Comparison of the sustainability of hydrogen supply chains including alternative hydrogen carriers

The Netherlands is known for the high penetration of natural gas use in households and industry, but the threat of climate change as well as earthquakes in the province of Groningen, caused by natural gas production, stimulate the search for alternative energy carriers such as hydrogen gas. Various hydrogen supply chains are currently being evaluated by scientists, industry stakeholders and policy makers. This study compares the following ways of green hydrogen production and supply: electricity from wind farms in the Netherlands is used for offshore and onshore electrolysis of water, electricity generated by solar PV parks in Algeria and Saudi-Arabia is used for electrolysis after which the hydrogen is transported via pipelines or as ammonia, resp., and transport of hydrogen as hydrogenated dibenzyltoluene from both locations. The sustainability of the hydrogen supply chains is assessed from a life cycle point of view. The ReCiPe 2016 and Environmental Footprint 3.0 (EF) are used for the environmental assessment and the Total Cumulative Exergy Loss (TCExL) method is used to calculate the exergetic sustainability. According to the endpoint scores of the three assessment methods, offshore hydrogen production with wind energy is preferred, with 1.4E-1 Pt (ReCiPe), 5.9E-4 Pt (EF) and 1.3E2 MJ (TCExL) per kg gaseous hydrogen in Rotterdam, while the relative ranking of the remaining options is inconclusive and the ammonia option consistently seems the least-preferred. It is advised that the systems be investigated in more detail before drawing firm conclusions about the order of preference and that also attention be paid to the economic and social pillars of sustainability. It is recommended that exergy be part of sustainability assessment of technological systems in general because of its independence of changing and subjective assessment models, weighting factors and other variables.