Select Committee on Welsh Affairs Written Evidence

Written Evidence from The Environment Trust


  The Environment Trust is working to bring the UK's first community owned tidal lagoon to Swansea Bay. Tidal lagoons use an offshore impoundment structure that looks like a rocky island. The impoundment is fitted with conventional low-head hydroelectric generating equipment and produces predictable power. The technology works best in areas with high tidal ranges, and Wales has the second highest tidal range in the world. Wales has the potential to lead the world in tidal energy.

  We hope to develop schemes in Newport and Rhyl after Swansea. There are 22 sites across the UK where this technology could be applied, and we believe that it could eventually supply up to 20% of the UK's energy needs.


1.1  About the Environment Trust

  The Environment Trust is a registered charity and a company limited by guarantee. We improve the social, economic and physical environment for community benefit. We were established in 1979, and have built an award winning millennium park in Mile End, a number of affordable "green homes" in London and now in Sheffield, and improved numerous green spaces in London. We also run environmental education programmes and established Fair Finance, the UK's first Financial Services Authority accredited community finance institution.

1.2  The Environment Trust's interest in Welsh Energy

  The Environment Trust has recently acquired the Welsh Biofuels wood pellet factory in Bridgend. We turned around its business plan and the business is now processing 10,000 tonnes of wood pellet a year. The business has expanded from six to 16 employees, is controlled by a majority Welsh board, including Win Griffiths, the ex-MP for Bridgend, and is committed to using its profit for community benefit in Wales. We are hoping to establish other factories in the UK using the Welsh Biofuels brand.

  1.3  The Environment Trust is working to install a tidal lagoon in Swansea Bay. This tidal lagoon, and the position and potential of tidal energy in Wales more generally, will be the main focus of this written evidence.

  1.4  The Trust welcomes this opportunity to give evidence to the committee, and will be pleased to appear as a witness, or to offer further information if necessary.


  2.1  Until now, the main way of generating energy from the sea has been tidal barrages, notably La Rance Barrage in France. Environmental problems have made tidal barrage technology unattractive because navigation is blocked, fish migration is impeded, shoreline habitats altered and the tidal regime is changed.

  2.2  Offshore tidal lagoon technology is a new way of generating electricity from the ocean. The technology is similar to conventional low-head hydroelectric technology, but by using tidal pools built from loose rock and located offshore, potential environmental damage is eliminated.

  2.3  Electricity is generated as the tidal lagoon fills and empties on the ebb and flow of the tide. The hydroelectric generating equipment is housed in a self-contained offshore impoundment structure or atoll built from loose rock. Using this offshore impoundment structure, water is impounded at high tide and delivered to turbines at low tide, and then the water is held out at low tide and delivered through the turbines at high tide.

  2.4  This diagram illustrates the power generation cycle of a tidal lagoon. At high tide the lagoon appears as a circle on the surface of the water, almost invisible from the shore. At low tide, it looks like a rocky island. As the structure is built from locally sourced rock, it can provide a vital habitat for wildlife. It can be located as little as a mile offshore, so it has no effect on shipping or navigation.


  3.1  The Environment Trust is working to create the UK's first tidal lagoon in Swansea Bay, with a declared net capacity (DNC) of 60MW. This would provide the whole of Swansea with electricity.

  3.2  This plant would save up to 194,332 tonnes of carbon emissions per year, which over the 50 year life of the plant amounts to 3,886,641 tonnes of carbon saved. Tidal lagoons could therefore play a vital part in allowing the UK to meet its carbon emissions targets.

  3.3  Subject to ERDF and Welsh Assembly support, the Environment Trust would make the lagoon in Swansea Bay community owned—the first community owned power plant in Britain. This would ensure that the profits from the sale of the electricity (estimated to be £8 million a year after the first three years).

  3.4  Because tides are totally predictable the output from a tidal lagoon can be estimated very accurately. The projected cost of electricity is likely to be 3.5p per KWh. For larger project in locations with higher tidal ranges, cost could be as low as 2p per KWh.

  3.5  Developing the Swansea Bay scheme will take three years, including the community consultation and consents process. Private loan finance for half the cost has been offered but, because this is the first scheme, private equity investment is proving difficult. Paradoxically, this offers a unique opportunity to translate government grant into community equity and provide a revenue stream to pay for community led regeneration into the future.

  3.6  In response to earlier concerns by Welsh Development Agency and Department of Trade and Industry officials, a detailed study by WS Atkins was commissioned. The Executive Summary is attached as an annex, but the main findings are as follows:

  3.7  Feasibility confirmed

  Atkins investigated the feasibility of construction, operation and eventual decommissioning of a tidal lagoon installation, with proposed capacity of 60 MW and annual generation of 187,000MWh. The installation concept envisaged an impounded area of some five kilometres square, in a water depth of 1—5 metres at mean low tide, with 24 bi-directional turbines each of 2.5MW capacity.

  3.9  The Atkins study has confirmed both the technical feasibility of the project and its ability to deliver the specified output, on a predictable basis with minimal regular maintenance and negligible operating costs. It further confirms that practical design solutions exist for all necessary structures and equipment. Working with the local utility, Western Power Distribution, a way has been found of connecting to the grid.

  3.10  No exceptional problems

  Atkins engineers studied the full range of exceptional issues related to the location, such as tide and weather conditions, likely settlement of structures on the seabed, disturbance of seawater circulation in Swansea Bay and possible ship navigational hazards. It was concluded that there were no inherent exceptional problems.

  3.11  The study finds that it should be possible to obtain all the plant, equipment and building materials and complete construction of the facility within 36 months. Looking well ahead, de-commissioning issues relating to the proposed installation were reviewed and found to present no particular technical problems.

  3.12  Costs

  Indicative costs were drawn up, based on investigations with various suppliers and contractors. If given the go-ahead, the next phase would be to put a specific design out to competitive tender, which would allow for more accurate capital cost estimates.

  Based on the Atkins findings, it is possible to produce electricity from the Swansea Bay scheme at a cost of 3.5 pence per kilowatt hour.

  3.13  River Tawe Test Project

  Despite the conventional hydroelectric technology used to generate electricity in a tidal lagoon, there has been some debate over the use of hydroelectric generators in this context. In response to this, the Environment Trust is working with the City and County of Swansea to bring back into use the currently unused turbine in the River Tawe. This would both be a valuable renewable energy scheme in its own right and a scaled down demonstration of how a larger lagoon would work.


  4.1  Wind energy dominates the renewable energy policy landscape in Wales, and lack of government support for or interest in tidal lagoons has made it difficult to secure financial backing for the pilot scheme in Swansea. The Crown Estate, who lease the land necessary to build the scheme is Swansea Bay, are adamant that they cannot proceed without a strategic lead from the DTI, in the form of the Offshore Renewables Strategy.

  4.2  The Offshore Renewables Strategy went for public consultation in 2002, but has not yet been published. The consultation document dealt solely with offshore wind power, and we are concerned that the potential of tidal power is being ignored. However, we do have a note of a meeting with DTI officials where they indicated they would look on tidal lagoon technology favourably.

  4.3  Tidal lagoon technology was dealt with favourably in the 2004 House of Lords Science and Technology Committee report, Renewable Energy: Practicalities. Both AEA Technology and Friends of the Earth have also backed the tidal lagoon scheme, with AEA Technology concluding that tidal lagoon technology is "mechanically feasible, environmentally benign and economically profitable."

  4.4  Once the Swansea Bay scheme is established, we would like to develop further lagoons in Newport and Rhyl. There are 22 further sites around the UK with tidal ranges high enough to support tidal lagoons—we believe that there is the potential to supply up to 20% of the UK's electricity needs from tidal lagoon technology.

December 2005

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