It Is Not the Same Green: A Comparative LCA Study of Green Hydrogen Supply Network Pathways

Green hydrogen (H2 ), a promising clean energy source garnering increasing attention worldwide, can be derived through various pathways, resulting in differing levels of greenhouse gas emissions. Notably, Green H2 production can utilize different methods, such as integrating standard photovoltaic panels, thermal photovoltaic, or concentrated photovoltaic thermal collectors with electrolyzers. Furthermore, it can be conditioned to different states or carriers, including liquefied H2 , compressed H2 , ammonia, and methanol, and stored and transported using various methods. This paper employs the Life Cycle Assessment methodology to compare 18 different green hydrogen pathways and provide recommendations for greening the hydrogen supply chain. The findings indicate that the production pathway utilizing concentrated photovoltaic thermal panels for electricity generation and hydrogen compression in the conditioning and transportation stages exhibits the lowest environmental impact, emitting only 2.67 kg of CO2 per kg of H2 .