http://www.cbc.ca/cp/science/080214/g021411A.html
DANIA BEACH, Fla. – Just off Florida’s coast, the world’s most powerful sustained ocean current, the Gulf Stream, rushes by at nearly 32 billion litres per second and it never stops.
To scientists, it represents a tantalizing possibility: a new, plentiful and uninterrupted source of clean energy.
Florida Atlantic University researchers say the current could someday be used to drive thousands of underwater turbines, produce as much energy as perhaps 10 nuclear plants and supply one-third of Florida’s electricity.
A small test turbine is expected to be installed within months.
“We can produce power 24/7,” said Frederick Driscoll, director of the university’s Centre of Excellence in Ocean Energy Technology.
Using a $5-million research grant from the state, the university is working to develop the technology in hopes that big energy and engineering companies will eventually build huge underwater turbine arrays.
In Canada, Nova Scotia Power owns and operates one of three tidal power plants in the world and the only one in the Western Hemisphere.
The plant harnesses the tidal action of the Bay of Fundy, which boasts the world’s highest tides. The plant uses a head pond to capture the flow of the water and operate the plant, which can product up to 20 megawatts daily.
New technologies are being created to capture the power of the tides, including the use of offshore floating tidal turbines, as well as turbines that are anchored to the ocean floor.
That’s what’s envisioned for the Florida coast.
Researchers hope to make it as cost-effective as fossil fuels. While the initial investment is higher, the currents that drive the machinery are free.
There are still many unknowns and risks. One fear is the “Cuisinart effect”: The spinning underwater blades could chop up marine life.
Researchers say the underwater turbines pose little risk to passing ships. The equipment would be moored to the ocean floor, with the tops of the blades spinning about 10 metres below the surface.
They would be at that depth because that’s where the Gulf Stream flows fastest. Standard navigation equipment on ocean vessels could easily guide them around the turbine fields if their hulls reached that deep.
Unlike offshore wind turbines, which have run into opposition from environmentalists worried that the technology would spoil the ocean view, the machinery would be invisible from the surface.
There would only be a few buoys marking the fields.
David White of the Ocean Conservancy said much of the technology is largely untested in the outdoors, so it’s too soon to say what the environmental effects might be.
“We understand that there are environmental trade-offs, and we need to start looking to alternative energy and everything should be on the table,” he said.
The Federal Energy Regulatory Commission has issued 47 preliminary permits for ocean, wave and tidal energy projects, said spokeswoman Celeste Miller.
Most such permits grant rights just to study an area’s energy-producing potential, not to build anything.
The Gulf Stream is about 30 nautical miles wide and shifts only slightly in its course, passing closer to Florida than to any other major land mass.
“It’s the best location in the world to harness ocean current power,” Driscoll said.
Researchers on the West Coast, where the currents are not as powerful, are looking instead to waves to generate power.
Vancouver-based Finavera Renewables, which also has energy projects in Portugal, Canada and South Africa, has a licence to test a wave-energy project in Washington state.
It will eventually include four buoys in a bay and generate enough power for up to 700 homes. The 35-tonne buoys rise above the water about two metres and extend some 20 metres down.
Inside each buoy, a piston rises and falls with the waves.
The company hopes to be the first in the U.S. to operate a commercial-scale “wave farm” off northern California.
The project with Pacific Gas and Electric calls for Finavera to produce enough electricity to power up to 600 homes by 2012. Finavera eventually wants to supply 30,000 households.
Roger Bedard of the Electric Power Research Institute said an analysis by his organization found that wave-and tide-generated energy could supply only about 6.5 per cent of today’s electricity needs.
Finavera spokesman Myke Clark acknowledged that wave energy is “definitely not the only answer” to U.S. power needs and is never going to be as cheap as coal.
However, Clark says it could be “part of the energy mix,” and could be used to great advantage off the coasts of Third World countries, where entire towns have no connection to electrical grids.
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