Jonathan Mosse reports: Some folk reading recent pieces in this column might feel that I’ve been a little harsh regarding the potential of hydrogen when looking at alternative fuels. In the interests of balance, here is a round-up of where on the road to sustainable propulsion this fuel resides today.
OVER the past five years or so, several regions within the UK with a maritime leaning have initiated pilot projects with ‘green leanings,’ and as of mid-2025, there are 11 major hydrogen projects that have secured government support under the first Hydrogen Allocation Round (HAR1) to commence construction, with operations expected between 2025 and 2028.
In addition to these, there are 27 new projects shortlisted under the second Hydrogen Allocation Round (HAR2), as of April 2025, aimed at expanding production further.
The initial 11 projects (124 megawatt (MW) in total) are the first wave of commercial-scale production and are located around the UK in Scotland (three), northern England (four), Wales (two) and the Midlands/south east England (two). Beyond these, the UK is developing regional hubs for production, storage, and distribution while, in the HAR2 pipeline, 27 new projects are in the running for funding.
The UK aimed for one gigawatt (GW) of electrolytic hydrogen production in construction or operation by 2025 and up to 10 GW by 2030. As of early 2026, the regional hydrogen landscape is rapidly expanding through several government-backed initiatives. There are currently 198 active hydrogen projects in the UK, with 24 already in operation.
However, these global figures embrace every possible end use for hydrogen, from supplies to a Scottish whisky distillery through to decarbonising a local natural gas facility. For a focus on hydrogen as a fuel for seagoing and inland waterways craft, it is worth examining the Maritime Hydrogen Highway project.
This major three-year research programme, led by the Port of London Authority (PLA), has confirmed that, in theory, clean hydrogen could power the maritime sector safely, affordably, and at scale. The £1.5 million project, funded by Maritime Research and Innovation UK (MaRI-UK), has explored the entire hydrogen supply chain, from offshore production using floating wind farms through to safe port-side handling and use in vessels, vehicles, and logistics.
Key findings show that hydrogen produced from UK-owned wind farms and transported by autonomous vessels could be delivered directly to ports, cutting emissions, avoiding the need for pipelines, and halving current hydrogen costs.
In its proposed form, the ‘highway’ runs from existing floating windfarms in the North Sea generating compressed hydrogen using an electrolyser, renewable energy and seawater. The hydrogen is put into containers which can be easily loaded onto vessels using traditional container cranes.
Autonomous vessels (ideally using hydrogen as fuel) transport the compressed hydrogen in containers to terminals on the Thames as opposed to the traditional method involving pipelines.
The containers can then be offloaded using existing port infrastructure and loaded onto trailers to deliver where the market demands, which might include both HGV and port operations as well as maritime requirements.
The project estimates the costs of hydrogen using this approach to be £6-£7/kg at the pump, much lower than the typical current cost of £14/kg. So, what’s the catch?
Hydrogen-powered vessels currently have a much higher total cost of ownership (TCO) than diesel, driven by significantly higher purchase prices and fuel costs, often costing to between 11–22% more for applications costed in 2023. While hydrogen offers lower maintenance and fuel costs per mile (once hydrogen prices drop), the initial investment, limited infrastructure, and lower energy efficiency compared to diesel make it less competitive, with parity unlikely before 2030.
The overall energy efficiency of commercial hydrogen production via water electrolysis generally ranges from 40% to 80%, although modern PEM electrolysers can reach 90%. Then the fuel has to be both transported and stored, usually at pressures of between 350-700 bars.
When hydrogen is used for energy storage (Electricity → H₂ → Electricity), the ‘round-trip’ efficiency is notably low, typically 35-40%. This is because energy is lost during both the electrolysis and the subsequent conversion back to power via fuel cells, internal combustion engines or turbines. And this ignores transport and storage costs mentioned above.
Clearly, simply sending that electrical energy generated from a North Sea windfarm down a cable, to the point where it can charge batteries to drive an electrically propelled vessel, makes far more sense in terms of efficient energy use.
Nevertheless, hydrogen’s appeal as a zero-carbon marine fuel is growing, but its path into the shipping mainstream remains steep, according to a new Lloyd’s Register report
The latest edition of the register’s Fuel for Thought series examines hydrogen from production through to onboard use and finds that while the fuel could play a significant role in maritime decarbonisation, it is far from a plug-and-play solution, while concerns remain around safety and infrastructure.
