“Modernizing our electrical grid is central to becoming a nation that’s more energy-efficient and provides cost savings for everyone,” he said.

At the center of the conflict is an agency called the Federal Energy Regulatory Commission, which has authority over wholesale interstate transactions. Wanting to encourage efficient use of power plants, and avoid construction of those that are needed only a few hours a year, the commission laid out rules for how to line up the volunteers to be unplugged. The rules are somewhat similar to the way airlines deal with an overbooked flight: Ask for passengers to give up their seats in exchange for a payment.

Under the current system, which is called demand response, a company that rounds up those volunteers will bundle together a group of customers — some big office buildings, a shopping center or a few industrial plants — that can shut down a bank of elevators, reset their thermostats, and maybe even close a production line for a few hours.

Bulk power grid operators have become eager customers for these services, which can slice wholesale prices that utilities pay at peak hours from $1,000 a megawatt-hour down to $200, Mr. Goodman said.

But the arrangement has rankled power producers, by reducing peak prices on their busiest, most profitable days. In the end, the producers say, they need that income to survive.

In 2011, their patience ran out.

That year, the Electric Power Supply Association sued the federal commission, saying that demand response should be regulated by the states, not the federal government because the transactions are retail, not wholesale.

In May, the United States Circuit Court of Appeals in Washington sided with the association.

Now, FirstEnergy, in a complaint filed with the commission this spring, asserts that the demand-response arrangement — by only focusing on the demand side — does not recognize just how much it costs to build and operate a power plant. The company has a certain experience with power outages, having played a central role in the cascading blackouts that crippled a huge swath of the country from the Midwest up through Ontario and New York in August 2003.