COMBATING GLOBAL WARMING - REDUCING CO2 EMISSIONS FROM COAL-FIRED POWER-PLANT

The threat of global warming is sufficient to warrant 'least regrets' measures to reduce emissions of greenhouse gases, in particular throug h increased efficiency in energy production and use. British Coal has set up a programme to contribute to the international responses to the threat. It is concentrating on investigating options for removing car bon dioxide from fossil-fuelled power plants in case expensive fallbac k options become necessary. Screening of the options commenced with fl owsheeting studies which estimated the thermal efficiency of a number of process schemes. These screening studies concluded that carbon diox ide (CO2) control could be retrofitted to existing coal-fired power st ations, but that the new generation of gasification-based systems is m ore promising. CO2 separation could be more easily integrated into adv anced power plants as they operate at high pressure, resulting in incr eased CO2 partial pressure which reduces the energy penalty associated with the separation. The CO2 would need to be exported as a liquid st ream for storage in exhausted oil or gas fields Costs of such power pl ants and CO2 disposal options have been developed. These studies sugge st that, using proven technology, the cost of electricity would rise b y about 42 per cent. If novel gas separation systems based on membrane s can be developed, the increase in electricity cost could be limited to around 34 per cent. This paper discusses the options and presents t he results of costing studies,