Select Committee on Science and Technology Seventh Report



11. Until recently most proposed tidal energy projects have been estuarine tidal barrages, such as that proposed for the Severn Estuary. (A 240 MW facility has operated at La Rance in France since 1966; a 25 MW plant in the Bay of Fundy in Canada since 1984; and a 100 MW plant in China since 1987.) Some theoretical work on tidal current turbines was conducted in the 1970s but the first installed system in the UK operated in the mouth of Loch Linnie in 1994.[30] More recent theoretical work has been funded under the European Commission's CENEX programme in order to identify the size of the exploitable European resource.[31] The Directorate General for Transport and Energy (DG TREN) of the European Commission has funded a parallel, more modest, study, to investigate the feasibility of exploiting the tidal current resource in Orkney and Shetland. The most advanced tidal energy project planned in the UK at present is Marine Current Turbine's tidal turbine scheme off the coast of Lynmouth, Devon.[32] If it receives DTI funding, the company aims to install a 300 kW prototype device early in 2002. There are several other companies developing tidal stream devices.[33]


12. For both wave and tidal energy technologies there has been increasing support and recognition in recent years from a number of bodies. The 1999 Report from the House of Lords European Communities Committee on "Electricity from Renewables" expressed surprise that the exploitation of energy from tidal streams was not further advanced.[34] The 1999 Report of the Marine Foresight Panel's Energies from the Sea Task Force concluded that both wave and tidal stream energy had the potential to supply a major part of Britain's energy needs.[35] The Royal Commission on Environmental Pollution's 2000 Report on "Energy - the Changing Climate" gave a similar endorsement to wave and tidal energy and recommended Government provide stronger support for the development of these technologies.[36] The Commission for Wave Power in Scotland - a group comprising trade unions, industry representatives, independent experts and politicians - was recently established to "capitalise on the industrial opportunities offered by Scotland's position as world leader in wave power".[37] The International Energy Agency (IEA) has established a new Implementing Agreement on Ocean Energy, focussing on wave energy and marine currents, as a "result of the importance of these energy resources.".[38]

13. Recently, the Government also has taken a more active role in encouraging the development of renewable energy. In November 2000 it published "Climate Change: the UK Programme", which sets out its long-term response to the challenges of climate change. This report identifies a number of policies aimed at improving energy efficiency, cutting polluting emissions and stimulating new, more efficient sources of power generation.[39] Of particular relevance to this inquiry is the Government's recognition that the recent reductions in UK power station emissions may not be sustained: "The large gains that have already been made came from the closure of older and less efficient coal stations and will not be repeated. There will be significant emissions of carbon dioxide as long as electricity generation is based primarily on fossil fuels, even with further improvements in technologies. As nuclear stations begin to close, and energy demand rises with economic growth, carbon dioxide emissions will begin to rise again unless there is a step change in the way energy is generated and used.".[40]

14. The Government is currently in consultation over a new Renewables Obligation, to be introduced in late 2001 and to extend to 2026. This will oblige electricity suppliers to use renewable energy sources for at least 10% of their supply by 2010 (see paragraph 7). One of the most ambitious renewable technology projects is the planned installation of 18 offshore windfarms around Great Britain. The farms were recently granted leases by the Crown Estate and, if they gain planning approval, will generate around 1,500 MW.[41] The development will cost £1.6 billion. This investment promises to provide valuable operating experience in the offshore environment and significant further prospects for large-scale expenditure on offshore energy technologies. Offshore wind turbines might also be located with wave and tidal energy installations to share infrastructure.

15. The Government has also become more positive about the prospects for wave and tidal energy in the UK. The Prime Minister in a speech at Chatham House, in March 2001, on "Environment: the next steps", stated that "We [the UK] have many strengths to draw on. Some of the best marine renewable resources in the world - offshore wind, wave energy and tidal power.".[42] In the speech he also announced an extra £100 million to support renewable technologies. The Cabinet Office's Performance and Innovation Unit (PIU) is currently conducting a study of Resource Productivity and Renewable Energy. There are several strands to the project, one of which is examining "a long-term strategy to promote the use of renewable energy" including "how to stimulate innovation, technological progress and improved working and household practices.".[43] The Unit aims to report its findings in September 2001. Ministers from the Scotland Office have recently visited Wavegen in Inverness and Islay and have praised its work.[44] We welcome the growing recognition by Government of the energy potential of a range of offshore technologies. We hope it will lead to a coherent strategy for technology development and long-term investment.

The resource


16. The oceans of the world, which cover approximately two thirds of the Earth's surface, represent a potentially vast source of energy. Indeed, it has been estimated that "if less than 0.1% of the renewable energy within the oceans could be converted into electricity it would satisfy the present world demand for energy more than five times over.".[45] The UK is particularly well-placed to exploit these resources, with a favourable wave climate and very strong tidal streams, such as the Pentland Firth, which separates Orkney from the north coast of Scotland, and those around the Channel Islands. The DTI's Energy Technology Support Unit (ETSU) estimated that practicably (as at 1999) the energy which could be obtained from around the UK was:

  • offshore wave - 50 TWh/year;

  • near shore wave (closer that 20 miles to the coast) - 2.1 TWh/year; and

  • tidal energy (at the 10 most promising sites only) - 36 TWh/year.[46]

To put these figures into perspective, the UK's annual electricity consumption is 329.9 TWh. The production of electricity accounted for 35.4% (80.7 million TOE) of the UK's total primary energy demand (227.8 million TOE) in 1999.[47]

17. This represents a massive and inexhaustible energy source, which very few other nations enjoy in such abundance. Indeed, it has been suggested to us that one reason why wave energy, in particular, has not developed more world-wide, is that, when the UK effectively abandoned its wave programme in 1982, other nations felt that, if it could not work in the British Isles' excellent wave climate, it could not work anywhere.[48] It should, however, be noted that other countries do have wave and tidal resources (for example many of the Pacific Rim countries) and there is a potentially large export market for any successful device (see paragraph 39 below). Given the UK's abundant natural wave and tidal resource, it is extremely regrettable and surprising that the development of wave and tidal energy technologies has received so little support from the Government.


18. For an energy source to be viable and useful in a modern electricity market, it does not necessarily need to be constant, but it must be reliable: a supplier must be able to predict when the supply will be available and in what quantities, so that it can be matched with alternative energy sources to meet demand. This poses a problem for many renewable energy technologies, such as solar and wind, as their output varies considerably over time and is difficult accurately to predict.

19. Tidal energy is the most predictable of the marine renewable resources. Its variation over the tidal cycles can be predicted with considerable accuracy well into the future.[49] The fluctuations which do occur over time (for example at spring or neap tides, when the tides are at their highest and lowest point) can be predicted hours, days or even years in advance if the stream has been properly studied.

20. Wave power, on the other hand, is dependent upon the weather and therefore subject to more significant fluctuations. We were told that during a storm the average kinetic power in one metre of wave crest can rise from an average of a few kiloWatts to MegaWatts.[50] However, owing to the large amounts of maritime data that have been accumulated over the centuries, it is possible to predict peaks and troughs of supply at least six hours in advance, allowing much easier integration into the Grid than some other renewables. The annual variations in wave energy (higher in winter, lower in summer) also broadly match the seasonal variations in energy demand.

21. James Martin, Generation Director of Scottish and Southern Energy, told us that he could foresee no problems in using wave and tidal devices to supply the Grid.[51] His company already used medium to long-term weather forecasts to integrate its hydro power and gas power facilities, and felt confident that wave and tidal power could be integrated in a similar manner. Dr Richard Yemm, Managing Director of Ocean Power Delivery Ltd., suggested that any problems of integration are much longer term, and will not come to the fore until renewable technologies supply a far larger proportion of the UK's electricity requirements.[52] Owing to the reliability and predictability of their output, there would be few problems for an electricity company in integrating wave and tidal energy into its supply.

Technological viability

22. The successful deployment of any wave or tidal energy device represents a major engineering challenge. Not only must it effectively convert the kinetic energy of the water into electricity, but it must survive the extremely challenging environment of the sea or ocean. It must overcome such factors as:

  • marine fouling (barnacles, seaweed, etc.);

  • access difficulties; and

  • storm damage.

Rough weather, in particular, has often been thought to rule out wave and tidal energy, especially offshore devices. For example, in its Response to the House of Lords Report, the Government stated that "We doubt whether ... wave energy generation machinery installed offshore could long withstand the extreme forces of the sea."[53] Similar doubts were expressed to us by the Institution of Civil Engineers.[54]

23. However, from the evidence we have received it seems that most of the problems raised against the technical viability of devices appear to be surmountable.[55] Devices have survived off the coast of Sweden and Japan for several years, and testing has been performed on a large number of prototypes.[56]

24. Most significantly, most of the problems of working in the sea have already been conquered by the offshore oil and gas industries, which have operated effectively in some of the world's worst sea conditions for the past 40 years or more. They have maintained extensive structures many miles from the shore, laid vast lengths of submarine pipelines and cables and developed such methods as cathodic protection to prevent corrosion.[57] Shipbuilders have also had to conquer many similar problems, for large, moving metal objects.[58] The recently announced plans for eighteen offshore wind farms (comprising approximately 540 turbines) will enable further valuable experience to be accumulated.[59] Professor Salter informed us that there were, in many respects, actually fewer technical obstacles for devices in the sea than for land devices; for example the damage caused to wind turbines in urban areas from sulphur dioxide pollution in the air was far greater than anything that would be experienced underwater.[60]

25. The area that appears to pose some of the largest problems for wave and tidal devices is that of encrustation (from barnacles).[61] At present, ships use toxic anti-fouling paints to protect their hulls but a more environmentally benign solution needs to be found. The forthcoming ban on tributylin (TBT) - the toxic anti-fouling paint used by 70% of the world's fleet - in Australia, matching the one enforced by the Japanese Government, has already spurred several large research projects into alternatives.

26. There appear to be no major technological barriers to the effective development of wave and tidal energy, which could not be solved by transferring expertise and knowledge from the offshore industries, through more multi-disciplinary research projects and through the construction of large demonstrator models.


27. The electrical energy produced by any device at sea needs to be delivered to the consumer. There are two stages of transmission, both of which have their own particular problems:

28. Transmission to the coast is principally a technical problem, which the companies we heard from were confident of solving, especially for non-floating devices.[62] Valuable lessons could be learned from the offshore oil, gas and wind industries and projects such as the 2,000 MW cross-Channel electricity interconnector, the new Northern Ireland-Scotland electricity interconnector and the 20 MW cable across the Pentland Firth to Orkney, which the islands depend upon for the security of their electricity supply and which crosses one of the world's strongest tidal currents.

29. The more difficult problem, and one that individual companies would find almost impossible to solve alone, is that of taking the electricity from the shore to the main demand load centres. Many of the sites around the UK with the highest potential wave and tidal energy (Western Scotland, the Channel Islands, the Pentland Firth, Shetland, Orkney, etc.) are distant from the major load centres (the North-West, Midlands and South-East of England). The UK's National Grid is, broadly speaking, "tapered" toward its periphery and was designed to supply electricity from a small number of large power stations at the 'centre' to the rest of the country.[63] It was not, generally, designed to receive energy from multiple sources in remoter parts of the country and transmit it to the main load centres (although, there are significant exceptions such as the Dounreay nuclear fast reactor in the north of Scotland). The transmission lines are particularly weak in the Western part of Scotland. This is a problem that Wavegen and Ocean Power Delivery face, with costs of half a million and a million pounds respectively merely to pay for the strengthening of the transmission lines necessary to connect their Islay devices to the Grid.[64] Mr Thorpe, however, stated that cost of connection to the Grid were "independently calculated to be much smaller than what the utilities are asking.".[65] The difficulties of Grid connections are probably the single most serious problem facing the successful exploitation of wave and tidal energy in the UK, and one which no single company can solve alone.

30. The problem is not merely a technical one but is directly affected by the structure of charges for Grid connection. In general, the current structure of charges levied by the National Grid Company plc in England and Wales does not encourage wave and tidal energy generators. It favours: (a) 'embedded generation' sources;[66] (b) generators who establish plants nearer to the main demand centres, or in areas where there are fewer generators (principally London, the South-East and the South-West of England); and (c) larger generators, producing more than 300 MW.[67] As wave and tidal generators, at this stage of development, are generally small and located away from the south of England, in areas which already have their electricity needs met from other sources, they will find it very difficult to meet the charges they face.

31. In its "Climate Change - the UK Programme" strategy document, the Government states that it sees its role as "facilitating and stimulating the emergence of new technologies ... [to] ensure that there are no institutional or structural barriers to transformation of the energy sector".[68] The problem of the Grid is clearly a structural barrier to the integration of wave and tidal energy into the UK's energy system. As one witness warned, there is a danger that the UK will "end up with a great generator but no socket to put the plug in.".[69] Previous Governments ensured the very costly connection to facilities such as the Dounreay nuclear fast reactor.[70] The present administration should be prepared to co-ordinate similar strategic investment for wave and tidal energy. If this is not done, the commendable targets set for renewable electricity are likely to remain rhetorical, not real.

32. We welcome the Minister's willingness to "look at either a role of banging heads together or a role of providing public assistance.".[71] We recommend that the Government should work with the National Grid Company, and other utility companies, to organise the strengthening of transmission lines required, if wave and tidal energy are to provide a significant amount of energy to the electricity market.

33. One alternative to paying for costly connections to the Grid is for wave and tidal devices, especially ones far offshore, to produce hydrogen by electrolysis.[72] This could be stored at sea and then periodically collected by ship. At least one company, Seapower Ltd., is considering this. A useful comparison would be in the smaller, more distant oilfields, where it is uneconomical to lay a pipeline. Here the extracted oil is pumped into tanks on the seabed, with a pipe running up to a buoy floating on the surface. The tanks are emptied on a regular basis by a ship, which anchors securely and hooks up to the pipe. There will be an increasing demand for hydrogen worldwide if, as is expected, hydrogen-fuelled cars become more widespread. The 2001 Budget, for example, included a "package of measures ... to encourage environmentally friendly fuels and to assist the move towards a hydrogen-based economy.".[73]

30   Also see: Cave P.R. and Evans E.M, Tidal Stream Energy: Economics, Technology and Costs, Water for Energy, Proceedings of the 3rd International Conference on Wave, Tidal, OTEC and Small-scale Hydro Energy, BHRA, July 1986. Back

31   CENEX, Tidal and Marine Currents Energy Exploitation, JOU2-CT_93-1355, February 1995. Back

32   Evidence, p 43. Back

33   Tidal energy companies who have submitted evidence to the inquiry: evidence, p 105 (; p 112 (; p 121 (; and p 135 (  Back

34   Electricity from Renewables, Twelfth Report of the House of Lords Select Committee on the European Communities, Session 1998-99, HL 78-I, paragraph 45. Back

35   Energies from the Sea - Towards 2020, Marine Foresight Panel Report, OST, April 1999, pages 12-14. Back

36   Energy - The Changing Climate, Twenty-second Report of the Royal Commission on Environmental Pollution November 2000, Cm 4749, page 144.  Back

37   Evidence, p 128. Back

38   Evidence, p 154. Back

39   Climate Change: The UK Programme, DETR, November 2000, Cm 2913, pages 7-8. Back

40   Ibid., page 61, paragraph 9. Back

41   Crown Estate Press Release: Potential offshore wind farm sites announced by the Crown Estates, April 5, 2001. See: . Back

42   Speech delivered at Chatham House, London on 6th March, 2001. See: . Back

43   See: . Back

44   Scotland Office News Releases: Scotland leading the way in wave power, 19th March 2001, SS0063; and Renewable energy making a splash on Islay, 30th March 2001, SS0081. Back

45   Progress through partnership, Marine Foresight Panel Report, OST, May 1997, URN 97/639, paragraph 2.8. See: . Back

46   Craig J., The Status and UK Resource Potential of Wave Power and Tidal Stream Energy, Irish Sea Forum, Joint Seminar on Irish Sea Renewable Energy Resource, St. George's Hotel, Llandudno, October 1999, page 19. Back

47   Digest of UK Energy Statistics 2000, DTI, pages 35 and 137. The figure for the consumption of electricity does not include 29.9 TWh in transmission losses. Back

48   Evidence, p 26. Back

49   Fraenkel, Qq 156-57. Back

50   Taylor, Q 35. Back

51   Martin, Q 110. Back

52   Yemm, Q 158. See also: HL 78-I, paragraph 333. Back

53   Electricity from Renewables: Further documents, First Report of the House of Lords Select Committee on the European Union, Session 1999-00, HL 18, p 15, paragraph 49. Back

54   Evidence, p 154, paragraph 1. Back

55   Evidence, pp 45-46, paragraphs 18-22; p 93, paragraph 1; p 95, paragraph 1; and p 137-8, paragraphs 20 and 24. Back

56   See, for example: evidence, p 94, paragraph 7; and p 140. Back

57   Evidence, p 45, paragraph 15. Back

58   Evidence, p 3, paragraph 20. Back

59   See: footnote 34. Back

60   Salter, Q 58. Back

61   Evidence, p 26. Back

62   Thompson, Fraenkel and Yemm, Q 131. Back

63   Evidence, p 111. Back

64   This problem was recognised in: The role of the Renewables Directives in meeting Kyoto targets, Royal Society and Royal Academy of Engineering, RS document 11/00, October 2000. Back

65   Thorpe, Q 70. Back

66   Embedded generation: a generator supplies electricity to its local distribution network, without the need for electricity to be transmitted on the high voltage National Grid system. So a generator in York, for example, would only supply electricity to Yorkshire Electricity. Back

67   Evidence, pp 171-2, paragraphs 6-13. Back

68   Climate change - the UK Programme, p 61, paragraphs 11-12. Back

69   Bronsdon, Q 7. Back

70   Thomson, Q 152. Back

71   Hain, Q 247. Back

72   Electrolysis: by passing an electric current through water, it is separated into its component parts, hydrogen and oxygen, and the hydrogen is stored. (In this case the electricity would be generated by an onboard wave or tidal energy device.)  Back

73   HM Treasury and DETR press release: Protecting the Environment and Supporting Britain's Road Transport, 7th March 2001. See also: Budget 2001: Investing for the long-term - Building opportunity and prosperity for all, HC 279, March 2001, paragraphs 6.50-52; and The Pre-Budget Report 2000: Fuelling the debate, 2nd Report of the Environmental Audit Committee, Session 2000-01, HC71-I, paragraphs 87-89 and 104. Back

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