricity transmission and distribution system along with energy storage capacity would also improve the ability to exploit wind energy resources (see the section Energy Carriers, Transmission, and Distribution in this chapter).
Along with technology advances, research on policy and institutional factors affecting the widespread implementation of wind systems is needed, as well as continued assessment of the potential adverse impacts of wind energy systems—for example, past research has shown that adverse impacts on flying animals, especially birds and bats, can be reduced both with advanced turbine technologies and by considering migration corridors when siting wind farms (NRC, 2007e). Siting is also critical in order to reduce potential negative effects on the viewscape, effects on noise, and unintended consequences on local wind and perhaps weather patterns (Keith et al., 2004). Concerns with the adverse effects of wind farms have led to substantial public opposition on some areas (Firestone et al., 2009; Swofford and Slattery, 2010). Further research and analysis of these factors would help decision makers evaluate wind energy plans and weigh alternative land uses—for agriculture, transportation, urbanization, biodiversity conservation, recreation, and other uses—to maximize co-benefits and reduce unintended consequences.
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