A recovering economy increased the peak demand for electricity this summer in the 13-state PJM Interconnection region. When adjusted for unusually warm weather, consumers' highest demand for electricity increased about 1 percent compared to summer 2009.

"It may seem like a small increase, but it's consistent with expected effects of economic recovery," said Michael J. Kormos, PJM senior vice president – Operations. "It's also a significant change from the reduction in peak demand experienced in 2009 and is the largest increase in weather-adjusted peak demand since 2006 when we recorded our all-time peak."

Peak demand is the greatest amount of electricity used in one hour. The power grid has to be built to handle that amount of power use. Enough resources – generation and demand response – have to be available to supply the peak demand. Power demand tends to peak in the summer in the PJM region because of the use of air conditioning.