Facing the acid test

Facing the acid test Environmental concerns associated with the burning of coal have existed for centuries. Over the last 20 years attention has moved from the emission of particulates, which have been reduced substantially following 'clean-air' legislation in OECD countries during the 1950s and 1960s, and is now focused on the emissions of oxides of sulphur (SO2) and nitrogen (NOx). Much uncertainty and a great deal of controversy surrounds the whole 'acid rain' issue. However, there is general agreement that serious damage to forests (principally in Germany), along with substantial acidification of lakes and streams (for example, in Norway and Canada), has already taken place. What is not clear is the extent to which acidic deposition has caused, or contributed to, these problems. If, as now seems likely, acidic deposition plays some part, the solution is still far from clear as the relative contribution of large power plants (coal and oil) compared to mobile sources (the principal pollutant from automobiles is NOn) is not known. Notwithstanding these uncertainties, 20 countries have now made a commitment to reduce SO2 emissions by 30% from 1980 levels (the UK is a notable exception). Of these, some appear likely to achieve substantially greater reductions, and a draft directive of the EEC calling for a 60% reduction in emissions by 1995 (again from 1980 levels) will probably be adhered to by a number of countries. In addition, the fitting of flue gas desulphurization (FGD) equipment on new coal-fired power stations is mandatory in some countries, most notably the USA, where such legislation has been in force since 1971. The control of pollutant emissions does not come cheap. The fitting of FGD equipment may increase capital costs by as much as 25% on a new power station, even more if retrofitting of old plant is required. It is perhaps not surprising, therefore, that some power utilities and coal producers in Western Europe appear to have little enthusiasm for the introduction of costly measures which may do little to alleviate the problem. Within the UK, a country responsible for one fifth of all SO2 emissions in Western Europe, the Central Electricity Generating Board is the dominant emitter, accounting for 60% of SO2 and a little under 50% of NO×. These bald statistics do not and should not imply any criticism of the CEGB; it is hardly surprising that one of the world's largest power utilities, which, miners permitting, depends on coal for 80% of power generation, should be responsible for a certain amount of pollution. Where the CEGB does expose itself to criticism is in its approach to the reduction of pollutants. The CEGB argues that no action on SO2 reduction should be taken until more is known about the interrelationship between power station emissions from tall stacks in the UK and forest die-back in Germany or lake acidification in Norway. It calls for a 5-10 year research programme aimed at reducing some of the uncertainties, after which any necessary action will be taken. The chances of such a strategy representing the least-cost option for the CEGB are high, particularly when account is taken of the fact that the cost and performance of FGD 378

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technology, should it be required, is likely to improve substantially in the next decade. When presenting such arguments, however, the CEGB fails to take account of any external costs it may be imposing on the environment by its emissions, both in the UK and abroad. If a link does exist between emissions of SO2 from power stations and damage to forests and lakes, then the delay option favoured by the CEGB will bring with it additional environmental costs. Evaluating such costs is always difficult, but it is clear that these costs could be very high, particularly if serious damage proved to be reversible only over very long time periods. The fact that uncertainty exists does not mean that the option which simply calls for more research is inevitably correct. Formal techniques for estimating the value of further information in this type of problem are now well established. There is no evidence, however, that these methods of decision analysis have been applied to the present problem, which means that the CEGB are acting on little more than a hunch. They may, of course, be right. However, until some attempt is made to compare the risks of pursuing a strategy which may be contributing to large-scale environmental damage with one which will certainly lead to a modest increase in UK electricity generation costs, the CEGB's position will continue to attract criticism and, to her neighbours, Britain will remain the 'dirty old man of Europe'.

Dr Nigel Evans Cambridge Energy Research Group Cavendish Laboratory Cambridge

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