Life cycle assessment of marine fuels - A comparative study of four fossil fuels for marine propulsion

Rapport, 2011

Maritime transportation is facing harder requirements on fuel quality and exhaust emissions in the coming decades, especially in the Emission Control Areas (ECAs). To address these requirements the shipping industry will either need to use alternative fuels or implement exhaust abatement techniques. Consequently, the maritime sector within ECAs is on the verge of a fuel and/or technology shift in the near future. At the same time, there is limited information regarding marine fuels’ overall environmental impact during their life cycle. The overall aim of this report is therefore to investigate the environmental performance of maritime fuels from a life cycle perspective. This has been done through a life cycle assessment (LCA) of four possible fossil marine fuels combined with two exhaust gas cleaning techniques. The geographical location is set to the North Sea and the Baltic Sea and the time perspective is 2015 to 2020. The following fuel alternatives are assessed: • Heavy fuel oil with a sulphur content of 1% (base scenario) • Heavy fuel oil with a sulphur content of 1% with a scrubber (fulfils the regulation within the sulphur ECAs 2015) • Marine gas oil with a sulphur content of 0.1% (fulfils the regulation within the sulphur ECAs 2015) • Marine gas oil with a sulphur content of 0.1 % with a selective catalytic reduction unit (fulfils the regulation within the sulphur ECAs 2015 and the Tier III regulation for nitrogen oxide emissions) • Liquefied natural gas (fulfils the regulation within the sulphur ECAs 2015 and the Tier III regulation for nitrogen oxide emissions) • Gas-to-liquid produced by the Fischer-Tropsch process (fulfils the regulation within the sulphur ECAs 2015) • Gas-to-liquid diesel produced by the Fischer-Tropsch process with a selective catalytic reduction unit (fulfils the regulation within the sulphur ECAs 2015 and the Tier III regulation for nitrogen oxide emissions) It is shown that the “use phase”, i.e. the combustion of marine fuels, is the dominant contributor to the overall environmental impact. Two main results are robust during all the modelled scenarios. Firstly, the global warming potential of the compared fuels are of the same order of magnitude. Maritime transportation with LNG as fuel can be attributed to comparable or a somewhat lower global warming potential than the other fuels depending on modelling choices. Secondly, the potential contribution to acidification and eutrophication is significantly lower for fuel alternatives that fulfil the Tier III requirement regarding nitrogen oxide emissions, i.e. the LNG fuel alternatives and the fuel alternatives with selective catalytic reduction units. A problematic issue related to LCA is how to allocate the impact from crude oil refining into marine fuels. This is problematic since there is a wide diversity of refineries and since the choice of allocation method could change the result. The problem is specific for marine fuels since they only contribute to a small part of a refinery’s overall impact. It is therefore suggested to perform a separate study with focus on how future changes in refinery production and different allocation methods will change the environmental impact of crude oil based fuels. It is also recommended that a study with a longer time perspective is carried out, in order to evaluate what fuels that are desirable in the future and what fuel properties that are important.