SeaGen turbine was commissioned in Strangford Lough in July 2008. Credit: Siemens.
SeaGen exported over 11.6GWh of power during its entire life cycle. Credit: Siemens.
The project was decommissioned in July 2019. Credit: ARCHIVED Department of Energy and Climate Change.

SeaGen turbine was the world’s first commercial-scale tidal turbine. It was developed by Marine Current Turbines (MCT) and was commissioned in Northern Ireland’s Strangford Lough in July 2008.

The 1.2MW SeaGen project, comprising of two 600KW turbines, required a total investment of £12m.

The project reached an important milestone in September 2012 by producing up to 5GW/h of power since its commissioning. It was equal to the power required by 1,500 households annually. The milestone indicated the completion of the demonstration phase of the project.

It exported over 11.6GWh of power during its life cycle and was successfully decommissioned in July 2019.

SeaGen tidal energy turbine project details

SeaGen was installed in Strangford Lough in May 2008. It was towed to the mouth of the Lough by a barge. The turbine as a whole weighed 1,000t and is 43m wide from tip to tip. Designed by engineer Peter Fraenkel, the rotors drove a generator that sent energy along a cable that then linked into the national grid across the Lough in Strangford village.

"SeaGen worked much like an ‘underwater windmill’ with the rotors being driven by the power of the tidal currents rather than the wind."

Built at Belfast’s Harland and Wolff’s shipyards, the birthplace of the Titanic, SeaGen took approximately 14 days to install with the system being bolted onto the Lough’s bed. SeaGen briefly delivered 150KW of electricity into the grid, while it was being commissioned in July 2008. Both turbines reached their full capacity in November 2008.

SeaGen had a mobile cross arm on a single supporting pile, which was 3m in diameter and 9m above the average sea level. The twin rotors generated electricity once the tide ran faster than 1m/s. At maximum speed, the tips moved at approximately 12m/s, which was approximately 1/3 of the average wind turbine speed. The two rotating blades turned at 14rpm and drove a gearbox system.

Grid connection of the Irish tidal plant

The project had the capacity to supply power to 1,500 homes. Irish energy company ESB Independent Energy bought the power generated by the turbines for its customers in Northern Ireland and the Republic of Ireland. The grid connection work was undertaken in partnership with Northern Ireland Electricity.

Technical challenges to tidal wind farm

The marine environment posed a number of unique technical challenges, not least installing SeaGen in an extremely aggressive tide race. SeaGen works much like an ‘underwater windmill’ with the rotors being driven by the power of the tidal currents rather than the wind.

Strangford Lough has a highly energetic tide race and so is recognised as one of the main tidal ‘hotspots’ in the UK and Irish waters. Other areas are the waters off Anglesey, the Pentland Firth and the Channel Islands.

MCT established a £2m programme to monitor SeaGen’s environmental impact, involving scientists from the Queen’s University Belfast and from the Sea Mammal Research Unit (SMRU) at St Andrew’s University.

The programme included the presence of a marine mammal observer on SeaGen at all times during the commissioning phase, where SeaGen only operated during daylight hours, to observe how it interacted with the Lough’s marine life.

There was also a sonar system, which monitored seal movements, operated by SMRU and partly paid for by the nPower juice fund.

The project was given an environmental all-clear in January 2012 under the Environmental Monitoring Programme led by environmental consultancy Royal Haskoning.

Finance for the Strangford Lough tidal facility

The project was partly funded by the UK Department of Trade and Industry (DTI) and the UK Government granted £5.2m towards it. Northern Ireland Electricity provided funding of £500,000 as part of NIE Smart (Sustainable Management of Assets and Renewable Technologies), which encourages the development of renewable power and energy-efficient alternatives throughout Northern Ireland.

In 2011, the project attained the UK Government’s operating performance criteria, qualifying it to benefit from the Marine Renewables Deployment Fund established by the Department of Energy and Climate Change.

Project planned for Anglesey

Tidal power could supply up to 10% of the UK’s energy within ten years, and SeaGen is the world’s first commercial tidal stream energy generator. It is more than four times as powerful than the world’s second most powerful tidal current system, the 300KW SeaFlow that was installed off Lynmouth on the north Devon coast more than five years ago.

The system will act as a prototype for even larger installations. Based on the Strangford Lough experience, the company plans to scale up the technology to build a 10MW tidal power farm within the next three years.

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

MCT is a UK-based company established in 2000. Siemens acquired approximately 10% interest in MCT in February 2010 and increased its stake to 45% in February 2012.

SIMEC Atlantis Energy acquired the entire issued share capital of MCT from Siemens in an all-share deal in April 2015.

Decommissioning of SeaGen

The decommissioning process for the project began in May 2016 and included removal of two 600kW powertrains. The topsides and crossbeam were taken out in August 2018, while the remaining tower and subsea structure were removed thereafter.

Keynvor MorLift was appointed as the principal contractor for the decommissioning project works, which included the decommissioning engineering, planning and offshore works.