Sustainability of (H2 + CH4) by Anaerobic Digestion via EROI Approach and LCA Evaluations

Abstract The contents of this Chapter focus on the theoretical sustainable energy approach and its application to hydrogen and methane production, on the basis of results obtained from experimental tests on the Anaerobic Digestion (AD) technology. The evaluation of sustainability is pursued through the Life Cycle Analysis (LCA), Energy Return on Investment (EROI) and Energy Payback Time (EPT) approaches. The EROI and EPT parameters are defined and applied to score the sustainability of the H2/CH4 energy carrier. The evaluation of the indirect energy following a Life Cycle Assessment is consistent for the sustainability analysis. The sustainability of AD technology strongly depends on the reactor diameter: for values lower than 1 m the technology is not able to sustain the wellbeing of the society; the effect of the insulating material as well as the labour could be very important, in this respect thus a sensitivity analysis on the sustainability is reported.