Integrated Life Cycle Sustainability Assessment – Hydrogen production as a showcase for an emerging methodology

GoalsLife Cycle Sustainability Assessment (LCSA) is an emerging methodology to map the sustainability of a technology. Although several publications have tackled this topic from different angles, the community is still exploring different approaches for LCSA. Often, there is a discrepancy between the demands on the approach and what can actually be implemented. In this work, we present a consistent approach for LCSA, which is still practical. This approach is applied on an advanced alkaline water electrolyzer (AEL) at three different European locations. Electrolyzers are an important technology for the future. It is the corner stone of many Power-to-X processes and can deliver fuel for an electrified transport system as well as feedstock for other industrial processes. When run with electricity from renewable sources, it reduces greenhouse gas emissions considerably.MethodsClassically, LCSA consists of Life Cycle Assessment (LCA), Life Cycle Costing (LCC) and social Life Cycle Assessment (s-LCA) based on a joint technical model. For an integrated and consistent LCSA, however, this is not enough. Therefore, in this work, a coherent impact category selection based on the sustainable development goals (SDGs) was conducted. Furthermore, for interpretation of the results an integration of the three sustainability dimensions is mandatory. Thus, multi-criteria decision-analysis is necessary. For this work, the outranking method PROMETHEE is chosen. It does not allow full compensation of the sustainability indicators, which reflects a possible view on sustainability.The analyzed system is a 6 MW pressurized electrolyzer. This electrolyzer is located in three different European countries, i.e. Spain, Germany and Austria, to illustrate the difference of industrial hydrogen production in industrialized countries with different structures in the electricity market. A state of the art technology is used under today`s conditions.ResultsWithin each sustainability dimension a different location is favorable. From an ecological point of view, hydrogen production in Austria is the best option because the electricity is mainly generated from hydropower. The lowest hydrogen production cost, however, can be found in Germany because the electricity prices for energy-intensive industry are lower compared to Spain and Austria. A more diverse picture is drawn from the results of the s-LCA. Austria has for most impact categories the highest social risks. However, in Spain some social risks are much higher than in the other two countries, e.g. risk of unemployment or the risk that workers are not sufficiently represented due to the lack of trade unions. With such diverse results, decision making is difficult and PROMETHEE can guide such a process. If every dimension of sustainability has the same importance and within each dimension, each impact category has the same importance MCDA using PROMETHEE comes to the result that industrial hydrogen production in Germany is most preferable