”Conclusion

Achieving substantial reductions in CO2 emissions requires either shutting down a large fraction of the current installed base of coal-fired power plants or retrofitting those plants for CCS. Previous studies have estimated that the additional fuel required (f2) to maintain constant work output for a PC retrofit is between 50% and 80%. An analysis of the thermodynamic limit indicates those values might be improved by harnessing more of the available waste heat and by improving the 2nd-law efficiency of temperature-swing separation systems. It appears difficult, however, to improve f2 for post-combustion capture to below 25% in practice. Our most likely efficiency scenario indicates that offsetting the energy penalty incurred from capturing and storing 80% of the U.S. coal fleet’s CO2 emissions will require either an additional 390–600 million tonnes of coal, an additional 69–92 gigawatts of CO2-free-baseload power, or a 15%–20% reduction in overall electricity use.”

(NOAHs fremhævelser)

"When 90% CO2 capture is implemented in a precombustion decarbonization IGCC and CO2 is compressed to 2,200 psia, the auxiliary power load increases by about 40 %, compared to the non-capture case."

"Carbon capture and storage (CCS) is considered a leading technology for reducing CO2 emissions from fossil-fuelled electricity generation plants and could permit the continued use of coal and gas whilst meeting greenhouse gas targets. However considerable energy is required for the capture, compression, transport and storage steps involved. In this paper, energy penalty information in the literature is reviewed, and thermodynamically ideal and ‘‘realworld’’ energy penalty values are calculated. For a sub-critical pulverized coal (PC) plant, the energy penalty values for 100% capture are 48.6% and 43.5% for liquefied CO2, and for CO2 compressed to 11MPa, respectively. When assumptions for supercritical plants were incorporated, results were in broad agreement with published values arising from process modelling. However, we show that energy use in existing capture operations is considerably greater than indicated by most projections. Full CCS demonstration plants are now required to verify modelled energy penalty values. However, it appears unlikely that CCS will deliver significant CO2 reductions in a timely fashion. In addition, many uncertainties remain over the permanence of CO2 storage, either in geological formations, or beneath the ocean. We conclude that further investment in CCS should be seriously questioned by policy makers."