Energy visionaries have long promoted the idea of Ocean Thermal Energy Conversion which uses the temperature difference of warm surface water to cold deeper ocean currents to boil a liquid (e.g. ammonia) to drive an electricity producing turbine. It is an elegant energy solution that is gaining more mainstream attention.
The thermal and kinetic energy potential of the world’s oceans remains largely untapped by energy producers. Earlier we featured a new Lockheed pilot project in Hawaii that evolves the once novel idea of capturing ocean thermal energy conversion into clean electricity. What other power generation schemes might emerge from our oceans?
What happened?
University of Michigan engineer Michael Bernitsas has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power.
The machine, called VIVACE, is being developed by Vortex Hydro Energy as the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth’s currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently.
VIVACE stands for Vortex Induced Vibrations for Aquatic Clean Energy. The array of devices doesn’t depend on waves, tides, turbines or dams. Instead it is a unique hydrokinetic energy system that relies on “vortex induced vibrations” that have damaged bridges for decades. Rather than try to avoid damage by these vibrations, VIVACE captures the motion power by mimicking the movement of fish.
The concept model of VIVACE looks nothing like a fish, but future versions should have the equivalent of a tail and surface roughness a kin to scales. The working prototype is one sleek cylinder attached to springs that hangs horizontally across the flow of water in a tractor-trailer-sized tank in his marine renewable energy laboratory. The water in the tank flows at 1.5 knots.
Bernitsas estimates that an array of VIVACE converters the size of a running track and about two stories high could power about 100,000 houses. Such an array could rest on a river bed or it could dangle, suspended in the water. But it would all be under the surface.
