Environmental impact assessment of hydrogen production technologies

This study discusses environmental impacts of hydrogen production from both fossil and renewable sources using a life cycle assessment approach. Global warming potential of steam methane reforming of natural gas was estimated at 9.35kg CO₂ eq/kg H₂ based on direct emissions from US hydrogen production facilities. When comparing all emission sources from the current hydrogen production facilities, CO₂ emissions from the facilities contribute most to the impacts on both human health and ecosystems. Renewable hydrogen production including wind- and solar-powered electrolysis, biomass gasification and biogas reforming presented much lower impacts than the natural gas-based production. Wind-powered electrolysis has the lowest global warming potential of 1.29kg CO₂ eq/kg H₂ whereas the highest impact was found in the biogas reforming system (3.61kg CO₂ eq/kg H₂). Construction and operation of wind and solar power stations contributed to 78-97% and 88-99% of global warming potential of the wind- and solar-powered electrolysis, respectively, while energy consumption during gasification and methane leakage during biogas production were the major contributors in the biomass gasification and biogas reforming systems. Although consumption of energy, materials and water, as well as higher production cost of the renewable hydrogen production systems indicate areas of improvement, potential of the renewable hydrogen being integrated into existing natural gas infrastructure with increasing production of renewable electricity are expected to promote the production of renewable hydrogen.