Use of bio-methane for auto motive application: primary energy balance and well to wheel analysis

To promote the development of sustainable energy systems, the biomass represents an interesting renewable source, due to its wide availability (often as waste to be disposed) and the versatility of the technologies and processes which can be employed in its exploitation. In this work, has been examined the use of the bio-methane, i.e. the gas resulting from digestion processes of wet biomass, further treated (by the so called "up-grading" process) to obtain a methane content useful to feed the combustion engines and representing a short-term solution to the dependence on fossil fuels. The study is focused on different scenarios taking into account several parameters affecting the overall efficiency of the process of production and use. The analysis takes into account the possible biomass supply chains, the different types of biomass exploitable as primary source and different technologies for conversion. The different stages from the production, through the up-grading, up to the availability at the tank have been evaluated. The latest Italian regulation in the distribution field is also taken into account. By a Well-To-Wheel analysis an estimation of the primary energy savings and greenhouse gas emissions reduction is performed, in comparison to the use of methane from fossil source.