Hydrogen Opposed Piston Engine Working Group formed

Several organizations, encompassing companies, research labs, and academia, have formed the Hydrogen Opposed Piston Engine Working Group. The Working Group consists of members undertaking research and development in the field of hydrogen combustion in an opposed-piston engine.

An opposed piston engine with hydrogen combustion could well provide the best-known thermal efficiency from a reciprocating engine, with the potential to match the in-vehicle efficiency of a hydrogen fuel cell. If so, it is a valuable potential option for long haul transit in our quest for sustainable transportation.

—James Turner, Professor of Mechanical Engineering, Clean Combustion Research Center, King Abdullah University of Science and Technology (KAUST)


The newly formed organization will host a series of meetings of its members to exchange research results, insights, and ideas.

The direct injection two-stroke engine could be a very promising and interesting option for hydrogen combustion to achieve zero NOx because of its advantages of high-power density and inherent much lower NOx emissions. These two-stroke advantages are even more significant with an opposed-piston engine thanks to its higher power density and efficiency.

—Pierre Duret of DI2S Consulting & Training and former director Powertrain and Sustainable Mobility, IFP School (France)


In a recently published whitepaper on hydrogen opposed-piston engines (H2-OPE), opposed-piston engine maker Achates Power explained that since there are no carbon molecules in hydrogen fuel, neither unburned hydrocarbons nor particulate matter is a concern for emission control from a hydrogen combustion engine. The only criteria emission of concern is NOx.

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This article originally appeared in Green Car Congress, May 26, 2022