Well-to-Wake (WTW) evaluations form the basis for assessing climate impacts associated with greenhouse gases emissions in the maritime industry. The NavigaTE model, aims to harness the insights from such evaluations and provide an end-to-end analysis of marine fuel value chains. NavigaTE version 1.0 contains a framework for WTW evaluations with placeholders for further input and development. Emissions data has been collected from primary and secondary sources for energy intensive processes and implemented in the model. Fuel production in the model is assumed to be off grid with their own energy supply.

Two low-emissions pathways exist for producing ammonia today

• Low emission ammonia is produced from hydrogen that is generated by either of two processes:

  • Blue hydrogen: Conventional methane reforming, combined with CO2 capture and storage

  • Electro-ammonia: Electrolysis of water, powered by renewable sources

• Grey ammonia has been excluded from the following analysis, because its price and emissions are higher than those of LSFO.

Several pathways can produce renewable methanol today

• Renewable methanol can be produced from three high TRL pathways today:

  • E-methanol, from electricity and CO2 or Bio-methanol, from gasification of biomass or biowaste – potentially boosted by additional hydrogen

  • Bio-methanol from reforming biogas made from biomass or biowaste – potentially boosted by additional hydrogen

• CO2 for E-methanol can be obtained either by capturing CO2 from a point where it is being emitted (point source - PS) or directly from the air (Direct air capture – DAC)

• Three methanol pathways have been left out of scope from the position paper:

  • The biogas-to-methanol route will be included in the next version of the paper

  • Methanol from the paper Kraft process was excluded due to too low potential to consider for a fleet perspective

  • Grey methanol was excluded due to higher price and emissions than LSFO

Renewable methane from biomass or electricity is a candidate for replacing fossil-based LNG and fuel oils in shipping

• Renewable liquefied methane can be produced from various pathways:

  • E-methane synthesized from green hydrogen and CO2 captured either from point-source or direct air capture

  • Bio-methane produced from anaerobic digestion on biowaste or biomass. (Boosting with green hydrogen not studied here)

  • Bio-methane produced from gasification of biowaste or biomass and methanation of synthesis gas. (not studied here.)

  • Purification / boosting of landfill biogas (not studied here)

• The produced methane will likely need to be transported to a liquefaction plant to be liquified. The availability of a methane certificate trading system changes the details of how this will be done

• For bio-methane, the liquefaction plant would likely be centralized due to the economies of scale of liquefaction. Pooling of bio-methane in natural gas pipelines and certificate trading will be an advantage

• E-methane plants must be built at larger scale than bio-methane plants, so liquefaction of methane may be performed locally. However, CO2 infrastructure is required to pool ample feedstock.

Bio-oils can be produced by several existing and maturing pathways

• Bio-oils encompass a range of technologies that convert biological material into an oil-like substance

• Bio-oils on the market include FAME and HVO, producible from waste oils orfood feedstocks. These have been excluded in the first version of the position paper due to low supply of waste feedstocks1 and the debatable sustainability of food-based bio-fuels

• New technologies are emerging for producing bio-oils from plentiful feedstocks, such as biomass and biowaste at low carbon intensities: Fast pyrolysis (FP) and Hydrothermal liquefaction (HTL)

• FP and HTL oil are producible in a range of qualities, depending on the amount of upgrading applied: Here we assess a low cost un-upgraded “crude” which requires blending with other fuels to reach specifications, and an upgraded “oil” achieved using hydrotreatment with catalysts which is usable in oil engines without blending

• The maximum blending grade of crude oils is being investigated, and current results indicate 30% for FP crude and 40% for HTL crude

• Lignin Diesel Oil has also been excluded from this first molecule paper due to insufficient information

• Pyrolysis Crude / Oil has also been excluded