If you're willing to wash your clothes at night to save money on electricity, the state now has a program that allows you to do it.

The Illinois Commerce Commission on Wednesday approved a program that will provide residential electric customers in Illinois with access to hourly, market-based wholesale electricity prices, starting next year.

That means that instead of paying a flat rate for power, which was set by a power auction, customers can choose to pay an hourly rate set by bidders on national wholesale electricity markets.

By knowing when electric prices are high, a customer can decide not to use as much power during high-cost times of day, like hot summer afternoons. Customers can save money by choosing to wash clothes after 10 p.m., for example, or by turning down the air conditioner during the day.

ComEd customers who have tried a pilot version of the program saved money, reduced their power use and cut stress on the electric grid, according to the Center for Neighborhood Technology, which is running a pilot program for about 1,100 ComEd customers. Customers in the pilot saved an average of 10 percent on their bills.

"I hope a lot of people sign up," said Robert Lieberman, an ICC commissioner who started the CNT's Real-Time Pricing Program while he was its CEO. "It will save them money. It's a great thing."

Real-time pricing has already been voted into state law. But the ICC needed to determine how the program would be implemented. The program is limited to 120,000 ComEd customers, but Lieberman said if there's greater demand, the ICC can reconsider the limit.

"This will put us in the forefront of dynamic pricing across the country," Lieberman said.

One aspect of the program that was not immediately clear was

how much participants would pay for the special electric meters needed to take advantage of the program.

The meters cost about $120 each. The participant would pay some of the cost as a monthly charge, while the rest of the cost would be spread out among all ComEd customers. More details will be available from ComEd next week.

The real-time option comes as the regular rate for ComEd customers is expected to rise by as much as 24 percent in 2007.

ComEd will name a third-party program administrator for the real- time program in the coming weeks, and the administrator will begin to accept program participants in early 2007.

mwisniewski@suntimes.com