GB Railfreight, an operator headquartered on the England-Scotland East Coast Main Line, has signed a memorandum of understanding with US technology developer HyOrc to examine retrofitting older diesel locomotives with hydrogen-ready propulsion. The agreement, branded Project Phoenix, sets out a framework for a pilot conversion rather than a funded procurement. It focuses on replacing the diesel power unit of a legacy freight locomotive and assessing whether a staged transition from gas fuels to hydrogen is technically and commercially viable on the UK network.
The proposal centres on adapting existing assets rather than procuring new hydrogen locomotives. HyOrc’s multi-fuel engine would initially operate on natural gas or LPG to deliver immediate emissions reductions before moving to full onboard hydrogen. The concept is intended to offer a decarbonisation pathway on non-electrified routes without new overhead infrastructure, while extending the working life of locomotives that currently dominate British freight operations. Although GBRf has invested in modern traction, it does have a legacy fleet of “Class 66” diesels, which still dominate the UK rail freight scene.
Pilot pathway and technical scope
The partners intend to build a UK demonstrator based on HyOrc’s one-megawatt factory system, which has been independently assessed by Bureau Veritas, a global leader in testing, inspection, and certification. Project Phoenix would scale this to a three-megawatt locomotive installation, replacing the diesel engine within an existing freight locomotive platform. The work will examine integration, performance and operating economics, as well as fuel supply and safety requirements associated with onboard gas and hydrogen storage.
HyOrc said its hydrogen-conditioning technology is designed to improve the efficiency and cost profile of onboard hydrogen use. The staged fuel approach is presented as a bridge between current diesel operations and future zero-emission traction. For freight operators, the concept seeks to reduce technical risk by avoiding a single-step transition while maintaining route flexibility on secondary corridors that are unlikely to be electrified. The technology is not absolutely new, but the agreement represents a fresh approach to updating the UK fleet.
Strategic context for GBRf
The study complements GB Railfreight’s wider fleet strategy, which includes the introduction of new Class 99 bi-mode locomotives. Those units take primary power from overhead wires, but also have a diesel engine, which is HVO-ready. Alex Kirk, Commercial Director at GB Railfreight, said: “Project Phoenix aligns with GBRf’s strategic commitment to lead the rail freight sector towards a more sustainable future and could play a key role in delivering our carbon reduction plan. By retrofitting part of our existing fleet with multi-fuel technology, it will offer a practical, low-risk route to decarbonisation. It enables us to extend the value of current assets alongside the introduction of our new fleet of bi-mode Class 99s.”
For GBRf, the initiative targets the continued reliance on legacy diesel traction, particularly the Class 66 fleet. The 1980s-designed units built in North America by EMD, which, although still the mainstay of operations in the UK (around 500 units across all operators), are not compliant with modern emissions regulations. Retrofitting selected units could provide an interim emissions reduction while longer-term traction options mature. The operator has previously argued that full network electrification will not be delivered quickly enough to meet freight decarbonisation targets, increasing interest in self-powered low-carbon alternatives.
Funding and industry implications
HyOrc indicated that it is exploring structured funding options through the UK government backed Connected Places Catapult accelerator programme. Lisa Carter, CFO of HyOrc, said: “Project Phoenix is a turning point for the rail industry. By retrofitting existing assets, we allow operators to decarbonise immediately, bypassing billions in new fleet costs. We are exploring obtaining structured funding through the Connected Places Catapult Accelerator.”
As a non-binding agreement, the memorandum establishes a feasibility framework rather than a confirmed project. Progress will depend on technical validation, business case development and external funding. If advanced to a demonstrator stage, the concept could provide a model for decarbonising diesel-dominated freight fleets in markets where electrification coverage remains limited.