Category Ocean Energy

Annexes

Besides an “index”, annexes include a comprehensive bibliography, a list of compa­nies, research institutions, universities that are involved in matters relevant or per­taining to tidal power plants and related matters. It may be safely estimated that compared to the list compiled three years ago, there is an increase of approximately 30%.

The bibliography has a majority of works written in the English language, al­though considerable effort was expended to list French language contributions to the topic. 1 It has been arbitrarily cut off in 1982 and 1992. Papers, books and all other printed material pre-dating 1982 constitute the first section. The next one spans the 1982-1992 decade...

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Economics

No major new technologies are needed for the current construction of tidal power plants, however, it may pay off to foster development and research the interface of a central’s output with national grids, calculate a sound estimate of its economic interest, design and site proper implanting, and of course environmental effect and sustainability (Frau 1993).

The regularity from year to year of tidal power (less than 5% variation) is one of its main advantages. Co-lateral advantages are proper to a site: the dam can ac­commodate rail or road traffic, provide navigation improvements, cheap electricity a virtually inexhaustible supply of energy; it can constitute a send off for un – or poorly-exploited regions and is pollution free—though not entirely environmentally benign.

Though capita...

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Environment and Economics

9.1 Tidal Power and the Environment

But for the in depth environmental assessment conducted by T. Shaw and his collaborators, little or no environmental study has been carried out prior to the con­struction of Rance or Kislaya plants.[230] Ex post facto examinations were conducted on both schemes. At the Rance site the only milieu considerations were to protect the plant, and to insure a minimum of perturbations for the entrance to the port of St Malo. In fact the major changes have been the loss of lanzons (Ammodyti – dae), the disappearance of some species and the take-over by others. High speed currents have been created near sluices and powerhouse, surges occur occasionally suddenly, sandbanks have disappeared, range of tides has decreased...

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In the Arctic

The world’s most northerly town, Hammerfest, in Norway, will be the first city to obtain its electrical power from a submarine station run by tidal currents. The 200 metric ton turbine is anchored on the seabed near Kvalsund. Its current capacity is 3 MW but it is to expand to 20 MW 36. The production would suffice to supply the needs of 1,000 homes. Costs have already reached $6.7 million (є5,73 million) and by entire project completion should have had a price tag of $14 million (є 11.97 million). The cost of produced electricity at $0.04-0.05 (Є0.034-0.043) is however triple that of hydro-plant produced power in Norway.

This tidal power will be integrated to the electricity mix in the local grid. The turbine is similar to a wind turbine. The current speed is 21/2 m/s.

A risk factor ...

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Vlieland and the Electricity de France

The French electricity provider company, Electricite de France, through an inter­mediate subsidiary, has proposed to the island of Vlieland, in the Dutch province of Friesland, to be the location for one of its demonstrations of renewable energy projects. Among the technologies is a 2 x 2 tidal current turbine, consisting of two pillars each with two rotor blades. The pillars would be anchored to the seabed. The blades, 15 m wide, would rotate 18 h a day generating a total of 1,400 kW. Coastal protection would be a collateral benefit.

The project itself would combine tidal current, wind turbines, and hydrogen and fuel cells. Electrolytic hydrogen would be produced using surplus energy, a way to store power or to load fuel cells for public transport.

If the plans materialize, Vlieland woul...

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Seaflow and Optcurrent

Canada is implementing a 250 kW demonstration plant[223] but Great Britain is in­stalling and grid-connecting a 300 kW horizontal axis turbine. [224] The latter is a Joule Program project code named “Seaflow”. The “Optcurrent” project is likewise a Joule Program undertaking involving Robert Gordon University and University College of Cork, besides IT Power.

The Seaflow project utilizes a Lynmouth turbine, a horizontal axis system mounted on a rigidly fixed vertical pillar. While the Stingray (see below) involves a linear lifted based device which relies on the same operational physical principles.

8.7.1 Stingray

The “Stingray” project is underway (Fig.4)...

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Current Developments

The various turbine rotor options are, as has been said for some time, quite similar to those for wind turbines, the horizontal axial-flow turbine and the Darrieus or cross-flow turbine. In the latter type, blades rotate perpendicularly to the flow.

Options to secure a rotor include mounting the unit beneath a floating pontoon or buoy, suspending it from a tension leg arrangement between an anchor on a seabed and a flotation unit on the surface (as has been proposed in the past), or seabed mounting, easy only in shallow environments.[222]

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The Contemporary Scene

Tidal river energy can be tapped both in the sea environment and in tidal rivers and streams. Its potential is large and a mere 10% of the energy in Great Britain was estimated sufficient to provide more than 5% of that country’s electrical needs a quarter of a century ago.[206] The 8-knot current of the river underneath the Golden Gate Bridge (San Francisco) can provide all the bridge’s needs in electricity. Like­wise were the Florida Current to be harnessed 25 GW of electricity could be pro­duced. An “aqua power barge”, capable to “harvest” energy along coasts and on tidal rivers, proposed in 1979, would use a high-impulse low-head turbine; with a 6 knots current 50 kW of installed power could be produced.

Patents have been taken out in the United States since the 19th cent...

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