Well-to-wake cost and emissions assessments for the Western Australia–East Asia green shipping corridor

The maritime sector, responsible for approximately 3% of global greenhouse gas (GHG) emissions, faces mounting pressure to decarbonize. In response, international “green shipping corridor” agreements have emerged as a prospective strategy to stimulate low-carbon shipping through incentives designed to hedge key stakeholders, catalyze new technologies, develop robust supply chains, and assess trade-offs. This study evaluates decarbonization pathways for the recently-proposed green corridor for iron ore shipping between Western Australia (WA) and East Asia (EA). Using comparative techno-economic analysis (TEA) and attributional life-cycle assessment (LCA) consistent with Resolution MEPC.391(81) adopted by the International Maritime Organization (IMO) in March 2024, we identify the most promising technical approaches to reduce the well-to-wake (WtW) GHG emissions of the current fossil-powered fleet while maintaining the competitiveness of the WA–EA iron ore corridor. A representative vessel, cargo, and voyage profile, based on the current bulk carrier fleet, is used to compare the total cost of ownership (TCO) and WtW GHG emissions among conventional and alternative options. We consider a 20 PJ/yr-scale deployment (in terms of lower heating value) of alternative energy carriers including “green” hydrogen, ammonia, and methanol fuels synthesized using wind energy and renewable CO2 resources in Australia. In line with MEPC.391(81), the analysis models the GHG emissions and costs throughout the fuel life cycle, including the production, transportation, densification, storage, bunkering, and end-use stages. Principal energy converters evaluated include internal combustion engines (ICEs) and electric motors (EMs) powered by fuel cells (FCs) or batteries, with all ICE options designed with selective catalytic reduction (SCR) to comply with IMO Tier II or Tier III NOx emissions standards. Compared to earlier efforts, the present powertrain model is significantly more detailed in regards to dynamic loads, fuel consumption and GHG emissions, and NOx abatement tradeoffs. The main results indicate that renewable ammonia ICE-powered vessels offer the lowest green premium, with a TCO 46% higher than conventional fuel oil vessels and 92% lower WtW GHG emissions in the baseline case without policy incentives. The study also finds that the capacity of iron ore bulk carriers, which are restricted more by cargo weight than volume, is minimally affected by the reduced energy density of alternative liquid fuels. Nonetheless, the representative scenario shows a high carbon abatement cost of $247 (USD) per tonne of CO2-equivalent. Such costs lie well above the typical $50-$100 range of proposed carbon taxes, highlighting the economic gap that must be addressed to realize such GHG emissions reductions within the WA–EA green corridor.