Costain to build £650m ‘power plant’ lagoon in Swansea bay

Costain has secured a deal to build a 9.5km long electricity-generating tidal lagoon in Swansea Bay, part of a £650m project that could be the first of several lagoons in the Severn estuary area.

The company behind the privately-funded renewable energy project aims to submit a planning application to DECC in October, hoping that approval by January 2015 would allow it to start a two-year construction contract in March 2015.

The 250MW power plant would generate electricity for 16 hours a day, using both the ebb and flow tides. A similar scheme, using the same Alstom turbines as the Swansea proposal, already operates in Brittany, France.

The company behind the project was set up by wind and solar energy entrepreneur Mark Shorrock, and is currently raising £2m in development funding from a public share offer.

A spokeswoman said that the company has set its sights on building “three, four or five” lagoons along the English and Welsh coastlines – a prospect that was given a boost earlier this week by the Select Committee on Energy and Climate Change.

The committee of MPs, chaired by Tim Yeo, published a critical report on a revised proposal to build the £25bn-30bn Severn Barrage, an 18km concrete structure. The proposal, from Hafren Power, was backed by Arup, Mott MacDonald and Bechtel, with indicative designs by architect Marks Barfield.

The report criticised the scheme, which would require a 30-year “contract for difference” (where the government would guarantee the price paid per megawatt fed into the National Grid) while other forms of renewable energy only require public subsidy for 15 years.

It also drew attention to the ongoing environmental problems resulting from a comparable barrage being built across an estuary in the Netherlands 30 years ago. It also said that calculations of 50,000 jobs created or secured by the project failed to consider job losses at nearby ports.

But the Select Committee report also suggested that renewable energy solutions with a lower environmental impact – such as lagoons – could be appropriate for the Severn Estuary. Extracts from the report say:

• Environmental impact is thought to be less since lagoons would not affect tides and water flow to the same extent and would not obstruct downstream and upstream migration of fish.
• A smaller-scale lagoon design may be more likely to gain support from a broad range of stakeholders, while still offering potential for employment benefit and energy generation.

Mark Shorrock, chief executive of Tidal Lagoon Swansea Bay, said: “We welcome comments by MPs on the Energy and Climate Change Select Committee recognising that tidal lagoons may have the potential to provide a lower-risk, lower-impact option for long term energy production in the Severn estuary. Furthermore, we are confident that we can demonstrate the robust evidence required about the costs, environmental and socio-economic impact and are absolutely focused on the creation of a tidal lagoon industry here in Wales.

“We have received overwhelming support for our proposals and tremendous interest in our community share offer. We therefore look forward to submitting our planning application in late 2013.”  

Costain is currently acting as project manager and design consultant in the pre-construction phases, and will also start geotechnical investigations this summer.

In Swansea Bay, Costain would create a bund wall up to 20m high, standing 12m above the water level at low tide and 3.5m at high tide. The lagoon would isolate tidal water at high tide, with electricity generated when it passes over a 550m long array of turbines which form a section of the lagoon wall.