If you're still one of those people who tend to think of wind energy as a bit exotic, only suitable for exceptional situations, even then not likely to contribute much to the big picture, it's time to stop being that kind of person once and for all. According to a report this week from Worldwatch, about 20,000 megawatts of wind capacity was installed in 2007, bringing the world total to 94,100 megawatts, or, more concisely, 94 GW. Wind was the leading source of new electricity in Europe and second only to natural gas in the United States.
Allowing for the customary factor-of-three discounting of wind capacity to account for wind's intermittency, 94 gigawatts is the equivalent of about 31 GW of baseload coal or nuclear generation--the same thing, in other words, as building 31 standard nuclear power plants. In terms of average household use rates, which often are put at about 1 kW, 31 GW is enough power for 31 million homes.
The United States led the way last year, adding 5,244 megawatts of wind, followed by China--a surprise! (see next issue of IEEE Spectrum magazine)--and Spain. Overall, Germany still has the largest wind total, more than 22 GW--the equivalent of four or five 1 GW baseload plants, taking into account that the discounting is higher for Germany (more like a factor of 4 or 5) because, having pushed wind harder, they've installed turbines in some less than ideal locations.
Even so, Germany's socialist and green leaders believe that wind can continue to meet most of the country's additional energy demand in the coming years, though more conservative leaders like Chancellor Angela Merkel do not agree.
According to another Worldwatch report, wind investments accounted for 47 percent of global investment in renewable energy technology last year, followed by photovoltaics, which was about 30 percent. New solar PV capacity came to 2.8 GW in 2007, according to Worldwatch's estimate, and about 3.43 according to a recent Lux report. Both estimate the cost of the new PV investments at about $21.2 or 21.3 billion.
The value of wind investments last year came to $31 billion. On a dollar per watt basis, that means that new wind is costing about $1.55, new PV between $7.6 (Worldwatch) and $6.2 (Lux). In other words, per unit capacity, photovoltaic energy is between four and five times as expensive as wind.