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 [gCO(2)e/MJ(bioCNG)] and 26.2 [gCO(2)e/MJ(bioLNG)]. 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 39 gCO(2)e and 33-36 gCO(2)e per MJ of biomass, respectively, compared with the diesel case, whereas the SI engine gave an emissions saving of 29-31 gCO(2)e. (C) 2016 Elsevier Ltd. All rights reserved.