Arctic Town Invests In Tidal Energy
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ARCTIC TOWN TO GET OFFBEAT TIDAL ENERGY
By Alister Doyle
Thursday, November 07, 2002
OSLO, Norway - In a novel use of clean energy, the world's most northerly
town will soon be the first to get electricity from a sub-sea power station
run on tidal currents tugged by the moon.
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.
Starting in 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," said Harald Johansen, managing
director of Hammerfest Stroem.
Other unorthodox sub-sea experiments to generate power from tidal currents
from Australia to Britain have not gotten 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
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 around 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 killowatts
and is due to expand to 20 mills from 2004, giving enough power for perhaps
Hammerfest, with 11,000 inhabitants, calls itself the world's northernmost
town. Johansen reckons the project there has cost 50 million Norwegian
crowns (US$6.7 million) so far and will cost 100 million by completion in
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 snakelike 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
"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-megawatt
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 39 feet. Nova Scotia Power's 20 megawatt 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
All the plants are tiny. Western-style nuclear generators typically have a
capacity of 500 to 1,000 megawatts and can be counted on for reliable power
generation, unlike many renewable energy sources.
In Norway, Hammerfest Stroem reckons that building tidal turbines could
become a business worth hundreds of millions of dollars. It notes many
experts used to dismiss windmill parks, now widespread in countries like
Denmark, as quixotic.
In Kvalsund, the water flows at about 8.2 feet per second apart from a pause
at high and low tides. By contrast, windmills are useless in calm weather
and have to be built to withstand hurricane force winds.
Solar power is a non-starter in winter in Hammerfest, where the sun sets for
about two months in mid-winter. The town was the first in Europe to get
street lighting almost 100 years ago.
But costs of the electricity are initially likely to be three times that of
typical hydro-generated electricity in Norway. Tidal power will be added to
the mix of electricity in the local grid and consumers will be obliged to
swallow the cost.
The tidal turbines weigh about 200 tons including the base and are well
below the keels of passing ships. They turn to face the tide when the
currents change direction. The turbines are designed to be maintenance-free
for three years, but divers can go down if needed.
British-based Marine Current Turbines, which plans to test a similar tidal
current system off Devon in southern England next year, says that
maintenance could be a problem for Hammerfest. "When you have strong enough
currents for tidal energy generation, there are few slack tides when divers
can work," said Peter Fraenkel, the group's technical director.
Marine Current Turbines' design, which sticks above the water, allows the
turbines to be winched up to the surface. "The size of this resource is not
understood," he said. He said that a British study a decade ago estimated
that the eight most promising sites off the British coast alone could
generate one-fifth of Britain's electricity.
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