Background

The emissions of CO₂ from power plants equipped with carbon dioxide capture systems are reduced by upwards of 85% compared to equivalent plants without capture. However the full environmental impact of a plant fitted with CO₂ capture will depend also on what changes are induced in emissions of other substances in gaseous, liquid and solid form. Furthermore due to the increase in fuel and chemicals consumption typical for a CCS plant emissions due to the “upstream” and “downstream” processes and particularly those  associated with increased fuel use, will also increase. Both these effects need to be taken into account if the technology is to be assessed on a life cycle basis. This study focuses only on the changes which are to be expected in the direct emissions, discharges and solid wastes of substances other than CO₂ from within the boundary of power plants fitted with CO₂ capture.

Conclusions

This report goes some way to quantify the changes which CCS will make in emissions and wastes other than CO₂ from power plant. A number of areas of uncertainty are revealed either due to lack of measurements or because processes are not yet fully developed.CCS processes in general offer reductions in gaseous emissions of most components but there are exceptions where small increases can be expected mainly related to increased fuel consumption. However solid and liquid wastes for all the processes show some increases and in some cases changes in nature. 

Recommendations

Further work needs to be done on all those areas flagged in the chart as being in some way uncertain. This work may need to be in the form of many more in depth measurement campaigns on pilot and demonstration capture plants but also some of the processes used to reduce or eliminate unwanted emissions and wastes need further development. Where gaseous emissions are highlighted as potentially increasing, attention needs to be given to the process selection and design to establish whether the increases can be mitigated or reversed. This work will need to be carried out by industry and research institutions and the role of IEAGHG should at present be limited to encouraging this work to be done, published in appropriate journals and presented at conferences and meetings.