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Topsoe has been selected to supply solid oxide electrolyzer cell (SOEC) technology for Carbon Neutral Fuels’ Project Starling in Workington, a facility planned to produce 25,000 tonnes of e-SAF annually from 2031.

UK SAF Policy Push Underpins Commercial-Scale Project

The agreement represents the first commercial deployment of Topsoe’s SOEC technology in sustainable aviation fuel production and comes as the UK seeks to expand domestic e-fuels capacity under its SAF mandate. Project Starling received £6mn from the Department for Transport’s Advanced Fuel Fund in July 2025, the largest award for an e-fuels scheme in the programme’s third round. The fund focuses on first-of-a-kind bio-based and hydrogen-derived aviation fuels, aiming to stimulate commercial production ahead of the mandate’s tightening targets.

Technology Scope and Electrolyser Requirements

Project Starling will consume 120MW of renewable electricity to produce hydrogen via high-temperature electrolysis. Although Topsoe has not confirmed the installed electrolyzer capacity, the project’s power input suggests an SOEC configuration of around 60MW. SOECs operate using high-temperature steam, allowing lower electricity consumption per kilogram of hydrogen when paired with industrial waste heat. In this case, hydrogen will be synthesised with captured CO₂ using a Fischer–Tropsch route, with Topsoe’s gas-to-liquids process recycling heat from fuel synthesis back into the electrolysis stage. This design reduces overall energy use and is intended to strengthen the economics of e-SAF production, which remains more expensive than bio-based alternatives.

Company Positions on the FEED Agreement

Topsoe has entered a front-end engineering and design (FEED) agreement with Carbon Neutral Fuels, and the Danish company will supply electrolyzer stacks from its new 500MW SOEC factory in Herning, Denmark. Initial deliveries are expected in 2028, pending a final investment decision (FID). Sundus Cordelia Ramli, Topsoe’s CCO for Power-to-X, said incorporating SOEC technology into Project Starling is “a moment of significant pride” for the company and highlighted that CNF will be its first SOEC customer for commercial-scale SAF production. CNF co-founder Alasdair Lumsden said the “levels of data and research backing the efficacy” of the SOEC systems were central to the company’s choice of supplier.

Project Timeline and Deployment Rationale

Construction of the plant is scheduled to begin in 2028, with commissioning targeted for 2031 subject to FID. The project, formerly known as ASAP-DAC, is positioned as a large-scale demonstration of power-to-liquids production using green hydrogen and direct air capture. Its developers argue that synthetic fuels will be necessary to meet long-term Jet Zero goals, particularly for long-haul aviation where electrification is not feasible.

Implications for Hydrogen-Based Aviation Fuels

If delivered, Project Starling would become one of the UK’s earliest commercial e-SAF facilities, providing a test case for high-temperature electrolysis in synthetic fuel production. Its progress will be closely watched amid wider scrutiny of e-fuel cost structures, renewable power availability and the role of hydrogen-based fuels in meeting aviation emissions targets. For policymakers and investors, the project offers an indication of whether SOEC-based pathways can scale in line with expected SAF demand growth through the 2030s.

Earlier this year, Topsoe has received another order to supply 55MW of SOEs for the e-methanol project in Spain.