A Japanese firm is beginning mass production of a metal-based hydrogen carrier that can increase the amount of stored H2.

Tokuyama, a Japanese chemical company, has commenced large-scale production of magnesium hydride. Despite its potential for efficient hydrogen storage compared to compressed or liquefied hydrogen and ammonia, magnesium hydride poses significant safety concerns due to its potential for violent explosiveness, raising questions regarding its cost-effectiveness and energy efficiency.

In collaboration with Bio-coke Giken Co., Tokuyama has established a hydrogenation reactor at its caustic soda plant, where residual hydrogen from the chlor-alkali process reacts with solid magnesium to form magnesium hydride, effectively trapping hydrogen molecules for storage or transport at ambient temperatures and pressures. The retrieval of hydrogen involves mixing magnesium hydride with water, resulting in the formation of hydrogen and magnesium hydroxide, effectively doubling the originally stored hydrogen molecules due to the presence of hydrogen ions in water. Tokuyama plans to produce 30 tonnes of magnesium hydride annually, containing 2.28 tonnes of hydrogen, capable of yielding 4.56 tonnes of hydrogen per year.

The company asserts that magnesium hydride could serve as a viable hydrogen carrier, offering high-density storage and chemical stability at room temperature and pressure, thus presenting a promising option for safe hydrogen storage and transportation. Despite claims of safety and cost-effectiveness compared to ammonia, concerns arise regarding the explosive nature of magnesium hydride powder, especially upon contact with water, raising doubts about its suitability for maritime transport.

Furthermore, experts like Paul Martin caution against the energy-intensive nature of using solid metal hydrides like magnesium hydride for hydrogen storage and transportation, highlighting the inefficiency of the process due to the substantial energy requirements for both production and extraction of hydrogen from the compound. Martin emphasizes the low energy cycle efficiency of such schemes, making them economically impractical for large-scale implementation.