The trucks will be equipped with fuel system technology developed by its Cespira joint venture (JV) with Canadian-based Westport Fuel Systems, which allows hydrogen to be used as a fuel in adapted diesel engines.

Volvo has not confirmed how many trucks are part of the trial, but has said they will be fuelled by green hydrogen.

The HPDI technology uses a small amount of diesel as ignition fuel to enable compression ignition before hydrogen is added. A version of the system using LNG and bioLNG is already used in over 10,000 Volvo trucks.

It’s not the first time the technology has used hydrogen on roads. In 2023, a prototype truck with hydrogen HPDI hauled around 40 tonnes of IKEA products in Sweden.

Dan Sceli, CEO of Westport, said that on-road testing will be a key demonstration of the efficiency and performance of the HPDI fuel system.

“Hydrogen use in an internal combustion engine with Cespira’s HPDI fuel system delivers nearly 100% CO2 reductions over diesel-fuelled trucks while allowing OEMs to preserve their existing engine architecture,” he added.

However, hydrogen engines are not emissions-free. They still produce nitrogen oxides, raising questions about urban deployment, and hydrogen’s reactivity can create instability in the combustion process.

Additionally, engine materials may need to be adapted to avoid hydrogen embrittlement and corrosion from water vapour created in combustion.

Proponents of the pathway argue it is a cheaper clean mobility pathway than fuel cell vehicles, due to the ability to reuse existing engine manufacturing capabilities.