Decarbonisation Technology – August 2021

Evolution of marine fuels – move toward a sustainable future LNG can play an important role in reducing GHG emissions of international shipping by at least 50% by 2050 and contribute to the IMO GHG reduction target

Oliver Schuller and Bambi Majumdar Sphera

T he international shipping industry is under immense pressure to reduce emissions. Cargo ships are particularly significant sources of air pollution. Their fuel oil is made from the bottom of the barrel of the refining process and includes substances such as sulphur and heavy metals. When burned, sulphur produces toxic gases and fine particles that harm the environment and living beings. Moreover, the greenhouse gas (GHG) emissions released through the combustion of these conventional Organization (IMO) is focused on reducing GHG emissions from international shipping by at least 50% by the year 2050 (compared with 2008 standards) to fight climate change. This historic nonbinding agreement will spur investments in clean-ship technologies, including alternative fuels, fuel cells and advanced sail designs. Liquefied natural gas (LNG), as one of the alternative marine fuels available on the market, seems to be a feasible solution to contribute to the IMO’s GHG reduction target. The environmental benefits of LNG as an alternative marine fuel compared with fuel oils are obvious concerning local pollutants such as sulphur oxides (SOx), nitrogen oxide (NOx) and particulate matters (PM) up to 90-95% in providing the same amount of propulsion power. In terms of GHG emissions, LNG would help curb carbon dioxide emissions by 20-25% less than conventional marine fuel oils. Different data, assumptions and methodologies used by different studies have made it hard to reach a consensus in the industry, government and the general public about the environmental marine fuel oils are a major concern. Therefore, the International Maritime

performance of LNG. The data issue is especially of prime concern since assumptions widely differ about methane emissions in the LNG supply chain and methane slip in ship engines. Assumptions differ because there have been major developments and improvements in reducing methane emissions over the past few years. Therefore, the question of using up-to- date primary data vs using outdated literature data is critical. Secondly, one must consider the complexity of the shipping sector when considering the data. The marine engine market, in contrast to the road transport market, for instance, consists of a multitude of different engine technologies for various shipping applications and power requirements. This results in different engines with two/four strokes, single/dual-fuel, combustion cycles, efficiencies, exhaust gas cleaning systems, along with the bunkering of different fuels, geographically specific supply chains, and so on. New emissions study SEA-LNG and SGMF commissioned Sphera to conduct a Life Cycle Assessment (LCA) study of marine fuels called Life Cycle GHG Emission Study on the Use of LNG as Marine Fuel . The study analyses the life cycle GHG emissions (from well- to-wake, WtW) of LNG as marine fuel compared with fuel oils. The study was first published in 2019 and updated in April 2021. The second study provides an update of GHG emissions to reflect ongoing technology developments in fuel supply and marine propulsion systems. It includes the latest data for the fuel supply consumption mixes, and the latest fuel consumption and emissions data for