Decarbonisation Technology - November 2023 Issue

w Sustainable marine fuels Marine transport accounted for 0.78 Gt eqCO2 per year in 2022 (IEA, 2023). In its initial strategy, the International Maritime Organization (IMO) had already adopted the use of energy efficiency and carbon intensity indices for new ship designs and retrofitting existing ships. In July 2023, the IMO adopted a revised strategy with the goal of reaching net zero emissions by 2050, which will require the uptake of alternative zero and net-zero GHG emission fuels (covered in more detail elsewhere in this issue). In contrast to SAF, a wider range of fuel types are under consideration for the decarbonisation of marine fuels, from gases such as hydrogen, ammonia, and bio-methane to lighter liquids, such as methanol and heavier bio-diesels. In common with SAF, these lower-carbon intensity alternative marine fuels are more expensive than conventional marine diesel. Reducing the carbon intensity of fuels is possible, and some plants are already producing biodiesel, SAF, and bioethanol. The following section will discuss available technologies from Axens to support the effort of GHG emission reduction. Integrating technologies for the production of renewable/low-carbon transport fuels Renewable or waste-derived feedstocks can be divided into three categories – renewable oils and fats, lignocellulosic biomass residues, and captured CO₂ with renewable hydrogen – each of which then determines which technology options can be used for conversion into sustainable fuels and chemicals, as shown in Figure 1 . Integrating renewable technologies within existing refinery processes may represent one of the quickest, most efficient, and economically viable transition pathways. Hydrogenation, can represent the most cost-effective way of producing low carbon-intensity hydrogen in the refinery, providing there is regulatory support for this route and that CO₂ is sequestrated (in depleted wells). Axens can provide such decarbonisation technologies with DMX and Advamine.

eqCO₂ per year in 2022 (IEA, 2023). The International Civil Aviation Organisation (ICAO) adopted a long-term aspirational goal of net-zero carbon emissions by 2050. The Air Transport Action Group (ATAG), an industry body, proposed a range of technical, operational, and behavioural solutions to reach the goal of net zero by 2050. The deployment of sustainable aviation fuels (SAFs) is expected to contribute a minimum of 53% towards this goal (ATAG, 2021). “ SAFs are drop-in fuels, fully fungible with conventional aviation jet fuels, which do not require equipment change, special infrastructure or modification of the supply chain ” Seven fuels are qualified under ASTM-D7566 for the production of SAF (CAAFI, 2023). Axens provides mature technologies for the three main pathways: • The HEFA pathway with the Vegan process for hydrotreatment of lipids to produce hydroprocessed esters and fatty acids (HEFA) • The Fisher-Tropsch (FT) pathway with the BioTfueL process (gasification and FT) to produce SAF from lignocellulosic biomass (Annex 1) • The Alcohol-to-jet (ATJ) pathway with the Jetanol process to produce SAF from low- carbon/renewable ethanol. SAFs are drop-in fuels, fully fungible with conventional aviation jet fuels, that do not require equipment change, special infrastructure or modification of the supply chain. However, SAFs are currently a few factors more expensive than conventional aviation kerosene.

Hydrogenation processes

Hydrogenation processes use substantial amounts of hydrogen. As already discussed, hydrogen from electrolysis relies on the availability of electricity from fully renewable sources. Retrofitting carbon capture technology to steam methane reformers


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