44. The river Severn has a tidal range of 14 metres, the second highest tidal range in the world.[78] The potential for harnessing this power by way of a barrage across the River Severn has long been recognised, the idea having first been proposed in 1849 The first major study of the likely environmental impact of a Severn barrage was carried out in 1981, with further research in 1989.[79] The case for a re-appraisal of the Severn barrage proposals has been put by the Severn Tidal Power Group, a consortium of construction firms representing McAlpine, Taylor Woodrow, Balfour Beatty and Alstom. The Group's proposal is for a 10 mile barrage running from Larnock Point near Cardiff to Brean Down near Weston-super-Mare, which would work by impounding the tide and then releasing the water through 216 turbines to generate electricity.[80] In May we invited representatives of the Group to give a presentation to the Committee.

45. The Severn Tidal Power Group estimates that a barrage could provide 5 per cent of UK electricity consumption by 2020, which would obviously be a significant contribution to the Government's target of increasing to 20 per cent the percentage of electricity generated from renewable resources.[81] This was the Government's own estimate in its 2006 Energy Review.[82] In addition, the energy produced would be carbon-free, resulting in significant savings in CO₂ emissions. The Minister for Science and Innovation said that "A Severn barrage would be one of the largest civil engineering projects in the world, and by far the largest single renewable energy generation scheme in the UK".[83]

46. However the Government's 2006 Energy Review also estimated that the construction of a Severn barrage would cost in the region of £14 billion, and noted that tidal barrages "generally are not competitive with other forms of low carbon generation".[84] The Review noted:

It is clear that while attractive in terms of energy generation and associated benefits, plans for a Severn Barrage would raise strong environmental concerns in view of the designations that apply to the Severn Estuary.[85]

47. By the time the 2006 Energy Review was published, the Government had already invited the Sustainability Development Commission (SDC) to conduct a major study into the potential for tidal power in the UK, including the Severn Estuary. The following year, the 2007 Energy Review contained a change of emphasis:

Tidal power represents a significant untapped resource. The geography of the UK means that we are particularly well positioned to harness the power of the tides to generate cleaner energy. ... Tidal power could make a significant contribution towards meeting the twin challenges of climate change and security of supply.[86]

48. The SDC's report Tidal Power in the UK was published in October 2007, and contains a detailed and thorough analysis of the proposals for a Severn barrage.[87] The report acknowledges that "the benefits of a barrage ... are extremely substantial from a climate change or energy security perspective".[88] However, it continues:

The reduction in carbon dioxide emissions from a Severn barrage depends heavily on the assumptions made on the carbon intensity of the displaced electricity.[89]

In other words, the better we get at producing electricity without CO₂ emissions (for example through nuclear power), the less attractive the cost:benefit ratio for a barrage becomes.

49. The construction of a barrage across the Severn would also lead to the loss of a protected mudflat habitat which is an important area for migrating birdlife.[90] As the SDC's report states, the 'hypertidal' nature of the estuary - precisely what makes it attractive for potential power development, "is also responsible for creating a series of unique conditions and habitats, such as extensive mud flats and mobile sand banks. Extracting energy from this dynamic regime in the form of a tidal barrage would fundamentally change the nature of the Severn Estuary".[91]

50. It is clear that a barrage would significantly alter the nature of the landscape and change the unique habitat of the Severn estuary, an environmentally sensitive area protected by numerous national and international designations.[92] The SDC report notes:

The Severn barrage proposals are located in an estuary that has high levels of environmental protection under national and international legislation, and its construction would involve large-scale and irreversible change to the hypertidal estuary system.[93]

The SDC's report concluded that "any proposal for a Severn barrage must fully comply with the Directives".[94]

51. Those in favour of the proposed barrage argue that national and EU environment legislation imposes an obligation for this to be compensated for, as the site is designated a special protection area under the EU Habitats Directive. Overall, they argued that bird and marine life would actually increase as a result of the barrage because of the consequent reduction in tidal range and reduced currents. On this point, the SDC's report notes:

The scale of habitat creation required to provide adequate compensation for a Severn barrage project would be unprecedented within the UK. Nevertheless, the SDC considers it technically, legally and financially possible ... given sufficient political will. ... It is clear that the compensation requirement would be the biggest test that any barrage proposal would have to face and may even determine the overall viability of the project.[95]

52. Those in favour of a barrage also believe that it would lead to a large reduction in the suspended sediment in the water, allowing greater penetration of sunlight and a more stable sea bed with more plant and animal life. The SDC cautiously acknowledged the effect a barrage might have on the sediment level in the Estuary, noting that:

…a barrage might result in deposition of up to 85 per cent of the mobile sediment load, which in turn may allow sufficient light to penetrate the water column to create a viable photic zone.[96]

53. Protection against flooding from high tides and storm surges was given as a further benefit by those in favour of the project, as 140 miles of South Wales, Somerset and Gloucestershire coastline would be enclosed by the scheme as proposed. Again, however, the extent of the protection which a barrage would afford is disputed by those opposed to the scheme, including Friends of the Earth Cymru.[97]

54. There is a further economic case to be made in favour of a barrage, in that the project proposed by the Severn Tidal Power Group would create an estimated 35,000 jobs at the peak of construction and lead to between 10,000 and 40,000 permanent jobs in the region.[98] Were this to be combined with improvements to the transport infrastructure by the provision of additional road and rail links, this would obviously represent a significant boost to the economy of the South Wales region.

55. Shortly before the publication of the SDC's report, the Secretary of State for Business, Enterprise and Regulatory Reform announced that Government was to conduct a feasibility study for a tidal power scheme in the river Severn, including a barrage. The study will examine the environmental impact a barrage would have and how these could be mitigated.[99] It will also assess the social and economic impact of a barrage, including the impact it would have on the infrastructure of the surrounding regions. The study will also consider how such a project might be financed, and assess the technology and engineering requirements.

56. We believe that the Government is right to conduct further detailed study of the Severn barrage proposal. Such a scheme has the potential to make a significant contribution to the Government's targets for increasing the percentage of electricity generated by renewables and for reducing CO₂ emissions. However, given the scale of the project and the extent to which it would impact on this environmentally sensitive and highly protected area it is essential that the most careful assessment is undertaken. This should include consideration of the adequacy and financing of any habitat compensation which is required, which would be on an unprecedented scale. A thorough assessment of the possible financing options should be included, as well as the impact which a barrage across the Severn would have on the infrastructure and economies of the regions concerned.

79   Bondi study EP 46; Tripartite study EP 57 Back

80   Severn Tidal Power Group, presentation to the Committee, 22 May 2007 Back

81   Meeting the energy challenge, Energy White Paper, DTI, Cm 7124, May 2007, p 144 Back

82   The Energy Challenge, Energy Review, DTI, July 2006, CM 6887, Box 5.2, p 100 Back

83   Hansard, 24 April 2007, col. 268WH Back

84   Note: STPG figure is £15 billion (at 2006 prices); The Energy Challenge, Energy Review, DTI, July 2006, CM 6887, Box 5.2, p 100. It is not clear whether these figures include the full cost of providing a compensatory habitat. Back

85   The Energy Challenge, Energy Review, DTI, July 2006, CM 6887, Box 5.2, p 100 Back

86   Meeting the energy challenge, Energy White Paper, DTI, Cm 7124, May 2007, Box 5.3.1, p 144 Back

87   Turning the Tide: Tidal power in the UK, Sustainable Development Commisson, 1 October 2007 Back

88   ibid, 5.3.4 p 144 Back

89   ibid, 4.4.2 p 83 Back

90   Source: RSPB, quoted in Hansard debate, 24 April 2007, col .265WH Back

91   Turning the Tide: Tidal power in the UK, Sustainable Development Commisson, 4.5.2 p 85 Back

92   ibid, 4.6.2 p 89 Back

93   ibid, 5.3.3 p 142 Back

94   ibid, 5.3.3 p 143 ("the Directives" refers to EU environmental legislation) Back

95   Turning the Tide: Tidal power in the UK, Sustainable Development Commisson, 5.3.3. p 144 Back

96   ibid, 4.5.4 p 88 Back

97   The Severn Barrage, report by Friends of the Earth Cymru, September 2007, 2.3 p 23 Back

98   Source: Severn Tidal Power Group  Back

99   Speech by Rt. Hon. John Hutton MP, Secetary of State for Business, Enterprise and Regulatory Reform, Labour Party Conference, 25 September 2007 Back