Achieving Euro 7 WHSC NOx Emission Targets from a Spark Ignited Engine Using Methanol-Hydrogen Co-Fuelling

E-methanol is increasingly seen as a promising clean fuel because its chemical makeup is close to fossil fuels, making it easier to use in existing engines. It offers a carbon-neutral option to help reduce greenhouse gases in sectors where cutting emissions is especially difficult, such as transportation. However, while e-methanol avoids adding new carbon dioxide, burning it in internal combustion engines still releases harmful gases like oxides of nitrogen (NOx) and other toxic by-products like formaldehyde and formic acid that damage both health and the environment.

This report explores a new strategy that combines methanol with hydrogen to run engines under “ultra-lean” conditions and its impact on emissions, performance and efficiency. Experiments were carried out on a single-cylinder spark ignition engine, with directly injected methanol and port fuelled injection of hydrogen. The findings show that adding about 10% hydrogen (energy basis) at low engine loads can extend the lean limit from air-fuel equivalence ratio (λ) of 1.7 to 2. This change cut NOx emissions by 99% and reduced formaldehyde emissions by 18% compared to pure methanol operation at stoichiometric. Furthermore, the NOx emissions were reduced sufficiently that engine could operate within Euro 7 World Harmonic Stationary Cycle (WHSC) limits.