Transitioning the global maritime sector will require new zero-emission fuels (ZEFs) and additional investments beyond the fuels themselves, including new technologies to retrofit vessels to run on ZEFs.
ZEFs include green ammonia, green hydrogen, e-methanol, and synthetic e-fuels produced from renewable sources of energy. E-methanol and synthetic fuels made with renewable electricity still release some carbon dioxide (CO2) when combusted, so, to produce net-zero emissions, some CO2 used to synthesize these fuels will also need to be captured from the atmosphere. While batteries are also a zero-emission option, their relatively low energy density makes them unsuitable for long distance shipping but can contribute to decarbonizing shorter domestic voyages.
As of 2021, the global share of ZEFs in shipping remained close to 0%. The uptake of green ammonia and green hydrogen, and construction of zero-emission ships capable of running on such fuels, remained in their infancy.
Currently, ammonia engines are expected to be commercially ready by 2025, while hydrogen engines already exist and other demonstration projects are underway, with a noticeable uptick of the latter appearing on today’s order books for new ships.
To keep the world in line with a 1.5 degrees C (2.7 degrees F) scenario, the share of these fuels should reach 5% by 2030.