Renew On Line (UK) 70

3. SDC on Tidal Barrage

The Sustainable Development Commission has been reviewing tidal energy options for the UK, and has come out in favour of the Severn Tidal Barrage, although with conditions:

• A Severn barrage must be publicly led as a project and publicly owned as an asset to avoid short-termist decisions and ensure the long-term public interest (but there s no hint of who pays!)

• Full compliance with European Directives on habitats and birds is vital, as is a long-term commitment to creating compensatory habitats on an unprecedented scale

• Further investigation of the environmental opportunity that might exist for combining climate change mitigation with adaptation through a habitat creation package that actively responds to the impacts of climate change over the long term

• The barrage must not divert Government attention away from much wider action on climate change.

In particular, the report notes that the UK also has an excellent tidal stream resource, and is leading the world in the development of a wide range of tidal stream devices, several of which are at the testing stage. The UK must stay the course in developing these technologies, as the export and climate change benefits are potentially very large.

On tidal lagoons, the SDC said that there was a lack of available evidence on the costs and environmental impacts, mainly due to the absence of any practical experience. We have called on Government to support the development of one or more demonstration project, which would help provide real-life data on their economic and environmental viability.

Pre-emption DBERRs John Hutton rather pre-empted the SDC report by announcing a week before it emerged, that the government would fund a multi-million pound study into a £15bn barrage looking at whether it would contravene EU rules on protected habitats (see below). He told delegates at the Labour Party conference in Bournemouth, that the Severn barrage was a truly visionary project, unparalleled anywhere in the world in scale, that alone could generate 5% of the UK s electricity by 2020 .

John Smith MP, whose Vale of Glamorgan constituency includes Lavernock Point, where the barage would make landfall in Wales, said I ve always been an avid supporter- before the debate about climate change, we had concerns about the lifespan of carbon fuels, and the cost of carbon fuels. And it s always struck me as a sensible way to generate large chunks of the energy requirements of the UK. Now climate change is a major concern it has resurfaced as a feasible proposition once again. Welsh Secretary Peter Hain said, It s great that we have such widespread support for this project from our Government. I m a huge enthusiast for this project and look forward to the publication of this report and working together to turn our vision into a reality.

But most environmental groups are strongly opposed. Neil Crumpton, from Friends of the Earth, said It s a great pity the Labour Government seems to be closing down what should be healthy and open debate about tidal technologies, particularly lagoons as distinct from the Severn barrage . More in Renew 171.

The report is at: www.sd-commission.org.uk/pages/tidal.html

• The SDC says the Severn barrage could supply 4.4% of UK electricity, but notes that tidal current turbines could collectively supply about the same total. It s less enthused by tidal lagoons, although the advantages seem significant: barrages are inevitably more ecologically invasive since they block off entire estuaries and they are also less efficient: according to the STPG, the Severn Barrage would have a load factor 24%, while according to Tidal Electric those for tidal lagoons would be 50% to 57% in the upper estuary, 36% in Swansea. Tidal Electric claim that a segmented lagoon with a series of divided cells could provide phased power, and pumped storage capacity, to match demand peaks. The case for tidal current devices is even stronger- they are modular and can be installed individually and are much less invasive then either lagoons or barrages.

Barrage Blocked?

Although Ministers are clearly keen on the Severn barrage, a problem emerged given that UK Biodiversity Minister Joan Ruddock had announced plans to give the Severn, Dee and Humber Estuaries protected status as Special Areas of Conservation (SACs). In particular it seem that the mudflats, sandflats and salt meadows in the Severn Estuary that would be affected by a barrage were singled out for mention in the Government s application for SAC status to the EU Commission. Ruddock said: In submitting these sites the Government has demonstrated its commitment to the protection and restoration of the UK s richly diverse wildlife habitats. We will work towards ensuring our environmental protection agenda and our aim to develop renewable sources of power are complementary.

She has indicated that there was a need to strike a balance between environmental protection and sustainable energy.

Welsh Secretary Peter Hain, who has backed the barrage idea strongly, commented By designating the Severn Estuary as a SAC we are ensuring that the special features of the estuary will be taken fully into account in any decision to develop tidal power .

However, according to a report in the South Wales Echo (1/9/07), the Barage consortium, the Severn Tidal Power Group, as a consequence backtracked from their proposal and said they would now consider rival proposals backed by green companies . A spokesman for the group added: What we want to see is an appraisal of all the ways that tidal power should be harnessed .

Friends of the Earth supports a rival proposal that includes small enclosed energy-generating lagoons throughout the estuary and a smaller barrage, which would also carry the London to South Wales rail line by the Second Severn Crossing. Neil Crumpton, of Friends of the Earth Cymru, said: If this is a genuine shift in stance then we welcome it. There is plenty of construction work for them in our plans.

Tidal Current Potentials

25% of UK electricity ?

ABPmer has published a new npower Juice funded study which identifies areas of exploitable tidal current energy resources within UK waters. It looks at the various technologies and notes that fixed vertical axis and horizontal axis turbines have a much larger potential tidal resource in terms of areas where they can be used, than hydrofoils, floating/yawing and injection devices.

Looking at the overall geographical constraints it concludes that around 3% of UK water could be suitable, and that about 36 gigawatts of tidal current device capacity might in theory be installed. It estimated that devices in under 40m depth might generate around a total of up to 94 Terawatt-hours (TWh) per annum- about a quarter of current UK electricity requirements. And although going further out to sea into deeper water would be harder (the power would have to be transmitted longer distances to shore), it would increase that total.

But there were many constraints limiting these large potentials. The report focusses on assessing the geographical resource and on such issues as competing use for the areas concerned. In addition there is the question of landing the power and of course obtaining finance. The report says that economics may also not be too good- it notes an OFGEM suggestion that even by 2020 electricity from tidal currents may cost twice that from offshore wind, although other estimates are lower (at around 6p/kWh), and of course there is a potential for technological progress (see Renew 168).

The report looks at what might be realistic in the next 5-10 years and looks at the best 50 sites, which it estimates might yield a total of 4.6 TWh p.a. from 1.5 GW, assuming tidal farms were limited to 30 Megawatts each. But if that limit was removed then a lot more power could be obtained- the report estimates up to 27.6 TWh p.a. in total, from around 10GW. Aldernay is seen as having the largest long term potential at around 5GW and 15 TWh, from many sites.

* For comparison, in Renew 168 we suggested that we might aim for a total of 10GW of wave and tidal current turbine capacity by 2020. That now looks quite low, as does, say, 100TWh, as a joint target- since wave should be able to supply more than tidal. Certainly, in the light of the ABPmer report, the

16TWh figure for tidal stream by 2027 in CAT s

Zero Carbon Britain plan (see later) looks like a significant under-estimate.

For the ABPmer report & associated GIS figures: http://www.abpmer.co.uk/allnews1623.asp