The SeaGen seabed tidal energy system, which recently started to deliver grid power at its full output on a continual basis, has become the first–ever marine renewable energy project to be accredited by the UK energy regulator OFGEM for ROCs (Renewables Obligation Certificates) and so will receive payment for the power it is generating. ROCs are the method by which the UK government rewards the commercial generation of clean energy and hopes to encourage investment in renewables.

Developer and operator of Seagen, Marine Current Turbines, is however seriously concerned that the current investment climate threatens the long-term future of the marine energy sector, noting that the ROC for marine energy is set at the same level as that for offshore wind, a far more mature technology. The company, along with other parts of the marine energy sector, is therefore looking to the UK government to adopt measures that will encourage new investment into the tidal and wave sectors. The Energy department has given direct support to Seagen, granting £5.2 million in funds to take it from the drawing board and into the waters of Strangford Lough. 

The machine, which works like an underwater windmill with its rotors driven by the tidal currents, was first deployed in May 2008, at Strangford Lough, Northern Ireland. The commissioning period took longer than expected, owing to some blade problems in the summer, but in July 2008 first power (160 kW) was briefly delivered to the grid, and by December 2008 the owners were able to run the machine up to its full power of 1.2 MW. As it moved towards full-operating mode the generator was run for periods of up to 22 hours a day, with regular inspections and performance testing undertaken as part of the project’s development programme. Electricity production stopped in January when a damaged blade needed replacement, but by March this year production was resumed and has continued ever since – although, oddly, only during daylight hours. This was one of the conditions set by the Environment Agency which insists that, for the immediate future, two observers, one of them on the rig itself, are present at all times to monitor the movements of the seal population. MCT reports that so far the seals seem quite happy with the situation and there is some speculation that they are starting to regard the turbine blades, which rotate at only 12-14 rpm, as a plaything put there for their benefit.

1.2 MW is the highest power rating so far of any tidal stream system anywhere in the world and exceeds the previous highest output of 300 kW produced in 2004 by MCT’s earlier SeaFlow system, off the north Devon coast of England.

The company’s next project is a joint initiative with npower renewables to take forward a 10.5MW project using several SeaGen devices off the coast of Anglesey, north Wales. It is hoped this ‘tidal farm’ will be commissioned around 2011/2012. 

The company is also investigating the potential for tidal energy schemes in other parts of the UK, and in the Bay of Fundy, North America.