By Ken Kukes, AquaEnergy Group
Aug. 5, 2003 — Ocean energy and offshore wave energy conversion in the United States is at a significant milestone. During the next decade, ocean energy technology developers will deploy pilot scale ocean power plants and transition to commercial plants in the U.S.
This capability comes at a time of increased interest in ocean energies at the National Academy of Sciences and the U.S. Department of Energy. Meanwhile, worldwide energy demand is expected to grow at a rate of 2 percent per year. By the year 2010, this will result in a global market of $5 billion.
The offshore power plant
AquaEnergy’s offshore plants consist of patented wave energy converters known as AquaBuOYs (see Figure 1), which are based on proven, survivable, buoy technology. Small, modular devices are moored several miles offshore where the wave resource is the greatest ; no sensitive (and expensive) shore real estate is required for the system. Offshore power plants are also non-polluting and anticipated to have a negligible impact on the marine environment. (See Figure 2.)
These plants are easily scalable to any size by adding as many buoys as required. They installed offshore, in the water depth of 150 to 250 feet. The total number of wave energy converters determines the plant capacity. Along the U.S. and Canadian West Coast, each device is expected to generate up to 250 kW.
AquaEnergy’s wave energy converters rely on the heaving buoy concept developed and patented by AquaEnergy’s partner IPS AB of Sweden. (See Figure 3.) Energy transfer from the motion of ocean waves takes place by converting the vertical component of wave kinetic energy into pressurized water flow by means of two opposing, full-cycle, hose pumps.
Pumped water is directed into a conversion system consisting of a Pelton turbine driving a conventional electrical generator. Wave energy converters are located offshore where wave resources are the greatest and thus, they do not have the resource power density limitations associated with onshore installations.
Wave energy research and development is presently at a pre-commercial stage with two shore-based installations and no offshore installations.
Offshore systems like IPS Buoy, Sweden, and Mighty Whale, Japan have provided some operating experience. In the coming year additional prototypes are expected to be installed : Ocean Power Delivery & Wavegen in the UK, Archimedes Wave Swing in Portugal and Wave Dragon in Denmark.
In the U.S., a consortium headed by AquaEnergy Group, Ltd. is working on the permitting and installation of the nation’s first 1MW offshore wave energy power plant in Makah Bay, Wash., that is currently undergoing detail design and environmental permitting.
In California, California State University in San Diego is working on ocean wave energy resource assessment in California.
In support of the Makah Bay offshore pilot power plant, AquaEnergy has worked with the Washington State congressional delegation to assure that ocean energy is recognized as a renewable resource in the U.S. national energy bill, along with biomass, solar, and wind resources, eligible for federal incentives for renewable energy production and puts the Department of Energy in a leadership role to support further development of ocean energy.
Kukes is executive vice president of AquaEnergy Group Ltd. ( http://www.aquaenergygroup.com).