Case Study on the Heat Pump Integration for Enhanced Efficiency in Battery-Electric Short-Sea Ferries

This case study investigates the potential of incorporating water heat pumps into onboard thermal systems to utilize low-temperature waste heat for onboard heating and enhance the efficiency and economics of all-electric battery-driven ferries. We analysed a hybrid-driven roll-on/roll-off passenger ferry operating in the Baltic Sea, gathering data on vessel operation, power, and heat provision in low-temperature cycles. We integrated real-time measurement data, energy flow analysis, and thermodynamic calculations to draw conclusions for a potential battery retrofit scenario featuring an all-electric operation and a battery system capacity of 10 MWh. Our results indicate that the integration of heat pumps in battery-electric mode can cover more than 50 % of the onboard nominal heat capacity of HVAC systems, with a seasonal coefficient of performance (SCOP) of 3.5 during the heating season. The overall electric energy demand of the vessel during the 6-month heating period is reduced by approximately 8 % compared with direct-electric heating.