Environmental Impact of Solvent Scrubbing of CO2

Publication Overview

Environmental impacts due to the capture of CO2 at power plants occur directly and indirectly. Direct impacts results from the avoidance of CO2 emission to air and can also occur due to changed emissions of NO2 and SOx as a consequence of CO2 capture and the emissions of solvent and its degradation products. Indirectly, an increase of environmental impact is caused by the decreased thermal efficiency, which leads to a higher fuel use, the production and transport of solvents and additives and the disposal of solvent and degradation products. The scope of the present study covers both the direct and indirect environmental impact of CO2 capture but transport and storage of CO2 are excluded.

Publication Summary

CO2 capture reduces the thermal efficiencies of power plants. The increased fuel consumption per net kWh of electricity results in greater environmental impacts, apart from those which are due to CO2 emissions. Some emissions to the atmosphere, particularly acid gases, will be reduced as a consequence of CO2 capture but post combustion capture processes will emit some solvent and decomposition products, which will have environmental impacts. The decreases in thermal efficiency due to current CO2 capture technology have been well researched, so the resulting environmental impacts are reasonably well known. However, there is a shortage of information available in the public domain to enable the other environmental impacts to be accurately quantified at present.

Further work to assess the environmental impacts of solvent scrubbing processes for CO2 capture is needed. This encompasses determination of emissions to the air of solvent and its degradation products, toxicity impacts of these products, and characterization and treatment of waste streams. This will be a particularly important issue for new solvents for which environmental impacts may be less well known.

It is recommended that environmental impacts of solvent scrubbing are discussed at the next meeting of IEA GHG’s CO2 Capture Network to encourage researchers, process licensors, manufacturers and plant operators to provide more information.

Development of new CO2 capture solvents should be focussed on those which have reduced environmental impacts.