Being the most economical of the renewable technologies, installation of wind turbines has grown rapidly in the last few years. In Fig. 3.2, we see that Europe

leads in this field, being more dependent on foreign oil than other continents. It has also had a head start, but other nations have been advancing more rapidly. Between 2006 and 2008, wind capacity has more than doubled in America and Asia. The units in Fig. 3.2 are in gigawatts (GW) or millions of megawatts. A large coal plant generates roughly 2 GW of heat, giving 1 GW of electricity. So the 65 or so GW of peak wind power in Europe in 2008 would replace, roughly, 65 coal plants. We will see later that the average power of wind turbines is much less.

The installed wind capacity of the top countries is shown in Fig. 3.3, again in gigawatts. We see here that the head start of the European countries is being rapidly

overtaken by the USA and China. Wind power has more than doubled in the USA and more than quadrupled in China in the two years. Denmark’s wind capacity is typical of many other small European countries, and it is shown here because Denmark has been a leader in developing the technology of wind turbines and their deployment onshore and offshore. Currently, 20% of the electricity in Denmark is supplied by wind.8 It is estimated that by 2013 electricity from wind will cost $0.055/kWh, compared with $0.05 from coal or gas, $0.06 from nuclear, and $0.22 from solar.8

At one time, after the Chernobyl accident, Germany wanted to eliminate all its nuclear reactors, replacing them with wind and solar plants. A feed-in law has been in place since 1990, requiring utilities to buy energy from green sources that feed into their grid.9 The plan was to install 500 MW of offshore wind in the North Sea by 2006 and 2,500 MW by 2010. The major players are the large utility com­panies E. ON Netz, REpower Systems, and the giant Swedish firm of Vattenfall. However, this was harder than they thought, the subsidy was too small, and the enviromentalists were too vocal. Only a few offshore turbines have been installed. Chancellor Angela Merkel lowered the costs by shifting the burden of new trans­mission lines to the power grid operators from the wind developers. Now 900 MW of turbines have been ordered, and E. ON Netz will spend $254 million (€180) to build a cluster of turbines in the North Sea, using some of the huge 5-MW turbines from REpower (later in this chapter). Nonetheless, wind is so capricious that it can supply only a small fraction of the energy now generated by nuclear reactors.9

In the USA, installed capacity was close to 30 GW by the middle of 2009, pro­viding 1.4% of the country’s electricity. The states with the most wind power are Texas (7.1 GW), Iowa (2.8 GW), and California (2.5 GW). The largest wind farms are the Horse Hollow, Capricorn Ridge, and Sweetwater farms in Texas; Altamont, Tehachapi, and San Gorgonio in California, and Fowler Ridge in Indiana.10 Wind supplies 5% of the renewable energy in the USA, compared with 1% for solar; and renewables account for 7% of total energy. The Great Plains states, like Kansas, have great potential for further development. The current rate of buildup (Fig. 3.3) is on track to attain the Obama administration’s goal of doubling clean energy by 2012. Little has been done so far about offshore wind capture. There are plans to try this on the East Coast. The technology will be far behind that of the Danes, who have been researching this for many years. The economic crisis may slow down the investment in this field. For instance, T. Boone Pickens had planned to spend $10 billion to build the largest wind farm in Texas, but the plans were scrapped when the price of oil dropped to the point where wind became too expensive. Ideology is again the slave of economics.

For the far future, the proponents of wind power have no such reservations. Figure 3.4 shows the predictions of the experts at Vestas Wind Systems of Denmark. The blue part of the curve shows the 16-fold increase of the world’s wind turbine capacity from 1997 to 2008. The red part of the curve shows the expected future growth up to 1.3 trillion watts by 2020. Whether this will actually happen is problem­atical. As we shall see, this would require a large amount of backbone power to back up the wind power, and too much fluctuating power may make the power grid unstable. The good news is that wind installations have a very small fossil footprint.

Fig. 3.4 Actual (blue) and predicted (red ) wind capac­ity, in gigawatts, from 1997 to 2020 [Vestas Wind, No.

16, April 2009. Original data from BTM World Market Update 2008 (March 2009)]