Assessment of the Current State of Carbon Capture for Climate Change Mitigation

Abstract

Carbon capture technologies are considered an important strategy to mitigate climate change by removing carbon dioxide from effluents of industrial sources, particularly power plants. This project compares three prominent carbon capture technologies in terms of their efficiency in removing carbon dioxide, their economic costs, and their environmental impacts. The findings showed that each technology possesses advantages and disadvantages. Post-combustion carbon capture using an amine solvent was shown to be most developed technology, however a literature review revealed many problems regarding high energy consumption, high corrosivity and high toxicity (particularly due to degradation products). Pre-combustion carbon capture was demonstrated to be a potentially more efficient carbon capture method due to gasification which produces a synthesis gas with high pressure and high CO2 concentration, from which the CO2 is captured. However, the gasification process adds complexity and has a high energy penalty, which reduces the viability of the process. Oxy-fuel combustion was revealed to be a promising technology which vastly increases the CO2 in the flue gas by combusting the fuel with oxygen of high purity, from an air separation unit (ASU). The requirements of oxygen for the ASU present a unique challenge for oxy-fuel combustion carbon capture. Furthermore, the sequestration of carbon dioxide presents many challenges including leakage and a high storage requirement to achieve climate change mitigation goals. Additionally, enhanced oil recovery was shown to be an alternative to sequestration, which offsets the benefits of carbon capture for climate change mitigation. Life Cycle Assessments revealed that post-combustion capture with an amine solvent has negative environmental effects that greatly offset its benefit. Techno-Economic Analyses demonstrated that all carbon capture technologies result in a considerable efficiency loss.In conclusion, this project highlights the need for further development of carbon capture to improve their ability to mitigate climate change. Particularly, research is needed to reduce the energy demands for gasification for pre-combustion capture and the ASU for oxy-fuel capture. More imperatively, more research is required to reduce leakage from sequestration sites of captured carbon dioxide. Moreover, this project highlights the importance of policy for carbon capture to be viable for climate change mitigation, particularly the redirection from the use of enhanced oil recovery to dedicated geological storage of captured carbon dioxide. At its current state, carbon capture was not seen to be viable for mitigating climate change, however it was demonstrated to be a promising technology.