Carbon Dioxide Compression

In PEP Report 180C, we examined the technology and economics of three potential process schemes associated with the post-combustion scrubbing of flue gases from coal-fired power generation. In post-combustion scrubbing, CO₂ is typically recovered at near atmospheric pressure. It must then be compressed prior to subterranean sequestration. The cost of this compression is a major contributor to the overall cost of carbon capture and sequestration. A novel means of conducting CO₂ compression is presently under development by a company called Ramgen. Their proposed compressor is based on jet aircraft engine technology. It raises the possibility of attaining an overall compression ratio of 100:1 in two 10:1 stages. In this review we examine the Ramgen concept as applied to carbon capture in coal-fired electric power generation.

The approach we have used is to evaluate the economics of a power plant where the Ramgen compressor is integrated with an advanced amine scrubbing unit. We have picked for our analysis the Mitsubishi Heavy Industries — Kansai Electric KM-CDR process using the proprietary hindered amine KS-1. We then compare this integrated process to a case we presented in PEP Report 180C where the KM-CDR process is integrated with a conventional centrifugal compressor unit. We have found that on a levelized cost basis with 90% CO₂ capture and compression, the Ramgen case shows slightly lower costs than the centrifugal compression case: $2.67 per MWh and $3.70 per ton avoided CO₂.