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Severn pillars

William Stanton FGS

William Stanton FGS thinks the Severn Barrage is a bore.

Geoscientist 18.4 April 2008

Yet another feasibility study of a possible Severn Barrage has been announced. The first was in 1849; but none, I believe, has considered the impact of Peak Oil (Geoscientist 17.4) on the proposals, which have concentrated on feasibility, cost, power generation and the likely effect on landscape and wildlife. Peak Oil is the point at which world oil production reaches its maximum and then starts to decline. According to the Association for the Study of Peak Oil and Gas, with which few oil experts quarrel seriously, the world is passing through Peak Oil now, which explains the rapidly rising prices of petrol and diesel and of the products that depend on them.

Peak Oil is a tipping point in human history – and it may (Geoscientist 18.3) be followed by another relating to coal. Before it, fossil fuels were available abundantly and cheaply. After it, our lives will become increasingly difficult. The reasons are simple: a farmer using diesel-powered machinery is at least 40 times more efficient at farming than a farmer deprived of liquid fuels. Artificial nitrogenous fertilisers, in quantities equal to about 15kg for everyone on earth each year, are made from natural gas, which is also peaking. So after Peak Oil, the most basic commodity of all, food, will become scarcer and more expensive, year after year. I fear that our concern for landscape and wildlife will, within a decade or two, be subordinated to our concern for personal survival.

So - should the barrage be built as quickly as possible, to help compensate for the growing scarcity of fossil fuels? Unfortunately, electricity is a poor substitute for oil when it comes to farming. Also, most renewable liquid fuels, such as bioethanol and biodiesel, are so energy-expensive to produce that there is little or no surplus energy available to stand in for conventional oil.

The barrage would not generate electricity continuously. As planned by the Severn Tidal Power Group, generation would only take place during the ebbing tide, or about 10 hours every day. Without pumped storage or other means of storing electricity, the gaps would have to be filled by a reliable (predictable) alternative supply, on a massive scale, that could be switched on and off at predictable times. Wind turbines, and solar and wave generators, are not reliable. Only hydropower fits the bill, and there is none of the necessary size in Britain. Reliable generators that operate 24 hours per day, such as landfill gas and nuclear, could not easily be switched off when the barrage was operating. Large conventional power stations would have to be kept ticking over as back-up, ready to fill the gaps – and that would defeat the object of the exercise.

Our future after Peak Oil is dark, the more so because the subject seems to be taboo to politicians and planners. In my opinion, building the barrage as currently proposed would do little to solve our problems of energy shortage in the future. Nuclear power, especially the latest fast breeder reactors, would be much more practical.