FEATURE - Arctic town to get offbeat tidal energy
Date: 05-Nov-02
Country: NORWAY
Author: Alister Doyle
Gigantic forces in the oceans - waves, currents and tides - have often proved too costly or awkward to harness, compared to wind or solar power in global efforts to cut reliance on nuclear power or on fossil fuels blamed for global warming.
From late November or early December, however, a tidal current will start turning the blades of a windmill-like turbine standing on the seabed near Kvalsund at the Arctic tip of Norway.
"We will be the first in the world to use tidal currents to generate electricity to be fed into the local grid," Harald Johansen, managing director of Hammerfest Stroem, told Reuters.
Other unorthodox sub sea experiments to generate power from tidal currents from Australia to Britain have not got to the stage of selling power. All the technologies mark a shift in traditional methods of exploiting the tide.
Tides have previously been tapped for use in power plants in France, Canada and Russia by building barrages to trap water in artificial lagoons at high tide. When the tide goes out, gravity sucks the water through turbines to generate electricity.
But giant damming projects are out of fashion because they can damage the ecology of rivers and coastlines. Seabed turbines, by contrast, are silent and invisible and fish can swim round them without getting sliced up.
"Of all the renewable energy technologies, ocean energy is probably the one in the earliest stages," said Mark Hammonds at the International Energy Agency (IEA) in Paris. "Many projects have proved to be too costly."
Tidal power exploits the gravitational pull of the moon, and to a lesser extent the sun, on the oceans as the earth spins. The seas rise and fall in a cycle of 12 hours and 25 minutes and can cause sweeping currents along the seabed at the same time, like the ones seen off the north Norway coast.
LIGHTS FOR 1,000 HOMES
The Norwegian sub sea turbine will have a tiny capacity of 300 KW and is due to expand to 20 mills from 2004, giving enough power for perhaps 1,000 homes.
Hammerfest, with 11,000 inhabitants, calls itself the world's northernmost town. Johansen reckons the project there has cost 50 million Norwegian crowns ($6.7 million) so far and will cost 100 million by completion in 2004.
High oil prices and pledges to curb emissions of greenhouse gases as part of the Kyoto pact to limit global warming, blamed on emissions from burning coal or oil, are helping make green technologies like tidal power more attractive despite their drawbacks.
Other systems to tap the oceans range from giant snake-like tubes that generate power when rocked by waves, to machines that extract power from the contrast between warm surface waters and chill temperatures at ocean depths.
But experts are uncertain about the potential, especially because of sub sea maintenance costs. Storms have wrecked many experimental ocean power stations.
"We need to harness all low-impact renewables we can develop. But offshore wind is more competitive and solar has more potential," said Greenpeace spokesman Truls Gulowsen.
The biggest tidal power plant in the world is a barrage across the La Rance river in northern France, in place since the 1960s. It has a 240 MW capacity, but Electricite de France has no plans to build new ones.
Canada's Bay of Fundy in Nova Scotia has the highest tides in the world, at about 12 metres (39 feet). Nova Scotia Power's 20 MW plant at Annapolis Royal, built in 1984, is the only one in North America, but the company is now focusing more on wind.
"There are ecological objections to building more tidal plants along the coast," said Margaret Murphy, spokeswoman for Nova Scotia Power.
All the plants are tiny. Western-style nuclear generators typically have a capacity of 500 to 1,000 MW and can be counted on for reliable power generation, unlike many renewable energy sources.
QUIXOTIC POWER?
In Norway, Hammerfest Stroem reckons that building tidal turbines could become a business
