Environmental impact assessment of end-uses of biomethane

Abstract The growing global population, hunger for energy and worried about climate change, demands the development of new sources of energy. In this scenario, biomass stands out due its renewability and availability. Biogas, one type of energy that results from the anaerobic digestion of organic materials, is composed of about 60% of methane and 35% of carbon dioxide, and can be converted to biomethane, a fuel with high energy content. Biomethane can be used in ovens for cooking, light-duty vehicles for transportation and heavy-duty vehicles for work. This study compared the impacts of the use of biomethane in all of these three end-uses applying the life cycle assessment methodology. Four impact categories were evaluated: acidification, climate change, eutrophication and photochemical oxidation, when replacing one traditional fossil fuel use for those biomethane end uses. The results showed that the replacement of Diesel Oil in heavy-duty vehicles was beneficial in all impact categories, the replacement of liquefied petroleum gas in gas ovens impacted positively only climate change and the replacement of gasoline-C in light-duty vehicles was disadvantageous (except for climate change). For all the uses, the replacement of the traditional fossil fuel by biomethane for climate change impact was beneficial. The contribution analysis showed that the burning of the fuel was the most relevant process for all four impact categories. This study aims to supply data for further analysis of the full life cycle of biomethane, considering the source of biomass, which can support a whole well-to-wheel approach.