A tidal power system has successfully completed testing, a “huge milestone” for America’s ocean energy industry, according to its Maine-based manufacturer. Ocean Renewable Power Company’s $2 million underwater system has generated grid-compatible power from tidal currents in the waters off Eastport in Washington County.
“We have now done performance testings of what we call our Beta tidal energy system here in Cobscook Bay, and the results came out exactly on the design curve,” CEO Chris Sauer says. This means that although the turbine’s power output varies due to the tidal cycle, the power can be converted into a format that will enable it to be fed into the grid.
The system generates renewable electricity by harnessing the energy of rivers and oceans. Rather than relying on dams, which can be costly and detrimental to marine environments, the systems are designed around a much smaller turbine-generator unit or TGU. It works much like a wind turbine, with rotating foils that power a central permanent magnet generator. But because it’s installed underwater, which is more than 800 times denser than air, the TGUs provide significantly more power than wind turbines at relatively low water speeds. The system is built primarily of composites to resist corrosion. As gearless units, the equipment requires no lubricants, and emits nothing into the surrounding water.
At river and ocean energy sites, the company would install TGUs in groups to form complete power systems. The modular design makes it easy to adapt to different site environments. To install systems in small rivers and sites with shallow tides, the company would secure arrays of TGUs to the riverbed or seabed using bottom support frames. For deeper tides and oceans, several TGUs are stacked to form larger, more powerful modules, which are then moored to the sea floor with a deep sea mooring system. Because the modules are buoyant, they can be suspended above the sea floor at a depth that’s safe for both sea life and vessels.
Sauer says the predictability of tides gives this form of power an advantage over other alternative energy sources. “You know exactly when you’re going to be producing how much,” he says. “With wind and solar, you don’t know. It depends when the wind’s blowing and when the sun’s out. We know exactly when tides are going to occur.”
Sauer hopes the first commercial system will be installed next year in Cobscook Bay — home to some of the strongest tidal currents in the world. This will be the first grid-connected tidal energy project in the United States. By late 2011, Sauer plans to have a 150-KW system in place, providing enough electricity for more than 50 homes. By 2017, he hopes to meet the power needs of all Washington County, and beyond. Until then, the next step is to get a federal permit so the first commercial project can be underway next year.
Ocean Renewable Power Company
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