Assessment of Maritime Options for International Hydrogen Shipments: Selection of Transport Systems

Abstract

This paper investigates the options for transporting hydrogen from the Middle East to Europe, taking the United Kingdom as an example, with a focus on systems that can be accommodated in existing shipping fleets. Potential hydrogen carriers were assessed which identified that two liquid organic hydrogen carrier (LOHC) pairs (i.e., toluene/methylcyclohexane and dibenzyltoluene/ perhydro-dibenzyltoluene) and liquid natural gas (LNG) were good candidates as hydrogen carriers. Ammonia and liquid hydrogen were also considered; however, their energy costs were significantly more than those of LOHCs and LNG. Methanol and formic acid were also ruled out because of the  (i) additional energy costs needed to concentrate methanol by distillation resulting from their manufacturing process; and (ii) additional carbon dioxide production at the recipient port, compared to steam methane reformation of natural gas. The use of liquid hydrogen transport may be more feasible, if the hydrogen’s ‘cold energy’ is utilised for cryogenic or cryomagnetic purposes. Within the bounds of calculation accuracy, we can consider that the comparative energy cost of both LOHC and LNG are indistinguishable making all three prospects for further analysis. Altogether, this study provides insight into which chemical processes might be best to pair with an emerging hydrogen economy.

Keywords: Blue HydrogenHydrogenTanker fleetLiquid Organic Hydrogen CarrierLNG Liquid hydrogen