An article in today’s Wall Street Journal makes the same mistake that most articles make re: wind capacity. In a piece on Siemens’ plans to expand international operations (subscription required), the Journal writes,
This year, Siemens expects installed capacity of 2 to 2.1 gigawatts. A gigawatt is equivalent to one billion watts, enough to power about 300,000 U.S. households.
Yes, a gigawatt is equivalent to one billion watts; but, no, a gigawatt of wind capacity alone is not enough to power 300,000 homes. Saying a certain wind capacity is “enough to power X households” is misleading, as it indicates that wind power is all you need to ensure the light comes on when you flip the switch. If you are not concerned with whether the power will work at all times, then, sure, your home can be powered solely by wind energy.
I see this all the time. For example, according to the American Wind Energy Association,
16,818 megawatts (MW) of wind power plants were in place in the U.S. at the end of 2007, serving the equivalent of 4.5 million average households. By the end of 2008, AWEA expects that number to jump to over 22,000 MW, which can serve the equivalent of over 5.5 million average households.
The reason this is not the case is that wind is not a baseload resource, like coal, natural gas, or nuclear power. Rather, wind (and, thus, wind power) is intermittent and requires conventional sources of power to back them up during times when the wind dies. Because the wind blows sporadically and because no large-scale electricity storage exists, wind alone cannot provide reliable energy for homes.
If we are going to use phrases like “enough to power” or “can power the equivalent of” X number of households, then we should qualify the statements, with information about the capacity factors of wind turbines, the amount of backup power needed, and the lack of commercial-scale electricity storage. Particularly with the massive expansion of wind power and other renewable resources, policymakers need — and consumers and taxpayers deserve — a complete picture of the pros and cons.