Nobody expects a Severn barrage to be built soon. But government opinion appears to be swinging in favour of the idea. The independent Sustainable Development Commission has just brought out a report that broadly supports a barrage. Though the environmental costs will be high, it says that mitigation measures will counterbalance some of the damage.
We now also have a better feel for the economics of the scheme or, more correctly, for both of the two main options for blocking the Severn. The bigger scheme blocks the estuary between Cardiff and Weston-super-Mare. It will cost about £15bn and deliver just under 5% of the UK’s electricity. The smaller – just downstream of the Severn bridges – will cost a tenth as much, or £1.5bn, but will provide a sixth as much power as the bigger project.
£15bn to build a barrage that decarbonises less than 5% of the UK’s electricity supply is a high price to pay. Scaled up to the whole of the electricity business, this is about 20% of one year’s GNP to replace coal and gas power stations. Even over twenty years, this cost is similar to Stern’s estimate of the cost of reducing the UK’s emissions for the economy as a whole. The smaller barrier delivers much less electricity, but at a capital cost per kWh of little more than half its larger cousin.
The Sustainable Development Commission acknowledges that private financiers are unlikely to put up the cash for the bigger scheme. The report doesn’t really discuss the viability of the smaller barrage but it is much more financially attractive. In terms of total capital cost and expected yearly output, the upstream barrage is very similar to the huge wind farm development called the London Array. The Array will be constructed with private capital. I believe that if the current renewable electricity support scheme remains in place a barrage across the upper Severn can be built with risk capital.
The Sustainable Development Commission thinks that the bigger scheme should be built with public funds. I am not convinced by this. The offshore wind resources around the UK are orders of magnitude greater than the useful energy of Severn tides. If the larger Severn barrage has construction costs of nearly twice the typical figures for offshore wind, wouldn’t it be better simply to speed up the licensing of wind farms?

Bjørn Lomborg, a professor at Copenhagen Business School, is the most formidable critic of those who think that cutting climate-changing gases is the most important problem the world faces. He made his name with ‘The Skeptical Environmentalist’ and his new book continues his drive to get the world to see global warming as just one of the world’s important problems.
The Pre-Budget review in early October disappointed green activists. Environmental measures formed a small fraction of the government’s initiatives. It doesn’t look as though Alistair Darling sees climate change as one of the priorities of this administration. But there were two important commitments: a revision to Air Passenger Duty (APD) and (via BERR) a competition to run a commercial-scale carbon capture project.
BT’s green credentials are well established. It is the largest commercial buyer of renewable electricity in the UK, emphasises the importance of carbon reduction across the organisation, and pushes voice and video conferencing at an unconvinced customer base. In any international ranking, BT’s sustainability measures get high marks.
Many agricultural crops can be turned into fuels. Diesel substitutes can be made from the oil in seeds. The sugars in cereals and tubers can be fermented into ethanol.
The Advertising Standards Authority is struggling to hold the line on the advertising of environmental benefits. In June, the Authority put out a series of instructions trying to impose clearer conditions on advertisers. But it continues to have to adjudicate on a series of difficult decisions. Last week saw a wind power developer taken to task for over-estimating the carbon savings from turbines. The Authority had to decide which type of power station would produce less power as a result of a new wind farm – coal or gas. It took advice from the National Grid and proceeded to tick npower off, even though the power company was following rules previously set down by the ASA itself.
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