Consumers' reductions in the use of electricity, known as demand response, set a record this week in PJM Interconnection during a power supply emergency.

PJM reported that 1945MW of consumer use of electricity were voluntarily reduced on Wednesday, Aug. 8, the day PJM ordered voltage reductions in its Mid-Atlantic Region. The demand response amount is similar to the amount of power used by a mid-sized city. By comparison, the 5 percent voltage reduction lowered use by about 1,000 MW.

"This was the largest amount of demand response we've ever had on one day, and it's an encouraging milestone," said Andrew L. Ott, PJM's vice president - Markets. "Participating consumers responded to price signals in the wholesale electricity market and to system needs. We continue working with state regulators and stakeholders to make demand response a larger resource to draw on. We're working with stakeholders to advance recommendations from our May symposium on demand response."

In PJM's wholesale electricity markets, consumers can be paid the same amount for reducing demand for electricity as generators are paid for supplying electricity.

On Wednesday, consumers participated in demand response in several ways: through the Day-Ahead Market, PJM real-time dispatch, self-scheduled, PJM's call for emergency load response and PJM members' "interruptible" rates.

Demand response can help maintain reliability by reducing the demands on the power supply system. It also can reduce wholesale prices for electricity by eliminating the need to run more expensive generating units.