For decades, scientists
have been trying to tap wave power as a source of renewable energy.
According to the World Energy Council—an international consortium
promoting sustainable energy—ocean waves could supply twice as much
electricity as the world now consumes. But wave action is so
dispersed, it’s difficult to harvest this power economically.
Wavegen, an Inverness, Scotland-based company, is trying. In
November 2000 it installed the world’s first commercial system to
generate electricity directly from the surf. Located near the town
of Portnahaven on the Scottish island of Islay, Wavegen’s
system—called the Land-Installed Marine-Powered Energy Transformer,
or Limpet—can generate 500 kilowatts of power reliably, enough for
about 400 homes.
Researchers have developed several mechanisms for capturing wave
energy, including tapered-channel systems that funnel waves into a
turbine, underwater turbines powered by currents, and float systems
that rise and fall on the water’s surface, driving pistons that
convert the motion into energy. Wavegen chose an oscillating water
column approach. Waves rolling into shore push up the water level
inside a large, partially submerged concrete chamber built into the
shoreline. The rising water forces the air trapped in the chamber
through a hole and into the mouth of a turbine. When the waves
recede, the falling water level in the chamber sucks air through the
turbine in the opposite direction. The key to the system is its use
of a so-called Wells turbine, whose blades rotate in the same
direction regardless of airflow direction. The spinning turbine
drives a generator that produces electricity. Limpet is seen as a
key test bed for furthering developments in wave energy technology.
Indeed, most of the progress in wave power is occurring in
countries with lots of coastline: Britain, Japan, Australia and New
Zealand. In the States, work on the technology slowed with U.S.
Department of Energy budget cuts in the 1980s. But ocean-wave energy
is still on the radar screen in California, where the California
Energy Commission is assessing its viability and San Diego State
University is putting together a consortium that could one day bring
wave power to American shores.