An environmental and economic assessment for biomethane injection and natural gas heavy goods vehicles

This paper presents a novel method to incorporate the seasonal variations in gas demand and technical considerations of gas networks into the assessment of environmental sustainability and economic viability of biomethane production and injection into the grid. A consequential life-cycle assessment (LCA) is conducted to determine the environmental impacts of offsetting diesel in heavy goods vehicles (HGVs) and natural gas for residential heating. This is combined with an economic analysis to determine the total cost of carbon abatement. The results find that biomethane use in HGVs or for residential heating shows a significant reduction in emission in the selected impact categories of global warming potential (GWP), fine particulate matter formation (PM), and terrestrial acidification (AP). However, the freshwater eutrophication (EP) impact shows a slight increase when used to offset residential heating. A sensitivity analysis of the methane emissions leakage from the anaerobic digester and upgrader, finds that when the cumulative methane emissions leakage exceeds 5.5%, the production of bioCNG can be more greenhouse gas (GHG) intensive than fossil diesel on a well-to-tank basis. The results of the TCA highlight the importance of considering the technical constraints imposed by gas networks on the grid capacity to accept biomethane when considering the techno-econo-environmental impact of a biomethane plant size and location, with a range of 73 €/tCO2–177€/tCO2 depending on the scenario. The authors conclude that while biomethane has significant potential as a sustainable alternative to reduce the consumption of fossil diesel for transport and natural gas for heating, consideration must be given to technical constraints of the gas network to maximise emission mitigation at minimal cost.