Study on hydrogen substitution in a compressed natural gas spark-ignition passenger car engine

Hydrogen substitution in applications fueled by compressed natural gas arises as a potential alternative to fossil fuels, and it may be the key to an effective hydrogen economy transition. The reduction of greenhouse gas emissions, especially carbon dioxide and unburned methane, as hydrogen is used in transport and industry applications, makes its use an attractive option for a sustainable future. The purpose of this research is to examine the gradual adoption of hydrogen as a fuel for light-duty transportation. Particularly, the study focuses on evaluating the performance and emissions of a single-cylinder port fuel injection spark-ignition engine as hydrogen is progressively increased in the natural gas-based fuel blend. Results identify the optimal conditions for air dilution and engine operation parameters to achieve the best performance. They corroborate that the dilution rate has to be adjusted to control pollutant emissions as the percentage of hydrogen is increased. Moreover, the study identifies the threshold for hydrogen substitution below which the reduction of carbon dioxide emissions due to efficiency gains is negligible compared to the reduction of the carbon content in the fuel blend. These findings will help reduce the environmental footprint of light-duty transportation not only in the long term but also in the short and medium terms.