Wave and Marine Power technologies

Wave and Marine Power technologies

Wave and marine broadly encompasses five different types of technology considered to be relevant to the UK.

• Tidal barrages - construction of a barrage, through which seawater flows to provide power to turbine generators. Tidal barrages, whilst a commercially proven technology, are not considered as viable in the medium-term until environmental concerns can be appeased.

• Offshore tidal current turbine - which generates electricity by using the energy in the currents created by tidal streams. Marine Current Turbines (MCT) has developed the first prototype, the "Seaflow Project", which underwent trials during 2003 off the coast of Devon. MCT plan a pre-commercial installation in 2004/05 of 3 to 4 extra units to give a combine power output of about 4 – 5 MW. The design is currently limited to water depths of between 20 to 40 m, although it is possible that suitable technology may become available in the next 10 years which will allow the exploitation of deeper fast-moving currents.

• Oscillating hydroplane – which generates electricity by using the energy in the currents created by tidal streams. The Engineering Business (EB) is currently developing a machine known as the "Stingray", which works on the principal of an oscillating hydroplane. Stingray underwent offshore testing in the Shetland Islands during summer 2003 and plans to construct a "pre-commercial" (funded by EB) demonstration installation of 5 - 10 one MW units in 2005/2006. Water depth is not critical to the siting of the generator and location is dependent upon the clearance required above it (for shipping etc). Speed of the tidal stream is the determining factor.

• "Pelamis" sea snake. When floating on the sea, hinged joints between its semi-submerged articulated cylindrical sections move with the waves, powering hydraulic motors which then generate electricity. The prototype "Pelamis" has been developed by Edinburgh-based Ocean Power Delivery, and is 120 metres long, 3.5 metres wide and 700 tonnes in weight. Several devices can be connected and linked to shore through a seabed cable, with a 30MW wave farm occupying one square km of sea. The 750 kW prototype is to be tested at the European Marine Energy Centre in Orkney during 2004.