A cradle-to-gate life cycle assessment for clean hydrogen gas production pathway using the CeO2/Ce2O3-based redox thermochemical cycle

Abstract

The present study is conducted to develop a two-steps redox thermochemical cycle based on combined ceria reduction and methane reforming through the CeO2/Ce2O3 redox pair. This cycle incorporates simultaneous water splitting for hydrogen production. To enhance the accuracy and reliability of the inventory data, the system is simulated using the Aspen Plus software package. Also, the goal of this work is to evaluate the carbon footprint of thermochemical based hydrogen production under different scenarios and to compare it with traditional technologies like steam methane reforming (SMR). The analysis takes into account both the plant manufacturing line (reactors), fuel processing (H2 production), redox particles oxygen carrier manufacturing (OC), H2 compression (power consumption) and H2 storage (pipeline manufacturing). The openLCA software with the European database environmental footprint is employed to compute the total carbon emissions of this thermochemical cycle during its overall life cycle. The study concludes that the base case scenario of this system has an overall GWP of 1751.14 g CO2 eq./kg H2 respectively. In the overall GWP, the share of plant construction and OC production was found to be around 1.67%, and 15.78% respectively. The conventional steam methane reforming is loaded with an overall GWP of 4472.83 g CO2 eq./kg H2. In terms of renewable energy input, the base case scenario of this hydrogen production system results in 1465.73 g CO2 eq./kg H2 with thermal energy produced from renewable sources. Comparative life cycle assessment (LCA) demonstrates that base case of CeO2/Ce2O3 has an 85.41% lower GWP emphasizing its environmental advantages over the SMR and Fe3O4/FeO redox pair carries an 84.06% lower GWP as compared to the conventional SMR with 1483.55 g CO2 eq./kg H2. The present study concludes that the combined ceria reduction and methane reforming chemical looping process with simultaneous water splitting may be a more promising option to produce hydrogen using renewable energy.