Sea Snakes Make Energy

The northern coast of Portugal has been invaded by what look like giant orange sea serpents (above). The "serpents," which are steel tubes 122 meters (400 feet) long, are a supplier of alternative energy. Their writhing motions convert mechanical energy to electrical power.

The orange tubes are called the Pelamis Wave Energy Converter. They don't float away, because they are anchored to the seafloor. Because the tubes are segmented, they gently undulate up and down and sideways in the surf. Those undulations activate hydraulic motors inside the tubes. Hydraulics is the movement of a fluid under pressure, which turns the motors. In turn, the motors drive generators that produce electricity.

The waves that flex the tubes are a renewable source of energy — they are naturally and continuously replenished. By 2008, Pelamis is expected to supply enough electricity via an underwater cable for 1,500 coastal homes. The projected goal for Pelamis is 30 tubes that will generate electricity for 30,000 homes.