The GTRC have been engaged in significant hydrogen (H2) related projects over the last few years, primarily in support of National Gas Transmission's proposal to include H2 in the UK gas grid.

As a consequence of this work, we are pleased to be able to share our latest publication, "Influence of emissions normalisation methods on H2–CH4 fuel comparisons in generic and NOx-abated gas turbine combustion", available in the International Journal of Hydrogen Energy: https://doi.org/10.1016/j.ijhydene.2026.154402.

This is the first publication of our PhD researcher Tomas Davies, supported by the GTRC team and demonstrates how the future landscape of NOx emissions regulation may need to evolve as low and zero carbon fuels, such as H2 and ammonia, are introduced into the gas networks, so as not to unduly penalise against non-carbonaceous fuels.

For this work, parametric experiments were conducted in our model gas turbine combustor using methane-H2 blends at pressures of up to 6 bar. Comparisons were made for unabated combustion versus abated combustion, using synthesised exhaust gas recirculation (EGR) as the NOx abatement strategy.

🔬 Summary of the most significant findings:

• Conventional, dry, 15% O₂ emissions normalisation can artificially inflate reported NOx emissions from H2 flames by up to ~37%, when compared with pure methane combustion emissions.
• While correction factors have been proposed to address this inflation, this approach quickly become unwieldy in practice.
• Alternative emissions normalisation methods can avoid these issues, e.g. a NOx emissions by fuel energy input normalisation method.