A new report by the Department of Energy says that waves off California's 1,100-mile coastline could generate more than 140 terawatt hours of electricity a year -- enough to power 14 million homes -- if tidal and wave energy was developed to its maximum potential.

The United States uses about 4,000 terawatt hours of electricity a year; 1 terawatt hour powers about 100,000 American homes.

"California's wave and tidal current resources offer real opportunities to generate renewable energy using water-power technologies in the future," Energy Secretary Steven Chu said in a statement.

Wave energy uses a variety of devices placed in the ocean to generate electricity, but the technology has not been widely used in the United States. The Department of Energy is sponsoring three demonstration projects off the coast of Oregon, in Washington's Puget Sound area and in Maine.

Currently, California has no wave energy project up and running, but the California Ocean Protection Council says one project off the coast of San Onofre has received a preliminary permit. The permitting process is complex and involves several federal and state agencies, including the Federal Energy Regulatory Commission and the Bureau of Ocean Energy Management.

"Wave energy projects have a very low profile -- much lower than a wind turbine," Mike Reed, team leader for water-power technologies at the Department of Energy, said in an interview. "The devices are located two to three miles off shore -- you can't see them from the shore."