Fully electric drive is viable with today’s ­lithium-ion battery technology for small coastal vessels, but it remains a distant goal for larger ships that carry a much greater weight of cargo over far longer distances and often have unpredictable operating requirements.

Surmounting the challenges for wider adoption of electricity in marine propulsion — particularly for ­bigger vessels — is likely to be led by developments in the automotive sector or other industries.

New solid-state lithium-ion technologies are showing great potential, and silicon anodes could replace graphite to boost capacities even further — but major technical obstacles still need to be overcome.