ENERGY-ICELAND: Osmotic, Tidal Power Show Promise

• by Lowana Veal (reykjavik)
• Tuesday, December 22, 2009
• Inter Press Service

Prototype power plants tapping these innovative sources are to be located in the West Fjords of Iceland and expected to be functional in the next few years.

Osmotic power, harnessed at estuaries, is probably the world’s newest form of energy. However, the basic technology behind it is over 30 years old as it is basically desalination in reverse.

Thorsteinn Ingi Sigfusson of Innovation Centre Iceland (ICI), who has been involved with the development of osmotic energy and tidal power, says that osmotic technology is relatively safe and simple.

'When you have a saline mass of water on one side and freshwater on the other, chemical energy separates these masses. The system uses a special diaphragm which lets the freshwater through from one side but does not let the saline water through in the opposite direction. This means that the freshwater penetrates into the saline with a resulting increase in pressure on the saline side,' the professor said.

'This pressure is consequently used for powering a generator. The pressure can amount to 100 m of water column and can subsequently be used to move a generating wheel linked to an electric generator,’’ Sigfusson said. 'At an estuary, two such masses of water meet. If you constantly design a situation where the freshwater and saline waters meet, you can harness this set pressure difference.’’

Sigfusson cited the example of the river Thjorsa in South Iceland, which is home to five existing hydroelectric power plants and four planned ones which are controversial.

'Where Thjorsa meets the sea, you could probably add 30-40 percent of the already harnessed power upstream. This does not involve any dams and the station can be placed underground, not visible to the eye, and will not harm any part of the river,' Sigfusson said.

Osmotic power has been developed in Norway as well, and the world’s first demonstration osmotic energy plant was opened there in late November. The Norwegian plant was developed in conjunction with the engineering company Statkraft.

Sigfusson says that the Norwegians decided 30 years ago that they did not want any huge hydroelectric plants and decided to develop alternatives. 'I don’t think any problems have arisen with the Norwegian osmotic plant,' he says.

As to the future of osmotic energy in Iceland, Sigfusson says: 'At the Energy Farmer seminar in Isafjordur, Northwest Iceland, the Westfjord Power Company (WPC) and ICI agreed to aim for a small desalination station in the West Fjords to be open to the public on Jun. 17, 2011. This will be at the existing Mjolka station, though there are other possibilities.'

As for tidal power, two types are envisaged. A tidal barrage plant - which will bear similarities to the Rance tidal plant in northern France built way back in 1966 - and a tidal current plant.

Bjarni M. Jonsson has been involved with the former. 'It will measure the height difference between low and high tides,' he says.

Jonsson carried out measurements on the magnitude and depth of tides in several fjords that empty out into Breidafjordur Bay as part of his master’s degree in Coastal and Marine Management.

Jonsson found that the real power that can be harnessed from the fjords would be 75-80 Mw. But there is an added bonus: if the barrage is constructed, two crossings will be built across adjacent fjords to house the turbines. Bridges for these fjords were already in the pipeline by the Icelandic Roads Authority, so the plan would combine both projects.

What happens next? 'We (myself, ICI, WPC and the West Fjords Economic Development Agency) have set up a small spin-off company called WesTide, to investigate further possibilities of this project,' says Jonsson.

A little further south, a company called Ocean Energy (OE) is also planning to harness the power of the West Fjords. Unlike WesTide, OE plans to use a turbine under the sea to generate power from the tidal current.

The company, which was set up in 2001, has already mapped the sea floor of the areas which seem most promising. The maximum harnessable power of the fjord appears to be 650 Gw hours/year in the first stage.

OE is currently awaiting a research permit to continue research into tidal currents. At the time it was set up, no permits were required - but now they are.

After the necessary research has been carried out, OE will look for a suitable turbine.

The turbine could conceivably come from Iceland, as on the former USAF base a new company called Valorka is developing a new kind of turbine which is primarily designed to be used in tidal power plants.

Company director Valdimar Ossurarson says that more research will be carried out next year with the aid of a grant received from the Technology Development Fund.

'The Valorka turbine is a new invention, but unlike most other tidal turbines it is not based on a windmill concept. The Valorka turbine will have a large surface area and is therefore more suitable for use in slower currents. Existing turbines need a current speed of at least 2 m/sec to work effectively, which only exists in some channels and fjords,' says Ossurarson.

'The Valorka turbine is expected to work effectively at the current speed commonly found by headlands and points. If this is confirmed in tests, our turbine may become the world’s first offshore tidal turbine. The Valorka turbine will be fully submerged, avoiding the environmental hazard of barrages,' he adds.

'There is a great deal of energy waiting to be used off the coast of Iceland: that’s where Iceland’s real resources lie,’’ Ossurarson said.

© Inter Press Service (2009) — All Rights ReservedOriginal source: Inter Press Service

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