LOHC for Hydrogen Storage

The Change of energy production to renewable sources leads to decentralized and time-varying provision of electrical energy. This requires the development of effective storage and transport technologies to handle surplus energy. Hydrogen can be produced with low emissions using renewable electricity, but is characterized by low volumetric energy densities. The handling of the explosive gas asks for high safety requirements, additionally. To overcome these limitations a number of chemical storage molecules are available.

LOHC (liquid organic hydrogen carrier) represent an attractive class of compounds for the storage and release of hydrogen. These liquids circumvent the problem of physical storage of hydrogen, which requires very high pressures (300 bar) or low temperatures (22-45 K). Likewise, the infrastructure already in place (tankers, ships, trains, etc.) is a significant advantage in using LOHCs as storage molecules.

Benzyltoluene (BT), a hardly flammable liquid, can be used as LOHC in this context. The loading of discharged H0-BT with six times the molar amount of hydrogen takes place catalytically under elevated pressure and temperature in an exothermic reaction. This produces the charged H12-BT, which enables the storage as well as the transport of energy. When energy is required, the hydrogen is released catalytically, in an endothermic reaction at a lower pressure level. The released hydrogen can in turn be fed into a fuel cell or combustion chamber for energy utilization, for example.