Mountaintop wind turbines produce most of their energy at night, when electricity demand and prices are low. That limits revenue and makes it hard for utility companies to meet state goals for high percentages of renewable energy.

Batteries could solve the problem, but they have always been too expensive. Still, a small New Jersey company, Grid Storage Technologies of Newark, plans to install two batteries on the grid late this year that would store bulk amounts of energy.

By charging up at hours when electricity is almost free and discharging the power when it is expensive, the thinking goes, the batteries would earn their owners a profit through arbitrage.

Grid Storage Technologies

Commercial success will probably have to await a higher volume of production, allowing manufacturing costs to fall, and the imposition of a price on higher carbon dioxide emissions. If Congress penalizes emissions of carbon dioxide from electricity generated by gas turbines, a rival source of power, that would also help renewable energy become more competitive.

By moving the power in off-peak periods, the batteries could also reduce the strain on transmission lines in some locations. They could also take the intermittency out of renewable energy sources like the wind and the sun. “It would make the wind dispatchable, which is the panacea for renewables,’’ said Pat Hemlepp, a spokesman for American Electric Power, a major utility company that has installed five sodium-sulfur batteries on its system.

A.E.P.’s batteries are still too expensive to pay for themselves by shifting cheap power to peak hours, but they do earn their keep by improving reliability, Mr. Hemlepp said.

Grid Storage Technologies says it has patented improvements for a battery that uses zinc, which is more plentiful and less expensive than lithium, the dominant material for new battery research. The zinc battery takes in oxygen from air as part of the chemical reaction that gives off electricity and need not rely on a second chemical incorporated into the battery.

Late this year, the company expects to have a 100-kilowatt unit connected at a Duke Energy substation in Charlotte, N.C., and a unit that is 10 times that size, one megawatt, at a test facility in Chalfont. Pa., operated by Kema, an energy storage consulting firm. The larger battery can store enough electricity to power an average house for about eight months.

It can deliver electricity for 12 to 16 cents per kilowatt-hour, said Benjamin C. Rogers, the company’s president and chief operating officer. That is above the average retail price of a kilowatt-hour, but below the peak cost in many areas and not much different from the cost of electricity from a natural gas plant that is built to run only in peak periods, a few hundred hours a year.

“It’s promising,’’ said Richard M. Fioravanti, Kema’s director of storage applications and support. If the battery can be produced at the price anticipated, he said, it could play several roles, including the delivery of backup power for factories and offices.