Natural gas fuelling for heavy‐duty on‐road use: current trends and future direction

Abstract

The use of natural gas as an alternative fuel offers the potential for significant benefits, including lower engine‐out emissions compared to conventional fuels. Most in‐use heavy‐duty natural gas engines use a premixed charge of fuel and air which is then ignited by a spark plug. While these systems meet current emissions standards, substantial further reductions are required to meet upcoming regulations. Efficiency penalties due to poor fuel utilization at low load with such premixed charge engines are also a concern. As a result, there is scope for further research into potential improvements to natural gas‐fuelled heavy‐duty engines, especially through direct injection. This work reviews the various alternatives, both in‐use and under development, for fuelling a heavy‐duty engine with natural gas. The emphasis is placed on providing an understanding of the performance of current heavy‐duty natural gas fuelled engines and improvements that future technologies may offer. The need for further fundamental and applied research, both computational and experimental, is also identified.