Pathways to global hydrogen production within planetary boundaries

Hydrogen is regarded as a key lever for decarbonising hard-to-electrify sectors and industries. Future projections suggest that a significant increase in global hydrogen production is required to limit global warming to 1.5°C. However, the planetary footprint of global hydrogen production is not well understood, particularly when considering potential interactions between Earth's biophysical systems. This study quantifies planetary footprint using a bottom-up hydrogen production system considering potential planetary boundary interactions. Here, we show that from 2025 to 2050, even under the most sustainable scenarios, global hydrogen production is unsustainable with multiple boundary transgressions. As opposed to current trends, we find that biomass-based production has the potential to amplify boundary transgression levels. We also find that an increased electrolytic hydrogen production capacity with concurrent carbon removal will be required to alleviate the planetary footprint of global hydrogen production. Our general analysis confirms the need to re-evaluate the “green hydrogen” concept, which, besides the sole focus on climate change, largely overlooks critical interactions between Earth's biophysical systems. Therefore, achieving absolute sustainability for global hydrogen production will require reconsidering environmentally viable production pathways.