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Sea change

Cover story: Renewable energy

MARINE TECHNOLOGY is crying out for help to become commercially competitive. The most advanced of a number of 'edgling marine projects is developer Ocean Power Delivery's wave powered string of sausages, Pelamis (NCE 26 February 2004).

Despite a government subsidy, Pelamis is still more then 10 years from being 'nancially viable. Without any help from the Treasury it will not be commercially viable for at least 20 years, says British Wind Energy Association marine renewables development manager Michael Hay.

Despite the UK being surrounded by sea with fast' owing tidal currents and a wave-battered coastline, marine renewables are 10-20 years from being commercially viable, if ever.

Marine generation falls into two camps - wave or tidal.

Marine equipment contractor The Engineering Business abandoned its tidal stream Stingray project (NCE 19 September 2002) because marine renewables are unlikely ever to become commercially viable, says managing director Tony Trapp.

'There is not suf'cient energy in the tidal stream. It would never be possible to build installations on a large enough scale or achieve the economies Despite the UK being surrounded by sea with fast' owing tidal currents and a wave-battered coastline, marine renewables are 10-20 years from being commercially viable, if ever.

of scale needed to make marine renewables commercially viable, ' Trapp says.

Following trials of the oscillating hydroplane Stingray and of turbine-style tidal-stream generators, Trapp claims they could never account for more than 2%-3% of UK electricity production.

But Hay is optimistic that new thinking will help developers overcome the challenge of placing tidal devices in fast' owing waters in far-' ung locations, and that grid connections to distant offshore installations can be achieved.

He also hopes that technological advances may make tidal schemes practicable in weaker tidal streams.

As with wind, Hay believes that the biggest risk to a marine energy future is lack of political support: 'Technology will overcome any barriers so long as the market is supportive.'

Marine projects at a glance

Plant: Pelamis

Developer: Ocean Power Delivery

Energy source: Wave

Development stage: Undergoing trials off the coast of Portugal

Anticipated construction cost per unit: Unknown

Construction period: Unknown

Life of plant: Unknown

Theoretical output per unit: 250kW

Actual output per unit: Unknown

Plant: SeaGen

Developer: Marine Current Turbines

Energy source: Tidal

Development stage: First commercial installation currently under way off the coast of Northern Ireland. Onstream in September.

Anticipated construction cost per unit: £3M

Construction period: 8-9 months

Life of plant: Turbine life greater than 20 years, steel post life greater than 40 years.

Theoretical output per unit: 1MW

Actual output per unit: 400kW

Plant: Breakwater turbine

Company: Wavegen

Energy source: Wave

Development stage: In discussion with clients about 'rst commercial projects

Anticipated construction cost per unit: Unknown

Construction period: Less than one year

Life of plant: Turbines 20 years, civils works upwards of 60 years

Theoretical output per unit: 18.5kW

Actual output per unit: 6kW

Plant: Sperboy Company: Embley Energy

Energy source: Wave

Development stage: Commencing 'rst stage of detailed design.

Anticipated construction cost per unit: £300,000

Construction period: two to three years

Life of plant: 50 years

Theoretical output per unit: 750kW

Actual output per unit: Unknown

Plant: Wave Dragon

Company: Wave Dragon

Energy source: Wave

Development stage: Prototype testing: 15,600 hours of continuous real-time testing. A 7MW device is being designed for deployment off south west Wales next year.

Anticipated construction cost per unit: Unknown

Construction period: six months for 'rst unit, and three months for every additional unit.

Life of plant: 50 years

Theoretical output per unit: 4,000kW - 15,000kW

Actual output per unit: Unknown

Plant: Pulse Tidal

Company: BMT Renewables

Energy source: Tidal

Development stage: Generating 'nal design.

Prototype testing expected to begin in spring next year

Anticipated construction cost per unit: Unknown

Construction period: Unknown

Life of plant: Unknown

Theoretical output per unit: 100kW

Actual output per unit: Unknown

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