peaker
n.— «The $60 million, 170 megawatt plant will be built near Mountain Home, Idaho, and used for what’s called a peaker plant. Peakers are relied on when peak summer demand is pushed by air conditioners and irrigation pumps and forces utilities to cover their demand with an idle unit instead of purchasing it from the more expensive wholesale spot market.» —“Idaho Power gets OK for ‘peaker’ plant” in Boise, Idaho Earthtimes.org Dec. 21, 2006. (source: Double-Tongued Dictionary)