Life cycle greenhouse gas assessment of a coal-fired power station with calcium looping CO2 capture and offshore geological storage

Abstract

Carbon Capture and Storage (CCS) is an essential technology for reducing global CO₂ emissions in the context of continued fossil fuel use in the power sector. To evaluate the emission reduction potential of any low-carbon generation technology it is necessary to consider emissions over the entire lifetime of the plant. This work examines the lifecycle greenhouse gas emissions of a 500 MW_e pulverised coal-fired power plant with post-combustion Calcium Looping (CaL) and off-shore geological storage. CaL uses solid CO₂-sorbent derived from abundant and non-toxic limestone (CaCO₃) and is currently being piloted at the 1–2 MW_th scale in Europe (Spain and Germany). This technology promises to be very competitive with the more mature chemical absorption processes, with the potential to reduce the efficiency and cost penalties of CO₂ capture. We demonstrate that the emission intensity of a coal-fired power plant with CaL is at least comparable with one using MEA-solvent technology (i.e., ∼ 229 gCO₂e/kWh vs. 225 gCO₂e/kWh). However, there is significant potential for additional emissions reduction when considering the recarbonation of exhausted sorbent in landfill. Furthermore, a coal-fired power plant with CaL could be carbon-neutral – or even achieve a net removal of CO₂ from the atmosphere. That is, if the exhausted sorbent is used in the cement industry substituting the input of fresh-limestone; or if the exhausted sorbent is disposed in the ocean forming bicarbonate.