The world's first commercial power plant converting the energy of sea waves into electricity [has] started working off Portugal's coast ... in a project that should be expanded nearly 10-fold over the next few years. Three articulated steel sea-snakes" moored to the seabed three miles off Portugal's northern coast, each about the length of a nuclear submarine, generate a total of 2.25 megawatts, enough to supply 1,500 households with electricity. "It's logged into the national grid, which makes it the world's first commercial wave power project," said Anthony Kennaway, a spokesman for Babcock and Brown investment firm which runs the Agucadoura project in northern Portugal. "We hope that in 15 years wave power will be where wind is now, that is extremely competitive. Portugal could be for wave power what Denmark was for wind," Kennaway said. Renewable energy, including water dams, accounts for 40 percent of power consumption in Portugal. Some experts say wave energy could meet up to 20 percent of the country's needs in the future. A total of 25 semi-submerged "sea-snakes" should be installed in the next few years, boosting the ... capacity to 21 MW, Kennaway said. The machines, each 140 meters (yards) long and 3.5 meters in diameter, are positioned head-on towards the waves so that its sections move with the waves. Each joint ... contains a hydraulic pump, which pumps high-pressure liquid through motors that in their turn drive power generators. The energy is then transmitted to a substation on shore via subsea cables.