Environmental assessment of marine fuels: liquefied natural gas, liquefied biogas, methanol and bio-methanol

The combined effort of reducing the emissions of sulphur dioxide, nitrogen oxides and greenhouse gases to comply with future regulations and reduce impact on climate change will require a significant change in ship propulsion. One alternative is to change fuels. In this study we compare the life cycle environmental performance of liquefied natural gas (LNG), liquefied biogas (LBG), methanol and bio-methanol. We also highlight a number of important aspects to consider when selecting marine fuels. A transition to use of LNG or methanol produced from natural gas would significantly improve the overall environmental performance. However, the impact on climate change is of the same order of magnitude as with use of heavy fuel oil. It is only the use of LBG and bio-methanol that has the potential to reduce the climate impact. The analysis did not show any significant differences in environmental performance between methane and methanol when produced from the same raw materials, but the performance of the methanol engines are yet to be validated.