Prospective Life Cycle Assessment: a Case Study of Hydrogen Production with Water Electrolysis

Hydrogen plays an important role in the discussion on achieving the climate change reduction target and is considered as a solution to a multitude of problems, such as decarbonizing mobility and industry. However, hydrogen production using polymer electrolyte membrane water electrolysis is not fully commercially deployed on a large scale and it has to be verified whether hydrogen produced with this electrolysis technology indeed may lead to environmental benefits in the future. For assessing new technologies and their future environmental impacts, the method of prospective life cycle assessment is well suited. As the further development of the technology as well as the general future situation are unknown, scenarios are developed using the morphological analysis method. These scenarios represent different possible future states with reduced material demand, improved system efficiency, or longer cell lifetime and lead to different potential results for the environmental impacts. Furthermore, the background system is also adapted to future situations using scenarios. The results indicate that the improvement of the electrolysis plant regarding efficiency, material demand, and cell lifetime leads to lower environmental impacts in all categories. This reduction in impact is rather small, as the electricity demand in operation currently dominates the results in most impact categories. In contrast, the projection of the background infrastructure into the future leads to strongly altered impact results. Half of the considered impact categories show strong decreasing impacts, while the other half is affected negatively. Global warming potential, for example, decreases by 92.0% due to the projection of the infrastructure into 2050. This means that in this specific case, the transition of the background scenarios, which represent the future production infrastructure and particularly the future energy supply, has a significant impact on the environmental consequences. The improvement of the electrolysis plant contributes rather small reductions, which is, nevertheless, inevitable to achieve the overall goal of a fully renewable energy-based energy system.