OverviewAutomotive onboard hydrogen storageEstablished technologiesChemical storagePhysical storageStationary hydrogen storageResearchSee alsoPortability is one of the biggest challenges in the automotive industry, where high density storage systems are problematic due to safety concerns. High-pressure tanks weigh much more than the hydrogen they can hold. For example, in the 2014 Toyota Mirai, a full tank contains only 5.7% hydrogen, the rest of the weight being the tank. System densities are often around half those of the working material, thus while a material may