'The 2020s will be a vital time for piloting and prototyping new fuels and hybrid propulsion arrangements. Vessels will need to transition from fossil-based fuels to zero carbon energy sources and technologies, while simultaneously increasing efficiency.'
(The Lloyd’s Register Maritime Decarbonisation Hub, London) >

https://www.lr.org/en/marine-shipping/maritime-decarbonisation-hub/decarbonising-shipping-the-global-challenge/