Renewable energy technology stores the wind underground

A New Jersey company said it has joined with Michael Nakhamkin, one of the top thinkers in energy storage, to develop new ways to trap wind-generated power in underground reservoirs.

Mr. Nakhamkin has helped develop technology to pull excess energy off the power grid – usually at night when usage has waned – to run compressors that pump air into sealed, underground caverns that once held oil, salt or natural gas.

During periods of higher demand, the air is released and heated to run air expansion turbines. The heating process uses about 100 megawatts of power from natural gas and 200 megawatts of power from the compressed air.

The announcement comes just as a drilling boom for natural gas heats up nationwide. Natural gas has supporters in both the private sector and in Washington because it releases fewer of the greenhouse gases that can lead to global warming and because it has been found domestically in massive quantities.

While this still involves fossil fuels, Mr. Nakhamkin said emissions, compared with traditional turbine systems, are far lower.

“This technology significantly reduces fuel oil and natural gas consumption,” he said.

In urban areas where underground storage isn't feasible, or where bedrock makes drilling expensive, ground-level pipes can be used to store the air, though capacity is diminished.

“We really think this is a game-changer for the renewables industry,” said Roy Daniel, chief executive officer of Energy Storage and Power LLC, a joint venture between PSEG Energy Holdings and Mr. Nakhamkin.

PSEG Energy Holdings is investing about $20-million (US) in the project, and plans to market and license the technology.

“We're pretty bullish on the market right now,” Mr. Daniel said.

Compressed air in a cave about a third the size of the New York Giants' football stadium – roughly 21,500,000 cubic square feet – would be enough to power a 300-megawatt turbine for 8 hours, Mr. Daniel said.

That load could power about 200,000 homes – a small city – for about 8 hours, said John A. Stratton, an electrical power systems professor at the Rochester Institute of Technology.

“That's a healthy load,” he said. “It's going to get us through the peak of the day by using excess energy at night.”

While the process isn't totally efficient – energy is lost while being transferred – it “makes wind a very different kind of energy than it is today,” Mr. Stratton said.