A comparative life cycle assessment of marine fuels: liquefied natural gas and three other fossil fuels
Journal article, 2011
Air emissions from shipping have received attention in recent years and the shipping
industry is striving for solutions to reduce their emissions and to comply with stricter regulations.
Strategies to reduce emissions can consist of a fuel switch, engine changes, or end-ofpipe
technologies, but they do not necessarily imply reduced life cycle emissions. The present
paper assesses the environmental performance of marine fuels from well-to-propeller using life
cycle assessment (LCA). Four fossil fuels are compared: heavy fuel oil (HFO), marine gas oil,
gas-to-liquid (GTL) fuel, and liquefied natural gas (LNG), combined with two exhaust abatement
techniques: open-loop scrubber and selective catalytic reduction. LNG and other alternatives
that comply with the SECA 2015 and Tier III NOx requirements give decreased acidification and
eutrophication potentials with 78–90 per cent in a life cycle perspective compared with HFO. In
contrast, the use of LNG does not decrease the global warming potential by more than 8–20 per
cent, the amount depending mainly on the magnitude of the methane slip from the gas engine.
None of the fossil fuels scrutinized here would decrease the greenhouse gas emissions significantly
from a life cycle perspective. The study supports the need for LCA when evaluating the
environmental impact of a fuel change, e.g. it is found that the highest global warming potential
during the whole life cycle is connected to the alternatives with GTL fuel.
liquefied natural gas
marine gas oil
heavy fuel oil