The environmental performance of a fossil-free ship propulsion system with onboard carbon capture – a life cycle assessment of the HyMethShip concept
The climate impact caused by the shipping industry has increased over the past decades despite attempts toimprove the energy efficiency of vessels and lower induced emissions. A tool in reducing climate and otherenvironmental impacts is new low emissions propulsion technologies. These new technologies need toreduce harmful emissions not only in the tailpipe but also over the entire life cycle. This study uses lifecycle assessment to investigate the life cycle environmental impact of a propulsion concept currentlyunder development: the HyMethShip concept. The HyMethShip concept combines electro-methanolenergy storage, an onboard pre-combustion carbon capture system, and a dual fuel internal combustionengine. The concept aims for an almost closed CO2 loop by installing CO2 capture onboard.
The CO2 isunloaded in port and converted into electro-methanol which is used to fuel the ship again. This is madepossible by a pre-combustion process converting electro-methanol to hydrogen and CO2. Theassessment is conducted from well-to-propeller and focuses on ship operation in the North Sea in 2030.The results indicate that this technology could be an alternative to reduce the climate impact fromshipping.
The results show a lower impact on acidification, climate change, marine eutrophication,particulate matter, photochemical ozone formation, and terrestrial eutrophication compared to internalcombustion engines run on either marine gas oil (0.1% sulphur content), biogenic methanol, fossilmethanol, or electro-methanol. Electricity with low climate and environmental impact is likely requiredto achieve this, and low NOx emissions from combustion processes need to be maintained. A potentialtrade-off is higher toxicity impacts from the HyMethShip concept compared to most other options, dueto metal needs in wind power plants.