Atlantic Canada’s Bay of Fundy has some of the world’s highest and most powerful tides. Every day, 100 billion tonnes of seawater surge in and out of the bay — a perfect source of clean, reusable alternative energy, if it can be properly harnessed.
Tidal power isn’t new, of course; small grain mills were powered by tides in Europe centuries ago. But tapping into the reliable, natural ebb-and-flow of water to generate electricity didn’t begin until the 1960s.
In 1984, Nova Scotia opened a small plant that takes advantage of the massive Fundy tide as it rushes up the Annapolis River, funnelling the surge through turbines to generate power.
That Annapolis plant produces about 20 megawatts a day, enough to power about 4,000 homes.
Now Nova Scotia is preparing for a much bigger Fundy project, one that is unique to North America and could eventually produce 100 MW of electricity, about 10 per cent of the province’s peak load.
The $50-million pilot project, set to begin by next fall or the spring of 2010, will be different from previous tidal efforts not only in size but also in method.
Rather than pushing water through turbines in the “barrage” style of a hydroelectric dam, three experimental turbines will be dropped into the deep waters of the bay and will operate more like underwater windmills.
“If it’s done the way we think it could be done, residents of Nova Scotia wouldn’t know that the tidal farm existed,” says James Taylor, general manager of environmental planning and monitoring at Nova Scotia Power Inc. in Halifax.
The provincial government has chosen three companies to take part in what’s called the Fundy Institute of Tidal Energy. The project will test three turbines for at least two years and feed about four MW to the province’s electrical grid for immediate use — something other trial projects don’t do.
A project at Race Rocks off Vancouver Island, for example, charges storage batteries but the power isn’t used commercially.
“Most projects to date have just been burning off energy,” says John Woods, vice-president of energy development at Minas Basin Pulp and Power Co. Ltd. of Hantsport, N.S., which will manage the Fundy project.
The test site will be in the Minas Passage, just west of Black Rock. The first challenge will be to put the massive turbines in the water; then underwater cables six-to-eight inches in diameter will be run about three kilometres to shore, where a small facility will feed the turbines’ energy to the power grid.
Another challenge will be to maintain the machinery in Fundy’s cold, fast-moving waters; the turbines will have to be extremely reliable. “Our best efforts are going into designing a maintenance-free operation for a four- or five-year period,” Mr. Woods says.
Three types of machines will be studied:
Minas Power will install a buoyant turbine, known as the Underwater Electric Kite, made by UEK Corp. of Maryland.
Nova Scotia Power will install a 10-metre-diameter turbine from Open Hydro Group Ltd. of Dublin, which has two such units installed at the European Marine Energy Centre off Scotland’s Orkney islands.
Clean Current Power Systems Inc. of Vancouver will provide the only Canadian-made turbine in the tests. Company president Glen Darou says its technology (already tested at Race Rocks) was designed from scratch for operation in 40 to 60 metres of sea water. Rather than trying to keep water out of the turbine generator, Clean Current designed a flooded one.
“When we applied for the patent in 2001, nobody thought that was possible,” Mr. Darou says.
The project will look not only at engineering and technology issues but also the impact on marine life, and even the tides themselves. Environmental research will be an important part of the tests.
The turbines’ designs aim to minimize the impact on marine life; their blades rotate fairly slowly, and the machines from Clean Current and Open Hydro have large openings in the centre, so neither fish nor objects that might damage the equipment should be drawn into the blades.
Mr. Darou expects marine life simply to swim around the turbines. “Fish and sea mammals are not stupid,” he says. “They do not run into rocks underwater.”
But there are still many questions, says Anna Redden, director of the Acadia Centre for Estuarine Research at Acadia University in nearby Wolfville, N.S., and the project will provide an opportunity to look for answers.
“There are a number of fish species that actually migrate in and out of the Minas Basin,” Ms. Redden says. These include Atlantic sturgeon and striped bass, and there are already concerns that the bass spawning grounds are declining.
Ms. Redden’s research team has already begun tagging fish and lobster to gather data on migration patterns, which they can use for later comparison to determine whether the turbines interfere with fish behaviour in the area.
And turbine action might also affect tidal currents and silt deposition, an issue Halifax’s Bedford Institute of Oceanography will be studying.
The impact on the lobster fishery is also a concern. Ms. Redden notes that lobsters congregate around items on the sea bottom, and may be drawn to the structures built to anchor the turbines. Because the turbines will be well above, they won’t pose a physical danger to lobsters, but because no trapping will be allowed in an area around the test zone, the local lobster catch might be affected.
Meanwhile, Nova Scotia isn’t the only province looking to exploit the Bay of Fundy tides.
Neighbouring New Brunswick has given Irving Oil Ltd. permission to assess 11 sites along that province’s Fundy coast. After studying the sites and narrowing the list, Irving hopes to launch trials at the best ones in about two years, says Jeff Landry, the company’s manager of business development.
Large-scale tidal power trials are on tap in other parts of the world. In addition to the Orkney Islands centre, which began feeding power to Britain’s electricity grid this year, ScottishPower recently announced plans for a three-site project that could start operating by 2011 and produce 60 MW. A larger project is proposed off South Korea, but would not be operating before 2015.
Three companies have been selected to install turbines in the Bay of Fundy. The experimental technology has the potential to convert the kinetic energy of the seawater that flows in and out of the inlet each day into 300 megawatts of electricity - enough energy to power close to 100,000 homes.
CLEAN CURRENT POWER SYSTEMS
The Vancouver company’s Mark III turbines are built to a simple design with one moving part and no drive shaft or gearbox. A tall column anchors it to the seabed and a central opening allows fish to pass through.
NOVA SCOTIA POWER
Nova Scotia Power Inc. already operates the Annapolis plant that harnesses the tidal action of the Bay of Fundy. Its OpenHydro Turbine is an Irish technology that, similar to the Mark III turbine, anchors to the seabed on concrete columns.
MINAS BASIN PULP AND POWER
This Nova Scotia company plans to install Maryland-based UEK’s hydrokinetic buoyant turbine. The turbine will be dropped into the water and float freely until it finds the optimal current. Anchors will fix it into position.