Tidal lagoon power could give Welsh economy a competitive edge by 2020

Friends of the Earth Cymru says that significant quantities of low cost renewable electricity generated by tidal lagoons could give the south and north Wales economies a competitive edge by 2020. The group is calling on the Welsh Assembly Government to reassess their unsupportive view of tidal lagoon technology following a positive report from a leading engineering consultancy (1). The report, by independent consultants WS Atkins Engineering confirms that the generation of electricity by tidal lagoons as proposed by the company Tidal Electric Ltd is viable. The report also confirms that a proposed lagoon scheme in Swansea Bay could generate electricity cost-competitively (2).

Friends of the Earth Cymru says that the Assembly Government should now support Tidal Electric Ltd in the company's vision to generate electricity from the large tidal energy resources of the Severn Estuary (3). The group say that potential investors in the proposed lagoon scheme in Swansea Bay , impounding 2 square miles of sea to supply the annual consumption of 30,000 people, will be looking to the Assembly and WDA for their view of the technology. If the Assembly and the Agency are unsupportive then that cannot help investor confidence.

Tidal Electric have said that Assembly acknowledgement would be a useful starting point and some funding for an environmental impact assessment, of what could still be the world's first lagoon scheme, in Swansea Bay would greatly help. A scheme may be built in China (4).

The Assembly Government has so far been non committal because it has been briefed by the DTI and WDA that Tidal Electric Ltd have underestimated the costs of their technology (5).

Friends of the Earth Cymru points out that the DTI and WDA briefings have missed the point that the cost of electricity generated by lagoons is dependent on the size of the scheme, the tidal range and that the economies of scale are significant. The DTI briefing appears to draw on the generation cost of a tiny scheme proposed by Tidal Electric to supply a small fishing community in a remote area of Alaska . Electricity from such a tiny scheme in a low 3 metre tidal area is going to cost far more than very large lagoons in the globally high 13 metre tidal range of the Severn Estuary (6).

Neil Crumpton, a campaigner at Friends of the Earth Cymru, said:

"The WS Atkins report should persuade the Assembly Government that the very high tidal range in the Severn Estuary and Liverpool Bay could be used to generate potentially very large quantities of low-cost renewable electricity by 2015 or 2020. Several lagoon schemes in the optimum areas of the Severn Estuary alone, if assessed as environmentally benign, could generate enough electricity to supply three and a half million people or about 6% of UK electricity demand."

"What's more, due to the economies of scale, the generation costs of large lagoons would be below three pence and as low as two pence per kilowatt hour. This would be on par or lower than the cost of electricity generated by gas and would give the south Wales economy a significant commercial edge globally in an environmentally conscious world. Similarly, a large scheme in Liverpool Bay could do the same for north Wales."

The campaigners are calling on economic development minister Andrew Davies AM to highlight the potential of the technology where it is assessed to be environmentally benign.

Notes

1) See Tidal Electric Ltd press release below

2) Estimated at 3.4 pence/kWhour from a 2 square mile impoundment in an 8 meter tidal range.

3) Tidal lagoon resource in the optimum areas of the Severn Estuary is estimated at 2.75 GW average (Welsh electricity demand is 19.5 TWhrs/year - based on UK per capita figures). See Friends of the Earth Cymru report The Severn Barrage or Tidal Lagoons in the Severn - A Comparison (www.foecymru.co.uk). Tidal lagoons could also store energy and could be used to balance the National Grid, possibly reducing the need for fossil-fuel fired back-up.

4) The Swansea Bay scheme was first proposed about three years ago but no Assembly or DTI support has been forthcoming. Tomorrow (Thursday) a deal to progress a 300MW lagoon scheme in China will be signed by Tidal Electric (see tidal Electric press release below for details). The Chinese scheme would be the world's first depending on environmental assessment, planning and construction time-scales unless the Swansea Bay scheme progressed speedily (construction time estimated in report at 3 years).

5) see extract of Assembly debate below

6) The power output of a tidal lagoon is directly proportional to the area impounded and to the square of the tidal range :

• for a 3 meter tidal range (Alaskan proposal) - the output factor is 9,
• for an 8 meter range ( Swansea bay, Liverpool Bay) - the output factor is 64
• for a 12 meter range (Severn Estuary) - the output factor is 144
• for a 13 metre range (Severn Estuary) - the output factor is 169

Note that it requires roughly twice the volume of aggregate to impound a 12 metre tide compared with an 8 metre tide.

In terms of economies of scale, the cost of the aggregate to impound a relatively larger area is less than that to enclose a smaller area (ie to impound 2 square miles would require about 4 miles of wall, to impound 20 square miles would require only about 16 - 19 miles depending on shape). As the cost of aggregate for the walls is a significant part of the cost of a lagoon scheme (about 50% for the Swansea Bay scheme) there are significant economies of scale.

The generation cost of the Swansea Bay scheme is 3.4 p/kWhour but a scheme 5 to 10 times bigger and further east up the Severn Estuary where the tides are higher would have costs of below 3 pence and as low as 2 pence/kWhour according to Tidal Electric Ltd. For comparison, the cost of gas generated electricity is estimated at not less than 2.4 pence/kWhour - depending on geo-political factors.

Welsh Assembly, Written Questions answered between 5 and 12 February 2004

Tidal Barrage or Tidal Lagoon Technology

Helen Mary Jones: Has the Minister had discussions with the WDA and/or the DTI about the prospect of tidal lagoons in the Severn estuary? (WAQ31965)

Helen Mary Jones: Has the Minister compared the costs, environmental impact and energy production capacity of tidal barrages and tidal lagoons? (WAQ31966)

Helen Mary Jones: Has the Minister considered the future prospects of tidal lagoons as major sources of electrical energy? (WAQ31971)

..... I am aware of the proposal from Tidal Electric Limited for a tidal lagoon project in Swansea bay. My officials have discussed this project with the promoters, the DTI and the WDA.

I would draw your attention to the view stated by Lord Sainsbury in a debate within the House of Lords on 13 January 2004 that 'the DTI had assessed its [Tidal Electric Limited's] claims using an independent consultant with a background in the technology. We think that those estimates are extremely optimistic and that electricity costs are likely to be much higher-possibly by a factor of four, which puts the scheme at the top end of the range.

Of course, if Tidal Electric's assumptions are correct, it has plenty of scope to convince investors of its case and could attract commercial funds.' (House of Lords Hansard-Volume No. 656, Part No. 20, Column 551, 13 January 2004 ).

I understand that this view was also reiterated by Stephen Timms, the Minister of State for Energy, e-Commerce and Postal Services at the DTI, during a meeting held on the 28 January with Win Griffiths MP, Oona King MP and Jon Aldenton, director of TEL. This also appears to be in accord with the in-depth appraisal that is being undertaken by the WDA.

However despite these serious concerns, in view of the great potential in Wales for marine renewable energy of various types, I have asked officials to continue to track closely future developments on this and other proposals.