Robust eco-efficiency assessment of hydrogen from biomass gasification as an alternative to conventional hydrogen: A life-cycle study with and without external costs.

Hydrogen is a key product for the decarbonisation of the energy sector. Nevertheless, because of the high number of technical options available for hydrogen production, their suitability needs to be thoroughly evaluated from a life-cycle perspective. The standardised concept of eco-efficiency is suitable for this purpose since it relates, with a life-cycle perspective, the environmental performance of a product system to its value. Hence, this work benchmarks the eco-efficiency performance of renewable hydrogen produced through biomass gasification against conventional hydrogen from the steam reforming of natural gas. For the eco-efficiency assessment, the harmonised environmental indicators of global warming, acidification and cumulative non-renewable energy demand were individually used, while the product system value was based on the levelised cost of hydrogen with/without internalisation of the external socio-environmental costs associated with climate change and human health. On the one hand, when the environmental and economic performances are separately considered, hydrogen from biomass gasification performs significantly better than hydrogen from steam methane reforming under environmental aspects (e.g., greenhouse gas emissions saving of 98%), whereas the opposite conclusion was found from an economic standpoint (levelised cost of 3.59 € and 2.17 € per kilogramme of renewable and fossil hydrogen, respectively). On the other hand, when combining life-cycle environmental and economic indicators under the umbrella of the eco-efficiency assessment, it is concluded that the renewable hydrogen option outperforms the conventional one, which is further remarked when implementing socio-environmental externalities. In this regard, a relative eco-efficiency score above 14 was estimated for the renewable hydrogen option when benchmarked against conventional hydrogen.