Several thousand MW of proposed wind farms are also on the drawing board, spurred in part by the recent extension of the federal production tax credit and in part by the impending completion of several billion dollars in new transmission lines being built to ease transmission congestion (see story this page).

Perhaps the most unusual project—poised for a construction start this summer—is the $400 million-plus plan by Houston-based Apex CAES to build a 317-MW compressed air energy storage facility at a underground salt dome in Anderson County.

Jack Farley, Apex's president and CEO, says that motors driven by low-cost electricity purchased during off-peak periods will inject air into the salt dome, and the resulting compressed air will be released from the cavern to drive turbines and generate power during periods when demand—and power prices—are higher.

Farley said that the feasibility of CAES projects in the ERCOT region were boosted last year when PUCT implemented several rules favorable to CAES and other energy storage projects.

There is only one existing operational CAES facilities in the US: a 110-MW facility in McIntosh, Ala., owned by PowerSouth, an electric cooperative group. It came on line in 1991.