Trucks that haul gaseous hydrogen are called tube trailers. Gaseous hydrogen is compressed to pressures of 180 bar (~2,600 psig) or higher into long cylinders that are stacked on a trailer that the truck hauls. This gives the appearance of long tubes, hence the name tube trailer.
Tube trailers are currently limited to pressures of 250 bar by U.S. Department of Transportation (DOT) regulations. Steel tube trailers are most commonly employed and the DOT weight limitations for on-road vehicles result in a limited carrying capacity of approximately 280 kg due to the heavy weight of the steel tubes. Recently, composite storage vessels have been developed that can deliver 560–720 kg of hydrogen per trailer and are within DOT's height, width, and weight requirements. Such tube trailers are currently being used to deliver compressed natural gas in other countries.
Railcars, ships, and barges can also be used to deliver hydrogen as a compressed gas or cryogenic liquid, or within novel liquid or solid carrier materials.1 These methods are currently uncommon and typically are not economical unless the hydrogen is in liquid form. The recent developments of tanks certified by the International Organization for Standardization (ISO tanks) that can carry large volumes of high-pressure hydrogen gas may help enable the delivery of hydrogen over rail or water.
1 See the National Renewable Energy Laboratory report Costs of Storing and Transporting Hydrogen.