Sea Change

Electricity Abroad Next year, the tranquil setting of Strangford Lough, Co .Down will become a stage for the presentation of a new, cutting-edge electricity generation technology with global implications.

The world’s first grid-connected tidal power station is almost online. SeaGen is a tidal turbine generation plant that is not only expected to contribute electricity to the Irish grid, but is also the first stage of a process that has the potential to transform the field of sustainable energy.

Strangford Lough was chosen as the site of the SeaGen project – a part of the North’s Environment and Renewable Energy Fund scheme – in part because of its swift tidal flow through the narrows. About 350 million cubic metres of water flow through the Narrows with every tide, moving at up to four metres per second.

The volume, speed and regularity of the tidal movements are the key to tapping this endlessly renewable source of energy. Although the potential of tidal flows for generating electricity has been apparent for many years, it is only in the last decade that the science of offshore engineering was sufficiently advanced to make the exploitation of this resource technically feasible and economically viable.

Of course, hydroelectric plants powered by river currents or dammed water flows have been in service for over a century. But finding a dependable and predictable way to harness the energy of the sea has been a more elusive goal.

Earlier efforts, like the Rance tidal power plant in Bretagne, France, were either estuary current plants which also benefit from a tidal flow, or were too small for anything but immediate local use – so-called tidal mills. (An old tidal mill once operated at the Strangford narrows near the SeaGen site.) The successful commissioning of SeaGen will thus represent an entirely new method for generating electricity, and significantly, a technology that is environmentally sound and potentially massive in its application.

The 1.2MW turbine will be powerful enough to light a thousand homes, yet its environmental impact will be negligible. The turbine will turn slowly enough not to pose any danger to any of the 2,000 marine species who live in the lough and being entirely submerged, will have no impact on the migrating Brent geese and Arctic terns who also call the Lough home every year.

The SeaGen turbine is presently at the Harland and Wolff facility in Belfast, where it has undergone final system assembly and testing. It is anticipated that the turbine will be installed in the second half of 2008.

Marine Current Turbines Ltd., the company which developed the technology, has already completed a ‘proof of concept’ 300kW turbine off Lynmouth in Devon, which has been operating since May 2003. Once SeaGen is up and running in Strangford Lough, the next phase will be the SeaGen Array – a small ‘farm’ of underwater turbines, involving as many as ten units like SeaGen, to generate an aggregate of around 10MW.

The company’s strategic goal is to have 300MW of installations completed by 2010, and after that, as the company says, their market is ‘literally oceanic in size.’

Germany, where new technologies for wind power are turning an underexploited resource into a major part of tomorrow’s energy mix.