manufacturing output of about 20 GW in 2007, of which approximately 5 GW went to the U.S. market (DOE, 2008b). An additional 8.4 GW of capacity was added in the United States in 2008 and 2.8 GW of capacity in the first quarter of 2009, both of which exceeded the trajectory for the 20 percent wind scenario. Even assuming that growth outside the United States is more modest, this scenario would still require a continued large expansion of the manufacturing base. Additionally, the scenario assumes that wind turbines have an average life of 25 years; sustaining annual installations at approximately 16 GW/yr beyond 2030 would be needed to accommodate repowering of aging turbines and meeting increasing electricity demand to continue the 20 percent wind generation level (Laxson et al., 2006; DOE, 2008a).

Given these challenges, the DOE’s 20 percent wind scenario considers the materials, capital, and employment requirements. Table 6.4 shows the level of raw materials that would be needed to meet the scenario. While some quantities are small relative to global production, Smith and Parsons (2007) conclude that supplying fiberglass, core materials (balsa and foam), and resins could be difficult, as could supplying a sufficient number of wind-turbine gearboxes. Assuming that the average-sized wind turbine would be in the 1–3 MW range, with some introduction of large 4–6 MW turbines, there would be a total of almost 100,000 wind turbines installed (Wiley, 2007; DOE, 2008a). This would mean that the average number of turbines installed would have to rise from its current level of 2000 per year to 7000 per year by 2017 (DOE, 2008a) and the average turbine size would be about 3 MW.

In 2030, the DOE’s 20 percent wind scenario would require well over 140,000 direct manufacturing, construction, and operations jobs, according to