1. The role of hydrogen in achieving low-carbon transition 2. Methodology 3. Total material requirements of the hydrogen sector 4. Wider low-carbon transition demand context 5. Sourcing and supply context 6. Emissions and water intensity 7. Conclusion: Meeting the challenge to produce hydrogen sustainably References 5 Sufficiency, sustainability, and circularity of critical materials for clean hydrogen 4 AEL Alkaline electrolysers CCS Carbon Capture and Sequestration CSM Climate-Smart Mining EL Electrolysers GHG Greenhouse Gas emissions HDV Heavy Duty Vehicle LDV Light Duty Vehicle LOHC Liquid Organic Hydrogen Carrier PEMEL Polymer Electrolyte Membrane electrolysers PEMFC Proton-exchange membrane fuel cells PGM Platinum Group Metals