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A bay that charges the batteries

Down East Maine's enormous tidal range - a bane to mariners - one day could be a boon to the region as a renewable source of electrical energy.

A 60-kW turbine suspended 20 feet under Maine's Cobscook Bay is producing electricity to recharge a bank of batteries that supplies power to a 41-foot utility boat at the Coast Guard station in nearby Eastport.

Dim lights

Just how great are the tidal changes in the area around Maine's Cobscook Bay? Click play to watch a time-lapse video from the Coast Guard. Mobile users can click here to watch on the Soundings YouTube channel.

The 13-ton turbine, which looks like a paddle wheel, is in a rectangular frame 14 feet wide, 14 feet deep and 46 feet long. Called a cross-flow turbine, its composite blades - actually carefully sculpted foils - spin in the tidal current, which flows at a speed of up to 6 knots four times a day during the 18- to 20-foot tidal changes typical of the waters flowing into and out of the Bay of Fundy.

The turbine drives a fixed-magnet generator, which powers the unit's monitoring systems and recharges the battery bank - eight 12-volt batteries stored on a 20-foot skiff tied to the turbine's 60-foot barge, Energy Tide 2. Once the batteries are recharged, the skiff is towed to the Coast Guard station and swapped out for a second skiff loaded with batteries, which goes back to the barge for recharging.

Ocean Renewable Power Co. switched on the power for the Coast Guard Aug. 18.

Dim lights

Click play to see the launching of the Energy Tide 2 and the hookup to the mooring in Cobscook Bay for testing. Mobile users, click here to watch the video on YouTube.

The battery banks supply electricity to the 41-footer's heater, its battery charger, radio chargers and other systems while it is dockside, says Capt. Jim McPherson, commander of Coast Guard Sector Northern New England.

Because Ocean Renewable Power already planned to test the tidal generator in Cobscook Bay, the Coast Guard awarded the company a $100,000 grant to put it to work supplying electricity to its station. When linked to an inverter, the battery banks supply one-third to one-half of the daily shoreside power needs of the 41-footer, says John Ferland, vice president of project development for the power company.

McPherson hopes to take alternative energy to other Coast Guard stations in Maine. "We hope to have a station one day that's completely off the grid," he says. "Zero consumption."

Read more in the November issue of Soundings magazine.

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Comments (3) Comments are closed
3 Thursday, 16 September 2010 17:51

They spend money building a useless device that has no value.....the amount of energy gathered is easily lost!
Look at the size of it....and for what?
Run some light bulbs?
There are far more creative ways to harness power with out this contraption.
Coast guard should spend it's money elsewhere.
PS: it's also not really harnessing power....just stealing ....maybe 10%. Its useful life is around 1 year
2 Thursday, 16 September 2010 04:05
william cormeny
This company should develop a collar turbine for each piling in a marina.If a low friction turbine can spin as water comes in or goes out of a port,then it can create a small current which can be fed under the decking to a larger battery charging apparatus ashore.
At night these batteries can not only provide light for the marina,it can charge the batteries on the boas which are in the slips.
1 Thursday, 16 September 2010 00:40
Awesome idea... I was excited to see some action and how it worked , but the first vids tide range did not look any different then any other maine location .. the second vid did not show the unit in action.. that would be worth seeing
fbtwit yt

Great Gear,