Life cycle assessment of renewable hydrogen transport by liquid organic hydrogen carriers

This study performs life cycle assessment of different hydrogen transport systems using liquid organic hydrogen carriers (LOHC). Renewable toluene and dibenzyltoluene (DBT) produced from wheat straw and bagasse were applied as hydrogen carriers in this analysis. Renewable hydrogen produced by wind-powered electrolysis was analysed for marine transportation at 11,000 km transport distance, simulating transport of hydrogen from South Australia (SA) to Asia. Global warming impact of the renewable DBT was estimated to be higher than the toluene, due to additional production process of DBT. The global warming impacts of production and transport of hydrogen using the renewable toluene and DBT were in the ranges between 10.2 and 10.6 kg CO2 eq per kg of released hydrogen. The energy-intensive dehydrogenation process was the major contributor to global warming impacts, with average contribution of 46.4%, while the transport contributed 15.6% to the impact. When the transport distance increased to 24,000 km, for transport of hydrogen from SA to Europe, the global warming impact increased by 17.3%, implying non-proportional increase of the impact. For shorter distance transport (1700-5000 km), truck shipping presented lower global warming impacts than marine transport, but the impact became higher at 7000 km transport distance. When the entire hydrogen transport system was assumed to operate with renewable energy and B20 (biodiesel blend of 20% vol), 51% reduction of global warming impacts can be achieved, indicating further reduction potential of the renewable hydrogen transportation system.