The ocean is a vast, largely untapped energy resource
Oceans cover over 70% of the earth’s surface. Oceans are the world’s largest collector and retainer of the sun’s vast energy. Ocean energy is continually renewed and available 24/7. The "fuel" of ocean energy is both free and clean. Just a small portion of the energy stored in the oceans could power the world.
With fossil fuels – particularly oil - running out and becoming increasingly expensive, ocean energy is becoming more competitive and attractive. The challenge is to convert this abundant source of energy into useable power for electricity and transportation.
For over 60 years, several forms of tapping energy from the ocean have been researched and implemented. Ocean energy has two forms:
||mechanical energy such as waves, currents and tides
||thermal energy, including ocean thermal, which takes advantage of the difference between cold, deep seawater and surface seawater warmed by the sun. Sea water air conditioning is an energy offset technology that uses cold, deep seawater to replace electricity for cooling.
Maui Electric Company is working with Oceanlinx on Hawaii’s first commercial wave energy project
In February 2008, Oceanlinx Ltd., an Australia-based high-tech company, announced plans to provide electricity to Maui Electric Company from Hawaii’s first wave energy project.
The plan is to provide up to 500 kilowatts from a stationary platform located 1000-2000 feet off shore from Kuiaha Bay on the northeast coast of Maui.
Oceanlinx offers a unique, commercially efficient system combining the established science of the oscillating water column with the company’s own patented turbine technology.
Rising and falling sea swells push and pull air past the turbine; its blades shift in response to the direction of the air flow, enabling the turbine to turn continuously in one direction. Electricity is then brought ashore through an undersea cable to a substation tied to the island electrical grid.
In Oceanlinx, Hawaiian Electric and Maui Electric have found an excellent wave energy technology that appears to make sense for Hawaii and many other places as well.
The project now plans to be operational by mid-2014. Oceanlinx will prepare an environmental impact statement for the project and apply for necessary permits and approvals.
Maui Electric Company is negotiating a purchase power agreement with Oceanlinx, which is subject to approval by the Hawaii Public Utilities Commission.
More information on Oceanlinx (previously Energetech Australia Pty. Ltd. founded in 1997) is available on-line at www.oceanlinx.com.
Wave Energy on Oahu
Because Hawaii has among the most powerful waves per square meter in the world, the Office of Naval Research is monitoring an experimental wave energy buoy off Kaneohe Marine Corps Base.
Hawaiian Electric has helped with the transmission connection to the electric grid.
The 40-kW experimental buoy, manufactured by Ocean Power Technologies, Inc. employs the bobbing motion of a buoy to drive an electrical generator.
Ocean Thermal Energy Conversion
Ocean thermal energy conversion (OTEC) takes advantage of the temperature differences between sun-warmed surface water and cold deep water to generate electricity. OTEC systems must have a temperature difference of at least 25 degrees Celsius to operate, limiting use to tropical regions.
Thermal energy conversion plants use the temperature difference to make steam from a quick boiling working liquid and pass the steam through a turbine generator to make electricity. Unlike electric generation from many other renewable energy technologies, which may vary with weather and time of day, an OTEC plant could produce electricity 24 hours/365 days a year. This capability also would make OTEC an attractive alternative to conventional base load power plants powered by fossil fuels.
Fresh water production is one potentially beneficial by-products of OTEC. The cold deep ocean water can be used for aqua-culture (fish farming) as it is pathogen free and nutrient rich, or air-conditioning and refrigeration in nearby buildings.
No commercial OTEC plant is in operation anywhere in the world. As OTEC extends from a land base, across the shoreline into the deep ocean, many different government agencies would be involved in permitting an OTEC plant and ensuring environmental impacts are monitored.
|OTEC plant at NELHA
Hawaii has experimented with OTEC since the 1970s at the Natural Energy Laboratory of Hawaii (NELHA) on Hawaii Island. It was found to be technically feasible but prohibitively expensive in comparison to oil prices at that time.
|Natural Energy Laboratory of Hawaii (NELHA)
Hawaiian Electric Company is in negotiations for a power purchase agreement with an ocean thermal energy conversion company. A preliminary agreement has been reached for a unit off the southwest coast of Oahu near the utility’s Kahe Power Plant. In addition, Lockheed Martin has expressed interest in developing a prototype unit in Hawaii.