Life cycle assessment of Power-to-Gas (PtG) technology - Evaluation of system configurations of renewable hydrogen and methane production

Power-to-gas (PtG) is a novel technology with many system configurations whose environmental performances require a comparative evaluation with conventional technologies before large-scale deployment. This paper presents a life cycle assessment (LCA) of the PtG concept, assessing the main parameters and system variations involved in producing hydrogen and methane. The global warming potential (GWP) of producing 1 MJ of hydrogen averages 5.1 and 1.2 gCO2eq when electrolyzers are powered by solar PV and wind, respectively. On the other hand, the GWP associated with producing 1 MJ of methane from plant-derived CO2 is 6.5 gCO2eq when electricity is derived from solar PV and 1.5 gCO2eq when wind is utilized as a power source. Except for acidification potential and abiotic depletion, the other characterization factors (e.g., PED, POCP) show a similar pattern as GWP. The well-to-wheel (WTW) carbon footprints per km of hydrogen FCV are 98 % less than diesel ICE, while compressed natural gas vehicles are 29 % less than gasoline ICE.