Hydrogen combustion engines lean on existing internal-combustion technology, but they still require some technical tweaks for maximum efficiency.
Engine maker Cummins recently unveiled a turbocharger designed for hydrogen engines, which burn gaseous hydrogen instead of gasoline or diesel. Called the CCS H2 ICE, the turbo helps compensate for the lower energy density and higher airflow needs of hydrogen compared to fossil fuels, according to a Cummins press release.
Hydrogen burns cleaner then gasoline or diesel, but it still produces some harmful criteria pollutants—like nitrogen oxide (NOx), which Cummins is familiar with. In 2024 the company agreed to pay a nearly $1.7 billion fine to settle a federal case in which it was accused of emissions cheating with diesel engines in Ram pickup trucks.
2025 Ram Heavy Duty
A higher-airflow lean burn is critical to minimizing NOx emissions in hydrogen combustion engines, according to Cummins, as is reducing turbo lag. The latter is caused when the turbo takes too long to build up boost, leaving to a delay between accelerator press and power delivery.
More precise control of the turbocharger can help deliver on these requirements. Several options exist for this, but for the CCS H2 ICE, Cummins chose a variable-geometry design with adjustable nozzles that can change airflow through the turbo on demand.
Peterbilt semi truck prototype with Cummins hydrogen combustion engine
Cummins gave indications it was going strong on EVs at one point, but it’s pulled back from what was hinted in those earlier concepts in recent years. It’s been emphasizing hydrogen combustion instead, showing a prototype hydrogen combustion engine in a Peterbilt semi truck in 2023.
While this new project is positioned to emphasize European fleets first, it could also be applied in U.S. trucks—with the supporting infrastructure, of course.
Cummins isn’t the only company investing in hydrogen internal combustion. Bosch has also made it a part of its hydrogen investments, alongside fuel cells. Toyota is looking at both hydrogen technologies was well, conducting hydrogen-combustion demonstration projects while continuing to develop a fuel-cell powertrain backed by large batteries for semi trucks and—the automaker has teased—possibly heavy-duty pickups as well.
