Commercial natural gas vehicles: tomorrow’s engine technologies for most stringent NO_x and CO₂ targets

Abstract

Engine developers for heavy duty commercial vehicles face major challenges in the coming years. On the one hand, the adapted in-service conformity load profiles will require a further reduction of pollutant emissions in low load operation, while on the other hand, limitations on greenhouse gas emissions will require further optimization of fuel efficiency. Due to its chemical composition, natural gas offers a theoretical CO₂ reduction potential of 25% vs. regular diesel fuel, assuming the same fuel energy provided, but natural gas also offers great reduction potential for pollutant emissions.

Several gas engine technologies are available on the market. This paper will describe two of the most promising technologies for mastering future increased requirements concerning pollutant criteria and GHG emissions reduction.

The first technology focus on is the positive ignited stoichiometric engine with exhaust gas recirculation and a three way catalyst. It enables the lowest nitric oxide and particulate emission compliance without additional fluids. Stoichiometric operation makes the most stringent emission limits feasible, including in the low-load range.