Life Cycle Modelling of Carbon Dioxide Capture and Geological Storage in Energy Production

Abstract

Carbon dioxide (CO2) capture and geological storage (CCS) is recognised as one of the main options in the portfolio of greenhouse gas (GHG) mitigation technologies being developed worldwide. The CO2 capture and storage technologies require significant amounts of energy during their implementation and also change the environmental profile of power generation. The holistic perspective offered by Life Cycle Assessment (LCA) enables decision makers to quantify the trade-offs inherent in any change to the power production systems and helps to ensure that a reduction in GHG emissions does not result in significant increases in other environmental impacts. Early LCA studies of power generation with CCS report a wide range of results, as they focus on specific CO2 capture cases only. Furthermore, previous work and commercial LCA software have a rigid approach to system boundaries and do not recognise the importance of the level of detail that should be included in the Life Cycle Inventory (LCI) data. This research developed a complete LCA framework for the “cradle-to-grave” assessment of alternative CCS technologies in carbon-containing fuel power generation. A comprehensive and quantitative Life Cycle Inventory (LCI) database, which models inputs/outputs of processes at high level of detail, accounts for technical and geographic differences, generates LCI data in a consistent and transparent manner was developed and arranged and flexible structure. The developed LCI models were successfully applied to power plants with alternative post-combustion chemical absorption capture and oxy-fuel combustion capture. The results demonstrate that most environmental impacts come from power generation with CCS and the upstream process of coal production at a life-cycle perspective. LCA results are sensitive to the type of coal used and the CO2 capture options chosen. Moreover, the models developed successfully trace the fate of elements (including trace metals) of concern throughout the power generation, CO2 capture, transport and injection chain. Monte Carlo simulation method combined with the LCI models was applied to quantify the uncertainty of emissions of concern. A novel analytical framework for the LCA of CO2 storage was also developed and applied to a saline aquifer storage field case. The potential CO2 leakage rates were quantified and the operational and geological parameters that determine the ratio of CO2 leakage total volume of CO2 injected were identified.