Select Committee on Science and Technology Appendices to the Minutes of Evidence


Memorandum submitted by the Environment Trust


  1.1  The predictability and reliability of offshore tidal power offers the UK an important source of clean, renewable electricity that can suitably fit into the New Electricity Trading Arrangements.

  1.2  Pre-feasibility studies confirm that offshore tidal power will be become economic through its inclusion in the Renewables Obligation and eligibility for Renewable Obligation Certificates. Funding does not appear to be a problem.

  1.3  The Environment Trust sees the possibility of synergistic uses of the offshore tidal power technology to advance other renewable energy technologies, such as wave and offshore wind power, in the UK.

  1.4  Presently, there are no funding opportunities from UK Government for tidal power. The Environment Trust would like to see the inclusion of all renewable energy technologies in the R&D and commercial support mechanisms developed by Government, facilitating UK expertise in the field.

  1.5  As offshore tidal power impoundment structures will be located in low-lying waters, the impact on shipping will be negligible.

  1.6  The Environment Trust considers that offshore tidal power will contribute to the local environment over time. The development of offshore tidal power will have visual, sediment transport and marine life impacts, but The Environment Trust believe the positive benefits of offshore tidal power will outweigh such negative impacts.


  2.1  The Environment Trust is a London-based development trust, which was established in 1979 to promote activities to improve the environment. The Trust has been involved in over 2000 projects ranging from the development of 200 "Green Homes" to the £25 million regeneration of Mile End Park in east London.

  2.2  The Environment Trust has also promoted the development of renewable energy and, inter alia, has been involved in a number of wind farm projects in the UK. Recently, the Trust has diversified into tidal energy and has entered into a partnership with Tidal Electric Ltd to develop a 30MW offshore tidal power plant in Swansea Bay.

  2.3  In view of this involvement in the tidal power industry, the Trust is responding to the Call for Evidence.


  3.1  From its work in Swansea Bay, The Environment Trust has established that offshore tidal power technology is a commercially viable form of renewable energy, given the Government's commitment to a Renewable Obligation Certificate of 3p/kWh.

  3.2  The basic technology has been used for many years in tidal barrages. For example, the La Rance tidal barrage has operated on every tide since it first started generating in 1965.

  3.3  Offshore tidal power is merely an adaptation of the barrage technology, building a circular impoundment structure in shallow offshore waters. Underwater low-head hydroelectric turbines are used to generate electricity on both the ebb and flood tides.

  3.4  The Trust is convinced that by using this technology in an offshore installation, the environmental concerns about tidal barrages can be resolved, whilst allowing synergistic uses of the impoundment structure for commercial activities.


  4.1  A pre-feasibility study has been carried out for the Swansea Bay project based on the capital cost estimates of the construction of the impoundment structure and the cost of equipment.

  4.2  Because of the predictability of the tides, the output of the installation can be estimated preceding development and, on the assumption that the proposed Renewables Obligation Certificate is available to offshore tidal power, the project demonstrates a commercial return.

  4.3  Discussions with potential investors are at an advanced stage for the Swansea Bay project. From the interest to date, it seems probable that sufficient equity will be in place to enable the project to proceed within three months.

  4.4  Apart from the Renewables Obligation Certificate, it is not envisaged that any public subsidy will be needed for the Swansea Bay project.

  4.5  The predictability, reliability and flexibility of offshore tidal power suitably fits in with the New Electricity Trading Arrangements, recently designed to improve the overall efficiency of the UK electricity supply market.

  4.6  Offshore tidal power is potentially one of only a few renewable energy technologies capable of offering flexible services into the Balancing Mechanism of NETA. As the source of energy is free the technology is not susceptible to fuel price fluctuations, increasing the long-term flexibility of the technology.


5.1  Present projects

  5.1.1  The Environment Trust is presently involved in one project in Swansea Bay to develop a 30MW offshore tidal power project. The project has received widespread support both locally and nationally.

5.2  Project failure

  5.2.1  The commercial, technical and environmental aspects of the technology have been examined in the pre-feasibility study for the project.

  5.2.2  Further, detailed studies will be carried out before the project proceeds to ensure that the project will not fail.


6.1  Role

  6.1.1  Offshore and tidal stream technologies offer the UK an opportunity to explore alternatives to the original tidal barrage concept.

  6.1.2  The Environment Trust is interested in both forms of the tidal energy but currently only focuses on offshore tidal power.

  6.1.3  The possibility that offshore tidal power could be combined with wind, wave and even biomass has been explored in a preliminary way, with positive results. However, in the short-term, the Trust intends to pursue the development of offshore tidal exclusively.

6.2  Greater Priority

  6.2.1  In the longer-term, The Environment Trust intends to promote both tidal and wave energy.

  6.2.2  Given the unique, free, power source available in the UK, the future potential of offshore tidal power appears to be considerable. The predictability of the tides and their exclusion from fuel-price fluctuations makes the technology one of the most reliable, predictable and flexible sources of energy in the UK.


7.1  Present research

  7.1.1  To date, research into offshore tidal energy has been carried out comprehensively by Tidal Electric Ltd.

7.2  Available funding

  7.2.1  Presently there is no financial support for Research and Development for tidal power from the UK Government. The recent calls for Research and Development projects for new and renewable technologies excluded tidal power, whilst including technologies such as solar, wave, small-scale hydro, wind, fuel cells and biofuels.

  7.2.2  The programme will be given £14 million during 2000-01 and £18 million for 2001-02. Tidal power is excluded from this programme whilst wave energy is included. Given the potential of tidal power, it might be appropriate to reconsider the allocation of funding to include all renewable energy technologies.

7.3  Co-ordination of national funding

  7.3.1  Co-ordination of national funding is not a serious enough issue for The Environment Trust because of the exclusion of tidal power to date. In the interest of developing the UK renewables industry, synergy between UK and international renewable programmes would appear a logical approach for the UK Government to take.


8.1  Marine Life

  8.1.1  It seems clear that offshore tidal power will contribute to the local environment over time. The impoundment structure is likely to have an impact in its locality during the construction phase.

  8.1.2  However, once the marine environment has adapted to the changing hydrodynamics, the structure will provide a base for marine life to colonise; effectively creating new habitat.

  8.1.3  Entrapment in the turbines housed in the seaward side of the structure will be alleviated through adequate screening and sounding. The impact will also only be during the movement of water from the sea into the impoundment structure (flood generation), as when the reverse occurs (ebb generation) it is envisaged the currents will be of significant magnitude to deter the entrapment of marine life.

  8.1.4  The major impact will be the visual impact of offshore tidal power, which can be alleviated through landscaping. Once the structure has been colonised, the visual impact of the impoundment structure will be minimised.

  8.1.5  Impact on sediment movements can be modelled and understood, allowing projects to assess where impacts will be at their minimum and hence focus identifiable locations.

8.2  Shipping

  8.2.1  The impact on shipping is likely to be negligible, especially as the structure is easily navigable and will be marked clearly through adequate lights and buoys. The impoundment structure's most favourable location is on a relatively flat seabed and such a location minimises the impact on commercial shipping activities, which require deeper water.

  8.2.2  Increased tidal currents can also be utilised to increase scour in shipping lanes [if configuration permits], effectively increasing the viability of ports by reducing the need to dredge shipping channels on a regular basis.

  8.2.3  Recreational shipping activities are likely to be enhanced, as the impoundment structure will create calm water on the shoreline side for an impoundment structure. This can effectively create a harbour area for small craft, thus increasing the number of locations along the coast to house recreational sailing vessels.


9.1  R&D Abroad

  9.1.1  To date, Research and Development into offshore tidal power technology has been conducted by Tidal Electric Ltd, in the State of Alaska, USA. The detailed study assessed the feasibility of a 6.3MW tidal power plant to meet the needs of the City of Cordova.

  9.1.2  The study proved the technical feasibility of the project, although political constraints have meant the project has been put on hold. Focus has now moved to the UK and the Severn Estuary/Bristol Channel, which has the second largest tidal range in the world.

9.2  Current projects

  9.2.1  Three projects are presently underway in Wales to develop offshore tidal power, with The Environment Trust involved in the Swansea Bay project.

12 February 2001

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