Accelerating green shipping with spatially optimized offshore charging stations

The decarbonization of marine transport is a global challenge due to the range and capacity limitations of renewable ships. Offshore charging stations have emerged as an innovative solution, despite increased investment and extended voyage durations. Here we develop a route-specific model for the optimal placement and sizing of offshore charging stations to assess their economic, environmental and operational impacts. Analysing 34 global and regional shipping routes, we find that offshore charging stations can reduce the cost for electric ships by US$0.3–1.6 (MW km)⁻¹ and greenhouse gas emissions by 1.04–8.91 kg (MW km)⁻¹ by 2050. The economic cruising range for 6,500 20-foot equivalent unit electric ships can increase from 3,000 km to 9,000 km. Voyage time costs for these enhancements vary between a 0% and 30% grace period of the original delivery time frame. We further investigate power-to-ammonia offshore refuelling stations as a proxy for e-fuels, which could potentially replace heavy fuel oil ships for routes over 9,000 km with only a 5% grace period.