A recent trial at Exeter Airport has generated new operational evidence that aims to help the global aviation industry understand how hydrogen-powered ground equipment might be introduced safely and practically, as well as what may needed to support wider adoption.
Led by Exeter Airport, Cranfield University and ULEMCo; the study tested a dual-fuel hydrogen–diesel ground power unit over multiple days in winter operating conditions.
A report from Cranfield Univeristy has found that the equipment performed both safely and reliably, and delivered measurable reductions in diesel use and carbon emissions whilst requiring minimal change for the ground teams operating it.
Findings also indicate areas where dual-fuel hydrogen technology may be most effective, suggesting that its greatest benefits could be achieved in equipment used continuously or for longer operating cycles.
The Winter Operations HyGPU project follows the success of the Zero Carbon Turn trial at Exeter Airport in April 2025, which achieved a number of UK firsts when three different hydrogen-powered technologies supported the live turnaround of a TUI Boeing 737. This latest project, which was funded and supported by the Connected Places Catapult and overseen by UK Civil Aviation Authority, aims to contribute practical evidence to the development of hydrogen infrastructure, operational procedures, safety frameworks and future investment decisions across the aviation sector.
The equipment completed 15 tests across eight operational days, with all tests lasting a total of almost six hours and consuming roughly 7.41kg of green hydrogen, displacing an estimated 24.23 litres of diesel and avoiding approximately 63.9kg of carbon dioxide emissions. No safety incidents or significant operational problems were reported during the trial period, and airport ground crew allegedly found ‘little practical difference’ between operating the converted equipment and using a conventional diesel GPU.
Cranfield University’s report has estimated that converting all seven of Exeter Airport’s existing GPUs to the same dual-fuel system could potentially save more than 11,000 litres of diesel and approximately 35 tonnes of carbon dioxide equivalent each year, and found ‘no clear evidence’ that lower ambient temperatures, which ranged from 4°C to 14°C during the tests, directly affected the GPU’s technical performance.
However, the findings did indicate that periods of inactivity, including overnight cold starts, may delay the point at which the equipment begins using hydrogen – this is because the dual-fuel unit starts on diesel and only introduces hydrogen after its engine reaches the required operating temperature. As a result, the report has stated that longer trials and a larger dataset would be necessary in order to confirm the relationship between inactivity, temperature and performance.
In all, the findings suggest dual-fuel technology may offer the greatest benefit for airport equipment used continuously or for longer periods. Equipment used for short, intermittent tasks may be better suited to other zero-emission technologies.
The Winter Operations HyGPU project forms part of the UK Civil Aviation Authority’s wider Hydrogen Challenge, which brings together industry, academia and regulators to examine the safe introduction of hydrogen across aviation. Eleven projects have contributed evidence to identify safety considerations, regulatory gaps and infrastructure requirements, informing the CAA’s hydrogen roadmap for scaling small-aircraft operations towards 2035.
The project builds on Exeter Airport’s Zero Carbon Turn trial in April 2025, which demonstrated several UK firsts, including the concurrent use of multiple hydrogen-powered ground vehicles, a hydrogen GPU powering a commercial aircraft, as well as the use of green hydrogen produced from renewable energy at a UK airport.
