Compliance strategies for containership fleets under the IMO Net-Zero Framework: a scenario-based techno-economic analysis of the Shanghai–Rotterdam corridor

The International Maritime Organization (IMO) endorsed the draft Net-Zero Framework at MEPC 83 in April 2025, establishing the first global greenhouse gas (GHG) pricing mechanism for international shipping. Its two-pillar architecture—a tightening GHG fuel intensity standard combined with tiered surplus and remedial unit pricing—creates non-linear compliance cost structures that interact with EU regional instruments in ways not yet examined at the fleet level. This study develops a scenario-based techno-economic model and applies it to a thirteen-vessel containership fleet operating the Maersk AE1 Shanghai–Rotterdam service over 2025–2040. Five compliance strategies are compared: a benchmark relying on remedial unit purchases, biodiesel and bioLNG blending, methanol vessel replacement, a methanol–biofuel combination, and selective fleet retrofitting. Results indicate that biofuel blending yields the lowest fifteen-year fleet cost at USD 4.02 billion, a 12% reduction relative to the benchmark, while approximately halving cumulative emissions. The driving mechanism is that overcompliance generates surplus unit revenues sufficient to offset the biofuel price premium. Sensitivity analysis shows that a 20% increase in compliance prices widens the cost gap to 32%, whereas fossil methanol vessel replacement worsens fleet compliance because its well-to-wake intensity exceeds that of heavy fuel oil. The findings suggest that early biofuel adoption on major East–West trade lanes offers both environmental and financial advantages under the IMO pricing architecture, with implications for fleet investment timing and the design of complementary regional regulation.