The European Maritime Safety Agency (EMSA) has issued a report on methanol and ethanol, saying they are good potential alternatives for reducing both the emissions and carbon footprint of ship operations.
As they are sulphur-free, use of methanol and ethanol fuels would ensure compliance with the European Commission Sulphur Directive.
The report stated that methanol and ethanol both have many advantages regarding environment impacts as compared to conventional fuels – they are clean-burning, contain no sulphur, and can be produced from renewable feedstocks. Emissions of both methanol and ethanol from combustion in diesel engines are low compared to conventional fuel oils with no after treatment, the report stated.
Investment costs for both methanol and ethanol retrofit and new build solutions are estimated to be in the same range as costs for installing exhaust gas after treatment (scrubber and selective catalytic reduction) for use with heavy fuel oil, and below the costs of investments for liquefied natural gas (LNG) solutions.
According to the report, the behaviour of methanol and ethanol fuels when spilled to the aquatic environment is also important from an environmental performance perspective as ship accidents such as collisions, groundings and foundering may result in fuel and cargo spills. Both methanol and ethanol dissolve readily in water, are biodegradable, and do not bioaccumulate. They are not rated as toxic to aquatic organisms.
A payback time analysis carried out for the study indicated that methanol is competitive with other fuels and emissions compliance strategies, but this depends on fuel price differentials.
Based on historic price differentials, methanol will have shorter payback times than both liquefied natural gas (LNG) and ethanol solutions for meeting sulphur emission control area requirements. However, with the current low oil prices at the end of 2015, the conventional fuel oil alternatives have shorter payback times.
The study points out another disadvantage of using methanol and ethanol. It states that both methanol and ethanol have an energy density that is approximately half that of conventional fuels. This requires larger storage volumes or more frequent bunkering, and could be a barrier for some ship applications.
Tests conducted on Stena Germanica, a cruiseferry operated by Stena Line, and a chemical tanker owned by Waterfront Shipping have demonstrated that safety considerations are not a barrier to the use of methanol fuel systems on ships, EMSA said.
‘Attractive fuel choices’
In conclusion, the EMSA said: “In summary, both methanol and ethanol are very attractive fuel choices from an environmental perspective because they are clean-burning, contain no sulphur, and can be produced from renewable feedstocks.
“Regarding engine technology, both have been shown to work well in heavy duty diesel engines, but there is limited experience with marine applications. Methanol has been used in a full scale ferry installation in 2015 and is being installed in new build chemical tankers for delivery in 2016.
“More projects and experience with different ship applications would be beneficial for demonstrating the potential of the fuels. Considering availability and supply, methanol and ethanol are both widely available globally but no specific infrastructure for marine fuel is in place.”