The world's first commercial wave farm started operating off the coast of Portugal at Agucadoura on Tuesday. It comprises three red "articulated sea snakes", each about 140 metres long and 3.5 metres in diameter, which generate about 2.25kW of electricity - enough to power 1,500 homes.
Scottish firm Pelamis Wave Power made the wave converters. They are moored to the seabed about 5km offshore using a special system that allows the machine to float head-on into incoming waves. Each machine has a number of segments linked with hinged joints. As the machine moves with the waves, it extracts power from the motion of the joints. Each joint contains a hydraulic pump, which pumps high-pressure liquid through motors that drive power generators. (There's a video of how it works on the Guardian's website).
The energy is then transmitted to a substation on shore at Agucadoura by undersea cables. This energy is then supplied to homes via the national electricity grid.