Carbon Footprint Assessment of the Value Chain of Green Hydrogen

Abstract

This study assesses the carbon footprint of the green hydrogen value chain in Germany, focusing on greenhouse gas emissions in kg CO₂-eq/kg H₂ for different stages of the value chain. A comprehensive, modular model of the value chain was developed to incorporate multiple scenarios for each stage enabling an assessment of the entire value chain’s emis-sions across different scenarios. Using a life cycle assessment approach, the results high-light the critical influence of the electricity source on the overall carbon footprint, with hy-drogen production contributing the most emissions. Wind-powered electrolysis resulted in 0.874 kg CO₂-eq/kg H₂, significantly lower than solar-powered electrolysis, which reached 6.067 kg CO₂-eq/kg H₂. Transport and storage choices also affected emissions, with pipe-line transport and salt cavern storage showing lower greenhouse gas emissions than road-based transport combined with above-ground storage. Sensitivity analyses confirmed the electricity source as the most influential parameter, while hydrogen transport and storage options showed smaller variations across sensitivity scenarios. The study further recom-mends minimizing storage duration in above-ground tanks to keep emissions below 1 kg CO₂-eq/kg H₂ stored. Hydrogen leakage was found to contribute only marginally to the overall carbon footprint. Overall, the findings emphasize the importance of including the carbon footprint of renewable energy sources in hydrogen certification and accounting processes. Favoring wind-powered electrolysis, alongside pipeline transport and optimized storage infrastructure, can significantly reduce emissions, supporting more sustainable hy-drogen supply chains.