The role of CO2 purification and transport networks in carbon capture and storage cost reduction

Abstract

A number of Carbon Capture and Storage projects (CCS) are under way around the world, but the technology's high capital and operational costs act as a disincentive to large-scale deployment. In the case of both oxy-combustion and post-combustion CO2 capture, the CO2 compression and purification units (CO2CPU) are vital, but costly, process elements needed to bring the raw CO2 product to a quality that is adequate for transport and storage. Four variants of the CO2CPU were modelled in Aspen HYSYS each of which provide different CO2 product purities at different capital and operating costs. For each unit, a price of CO2 is calculated by assuming that it is an independent entity in which to invest and the internal rate of return (IRR) must be greater or equal to the minimum rate of return on investment. In this study, we test the hypothesis that, owing to the fact that CO2 will likely be transported in multi-source networks, not all CO2 streams will need to be of high purity, and that it may be possible to combine several sources of varying purity to obtain an end-product that is suitable for storage. We find that, when considering study generated costs for an example network in the UK, optimally combining these different sources into one multi-source transport network subject to a minimum CO2 purity of 96% can reduce the price of captured CO2 by 17%.