Life cycle assessment of chemical looping air separation systems for electricity production

In 2013, the UK energy supply sector, including the production and use of electricity and natural gas, was responsible for 47% of the total domestic greenhouse gas emissions. In 2009 and 2014, the EU set binding targets to cut... [ view full abstract ]

In 2013, the UK energy supply sector, including the production and use of electricity and natural gas, was responsible for 47% of the total domestic greenhouse gas emissions. In 2009 and 2014, the EU set binding targets to cut the greenhouse gas emissions by at least 20% and 40% (from 1990 levels) by 2020 and 2030, respectively. Increased environmental awareness and political support are pushing towards the development of advanced energy technologies with high energy efficiency and CO₂ capture to meet emission reduction targets.

In this context, CO₂ Capture and Storage (CCS) appears as a necessary option to reach the above targets. Chemical looping has been identified ¹ as a very promising carbon capture technology for energy production thanks to the decoupling of the oxidation and reduction reaction and the inherent CO₂ separation.

In this work, particular focus is put on the chemical looping air separation (CLAS) technology specifically used for oxy-fuel combustion and electricity production. The objective of this work is to develop a comprehensive framework based on the Life Cycle Assessment (LCA) methodology that can assist decision makers in the evaluation of the environmental burdens of the CLAS technology while comparing it to fossil and renewable alternatives, including electricity from hydro power, electricity from wind power, electricity from nuclear, electricity from photovoltaic, electricity from biogas, electricity from biomass, electricity from waste, electricity from hard coal and electricity from natural gas. UK country specific data are used in this cradle-to-grave approach and the LCA boundaries have been expanded to include the production and recovey of valuable products and materials. A hot spot analysis of the chemical looping air separation technology for electricity production has also been performed to identify the unit operations that cause the highest environmental impact.

The results, analysed per MJ of electricity produced, show how the chemical looping technology consistently performs better than the other technologies analysed especially thanks to the recovery of the pure CO₂ stream used for industrial purposes, which avoids the production of CO₂ from fossil resources.

References

1.        Adanez, J., Abad, A., Garcia-Labiano, F., Gayan, P. & de Diego, L. F. Progress in Chemical-Looping Combustion and Reforming technologies. Prog. Energy Combust. Sci. 38, 215–282 (2012).