Life cycle greenhouse gas assessment of hydrogen production via chemical looping combustion thermally coupled steam reforming
Chemical looping combustion thermally coupled steam reforming (CLC-SR) emerges as a new alternative to achieving hydrogen production simultaneously with inherent CO2 capture. To evaluate the environmental performances of any competing technology, it is of necessity to consider total emissions in association with the technology over its entire lifetime. In this study, a life cycle greenhouse gas emission (LCE) assessment of the CLC-SR is conducted, together with a comparison with the conventional natural gas steam reforming (SR). The energy efficiency of 75.2% for achieving 97.0% inherent CO2 capture is obtained in the CLC-SR, with the LCEs of 3009 g CO2 eq./kg H2, approximately accounting for one third in those of conventional natural gas SR. The main LCE contributors in the CLC-SR are plant operation and natural gas losses from the natural gas production and transport. To further meet the emission reduction potential, several key parameters are varied to illustrate their influence on LCE performances of the CLC-SR, including reformer operation temperature, different types of oxygen carriers (OCs) and the lifetime of OCs. The results of this investigation demonstrate the CLC-SR is a promising alternative to conventional SR for cleaner hydrogen production from a LCE perspective.