How Would a Switch to a Future Hydrogen Economy Influence the Atmosphere?

Switching from a fossil fuel to a hydrogen-based energy system is likely to cause significant changes in the magnitude and composition of anthropogenic emissions. On the `good' side, the hydrogen economy may achieve reductions in emissions of CO and NOx, improving air quality. On the `minus' side man-made emissions of H₂ could increase through leaks, influencing the oxidising capacity of the atmosphere and stratospheric ozone. Model simulations using a 2D interactive model of the atmosphere have been performed for a selection of hydrogen economy emission scenarios. Results suggest the impact on stratospheric ozone may not be as large a problem as first thought, but that unwelcome tropospheric effects may be significant. There are strong atmospheric trade-offs between hydrogen and other gases, particularly methane.