Extracts from the Nov-Dec 2002 edition of Renew
These extracts only represent about 25% of it

9. Cleaner Coal ?

The recently published Review of the case for Government support for Cleaner Coal Technology Demonstration Plant recognised that the main challenge is now reducing CO2 emissions, given that technologies to manage SO2 and NOx emissions are now well established and already installed in some coal-fired plant around the UK. The main ‘cleaner coal’ technologies are fluidised bed combustion, in which a bed of pulverised coal, with limestone added and air blown through, burns more completely and reduces acid emissions, and Integrated Gassification Combined Cycle Turbines, in which coal is gassified and the hot gases are then used in a conventional combined cycle gas and stream turbine system. Neither technology will reduce carbon emissions directly, although both are more efficient than conventional coal fired plant, and it is easier to collect carbon dioxide gas from the gassification stage of a IGCC system, for subsequent sequestration (storage) in gas or oil wells. Only in that sense is this ‘clean coal’.

The Review concluded that at present electricity price levels there was ‘ no economic case for building new coal plant’, given that ‘even without carbon capture and storage, new CCT plant would produce electricity in the range 2.6-3.7p/kWh; with carbon capture and storage, this would rise to something like 4.8- 5.8p/kWh’.

However, it did say that there was ‘a respectable case for modest government support to help the development of some supercritical components suitable for retrofitting to existing conventional plant, on the basis that the risks involved in being the first to adopt such components are currently such as to deter the generators from committing to a project’. It added ‘Domestic reference plant would also be helpful for exporters selling into countries such as China and India’.

Certainly the technologies are as yet only partly developed and they are expensive- a study by Dr Jim Watson from SPRU a few years back, suggested that fluidised bed technology costs around twice as much per kilowatt installed as conventional plant, and IGCCT even more. Sequestration would add even more to the cost- perhaps 50% more. So, with gas CCGT so much cheaper (half the cost of conventional coal plants), its hardly going to be the main way ahead, except in countries where there is no gas easily available and lots of dirty coal. Like China.

See: www.dti.gov.uk/cct/cctdemohome.htm