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Tapping the Motion of the Ocean: Could the Tides Power Our World?

The city of Eastport, Maine is made up of a small group of islands just to the east of the eastern-most point of our eastern-most state. It...

The city of Eastport, Maine is made up of a small group of islands just to the east of the eastern-most point of our eastern-most state. It houses about 1,300 residents, known for their dry humor, for their humbling heartiness, and for watching the sun rise hours before the rest of us get out of bed. The city boasts its annual pirate festival, its vague tie to a Mickey Rooney movie about a dragon, and the rip-roaring ocean tides that sweep its shores. To the east of Eastport lies Passamaquoddy Bay—an inlet of the Bay of Fundy through which 70 billion cubic feet of tidal water flow every six hours. For over 90 years, harnessing this tremendous force to generate electricity has been on the minds of Mainers. In September of 2012, their wait was over.

The power of the ocean tides has never been lost on Mainers. As early as 1749, the Perkin’s Tide Grist Mill in Kennebunkport was using a submerged tidal turbine in the mouth of the Kennebeck River to mechanically power its milling operations. This mill, and many tide mills just like it up and down the Maine coast, operated in this fashion throughout the 18th and 19th centuries. The Perkin’s mill ran for 186 years, until it finally shut down in 1935 due to the rise of the railroads and grain from the mid-west.

It was as electrical power swept across the U.S., and the power grid was expanded, that folks in Eastport began eyeing the powerful tidal currents as one method of generation. In 1920, a young hydroelectric engineer, named Dexter P. Cooper, proposed a plan to build a “tidal harness” that would create a series of dams and and locks around the city of Eastport—in order to further funnel the already-powerful tide into a narrower channel containing tidal turbines.

The plan came to be known as The Passamaquoddy Tidal Power Project (or the "Quoddy Dam" Project) and—with the help of local resident and president, Franklin D. Roosevelt—the project started construction in 1935 with U.S. Public Works Administration funding. Part-way through construction, however, funding for the ambitious and forward-thinking project was cut by Congress. (The concrete pilings that were built to hold the dam now hold up Maine Highway 190.) For the moment, tidal-electricity remained a theory.

Seventy-seven years later, on September 13 of this year, a private company named Ocean Renewable Power Company in collaboration with the Maine Public Utilities Commission, finally flipped the switch on four TideGen submersible turbines in Cobscook Bay, just west of Eastport. It took the company just a few months to install the turbines, but they spent years working through permits, bureaucracy, and red tape. Instrumental in the endurance of the project was the support of the local public utility, Bangor Hyrdo-Electric Company, and the state’s Republican Senators Susan Collins and Olympia Snowe.

The flip of that switch marked the first time in history that electricity flowed from any ocean-based resource—wind included—to the power grid in North or South America.

The four TideGen turbines are a pilot program. They are currently only generating 180 kilowatts of electricity at peak—enough to power up to 30 homes. If these turbines perform as expected, ORPC will expand the Eastport turbine generator field to a capacity of 540 kilowatts—powering up to 100 homes in eastern Maine.

Coastal towns and cities around the globe are watching this experiment with great interest. If it proves successful, tidal-power generation—due to its relatively low barriers to entry—could quickly become a major player in the world’s energy mix. Tidal power is attractive. It's renewable and clean. It's dead reliable as—come hell or high water—the tides will never stop. And finally, the turbines are underwater, which both shields them from the increasingly powerful storms of climate change and also makes them invisible from land—clearing the Not-In-My-Backyard hurdle that has plagued the wind power industry for decades.

Earlier this year, the Department of Energy released a nationwide tidal energy resource assessment stating that—with current (nascent) technologies—the U.S. could generate 250 terawatts of power using tidal turbines. Current wind and solar installations combined to produce 172 terawatts of electricity in 2011 while the country’s hydroelectric dams produced 285 terawatts. (Here's an interactive map of the country’s tidal resources.)

As with any new energy technology, tidal energy will need private investment and political support in order to survive. This technology is only a few months old and is already promising. As reported here earlier, recent investments in solar power helped engineers break the 1/3rd of the sun barrier and recent investments in wind technology has lowered the cost of operating a turbine by about 40 percent. Future investments in tidal turbines will boost efficiency and lower cost—making the DOE’s current 250 terawatt projection moot and low. (In 2011 the DOE projected that wind could power 20 percent of the U.S. economy by 2030, but two recent independent studies have shown that using current technologies, wind could power the whole world.) With the right investments, support, and brainpower, could tidal energy become a major contributor in our energy mix? Could it one day invisibly and safely power our whole world? The stubbornly optimistic residents of Eastport believe so. And I wouldn’t bet against them.

If you live in a coastal state and would like to support tidal power investment and research, let your governor, senators, and congressmen know.

Image via Wikimedia Commons

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