More wind = more backup

[S]wings of 500 megawatts of wind can disappear from a system in an hour or less, creating scheduling havoc for system operators, as it did in Texas in February 2008. The system operator relied on interruptible contracts with industrial customers to retain reliability during that event. ... The maximum change in Colorado over a 24-hour period was a 743-megawatt increase and a 485-megawatt decrease. In Minnesota, the utility saw as much as a 517-megawatt increase and a 488-megawatt decrease, [Eric Pierce, Xcel Energy's managing director of energy trading,] said. ... When wind outages are more widespread, spinning and operating reserves are required just like for any thermal operator. In some areas, no enough excess is currently available if winds shift suddenly. What seems to be developing is an industry consensus that as renewable energy penetration increases, reserve margins will need to be larger across [a] regional transmission organization.

-- William Opalka, Energy Biz, May/June 2009

wind power, wind energy