Carbon recycled methane produced by methanation technology can be recognized as zero-emission ship fuel, according to a technical paper by Japan’s Ship Carbon Recycling Working Group.
Formed in 2019 by nine companies within Japan’s Carbon Capture & Reuse Study Group, the Ship Carbon Recycling Working Group had been working to explore the feasibility of the concept of utilizing methanation technology for zero-emission ship fuels.
As the effects of climate change become apparent, carbon recycling, a method used to capture and reuse emitted CO2, has been attracting attention as one of the paths to decarbonization. Since it is a basic premise for the Group’s activity that carbon recycled methane can be recognized as zero-emission fuel, the Group firstly worked on the evaluation of its potential.
While IMO has yet to develop the rules for calculating emissions from the onboard fuel combustion of carbon recycled methane (Tank to Propeller), the importance to be cognizant of CO2 emissions in the fuel supply process (Well to Tank) has been noted, MOL stressed.
The WG has assumed and evaluated the following four processes as the supply chain for carbon-recycled methane fuel: (1) CO2 separation and capture, (2) CO2 transportation, (3) methanation fuel synthesis, and (4) methanation fuel liquefaction.
As a result, the CO2 emission per unit calorific value of carbon-recycled methane fuel by methanation was calculated as approximately 27-gCO2/MJ (regarded as Well to Propeller). This figure is comparable to other alternative fuel candidates generally recognized as zero-emission fuels, confirming that carbon-recycled methane can be recognized as zero-emission ship fuel. In addition, further reduction to approximately 20-gCO2/MJ is expected by improving the efficiency of the separation and capture technology, and using electricity produced from renewable energy.
Methanation is a technology for synthesizing methane, by causing a chemical reaction between hydrogen and CO2 in a reactor vessel filled with a catalyst. It uses emitted CO2 separated and captured from industrial facilities. A technical paper describing the details of the calculation procedure and evaluation conducted by the WG has been published in the journal of Japan Institute of Marine Engineering.
In order to verify the 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, prevention of methane slip, supply infrastructure of liquefied methanation fuel, and economic viability.
Project partners included EX Research Institute Ltd., Hitachi Zosen Corporation, Japan Marine United Corporation, JFE Steel Corporation, JGC Corporation, MOL, ClassNK, Nippon Steel Corporation, and Sanoyas Shipbuilding Corporation.
