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Tuesday, January 06, 2009

Alternative energy

Interesting article in yesterday's Guardian on the proposal to construct a barrage across the River Severn. Tidal Electric, which wants to generate electricity by using up to 13 tidal lagoons built on the estuary floor from rock instead of a barrage has accused Government consultants of miscalculating the costs so as to promote the barrage scheme above the lagoons.

Studies carried out by the engineers AS Atkins, for Tidal Electric, have suggested that the lagoons could generate twice as much power, per square mile impounded, than the barrage, and therefore generate about 25-40% more energy without damaging the shoreline. However, the plan sent by Parsons Brinckerhoff to ministers says the tidal lagoon option would be eight times more expensive than the barrage scheme and would not generate as much power.

It is difficult to believe that the barrage will cost less than tidal lagoons to construct or even that it will keep within the £14 billion estimated budget. If we are to proceed with it then there must be an authorative and independent assessment of the costs of all alternatives to ensure that we are getting value for money.

I am also struck by the parellels between this row and what has happened in Swansea Bay where there are proposals to construct a tidal lagoon. It seems that this project has been thwarted at Government level, both at Westminster and Cardiff Bay, despite many experts believing that it is feasible and cost-effective.

I am not anti-wind power but there does appear to be an element of truth in accusations that the Government is incapable of looking objectively at any other non-fossil energy source and that Ministers and civil servants are promoting turbines at the expense of other feasible and more reliable alternatives. Lagoons are hardly cutting edge. It is not as if the government is being asked to invest in or approve untried technology. Maybe it is time they gave them a chance.
I have always been sceptical about the Severn Barrage simply because of the amount of material the river carries in suspension particuarly in winter. My recollection of basic geography is that when the rate of flow of a river which has material in suspension is checked all the material is deposited so presumably for the barrage to operate successfully there would need to be an enormous dredging operation - and where would the sand go? In the case of tidal lagoons, Oldbury Power Station is cooled by a tidal lagoon which needs a dredger on 24/7 operation to keep the lagoon clear. I doubt the practicality (and practicablity of the idea). The costs of maintenance would be enormous.
Personally, I would like to see more micro-generation. Where households take responsibility and ownership for their own energy generation, be it small wind turbine, or hot water solar panels or photo-voltic cells.

We could also cut down on our "food miles" by growing our own, or part-growing our own. Composting kitchen waste and using rainwater to flush toilets....
I agree with you entirely. You do ot have to be an engineer to realise that lagoons constructed from stone brought by sea, and dredged agregate ( which is a bi-product of keeping shipping channels open, so is free and local) will be cheaper to construct than a barrage built largeley of Concrete ( A huge source of Co2 - 5% of global emmissions - more than air traqnsport!) delivered by road.

Lagoons also generate electricity on the ebb and flow tides, and can be configured to act as pump storage facilities.

They add new habitats rather than destroying exisiting ones (which is why the RSPB are supporting them and oposing the barrage), and the enclosed lake can be used for commercial fish farming an lesiure use.

I would have thought it was a no brainer. Canada and China think so. Why doesn't Wales and the DTI? vested interests?

The Bristol Channel is an ideal site for these, as unlike the bay of fundy in Canada, which is the only place in the world to have a larger tidal range, it is close to large populations, and the cost of distibution, and the distribution losses would be minimal.

Tidal lagoons can be used as wave breaks and defnces against tidal surges in places like Conwy, and would cost little more than the flood defences being proposed - with the added benefit of 'free' electricity.

Unlike wind, lagoons offer a predictable generating capacity, and so balancing the grid would not be a problem. The blackout in Europe a few years ago was thought to be due to Wind generation failing suddenly.

The way tidal electric have been treated by th WAG and the DTI is a disgrace. Andrew Davies refused to meet them, and continually misrepresented their proposal. They were fully funded by private finance, but were willing to ener into a PFI. He said they wered asking for Government funds.

Seeing how we are going to have to relinquish a large amount of convergence funds, surely this could have been used for an important infranstructure project such as the Swansea tidal lagoon!
Interesting debate here. It is a genuine puzzle that the Severn Barrage is still supported as the cheaper option, given that even on revised figures the immense economic dislocation caused to one of the country's most important industrial ports - The Avonmouth at Bristol, where many of our imported cars are brought in (OK perhaps not at the moment, but in ordinary times) - would outweigh a cheaper barrage option. That's even before we talk about devastating Slimbridge and Alney Island, and the higher risk of floods (I hadn't thought of that one Richard T, despite living in the area, but he's quite right about the amount of debris the Severn carries, especially wood and silt).

The lagoons sound good to me. After all, the Victorians used to build coastal swimming pools on much the same sort of principle - surely we could manage it too, even in fairly deep water? And better yet, why stop at the Severn? The Dee estuary also is possessed of high tides and strong currents as well as a sensitive ecology, couldn't something similar work there and power Liverpool and Manchester?
Sorry to call you on this Peter, but it is obvious that a barrage which cuts across the existing estuary is going to impound a vastly greater body of water per ton of concrete than a lagoon! A barrage relies on the existing coast behind it to provide enclosure at high tide level. A lagoon would require all round enclosure. I'm afraid lagoons are a chimera for those who would conceal their own preference to leave the Severn as it is and not to tap the tidal range in the most effective way.
The 'Severn Tidal Power Reef' is the only project that has started from the 'environmental stand point' and looked for a solution. All others have started with the technology and then fudged the environmental issues to vairying extents. The RSPB recently commissioned W.S.Atkins to see if it was feasible, given its environmental benefits and they reported back to say that 'yes' it would work and that it could generate as much or more electricity and at a lower capital cost. So why is there doubt that the Government will even consider some of these more advanced concepts?
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