During a few hours of last week's East Coast heat wave, thousands of megawatts worth of electricity--enough to power hundreds of thousands of homes--were temporarily removed from the grid, a practice grid operators expect to do more often to weather energy supply crunches on the grid.
PJM, which operates the wholesale electricity market in 13 states, on Monday reported that it put into effect an "emergency" demand response program last week, tapping over 2,500 megawatts worth of energy reductions, dispersed over thousands of sites, to ensure that electricity flowed during times of peak demand.
The last time PJM called in these "demand side resources" was an August day three years ago. But automated efficiency technology, particularly dialing back electricity usage during peak times, is becoming one of the most effective smart-grid tools for maintaining the balance between electricity supply and demand.
"In past days, a utility would talk about voluntary appeals to lower usage or using peaking power plants. Now demand-response programs are actually part of the mix," said Dan Delurey, the president of the Demand Response and Smart Grid Coalition. "It's not just one-offs any more--it's part of the new system."