A technical paper published in the latest issue of the journal of Japan Institute of Marine Engineering suggests carbon-recycled methane produced by methanation technology can be recognised as zero-emissions ship fuel
The paper describes the calculations and evaluations carried out by the Ship Carbon Recycling Working Group (WG) of Japan’s Carbon Capture & Reuse (CCR) Study Group.
Carbon recycling is the process of capturing and reusing emitted CO2 and while IMO has yet to develop the rules for calculating emissions from the onboard fuel combustion of carbon recycled methane, it has noted the importance of CO2 emissions in the fuel supply process.
The assumed supply chain in the study spans multiple countries. Which country emitted the CO2 may need to be considered, including oceangoing shipping transportation, but has yet to be determined as no international framework or agreement has been formed.
The WG has assumed and evaluated four processes as the supply chain for carbon-recycled methane fuel: CO2 separation and capture; CO2 transportation; methanation fuel synthesis; and methanation fuel liquefaction.
As a result, the CO2 emissions per unit calorific value of carbon-recycled methane fuel by methanation was calculated as approximately 27-gCO2/MJ.
The group reported this figure is comparable to other alternative fuels generally recognised as zero-emissions fuels, indicating carbon-recycled methane can be recognised as a zero-emissions ship fuel. The group also expects further reductions to approximately 20-gCO2/MJ can be made by improving the efficiency of the separation and capture technology, and using electricity produced from renewable energy.
To verify feasibility of carbon-recycled methane as a ship fuel, the WG will continue to work on issues such as CO2 transportation by large-scale liquified CO2 carrier vessels, supply of hydrogen from renewable energy, preventing methane slip, the supply infrastructure of liquefied methanation fuel, and economic viability.
A technical paper describing the details of the calculation procedures and evaluation involved in this study will be published in Vol.56, No.4 of the Journal of Institute of Japan Marine Engineering.
The WG was formed by nine Japanese companies within Japan’s CCR study group in July 2020 to explore the feasibility of this concept. Members include EX Research Institute Ltd, Hitachi Zosen Corp, Japan Marine United Corp, JFE Steel Corp, JGC Corp, Mitsui OSK Lines, ClassNK, Nippon Steel Corp, and Sanoyas Shipbuilding Corp.
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