The rush to use greener fuels in shipping is like the start of a hurdles race: runners are looking to accelerate away from the starting line but face many obstacles ahead.

One of the biggest hurdles they need to jump is the price gap between alternative and fossil fuels.

Contracts for difference (CfDs) worked successfully in equalising the cost of producing electricity to aid the emergence of the UK offshore wind industry, and so have been touted for shipping.