Lessons learned from the commercial exploitation of marine battery energy storage systems

Large, reliable, and economically viable battery energy storage systems (BESSs) play a crucial role in electrifying the maritime industry. In this paper, we draw from the experiences of over 750 recent commercial marine BESS installations to bridge the gap between research findings and industrial needs in four key areas: (i) Decision-making for installations: We introduce a go/no-go-decision matrix for assessing the feasibility of installations in a maritime context. (ii) Safe and cost-effective installations: This study evaluates the risks and expenses associated with these BESS installations, including retrofitting a 500 kWh BESS (total costs: 1.3 million euros; 2600 euros per kWh), installing a 4.5 MWh BESS (5 million euros; 1100 euros per kWh), and an unsuccessful attempt to retrofit an 800 kWh BESS. (iii) Operation analysis: We delve into the operational outcomes of BESSs deployed on 47 offshore supply vessels (OSVs) (ranging from 452 to 1424 kWh) and a large 4.5 MWh BESS on a newly constructed cruise ship. The application of the equivalent full cycle (EFC) method reveals that the operational EFCs were notably lower than the designed EFCs. The proposed two new evaluation criteria assess the annual fuel saving resulting from BESS installed per kWh and per EFC. Over a two-year period, the 4.5 MWh BESS demonstrated fuel saving of 1–2 % as compared to the 5 % target. Addressing converter losses during low-power BESS operation modes necessitates further investigation. (iv) Further development: This study advocates for research aimed at enhancing safety measures, exploring onshore/offshore power supply and charging, optimizing multi-objective operations, and progressing towards zero emissions. The insights gathered in this paper can serve as a valuable resource for ship support ship owners and operators seeking to kick-off faster or to install more BESSs on their vessels and optimize their operational effectiveness.