Image Courtesy: HÖRMANN Vehicle Engineering
Engineers in Germany are exploring a new way to store hydrogen on tractors by integrating pressurized fuel tanks directly into the machines’ hollow wheel structures. The idea is aimed at solving one of the biggest practical problems facing hydrogen-powered agricultural equipment: how to carry enough fuel without sacrificing space, balance, or operating time.
The concept is being studied as part of Germany’s H2Agrar project, a large-scale hydrogen agriculture initiative focused on testing hydrogen-powered farm machinery in real-world conditions. Instead of mounting bulky hydrogen tanks on tractor roofs or near the cab, researchers are investigating whether the unused inner space inside large tractor wheels could safely house hydrogen storage systems, according to Fuel Cells Works.
One of the main motivations is range. Current hydrogen tractors, such as the Fendt Helios prototype, already use compressed hydrogen stored at pressures up to 700 bar. The Helios carries five roof-mounted tanks holding a combined 21 kilograms of hydrogen, enough for roughly five to eight hours of operation depending on workload.
The tractor uses a 100-kilowatt fuel cell paired with a battery system to power an electric drive motor and onboard systems. According to developers involved in the project, the machine performs similarly to diesel-powered tractors of comparable size and output.
However, hydrogen presents unique storage challenges. Even when highly compressed, hydrogen contains less energy by volume than diesel fuel. That means hydrogen-powered vehicles often need larger or more creatively designed storage systems to achieve acceptable operating range.
Researchers believe wheel-integrated storage could help redistribute weight more efficiently while freeing up valuable space elsewhere on the tractor. Large agricultural wheels already contain significant internal volume, making them attractive candidates for integrated storage systems.
The engineering challenge, though, is substantial. Any hydrogen tank inside a rotating wheel would need to withstand constant vibration, pressure stress, and impacts while also maintaining safe fueling connections and hydrogen transfer systems.
The broader H2Agrar project began in 2021 with support from the German state of Lower Saxony. It combines hydrogen production, refueling infrastructure, and agricultural vehicle testing within a single regional network. Hydrogen used in the project is generated from a local wind farm using electrolysis systems capable of producing up to 900 kilograms of hydrogen per day.
The project also includes a dedicated hydrogen filling station capable of dispensing fuel at both 350 and 700 bar pressures. The Fendt Helios tractors continue operating on farms as researchers collect real-world performance data.
At this stage, the wheel-storage concept remains under evaluation, and it is unclear whether it will move beyond the research phase into full prototype development. Still, the idea reflects the growing push to make hydrogen-powered heavy machinery more practical for long working days in agriculture and construction.
As countries look for alternatives to diesel-powered industrial equipment, solving the storage problem may prove just as important as developing the engines themselves.