The nation's first commercial tidal power plant is going online this week near Eastport, Maine, with a 34-ton rotating seafloor turbine that looks like an old-fashioned push lawnmower blade but generates enough electricity for 25 nearby homes. The $21 million project will be harnessing the energy of swiftly moving currents that rise and fall more than 12 feet every day.
The Ocean Renewable Power Company has been developing the project for the past eight years, and recently signed a power purchase agreement with Maine utility officials. That helped take the project out of the testing phase and into development. A generator was lowered 85 feet below the waters of Cobscook Bay on Wednesday, Aug. 15, and connected with a turbine unit that’s already set up on the seafloor, said ORPC president Ray Sauer. Power should start flowing by Sept. 1.
The turbine blades “are similar to an airplane wing,” Sauer said. “Water moves over the foil and gives it lift, which rotates the turbine that turns a shaft and generates electricity.”
The electric power is fed directly into the local grid through an underwater cable -- just like wind power. While attempts to harness tidal power has been kicking around for a long time -- recent advances in composite materials for turbine blades and sealed water-proof generators have helped make it a reality, Sauer said.
Aside from raising money, Sauer said the toughest thing is dealing with the foul weather and corrosive marine environment that can do real damage to construction equipment and the people who run them.
“We’re just at mouth of the Bay of Fundy,” he said. “It’s not pleasant in the winter.”
Over the next four years, ORPC has been given a permit to install 20 turbine generating units that will provide power for 1,500 homes in the Eastport area. Maine’s public utility is helping subsidize the cost of the tidal power so that homeowners won’t be paying the extra tab for using this renewable, but still expensive energy source.
“We’ve proven that the power system works and the challenge is how do we make it more efficient and reduce costs,” Sauer said.
The project in Maine is just one of several across the United States that are coming to fruition after years of trial-and-error. Verdant Power has been testing an underwater turbine in New York’s East River for the past decade that it hopes will generator power to homeowners on Roosevelt Island. Federal regulatory officials approved Verdant’s power purchase agreement in January 2012 and the company says it will begin installing them in 2013.
Other tidal power projects are underway in Cook Inlet, Alaska and Puget Sound, Wash., according to Sean O’Neill, president of the Ocean Renewable Energy Coalition, a Washington, DC based trade group representing tidal and wave energy firms.
O’Neill says more than 100 kinds of ocean power technology systems are being used in coastal areas places like Ireland, Scotland, Netherlands, New Zealand, Chile and Spain. IBM has helped rig Galway Bay, Ireland, with tidal power turbines, for example.
O’Neill says regulatory hurdles have hampered tidal power projects in the United States, compared to Europe, but U.S. projects are catching up. ORPC and other firms are working on designs to produce power by turbines that float in rivers. And O’Neill sees a day soon when a string of turbines could line the Florida Straits, a narrow channel where the massive Gulf Stream current is squeezed between Ft. Lauderdale and Bimini Island – forcing the water to reach speeds up to 4 miles per hour.
“Tapping the Gulf Stream could provide 24/7 baseload power to South Florida,” O’Neill said.