Carbon footprint analysis of advanced electrolysis technologies for industrial-scale green hydrogen production

This study presents a comparative carbon footprint analysis of three advanced electrolysis technologies used for industrial-scale green hydrogen production — Alkaline Electrolysis (AEL), Proton Exchange Membrane Electrolysis (PEM), and Solid Oxide Electrolysis Cell (SOEC). The environmentally sustainable production of hydrogen is directly related not only to energy efficiency but also to the greenhouse gas emissions generated throughout the life cycle of the production process. In this context, the mentioned technologies were analyzed using the Life Cycle Assessment (LCA) method in accordance with ISO 14040/44 standards. Based on the production of 1 kg of hydrogen for each technology, three scenarios were created depending on the energy source (solar, wind, and grid electricity), and the carbon footprint was calculated using the ReCiPe method. The results indicate that the type of energy source used is a critical determinant of the carbon footprint. While systems operating with grid electricity result in significantly higher emissions (e.g., ~9.4 kg CO₂-eq/kg H₂ for AEL), using renewable energy sources can reduce this value by up to 70%. In particular, solar-thermal-assisted SOEC systems were found to have the lowest emission value, approximately 0.6 kg CO₂-eq/kg H₂. On the other hand, the production of rare-metal-based components used in PEM systems contributes to considerable environmental impacts. The findings demonstrate that green hydrogen technologies must be evaluated not only from a technical perspective but also in terms of their environmental performance to achieve carbon neutrality targets. In countries like Türkiye, which have high renewable energy potential, the level of integration between the selected hydrogen production technology and the energy source plays a critical role in minimizing the carbon footprint.