Scope for reductions in the cost of CO 2 capture using flue gas scrubbing with amine solvents

Abstract

A previous IEA GHG study of CO₂ capture from a pulverized coal (PC) power plant using an amine solvent for flue gas scrubbing has been used as the basis for calculations of the reductions in electricity and CO₂ avoidance costs that might be achievable through improved thermodynamic integration between the CO₂ capture plant and the steam cycle, the use of a solvent with lower regeneration energy requirements and solvent storage to allow rapid load changes and electricity ‘storage’. It was predicted that the efficiency penalty for CO₂ capture for PC plant with flue gas scrubbing using an amine solvent can be reduced to 20 per cent (from 28 per cent) with improved thermodynamic integration and lower-energy solvent, giving a 10 per-cent reduction in electricity costs, from $63.5/MW h to $57.4/MW h, and a 25 per cent reduction in the cost of CO₂ avoid from $45/t to $34/t. These values are both lower than predictions for the gasifier-based coal power plant in the original IEA GHG study. Reductions in the average cost of electricity of 6–7 per cent were estimated using solvent storage, giving a cost of electricity of $56.73/MW h and $33/t CO₂ avoided for an integrated plant with monoethanolamine (MEA) as the solvent. Also, CO₂ venting would allow an additional 20-25 per cent increase in output to be maintained indefinitely when $/MW h electricity prices were 2–3 times greater than the $/t penalty for CO₂ discharges.