STEPS TOWARDS THE MINIMISATIONOF CO2 EMISSIONS FROM COAL-FIREDPOWER PLANTS

摘要

On the one hand and due to its unfavourable C/H ratio causes coal the highest specific CO2rnemissions compared to the other fossil fuels and on the other hand coal will continue to playrnan important role in power generation in Europe and worldwide due to its advantages like the availability of the worldwide coal resources and their price stability compared to natural gas and oil.rnThe efficiency increase of coal-fired power plants is considered as a first step towards thernreduction of CO2 emissions. The existing potential in increasing the efficiency of coal-firedrnpower plants from today′s average values to today′s state-of-the-art can fulfil thernrequirements of the Kyoto protocol for the EU countries. As development programs for thernfurther increase of the efficiency beyond today′s state-of-the-art are already in place, thisrnpotential cannot be considered yet as exhausted.rnFurther steps for the reduction of CO2 emissions can be the retrofitting of existing coal-firedrnpower plants with the MEA technology. This option, which was applied already in the US forrnreasons of separating a CO2 stream out of a power plant′s flue gas, is already commerciallyrnavailable. Nevertheless, this application is connected with a reduction of net power outputrnand consequently of efficiency.rnAnother option is the oxygen-fired concept for both pulverised coal (PC) steam generatorsrnand circulating fluidised bed (CFB) steam generators. This concept uses pure oxygen plusrnrecirculated flue gas (mainly CO2) as a combustion medium, resulting in a flue gas streamrnwith a high CO2 concentration. Consequently, CO2 can be separated from the flue gas stream relatively easily. As such, this technology is geared towards CO2 mitigation, either throughrnthe retrofit application route or greenfield.rnFinally, this paper gives an overview over some other long term technology options for CO2rncapture like chemical looping, IGCC, or carbonate cycles and compares them in terms ofrndevelopment stage and of economic implications.