The change to more sustainable fuels in shipping is important and urgent. This chapter describes the main renewable fuel production pathways and potential energy carriers for ships. Furthermore, criteria to consider when evaluating fuels for shipping are also described and some examples of how different fuels perform against the criteria are shown. There are several pathways to more sustainable fuels. For existing ships, mainly renewable fuels that can be used without any extensive retrofit will be needed. Technically, ships running on LNG can shift to renewable liquefied methane, ships running on diesel can shift to hydrotreated vegetable oil or be retrofitted to run on renewable methanol. For newbuilding's there are several technology pathways, and the choice may depend on the type of ship segment and operational pattern. For costal and short sea shipping, battery-electric propulsion is possible while deep sea shipping could use e.g., electro-methanol or renewable hydrogen. A way to reduce the risk of new environmental problems or unforeseen challenges is to consider a broad set of sustainability criteria when producing, assessing, and selecting fuels and propulsion combinations, and when formulating policy and regulations.
Sustainable Energy Systems on Ships, 2022, pp 403-428,