Energy and economic assessment of LH2, NH3, TOL/MCH and H0-DBT/H18-DBT for large-scale hydrogen transport

The transport of hydrogen from regions rich in renewable energy resources, where green hydrogen can be produced at a low cost, to countries with high energy demand, but limited resources, requires its conversion into a "hydrogen carrier", a substance capable of efficiently storing it. Techno-economic analyses are carried out on the value chains of ammonia (NH3), liquefied hydrogen (LH2), toluene/methylcyclohexane (TOL/MCH), and dibenzyltoluene/perhydro-dibenzyltoluene (H0-DBT/H18-DBT) for H2 transportation. A case study is examined in which hydrogen is transported from North Africa to Italy. The value chain includes H2 conversion into a carrier, storage, maritime transport, distribution, and reconversion back to H2. The conversion and reconversion processes correspond to liquefaction and regasification for LH2, synthesis and cracking for NH3, and hydrogenation and dehydrogenation for TOL/MCH and H0-DBT/H18-DBT. NH3 emerges as the most cost-effective and energy-efficient carrier when hydrogen is delivered to a hydrogen valley to serve nearby industries. The synthesis of ammonia, starting from green hydrogen, stands out as the primary cost driver of the value chain, followed by the ammonia cracking process. Ammonia cracking is the main source of energy inefficiency, highlighting the advantage of using ammonia directly where possible to avoid this step. For H2 application in the road transport sector, which involves its distribution to multiple refuelling stations operating at high pressure, LH2 is the most cost-effective and energy efficient carrier, provided that reconversion to hydrogen occurs at the refuelling stations. In this value chain, the liquefaction process represents the main cost driver and source of energy inefficiency.