Transition to near-zero emission shipping fleet powered by alternative fuels under uncertainty

Achieving a transition to a near-zero emission shipping requires deploying ships which are powered by low- or zero-carbon alternative fuels. This study delivers a transition plan for the fleet, including the selection of fuel type (among diesel, bio-LNG, bio-methanol and ng-ammonia) for each ship, and determining the number and sizes of ships to add or remove from the fleet in each time period through ship purchasing, chartering and retrofitting, so as to operate the resulting fleet at minimum net cost considering emissions, investment and operating costs and revenues under uncertainty. Results indicate that a single fuel cannot dominate the future. The transition from diesel to bio-methanol is favourable when life-cycle (well-to-wake) emissions are considered, whereas transition from diesel to ng-ammonia dominates when tank-to-wake emissions are considered. In the scenarios where emission costs are high, total emissions are reduced primarily thanks to chartering and retrofitting depending on the ship size.