An investigation was conducted on the emissions and efficiency from hydrogen blended compressed natural gas (CNG) in light duty vehicles. The different blends used in this investigation were 0%, 15%, 30%, 50%, 80%, 95%, and ~100% hydrogen, the remainder being compressed natural gas. The blends were tested using a Ford F-150 truck and a Chevy Silverado truck. Tests on emissions were performed using four different driving condition tests.

Previous studies by Don Karner and James Frankfort on another Ford F-150 using a 30% hydrogen blend showed that there was substantial reduction when compared to gasoline in carbon monoxide (CO), nitrogen oxide (NOx), and carbon dioxide (CO2) emissions while the reduction in hydrocarbon (HC) emissions was minimal.

This investigation was performed using different blends of CNG and hydrogen to evaluate the emissions reducing capabilities associated with the use of the different fuel blends. The results were then tested statistically to confirm or reject the hypotheses on the emission reduction capabilities.

This research investigation has shown that employing hydrogen with compressed natural gas offers an interim solution, in which lower carbon-based emissions result while having nearly constant fuel utilization efficiencies over the various hydrogen/compressed natural gas blends. Because conventional fuels reach misfire condition (incomplete combustion) before NOx values can be reduced below the current and future regulations, nitrogen oxides emissions may not necessarily be reduced (due to combustion in dilution air) as a result of employing higher hydrogen concentrations. Despite this feature, employing hydrogen with compressed natural gas offers an interim solution until the hydrogen economy becomes a reality.