IN Brief:
- SER tested Ultimate Cell equipment on a 35-tonne excavator and an 18-tonne loading shovel.
- Company-reported peak excavator savings exceeded 25%, while some loading-shovel comparisons exceeded 10%.
- The system retains the diesel engine and offers an interim reduction measure rather than zero-emission propulsion.
Stevens Equipment Rental has completed a nine-month evaluation of Ultimate Cell hydrogen-on-demand equipment on two heavy machines, reporting lower diesel consumption under the operating conditions monitored during the trial.
The study covered a 35-tonne Volvo excavator and an 18-tonne loading shovel. SER and Ultimate Cell used original-equipment-manufacturer telematics to establish a three-month fuel-consumption baseline before installation, followed by six months of active monitoring.
SER reported consistent savings from the excavator, with reductions exceeding 25% under peak conditions. Based on 2,000 operating hours a year, the company estimates that the machine could save thousands of litres of diesel and more than 10 tonnes of carbon dioxide.
The loading shovel recorded an overall reduction during the monitored period, with savings above 10% in some comparisons with a conventional machine operating under similar conditions. The published results do not provide a single guaranteed fleet-wide percentage.
A diesel-reduction measure, not a replacement fuel
The retrofit uses electricity from the machine battery to split an electrolyte fluid into hydrogen and oxygen. Small quantities of the gases are introduced into the engine air intake, where the supplier says they support a more complete diesel burn.
The diesel engine remains the machine’s principal power source. The retrofit therefore does not convert the equipment into a hydrogen-powered or zero-emission machine, and its carbon benefit depends on the reduction in diesel consumed during comparable work.
That distinction is important for project carbon reporting. Contractors can record measured fuel savings where telematics and baseline data support them, but should not describe the machines as zero-emission plant or attribute avoided emissions beyond the verified reduction in consumption.
Mark Need, sales manager for Scotland and the north of England at SER, said: “We are taking a pragmatic approach to decarbonisation.”
The system is non-invasive and can be removed, returning the machine to its original configuration or allowing the equipment to be transferred to another asset. The supplier says routine maintenance is limited principally to replacing electrolyte fluid at extended intervals.
SER has now incorporated the technology into its commercial rental offering, allowing customers to request fitted machines for projects where fuel and carbon reductions form part of the delivery requirements.
The rental route lowers the commitment required from contractors interested in testing the technology. SER retains control of installation and maintenance, while customers can compare performance against their own applications, operators, site conditions, and reporting requirements.
The results should nevertheless be interpreted as company-reported field data rather than an independent certification of a universal saving. The source material states that results were normalised for workload, idle time, and operating conditions, but fuel performance will continue to vary with machine type, terrain, application, operator behaviour, and duty cycle.
A high-utilisation excavator working consistent production cycles offers a stronger basis for comparison than a machine moving between intermittent tasks. Weather, haul distance, material density, ground conditions, attachment choice, and idle time can all change consumption without any alteration to the retrofit.
Telematics provides a more credible measurement method than fuel-card totals alone because it can relate consumption to operating hours and machine activity. Contractors evaluating the system should still examine the baseline period, comparable workload, data exclusions, maintenance records, and whether any other changes occurred during the trial.
The technology is aimed at the installed diesel fleet at a time when zero-emission alternatives remain difficult for some heavy applications. Battery-electric machines are becoming available in smaller and urban categories, but large earthmoving equipment can face limits around range, charging power, shift length, and remote-site infrastructure.
A transferable retrofit may extend the period in which an existing machine operates with lower fuel use, avoiding immediate replacement of otherwise serviceable equipment. The commercial case depends on installation and maintenance costs, annual utilisation, achieved savings, residual life, and the price of diesel.
It may be most relevant to infrastructure, quarrying, bulk earthworks, and other applications where equipment runs for long hours and small percentage improvements accumulate across a fleet. Low-utilisation assets will produce a smaller absolute saving even where the percentage reduction is similar.
The nine-month evaluation provides a useful operational dataset, but it does not settle the wider question of heavy-plant decarbonisation. Ultimate Cell remains an intervention within a diesel powertrain, offering a potential reduction while the industry develops machines and supporting infrastructure capable of removing fossil fuel altogether.
