Comparison of Biomass-Based Synthetic Natural Gas Production Scenarios: Cradle to Gate Life Cycle Assessment

Abstract

In studies comparing the environmental impacts of renewable fuel production using biomass feedstock with fossil-based alternatives, the analysis often focuses on net greenhouse gas (GHG) emissions, excluding biogenic carbon dioxide emissions. However, this neglects the high carbon intensity of biomass-based processes, a factor often overlooked when calculating net GWP emissions, as suggested by the IPPCC. To fill this gap, this study considers CO2 biogenic emissions and relevant impact categories affected by the use of biomass such as acidification potential, eutrophication potential, particulate matter, land use and water use, following the environmental footprint 3.1 method. The aim of this study is to provide a comprehensive overview, identify the key environmental hotspots of different scenarios, and propose areas for improvement. For this a cradle to gate life cycle assessment is (will be) performed using experimental and simulation data from previous studies. The study highlights the importance of renewable electricity sources and CO2 capture in tackling GHG emissions. It also shows that the choice of feedstock can significantly impact other environmental categories, such as land use, eutrophication, and acidification, emphasizing the need for sustainable farming practices and the development of technologies aiming to use residues and waste as feedstock. Most importantly, by calculating the biogenic CO2 emissions the study shows that these are not negligible. Therefore depending on how biogenic CO2 emissions are accounted for, these technologies could emit more CO2 than current systems, reinforcing the need to focus on reducing the carbon dioxide stock in the atmosphere. The results of this analysis will contribute to decision making by highlighting the most promising directions for the development and improvement of these technologies.