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FERC holds tidal power scoping meeting Staff from Federal Energy Regulatory Commission to be in Anchorage in August for Turnagain Arm Tidal Electric Energy Project plan Kristen Nelson Petroleum News
Could there be a new island in Turnagain Arm’s future — along with 240 megawatts of tidal-generated electricity?
Dominic S.F. Lee of Anchorage is proposing a hydrokinetic energy project for Turnagain Arm which would include a bank of turbines in Turnagain Arm, backed by a water reservoir 1 mile by 2 miles in diameter to store water for use during slack tides.
Federal Energy Regulatory Commission representatives were in Anchorage Aug. 9 for scoping meetings on the proposal.
Lee originally applied to FERC in 2009 for a tidal fence project in Turnagain Arm using Davis turbines. The company sponsor for that project was Anchorage-based Little Susitna Construction Co.
But in a May 10 filing from Turnagain Arm Tidal Energy Corp., Lee told FERC that after further engineering study “it was determined that the Davis turbines deployed in tidal fence arrangement … were considered experimental and were not accepted for current use.”
Lee said at the FERC scoping meeting that Turnagain Arm Tidal Energy Corp. was formed in 2009 specifically for the Cook Inlet energy project.
The revised plan, based on a tidal power project in La Rance, France, which has been in operation since 1966, would use a “bulb type of turbine,” with a barrage 1,000 feet long and 100 feet wide five miles from Possession Point near Fire Island.
Lee said the bulb-type turbines have been in operation at La Rance for more than 45 years with no recorded breakdowns.
The construction cost is estimated at $760 million, Lee said, and would produce 240 megawatts of power.
Reservoir 1 mile by 2 miles The barrage would be backed by a reservoir 1 mile by 2 miles — a storage tank for water to be used to drive the turbines during slack tide. The height of the tank would be 20 feet about high tide.
Lee said that while tidal power is predictable, it is intermittent because of the slack tide period — hence the storage tank. He said the slack tide in Turnagain Arm is short, 15 to 30 minutes, and the reservoir provides moving water for energy production during the slack tide.
The project would be in Turnagain Arm, southwest of Fire Island, with a submerged cable running onshore to a switch yard in Anchorage and onshore to a control building on Point Possession at the northern end of the Kenai Peninsula.
A new island Lee said at the morning scoping meeting that Turnagain Arm is an ideal place for tidal power because it has the fourth-highest tides in the world. He said the Rance Tidal Power Station in Brittany has been producing continuously since 1966 and providing power at 1.2 cents per kilowatt hour since costs were paid off in 1986. Because the tidal power project in Brittany is connected to the national power grid, slack tide isn’t an issue with that project, he said.
But Anchorage is not on a national grid, so the storage tank provides water to move the turbines during slack tide.
Slot gates would be open during flood tide and closed in ebb and slack tide. During flood tide a pump system would fill the storage tank to 10 feet above high-tide level and during slack tide slot gates would be raised and the turbines would be turned by water coming out of the storage tank.
The reservoir would have a concrete wall surrounded by rock. Lee said the barrage and reservoir would function as an island; fish and sea mammals can swim around it and it may provide habitat for birds and sea mammals, he said.
Wildlife questions In response to a question about fish studies for the French project, and whether there were whales in that area, Lee said that fish 3-4 feet long swim through the French project. He said the turbines turn slowly, slower than a revolving hotel door.
Beluga whales, he said, would be blocked from the turbines in the Turnagain Arm project.
Asked whether fish could be trapped in the reservoir, Lee said water flows in and out and the gates open and close, so fish could get in but could also get out when the gates are open.
Asked about rock for the project, Lee said TATEC has a memorandum of understanding with a rock quarry owner who has 15-30 million cubic yards available; the project, he said, would need 10-12 million cubic yards.
Asked about screening for water being pumped into the reservoir, Lee said water would be drawn from an area more than 180 feet deep, where fish are not expected. The project area itself is in water about 60 feet deep.
Other questions and issues from regulators — including the Alaska Department of Fish and Game, the U.S. Fish and Wildlife Service, the National Park Service and the National Marine Fisheries Service included: impact of pumping on marine species; ice formation in the tank in winter; affect on hydrology in Cook Inlet and on some deeper channels in the inlet that may be important to belugas; possible changes in tidal regime due to changes in geometry and bathymetry of Cook Inlet; possibility of sedimentation around a new island; ability to see sediment buildup in inlet conditions; whether project would cause more channel movement in Turnagain Arm; and whether an island a mile wide would impact bore tides in 18-mile wide area.
EIS required Kim Nguyen, the FERC project engineer, said an environmental impact statement will be required for the project.
She said agencies need to submit study requests and comments within 30 days under the integrated licensing process for the license.
There is a six to eight month period for FERC to define study plans, Nguyen said.
A second scoping document, if needed, would be issued Oct. 24; there is a resolution process for any study disputes scheduled for April through June of next year. The first study season would be in 2012; if necessary a second study season would be held.
TATEC would file a preliminary licensing proposal in September 2014; a final EIS would be issued in July 2015 and a license order in September 2015.
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