Life cycle assessment of hydrogen production from biogas reforming

Abstract

A H2 production system via biogas reforming was comprehensively investigated by life cycle assessment (LCA), after identification of the optimal thermodynamic operating conditions computed from a detailed analysis of the involved chemical reactions. The system boundaries for the LCA include biogas production, biogas reforming as well as construction and decommissioning steps. The biogas production data are adapted from a literature review, whereas the reforming inventory data are obtained from process simulation in Aspen Plus™ software. The life cycle inventory data for the H2 system are computationally implemented into SimaPro 8. Different environmental impact categories, following the ILCD 2011 midpoint impact assessment method, were calculated. An energy analysis is also carried out, based on cumulative energy demand and on non-renewable primary energy consumption as additional impact categories. The results obtained show that the total greenhouse gas emissions of the system are estimated to be 5.59 kg CO2-eq per kg of H2 produced, which represents about half of the life cycle GHG of conventional H2 production systems via steam methane reforming. Most environmental impacts are influenced by the amount of artificial fertilizer displaced by the digestate as well as by the impact credits for recycling of the plant construction materials and equipment. Overall, the LCA of the biogas-to-H2 system shows very advantageous results. Accordingly, the authors recommend the use of biogas as an ecofriendly source for sustainable H2 production.