The cheapest way of complying is to switch much of UK electricity generation from coal to gas fired power stations. While coal provides 66 per cent of power now and gas less than 1 per cent, by 2000 coal's share is expected to fall to under half and gas to rise to a quarter - and its share is expected to go on rising.
The air should become a little cleaner as sulphur dioxide emissions fall. This is a pollutant which causes acid rain and smogs and power stations are responsible for 72 per cent of it.
Lower coal use will also help Britain to stabilise its rising emissions of carbon dioxide, the chief cause of man-made global warming. It is cheaper to import foreign coal containing less sulphur than to build the costly equipment that strips sulphur dioxide from the exhaust gases going up the smoke stack when high-sulphur British coal is burnt.
Current thinking is that once Britain has accelerated North Sea gas production to generate much of the nation's electricity, reserves will last only 10 to 20 years. There are enormous gas fields in the Norwegian sector of the North Sea which the nation will connect up to. But the future price of gas is highly uncertain - it may be as prone to catastrophic fluctuations as oil prices in the 1970s and 1980s.
There are therefore strong arguments for keeping an efficient, technologically advanced British coal industry alive to provide a future alternative to imported fuel. If coal production is ever to rise again, the next generation will have to dig new mines - abandoned ones start to collapse within days.
Renewable energy from sources such as wind, waves and tides could help. But it is most unlikely to provide more than a quarter of the nation's power needs by the year 2020 at tolerable costs. Nuclear power could also play a part.
But coal has enormous advantages. There is enough to last 600 years at present consumption rates, according to British Coal. Its price should be stable and the supply is secure.
Critics argue that the latest round of pit closures leaves the industry so small that it is in danger of disappearing completely within a couple of decades.
Overseas demand for modern coal mining and burning technologies will grow rapidly in the coming decades. China and India are relying on their coal reserves for their industrialisation. As Britain's coal industry shrinks it becomes increasingly difficult to penetrate the new overseas markets.
Demand for 'clean coal' technologies could be an area of strong growth. This covers ways of recovering more energy from the fuel for power and heating, and of burning it in a way which produces less sulphur dioxide and oxides of nitrogen, coal's two chief air pollutants.
British Coal's largest test plant for clean coal technology at Grimethorpe, near Barnsley, is now closing down after 12 years of trials and research.
British Coal wanted to build a prototype power station of some 200 megawatts' capacity as a next step incorporating the most promising of the new technologies but neither the electricity generators nor the Government have been willing to meet a large part of the pounds 250m bill.
Electricity consumers now pay a subsidy to support nuclear power and renewables, known as the Non Fossil Fuel Obligation. There may soon be a case for them paying a small Domestic Coal Obligation, to keep a remnant of the industry alive.Reuse content