Mitigating Power Deficits in Lean-Burn Hydrogen Engines with Mild Hybrid Support for Urban Vehicles

Strategic Insights -

A study on mechanical engineering has made significant strides in reducing carbon emissions in urban transportation by exploring the use of hydrogen-fueled internal combustion engines. Researchers from the Facultad de Ingenieria in Uruguay, led by Santiago Martinez-Boggio, investigated whether integrating a mild hybrid electric system could mitigate the performance losses associated with lean hydrogen combustion in a small passenger vehicle. The findings demonstrate that the best lean hydrogen hybrid configuration achieved reductions of 18.6% in energy consumption in the New European Driving Cycle and 5.5% in the Worldwide Harmonized Light Vehicles Test Cycle, putting its performance on par with the gasoline hybrid benchmark.

Key Takeaways:

  • The study found that integrating a mild hybrid electric system can mitigate the performance losses associated with lean hydrogen combustion in a small passenger vehicle, achieving reductions of 18.6% in energy consumption in the New European Driving Cycle and 5.5% in the Worldwide Harmonized Light Vehicles Test Cycle.
  • The best lean hydrogen hybrid configuration consumed 41.2 kWh/100 km, nearly matching the 41.0 kWh/100 km of the gasoline P0 configuration.
  • The mild hybrid system kept the hydrogen engine operating predominantly within its high-efficiency region, confirming that lean hydrogen combustion, when supported by appropriately scaled mild hybridization, is a viable near-zero-emission solution for urban mobility.
  • The study involved a Design of Experiments approach to vary the electric motor size (from 1 to 15 kW) and battery capacity (0.5 to 5 kWh) while maintaining a fixed system voltage, optimizing both the component sizing and control strategy.
  • The researchers employed a validated one-dimensional engine model and a full zero-dimensional vehicle model to simulate the performance of the lean hydrogen hybrid configuration.
  • The study demonstrated that the lean H2 hybrid consumed nearly the same amount of energy as the gasoline P0 configuration in the New European Driving Cycle, with an average consumption of 41.2 kWh/100 km.

Statistics:

  • 18.6% reduction in energy consumption in the New European Driving Cycle with the lean hydrogen hybrid configuration
  • 5.5% reduction in energy consumption in the Worldwide Harmonized Light Vehicles Test Cycle with the lean hydrogen hybrid configuration
  • 41.2 kWh/100 km average consumption of the lean H2 hybrid in the New European Driving Cycle
  • 41.0 kWh/100 km average consumption of the gasoline P0 configuration in the New European Driving Cycle

Sources:

  • Mitigating Power Deficits in Lean-Burn Hydrogen Engines with Mild Hybrid Support for Urban Vehicles. Vehicles, 2025, 7(3):88. (https://doi-org.sdpl.idm.oclc.org/10.3390/vehicles7030088)
  • Journal of Engineering, October 13, 2025, p 2583.