GB Railfreight (GBRf) has agreed with US-based HyOrc Corporation to develop Project Phoenix, a UK pilot to repower a Class 66 diesel freight locomotive with a 3 MW multi-fuel propulsion system. Under the programme, the locomotive’s original diesel engine would be removed and replaced with a modular HyOrc power unit for main line freight testing.
HyOrc’s own documentation describes Project Phoenix as a “greener rail freight opportunity” involving a Class 66 retrofit in which the chassis and basic locomotive frame are retained while the new power system is installed. The pilot would see the locomotive run initially on natural gas or LPG before moving to hydrogen within two to three years, depending on fuel infrastructure availability.
The case study features a 2.8 MW external-combustion, multi-fuel HyOrc installation on the Class 66 platform. The system uses a patented Organic Rankine Cycle (ORC) turbine combined with a combustion unit that can operate on hydrogen, natural gas, LPG, biogas or e-methanol, offering a broader fuel flexibility than traditional internal combustion engines.
The 3 MW target for Project Phoenix situates the repowered locomotive in the heavy freight power band. A standard Class 66 diesel produces about 2.46 MW (3,300 hp); a 3 MW HyOrc unit would represent a boost in installed power while replacing the diesel prime mover with a cleaner, hydrogen-capable propulsion system. The choice of the Class 66 reflects its role as GBRf’s core heavy freight workhorse and the ready availability of chassis and service expertise. (Fleet details based on GBRf locomotive roster.)
According to HyOrc’s retrofit case study, a repowered Class 66 could achieve a range of 700–920 km between refuelling stops and cut CO₂ emissions significantly compared with diesel operation, with interim emissions on LPG and further reductions once hydrogen is adopted. The study also describes lifecycle economics, including capital and operating costs and estimated payback, though GBRf and HyOrc have not publicly confirmed these figures for Project Phoenix.
Under the phased approach, the locomotive would first operate on onboard natural gas or LPG while hydrogen refuelling infrastructure matures in the UK. In the final configuration, HyOrc’s hydrogen-conditioning system would be integrated to manage onboard hydrogen supply and utilisation.
For GBRf, the pilot is positioned as a way to extend the service life of existing Class 66 locomotives and reduce emissions on non-electrified routes without procuring entirely new hydrogen rolling stock. The operator is simultaneously introducing bi-mode Class 99 locomotives as part of its broader fleet renewal programme.
