Decarbonising the high-traffic corridor is seen as an early testbed for green shipping corridors, aligning UK and Irish Net Zero goals. In 2024, nearly 1.6 million people travelled the route.

The Greening the Irish Sea – Central Corridor report by consultancy Ricardo concluded that green methanol, produced either from bio-methanol or from hydrogen combined with captured CO₂, is the most viable near-term alternative fuel for the route.

The fuel can be adopted through retrofits on existing high-frequency roll-on and off cargo and passenger (RoPax) vessels operated by Stena Line and Irish Ferries. Both ports will also require OPS to cut emissions further.

Dublin, however, faces grid capacity risks in meeting its 2030 OPS mandate, under the EU’s Alternative Fuel Infrastructure Regulation (AFIR). Current indications suggest the required power may not be available within this timeframe.

Therefore, if Dublin builds OPS but Holyhead doesn’t, operators won’t claim the full emissions benefit or compliance credit, alongside potential investment misalignment.

Ricardo and its partners also highlighted the scale of resources that will be needed to produce the required methanol for the route.

Around 150,000 tonnes of methanol per year would require 30,000 tonnes of low-carbon hydrogen – 2.1% of the UK’s 2030 target – 225,000 tonnes of CO₂, and 1.8TWh of electricity.

Additionally, other alternatives such as hydrogen, ammonia and battery electric have been assessed, and they were not ruled out entirely.

The report determined that hydrogen was technically possible, but complex due to cryogenic storage, high costs and infrastructure. 

The study found local hydrogen production would be more feasible on the UK side, given land availability and proximity to existing and planned projects.

Meeting corridor demand would require the output of a medium-to-large dedicated green hydrogen facility each year, with locally sourced renewable electricity.

Ammonia has strong environmental potential but is too hazardous for passenger vessels in the short term. Meanwhile, battery-electric was considered only viable for brand-new, purpose-built vessels — not feasible for retrofitting the current fleet.

Ricardo’s Matthew Moss reiterated that the corridor is a realistic location to trial alternative fuels such as these.

“While additional infrastructure investment will be required, methanol offers a pathway that can be enabled in the near term through vessel retrofits and established handling practices,” he said.

“To build on this work, clear policy signals and government support will be essential in creating the conditions for investment and deployment, helping accelerate the wider decarbonisation of the maritime sector.”

The report was conducted by Ricardo in collaboration with Irish Ferries, Stena Line, Dublin Port and the Port of Holyhead, with additional input from EDF UK R&D and Maynooth University.