Oscillating Water Column

An oscillating water column, or OWC, is a wave energy converter built around a partly submerged chamber holding a column of air above the seawater inside it; incoming waves force the water up and down like a piston, pushing air back and forth through a power take off system, typically a turbine designed to keep spinning in one direction no matter which way the air is flowing, which converts the airflow into electricity. Scientific American reported 34 whistling buoys using the principle operating off the United States coast as early as 1885, and Japanese naval commander Yoshio Masuda built the first OWC designed to generate electricity, a navigation buoy in Osaka Bay producing 70 to 500 watts, in 1947; Professor Alan Arthur Wells developed the bidirectional Wells turbine commonly used in OWC power take off systems in the late 1970s. More recent installations include the LIMPET plant, which generated 500 kilowatts from a single turbine when it began operating in 2001, and the Mutriku facility in Spain, which has produced about 300 kilowatts from 16 turbines since 2011, enough under good conditions to power 250 houses.