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 through 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 carbon dioxide from fossil-fuelled power plants in case expensive fallback options become necessary. Screening of the options commenced with flowsheeting studies which estimated the thermal efficiency of a number of process schemes. These screening studies concluded that carbon dioxide (CO2) control could be retrofitted to existing coal-fired power stations, but that the new generation of gasification-based systems is more promising. CO2 separation could be more easily integrated into advanced power plants as they operate at high pressure, resulting in increased CO2 partial pressure which reduces the energy penalty associated with the separation. The CO2 would need to be exported as a liquid stream for storage in exhausted oil or gas fields Costs of such power plants and CO2 disposal options have been developed. These studies suggest that, using proven technology, the cost of electricity would rise by about 42 per cent. If novel gas separation systems based on membranes can be developed, the increase in electricity cost could be limited to around 34 per cent. This paper discusses the options and presents the results of costing studies,