Life cycle assessment (LCA) is a well-established methodology for the evaluation of the environmental performance of product systems. However, a large number of combinations of methodological choices is possible in LCA studies, threatening consistency when comparing different authors’ studies. Regarding hydrogen, a specific LCA harmonisation initiative has recently been undertaken. Within the framework of this initiative, harmonisation protocols and libraries of life-cycle indicators of hydrogen have been developed in order to improve the robustness of comparative LCAs. Nevertheless, these libraries are currently affected by the lack of fossil-based hydrogen options. Hence, this study fills this gap by calculating harmonised carbon and energy footprints of hydrogen for a set of 15 new case studies involving relevant production pathways: gasification, reforming and autocatalytic decomposition of fossil feedstock, and electrolysis powered by fossil and grid electricity. Overall, the resulting extended library of harmonised life-cycle indicators stresses the role of renewable hydrogen as a key requirement in the path towards an environmentally-sustainable hydrogen economy.

生命周期评估（LCA）是一种成熟的方法，用于评估产品系统的环境绩效。但是，在LCA研究中，可能会有大量方法选择的组合，这在比较不同作者的研究时会威胁到一致性。关于氢，最近已开展了一项具体的LCA协调倡议。在该倡议的框架内，已经开发了氢的生命周期指标的协调协议和库，以提高比较型LCAs的鲁棒性。然而，这些图书馆目前受到缺乏基于化石的氢选择的影响。因此，本研究通过为涉及相关生产途径的15个新案例研究中的一组计算协调的碳和氢的能量足迹来填补这一空白：化石原料的气化，重整和自催化分解，以及化石和电网电力驱动的电解。总体而言，由此产生的扩展了的生命周期指标统一库强调了可再生氢的作用，这是实现环境可持续氢经济的关键要求。