Zero Emission Coal Based Power Generation

Coal will remain the largest source of electric power for some decades but there are challenges to be met in the form of emissions of pollutants and of the greenhouse gas CO2. There is therefore a need to develop coal-fired power generation systems capable of near-zero emissions (ZETs).

It is also essential, in parallel with development of ZETs, to continue to drive up the efficiency of conventional coal technologies to keep them in place as a springboard for ZETs commercialization.

For conventional pollutants, emissions from ZETs plants will need to be comparable with natural gas-fired combined cycle (NGCC) plants fitted with selective catalytic reduction for NOx control. Mercury emissions limits or degree of removal requirements will also need to be applied in some countries. For CO2 removal, and achieving at least 80% removal will be needed for contributing to tackling greenhouse gas emissions.

All of the present day coal-fired technologies for power generation could be adapted to capture 80-90% of the CO2 that they release. The important ones are pulverized coal combustion (PCC), and Integrated Gasification Combined Cycle (IGCC). PCC is so widespread that it has to be selected as one of the main bases for future ZETs.

There are good prospects for increases in the efficiency in both technologies, through gas turbine developments for IGCC and advancing steam conditions for PCC, and through reductions in the energy penalties of CO2 capture.

By the time that ZETs will be deploying, PCC will have reached very high conditions, with some plants employing steam temperatures above 700ºC. This will not give issues for CO2 capture from conventional flue gas but implications for oxy-firing require to be examined.

More conventional IGCC demonstrations are needed but orders have been slow in emerging because of cost and availability issues.

Submitted By

Mr. Ashwani Joshi

Associate Professor

EE Departmnt