The international aviation and maritime sectors are important contributors to global greenhouse gas (GHG) emissions (IEA, 2020, IMO, 2020). In this context, the international association of each sector has established strategies to deal with GHG emissions. The International Air Transport Association (IATA) goals include a 50% reduction in the carbon footprint by 2050 compared to 2005 levels (IATA, 2020). Likewise, the International Maritime Organization (IMO) proposes a reduction of 50% in GHG emissions in 2050 compared to 2008 absolute levels (ICCT, 2018).
Both sectors are usually referred to as hard-to-abate, given the lack of commercially available decarbonization technologies and expected growth in demand (SHARMINA, EDELENBOSCH, et al., 2020). Although a set of efficiency measures has been proposed to reach the emissions reduction goals, they are unlikely to offset the expected activity growth for aviation and shipping. Hence, the development of renewable and carbonneutral fuels is a crucial measure.
In addition, although aviation fuels represent highly qualified liquid fuels (very strict specifications of physicochemical properties and carbon chains), marine fuels (bunkers) must have high energy density and low cost, in order to deal with the type of energy service required by them (long-distance navigation and generally for the transport of low value-added goods). Thus, aviation fuels usually make up the margins of oil refineries, as ‘premium fuels’, while bunkers are generally produced by residual streams and must meet the compromise between quality and price.
In these circumstances, biofuels and electrofuels can be promoted as alternatives to both sectors. Biofuels are produced through technologies that use biomass as the main input, while electrofuels are usually produced from electrolysis-based hydrogen, which could be used in different chemical syntheses. In both cases, there are routes mainly proposed to produce sustainable aviation fuels (SAF) that co-produce marine fuels, meaning that the decarbonization of the aviation sector can lead to a co-benefit in the maritime sector.