(PRWEB) September 24, 2003
Homes on the Arctic tip of Norway started getting power from the moon on Sept 20 via a unique sub-sea power station known as 'The Blue Concept', at Kvalsund Sound, driven by the rise and fall of the tide...near the town of Hammerfest.
The tidal current caused by the gravitational tug of the moon on the earth, started turning the 10-metre blades of the turbine, which is bolted to the sea-bed to generate electricity for the local grid.
The prototype looks like an underwater windmill and is expected to generate about 700,000 kilowatt hours of non-polluting energy a year or, according to the national TV station, NRK, enough to light and heat about 75 households and they expect to double this figure in the commercial version.
"This is the first time in the world that electricity from a tidal current has been fed into a power grid," Harald Johansen, managing director of Hammerfest Stroem which has led the project, said.
The plant in the Kvalsund channel, which had cost about 80 million crowns [$11 million] by launch time, is a tiny contributor to help cut dependence on fossil fuels like oil and gas blamed for global warming.
The water flows at about 2.5 m per second for about six hours when the tide is rising through the Kvalsund channel, pauses at high tide and then reverses direction. The tide is 12 hours total per day, with 6 hours rising, 6 hours falling, six hours rising, six hours falling. The blades on the turbine automatically turn to face the current.
A challenge in a tidal environment is that access becomes difficult. Accordingly, the mills are given a modular design, allowing all critical components to be lifted out of the water in one operation for maintenance and repair. These module systems are adopted from the offshore and shipping industries.
In contrast to wind that may come from almost any direction, tidal currents move only back and forth, unless the strait is very wide. By rotating the propeller blades around their own axis at slack water when the current turns, the mill is ready for the reversing current ["pitch control"]. Thus the nacelle of a tidal mill with pitch control can remain fixed, while the windmill nacelle needs to be rotated into the direction of the veering wind.
To determine whether the tidal power plant will have any significant negative impact on the marine environment which might require special measures to preserve the eco-systems, Hammerfest StrÃ¸m AS has initiated co-operation with the consulting company Akvaplan NIVA and The Norwegian Institute for Nature Research.
Another important part of this cooperation is to predict possible adverse biological impacts on the installations, such as reduced efficiency and/or corrosion due to fouling.
If successful, the project could put to far wider use the predictable tides in green energy and generate millions of dollars in orders.
Windmills, by contrast, are not as efficient because they are useless in calm weather and have to be built to withstand hurricane-force winds.
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REUTERS[ SATURDAY, SEPTEMBER 20, 2003 11:33:29 PM ]