Hydrogen is a lonely element. It can’t exist by itself and needs to combine with a partner such as oxygen, transforming into water. Because the gas is far from stable, in order to transport it on ships over long distances it must be converted into a liquid to reach a state known as a liquid organic hydrogen carrier (LOHC).

Among the various pathways to transport hydrogen (H2), the Japanese government has picked out three as the most promising: converting H2 gas into a liquid, combining it with a special chemical to create methylcyclohexane (MCH), or moving it as ammonia, a compound of H2 and nitrogen. Methanol, another H2 carrier option, has been ruled out for now since it releases CO2 when combusted.

Selecting the carrier option is important. It determines the technology that will be installed to produce the fuel; what transportation and storage infrastructure must be built; and, even what kind of consumers the fuel will attract. After all, applications such as space rockets require only the purest form of liquid H2. This form of H2 is very versatile, but expensive. Most of the global demand today is satisfied with a standard form of ammonia, which is added to CO2 to create the widely used fertilizer: urea.

For Japan, all LOHCs have certain merits, but the one most likely to dominate at least the initial period of hydrogen market development is ammonia. The latter is being tested today to become a major fuel for power generation. Top power utility JERA has set the goal of commercializing the firing of ammonia by 2030. So it may be no surprise that the IEA estimates that ammonia is expected to account for 80% of H2 carrier volumes by 2030. But ammonia cannot be used in all applications, while turning it back into hydrogen (a process known as cracking) is inefficient. So, where does that leave the other LOHCs? Recent advances in liquid H2 and MCH technology suggest these carriers could also play a significant role.