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


Memorandum submitted by the Royal Society of Edinburgh


  1.  The Royal Society of Edinburgh (RSE) is pleased to respond to the Select Committee's request for comments on wave and tidal energy. The RSE is Scotland's National Academy of Science and Letters, comprising Fellows elected on the basis of their distinction, from the full range of academic disciplines, and from industry, commerce and the professions. This response has been compiled with the assistance of a wide cross section of Fellows and approved for distribution under delegated authority for the Council.

  2.  The specific questions identified in the call for evidence are addressed below.


Is the technology available for efficient generation of power from waves and tides?

  3.  The concepts for generation from wave and tidal resources are well-developed, but the technology is not yet mature for either.

  4.  Water-based technologies have an advantage over wind and solar in that the energy flux is an order of magnitude higher, typically 4kW per metre squared compared with 400W, and often much less, for wind and solar technologies. Modern load management techniques have also substantially alleviated earlier intermittent load fluctuating problems pertaining to both tidal and wave power among other renewable sources. However, factors relating to system integration still have to be considered even now for both tidal power and wave power.

  5.  Wave energy converters need hydrodynamic characteristics to enable them to operate at maximum efficiency over the normal range of sea conditions, yet they must be robust enough to withstand the worst storms. Despite its large potential resource for the UK of 40-50 TWh/year (approximately 15-20 per cent of UK electricity generation output), no economic large scale wave energy device has yet been produced, and load management and integration problems are still quite severe.


Will wave and tidal energy become commercially viable in the near future, and attractive to the private sector as a profitable investment?

  6.   Most likely sources of wave energy are on the West coast of Britain, and at some considerable distance from likely large users of electricity. Hence the total costs for design and erection of the energy generators, and the power transmission system must be analysed and estimated in relation to the market, and the price which the market will pay. Too often in the past, seemingly attractive projects have foundered because of over-optimistic initial assumptions. The problem of grid connection is common to all renewable sources as distribution grids tend to be "tapered" towards their periphery, which is often where the renewable energy is available. The intermittent nature of the supply also puts it at a disadvantage with the New Electricity Trading Arrangements (NETA) under which fluctuating supply attracts a penalty.

  7.  The economic advantage of wave and tidal power will also depend upon the relative values of imported and exported energy and on the ability of the supply system to meet the pumping demand. It will be difficult for either to become commercially viable if the present economic indicators continue to be used. However, if a new approach is taken to assess the value of renewable resources, then viability may become possible. Recent moves towards "green credits" are moves in the right direction but more could be done. These new arrangements require suppliers to provide 10 per cent of their supply from renewable sources by 2010 or pay a penalty. However, at present the price of electricity produced by wave and tidal stream technologies comes in at above 5p per unit (the capped price of the renewable electricity to be supplied in this arrangement). It will be difficult, therefore, to see why electricity suppliers should enter into such contracts with wave and tidal power providers, when they can buy themselves out at 5p per unit. In addition, tidal stream energy is not included in the Renewable obligation list of acceptable technologies despite its potential.


What projects are currently running in the UK and how successful have they been?

  8.  The main wave energy project is a shoreline device, now called Limpet, on the Island of Islay and is run jointly by WaveGen and Professor Whittaker from the Queen's University Belfast. It operated sucessfully for 10 years and has now been superseded by the Mk2 device which has been operating since November 2000 and generates 500kW. While the concept has been proven, it is onshore and so limited in power rating and it requires specific shoreline characteristics. A significant problem has also been in transmitting the power to the grid, with the existing grid line to the main land requiring significant and costly strengthening.

  9.  In terms of tidal stream energy, and science is well understood but the technology requires further development. One 300kW unit is about to be installed by Marine Current Turbines of Lynmouth in Devon and The Engineering Business has also demonstrated a small model device which they are seeking to upgrade to upgrage to a demonstration stage.

Why did past projects fail?

  10.  Wave and Tidal Energy technologies lack a large corporate sponsor and this lack is of critical importance. In the past, commercial pressures have also driven some projects too fast, with credibility being lost through embarrassing and high profile failures.


What role should wave and tidal energy have in the Government's renewable energy strategy? Should they be a higher priority?

  11.  Wave and tidal stream devices have the potential to be as important as onshore wind energy but the technology needs to be demonstrated and encouraged if it is to develop.


What Research and Development is being undertaken at present? Is national funding for R&D being well co-ordinated?

  12.  A few research teams have modest programmes. For example Professor Salter at the Department of Mechanical Engineering, University of Edinburgh is working on wave power using a modified Swedish buoy system. However, the Edingburgh wave tank, where this work is being undertaken, is scheduled for demolition.

  13.  The Department of Trade and Industry (DTI) supports a wide range of work on renewable energy under its New and Renewable Energy programme, managed on behalf of DTI by the Energy Technology Support Unit (ETSU). The EPSRC also have a Renewable and New Energy Technologies programme.


What are the environmental implications of wave and tidal energy, particularly for marine life? How will such devices affect shipping?

Wave energy

  14.  The environmental effects of wave power were considered some years ago as part of a Department of Energy programme concentrating on large 2,000mW Offshore installations off the Outer Hebrides. A decrease in the wave energy incident on shores and shallow inshore waters could result in changes in the numbers and species of the local flora and fauna, and the reduction in wave height could also lead to less replenishment of water to splash-filled pools. They may also lead to the growth, rather than the erosion, of beaches. Off-shore installations will also require shore base support facilities as well as a fleet of support vessels.

  15.  The onshore Islay Wave station is viewed by many as not contributing to the local visual amenity and some designs of air-turbine may produce unpleasant noise which could be audible above the background of wind and waves. Offshore devices will have less visual impact but may come into conflict with fishing activities in terms of risk of collision and the fouling of fishing gear on mooring systems. Offshore devices may, however, create calm conditions lee-side which will make sailing less dangerous.

Tidal Stream

  16.  Tidal stream devices are judged to be considerably less obstrusive than wind turbines and barrages and the likely hazard to navigation will be no different from that exhibited by current offshore installations. The impact on marine life has yet to be assessed.


How does Britain compare with other comparable nations in R&D in this field? What projects are currently being undertaken abroad and how successful have they been?

  17.  Because Britain has one of the best world resources of wave and tidal climate, we are well-placed to develop this potential and the Limpet wave-power device is one of the most advanced systems world wide.

  18.  There are smaller systems wave-power devices powering buoys and remote instrumentation at sea. For example, the Japanese TWG-3 is currently used by Trinity House Light House Service as well as in Denmark and Japan. Blue Energy in Canada has also developed a 25kW Darrieus vertical axis turbine. The Portuguese have built an oscillating water-column device in the Azores and further work on tidal stream devices is being undertaken in Norway, Italy and China.

  19.  Several designs have been developed and tested around the world and over the last 10 years and predictions now show that from an initial generating cost of 20p/kWh in 1980, cost will be down to 6p/kWh in 2001.


  20.  In responding to this inquiry the RSE would like to draw attention to the following Royal Society of Edinburgh responses which are of relevance to this subject: Energy and the Environment (December 1998) and New and Renewable Energy (May 1999). Copies of the above publications are available from the Research Officer, Dr Marc Rands (email: [email protected]).

16 February 2001

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