Introduction
Methyl and ethyl alcohol fuels, also referred to as methanol and ethanol, 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 European Maritime Safety Agency (EMSA) commissioned this study to gain more information about the benefits and challenges associated with these fuels and to evaluate their potential for the shipping industry.
Previous and current projects
Methanol has been investigated as a marine fuel in a few past research projects, two of which involved pilot test installations on ships. The Swedish EffShip project identified methanol as a promising marine fuel after studying alternatives and carrying out laboratory testing on a diesel concept engine. This led to further testing and development within the SPIRETH project, which led to the world’s first methanol conversion of main engines on a passenger ferry, the Stena Germanica, in 2015. Waterfront Shipping has commissioned seven new chemical tankers with dual fuel methanol engines to be delivered in 2016. New research projects underway or recently started include a German Project, Methaship, to develop designs of methanol passenger vessels, and the EU Horizon 2020 project LeanShips, which includes a work package to test a marine methanol engine in a laboratory. These new projects demonstrate the growing interest and potential of methanol as a marine fuel. No projects have been identified for ethanol on ships, but it has been used in diesel engines in road transport for many years.
Properties, safety and regulations
Methanol and ethanol are both colourless, flammable liquids. Methanol is the simplest of alcohols and is widely used in the chemical industry. It can be produced from many different feedstocks, both fossil and renewable, with the majority produced from natural gas. Renewable methanol is produced from pulp mill residue in Sweden, waste in Canada, and from CO2 emissions at a small commercial plant in Iceland. Ethanol is also an alcohol and is mainly produced from biomass, with the majority on the world market produced from corn and sugar cane. Both methanol and ethanol have about half of the energy density of conventional fossil fuels, which means that more fuel storage space will be required on board a vessel as compared to conventional fuels. They can also be corrosive to some materials, so materials selection for tank coatings, piping, seals and other components must consider compatibility. Methanol is classed as toxic so requires additional considerations during use to limit inhalation exposure and skin contact. Ethanol is not classified as toxic to humans.
The flashpoints of methanol and ethanol are both below the minimum flashpoint for marine fuels specified in the International Maritime Organizations (IMO) Safety of Life at Sea Convention (SOLAS). This means that a risk assessment or evaluation must be carried out for each case demonstrating fire safety equivalent to conventional fuels for marine use. Guidelines are currently in draft for the use of methanol and ethanol fuels on ships, for future incorporation in the newly adopted International Code of Safety for Ships Using Gases or Other Low-Flashpoint Fuels (IGF Code). This will facilitate the use of these fuels on board ships. The previously described Stena Germanica and Waterfront Shipping chemical tanker projects both carried out risk assessments and were approved for installation, demonstrating that safety considerations are not a barrier to the use of methanol fuel systems on ships.
Availability
Methanol is widely available as it is used extensively in the chemical industry. There are large bulk storage terminals in both Rotterdam and Antwerp, and it is transported both with short sea shipping and by inland waterways to customers. Ethanol is the most widely used biofuel in land based transportation and can be found at most large chemical storage hubs in Europe.
Environmental impacts
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 aftertreatment. Particulate emissions are very low, and nitrogen oxide emissions are also lower than with conventional fuels, although the amounts depend on the combustion concept and temperature. If a pilot fuel ignition concept is used with methanol and ethanol there will be a very small amount of sulphur oxide emissions which will depend on the amount and sulphur content of the pilot fuel.
The environmental impact of production and use of methanol “well to wake”, using greenhouse gas equivalents as an indicator of global warming potential, varies according to the feedstock. Methanol produced using natural gas as a feedstock has “well to tank” emissions similar to other fossil fuels such as LNG and MDO. Bio-methanol produced from second generation biomass such as waste wood has a much lower global warming potential than fossil fuels and is lower than ethanol by most production methods. “Well to wake” emissions from ethanol are lower than fossil fuels but the amount varies with production methods and feedstock. For example the ethanol produced in Brazil and in Sweden has much lower “well to tank” greenhouse gas emissions than that produced from corn in the US.
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.
Cost and economic analysis
Prior to the recent oil price crash, methanol prices were below the price of low sulphur marine gas oil (MGO) on an energy basis for two years from 2011 to 2013, making it an attractive sulphur compliance option. With the low oil prices in 2014 and early 2015, methanol was comparatively more expensive but in late 2015 the price of methanol has started to move closer to the levels of MGO again. Cheap natural gas, a primary feedstock for producing methanol, contributes to lower production costs and thus methanol may be economically attractive again compared to conventional fuel alternatives. Ethanol prices have been higher than MGO traditionally, similar to other types of biofuels. Fuels from non-fossil feedstock, including bio-methanol, tend to have a higher price than fossil fuels.
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 SCR) for use with heavy fuel oil, and below the costs of investments for LNG solutions. Operating costs are primarily fuel costs. The payback time analysis carried out for this study indicate that methanol is competitive with other fuels and emissions compliance strategies, but this depends on the fuel price differentials. Based on historic price differentials, methanol will have shorter payback times than both LNG and ethanol solutions for meeting sulphur emission control area requirements. With the current low oil prices at the end of 2015, the conventional fuel oil alternatives have shorter payback times.
Disclaimer: The content of this report represents the views of the authors only and should not be taken as indicative of the official view of the European Maritime Safety Agency (EMSA), or of any other EU institution or Member State. EMSA, SSPA and Lloyd’s Register assume no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document.
European Maritime Safety Agency (2017). Study on the use of ethyl and methyl alcohol as alternative fuels in shipping. Retrieved at January 25, 2018, from http://www.emsa.europa.eu/news-a-press-centre/external-news/item/2726-study-on-the-use-of-ethyl-and-methyl-alcohol-as-alternative-fuels-in-shipping.html