Tidal Power in Maine? Not for Many Moons ; With the Technology in Its Infancy, It Will Be Decades Before Our Homes Are Lit By the Tides.
Are Maine’s big rivers and ripping tidal currents the solution to the state’s future energy needs?
Maybe. Or, maybe not.
With the price of oil rising and electricity rate hikes lined up like breakers rolling onto the beach, it’s no wonder that several entrepreneurs are pushing tidal power as the latest source of renewable, nonpolluting energy.
The Federal Energy Regulatory Commission is currently evaluating six study applications for tidal projects in Maine, applications that state officials say are likely to be granted.
While the prospects for tidal power may appear limitless, we have a long way to go to get there. Before Maine jumps in with both feet, officials need to make sure the technology works, the environmental impact of economically viable projects is manageable and that ratepayers aren’t left in the deep end if things don’t pan out.
MORE POWER NEEDED
A recent study by the Electric Power Research Institute shows Maine is one of the places most favorably situated for tidal power in the United States.
Certainly it makes sense for Maine to diversify its generating portfolio. The New England grid, of which Maine is a part, relies on natural gas, oil and coal for about 60 percent of its energy mix. Most of the rest – 27 percent – comes from nuclear plants, with wind energy, biomass and other sources comprising the balance.
Looking to the future, there are currently about 1,000 megawatts of renewable energy in the form of biomass and wind farms proposed or under construction in Maine. It’s appropriate for state officials to look for ways to reduce our dependence on fossil fuels, whose emissions contribute to global warming.
Yet, it could be decades before efficient underwater turbines are developed, tested and installed in the kind of numbers needed to make a difference. And regional demand could begin outstripping its capacity by 2007.
So tidal power won’t be in the mix of the next round of power- plant construction. Some question whether planners should expect an operational tidal station before 2030.
A NEW WAVE OF INTEREST
Six study proposals have so far been advanced for sites in Maine. Four involve what’s called tidal in-stream energy conversion technology, which is roughly analogous to underwater wind turbines. The study sites are in the Piscataqua River on the New Hampshire line, the Kennebec River near The Chops and the Penobscot River near Verona Island. The site with the best potential, according to EPRI, is the Western Passage of Passamaquoddy Bay, with its 20-foot tides.
Two of the studies examine an older approach that essentially requires the construction of a dam across an embayment, which is then filled with seawater and drained through turbines much like a hydropower dam.
Those are proposed for sites near Cutler and Half Moon Cove near Quoddy.
First harnessed with dams and water wheels, the energy of moving water has long been important to the state’s energy mix. Even now, about 7 percent of Maine’s electricity comes from hydropower.
Unlike wind, tides are predictable, rising and falling twice a day in accordance with the gravitational pull of the moon and, to a lesser extent, the sun. That’s why some call it “lunar power.”
Water is also much denser than air. Tidal currents deliver more force per square inch than wind.
HOW TIDAL POWER WOULD WORK
Instream tidal generators would capture this energy where it’s at its greatest: at the mouth of rivers and embayments where river currents are enhanced by the tides.
Instream tidal generators may offer a way to alleviate aesthetic concerns often voiced by critics of energy projects. A properly built generator could theoretically capture energy from both rising and falling tides.
The report estimates tidal generators in the Western Passage could produce electricity at between 4.2 cents and 6.5 cents per kilowatt hour. By contrast, Central Maine Power’s standard offer is 8.4 cents per kwh.
Yet it would be a stretch to say instream technology is in its infancy. One experimental project is in the United Kingdom, with a second planned for New York’s East River. The only existing tidal power plants use dams to impound tidal waters before releasing them through conventional hydro generators.
The permits being sought for the six Maine study sites cement the right of the claimant to use the site in the future. They don’t permit a study to begin. In order to install a demonstration project, tidal developers will need approval from the Maine Department of Environmental Protection.
MANY RIVERS, MANY USES
One big question is whether these underwater turbines, whose blades could be quite large, will create a hazard to navigation, especially at low tide.
State officials ought to examine whether the structures impede the movements of sea-run fish. They must ensure that any whirling parts don’t make chum out of endangered species like shortnose sturgeon, Atlantic sturgeon and Atlantic salmon .
Yet at this point, officials don’t fully understand how to evaluate these projects. No one really knows what an array of turbines will do to currents or how removing energy from the water may impact the tidal system.
The spatial requirements may be substantial. A dam might sweep across an entire bay. The Penobscot instream project envisions 100 turbines, arranged in clusters, each with a generator, anchor system and transmission line. Depending on how far apart they’re spaced, they could basically fill the channel for the length of Verona Island.
Officials ought to be extremely vigilant to protect our rivers, which are only now recovering from more than two centuries’ worth of abuse to serve a wide variety of interests. It would be foolish to now embark on another era of river development that undermines the hard-fought gains of the past several decades.
Still, it would be foolish to ignore the potential of a clean, renewable energy supply that will be with us for as long as the moon fills the night sky.
(c) 2006 Portland Press Herald. Provided by ProQuest Information and Learning. All rights Reserved.