AWEA Blog: While wind energy is variable, it is not completely random and unpredictable

As the previous cross-posted article by Simon Mahan suggests, the fact that no power plant runs 100 percent of the time and that other energy sources besides wind turbines have their issues is beginning to catch the attention of commenters in the blogosphere.

Of course, that's not too surprising, since those issues have been revealed by a series of recent in-your-face events. The latest? Last week's earthquake in the eastern U.S., which briefly knocked a nuclear power plant offline (and caused yours truly's heart to skip a few beats--a 10th-floor office is no place to be in a quake). It follows:

- The quake and tsunami which devastated Japan's Fukushima nuclear power complex (Japanese wind farm plants were largely unaffected, and quickly back in operation).

- February's unexpected freeze and ice storm in Texas, which damaged fossil fuel generating equipment and led to rolling blackouts.

- The recent heat wave in Texas, ditto on problems with fossil fuel units, though blackouts were avoided.

- A statement from a spokesman for ERCOT (Electric Reliability Council of Texas) that if the drought there does not ease by fall, some power plants may have to shut down due to lack of water for cooling.

- More heat in Alabama, requiring the Tennessee Valley Authority's Browns Ferry nuclear power plant's output to be cut by 50 percent due to high temperatures in the river it uses for cooling water. The same plant was idled four years ago for the same reason.

Now, let's be clear: I am not, repeat not, saying that wind power can serve as a source of electricity to meet peak demand in the same way as fueled power plants. At the same time, wind turbines should not be criticized for not operating all the time. No power plant operates all the time. What matters most is predictability. Some points to remember:

- While wind power is variable, it is not completely random and unpredictable. The science of wind forecasting has made major advances in the past 10 years, making changes in wind speed and power generation something that utility system operators can plan for, just as they use weather forecasts to predict how weather-driven changes in the use of air conditioning and electric heating will cause changes in electricity demand.

- Wind power requires virtually no water to generate electricity, a blessing in times of serious drought.

- Balancing electricity supply and demand is a complex task, and system operators are used to turning various types of power plants on or off to match demand as it rises and falls throughout the day. Even though wind energy is variable, it varies slowly--unlike conventional power plants, which typically fail instantaneously—which is important, because the reserves used to accommodate slow changes are typically 40 times cheaper than those used for fast changes.

- It appears that wind patterns at coastal and offshore wind farm sites do tend to match up well with periods of peak summer demand.

- It's increasingly clear that wind power, just as advocates have long claimed, is an abundant resource that can provide a significant percentage of the electricity supplied by a utility system. This year through May, the Energy Information Administration (EIA) reports that wind power provided the following percentages of electricity generated: Iowa 21%, South Dakota 19%, North Dakota 16%, Minnesota 14%, Wyoming 13%, Kansas 10%, Colorado 9%, and Texas 8%.