Extension of the lean limit through hydrogen enrichment of a LFG-fueled spark-ignition engine and emissions reduction

In this experimental investigation the affect of hydrogen addition to a landfill gas-fueled naturally-aspirated spark-ignition engine was explored. Hydrogen concentrations of 0%, 30%, 40%, and 50% by volume were added to simulated landfill gas (60% CH₄ and 40% CO₂). Efficiency, coefficient of variance of indicated mean effective pressure, and CO emissions were measured from near stoichiometric mixtures up to the lean operating limit. Engine-out NOx emissions were compared to predicted future best available control technology targets for NOx emissions in landfill gas-to-energy projects. From this study, it was determined that with 40% hydrogen by volume untreated exhaust NOx emissions can meet the 0.22 g/kWh NOx target while retaining 95% of baseline power and low CO emissions.