Potential of Synergies in a Vehicle for Variable Mixtures of CNG and Hydrogen

Synergies in infrastructure and customer acceptance can be achieved by running internal combustion engines on mixtures of hydrogen and natural gas. Alongside the bridging effect between natural gas and hydrogen, such mixing offers advantages in terms of reduced emissions and improvements to the combustion process. The wide ignition limits and high flame speed of hydrogen have as positive an impact on the combustion of H₂NG mixture as does the higher energy density of natural gas on range.

A bi-fuel gasoline-natural gas vehicle was adapted to operation with gasoline, natural gas, hydrogen and any H₂NG mixtures. For that purpose, the intake manifold was replaced by an aluminum construction, the injectors were replaced and the ECU had to be adjusted. Essentially quality-controlled hydrogen operation was possible throughout the engine map. As for the vehicle, the original tanks were replaced by 350 bar hydrogen tanks, and all obligations for road homologation were fulfilled through gas-tight encapsulation of the whole tank system. An innovative electronic gas safety system was developed and employed with online monitoring of fill level, gas consumption and leak tightness.