Well-to-wheel analysis of bio-methane via gasification, in heavy duty engines within the transport sector of the European Union

Abstract

Bio-methane from biomass gasification (bio-methane) is expected to play a major role as a biofuel in the heavy transport sector, since the production process has reached the technical maturity required for large-scale exploitation, and the fact that bio-methane can be distributed through the compressed natural gas (CNG) and liquefied natural gas (LNG) supply chains. Assuming that the burning of biomass is climate-neutral, we compared the well-to-wheel (WtW) emissions from the use of bio-methane in heavy duty engines with those from currently used fossil alternatives: CNG, LNG, and diesel. The well-to-tank (WtT) analysis of bio-methane is based on the case study of the new GoBiGas plant in Gothenburg (Sweden), which is the largest bio-methane plant in the world currently in operation. Finally, tank-to-wheel (TtW) section compares three different state-of-the-art heavy duty gas engines: a spark-ignited (SI) gas engine; a dual fuel (DF) engine; and a high-pressure direct injection (HPDI) engine.The WtT emissions for compressed bio-methane (bio-CNG) and liquefies bio-methane (bio-LNG) were estimated at 21.5 [gCO2e/MJbioCNG] and 26.2 [gCO2e/MJbioLNG]. As compared to diesel the WtW emissions from bio-methane were reduced by 60–67%, 43–47%, and 64% when used in SI, DF, and HPDI engines, respectively. HPDI and DF are the most efficient technologies for the utilization of biomass, reducing emissions by 39gCO2e and 33–36gCO2e per MJ of biomass, respectively, compared with the diesel case, whereas the SI engine gave an emissions saving of 29–31gCO2e.