How does the Oceanlinx wave energy device work?The Oceanlinx company, which plans to install several wave energy machines with a total capacity of about 2.7 megawatts off Maui’s northern coast, has designed their devices around the “oscillating water column” (OWC) concept. OWC is one of many methods of tapping the potential energy in ocean waves that are being explored.
What is an oscillating water column? The common comparison is a natural “blowhole” along the seashore. In a blowhole, such as the famous Halona Blowhole near Makapu‘u on O‘ahu, a lava tube or cave in a cliff opens at sea level. There’s a hole in the landward side of the cave roof. An ocean swell that enters the cave will push air out of this blowhole, and if the wave is big enough the water will also spout out energetically, creating a fountain. Then, as the wave recedes, the water and air are powerfully drawn back into the cave through the hole.
Essentially, an OWC device creates a man-made blowhole, tapping the energy in the air as it is forced in and out of a chamber by the surging swells of ocean waves. Unlike a natural blowhole, an OWC wave power device can be located out to sea, away from the shore.
Oceanlinx’s device consists of a large steel chamber, which acts like the natural cave of a blowhole. At the top, there’s a horizontal tunnel, which guides and constricts the air as it is pushed out of the chamber by an incoming ocean swell. Within this tunnel, Oceanlinx’s patented turbine will be installed.
This turbine has reversible pitch blades. Designed as airfoils (similar to airplane wings or wind turbine blades), the blades catch the high-speed air as it gushes out of the chamber, spinning the turbine. Then, the blades reverse, presenting a different face to the air as it rushes back into the chamber, allowing the turbine to keep rotating in the same direction. The turbine is connected to an electrical generator, producing electricity.
There are other OWC devices elsewhere. There is, for instance, an OWC device called “the Limpet” on the Isle of Islay, which has provided electricity to the Scottish national electric grid for several years. The Limpet uses a different turbine design. And Japan’s Marine Science and Technology Center has a demonstration floating OWC system called the “Mighty Whale.” There are other companies developing devices that work on this concept as well.
In partnership with the state’s energy office, the Maui Weekly provides this feature to help Valley Isle homeowners reduce their utility bills and increase their environmental awareness.