Energy

How it's transported

Hydrogen not only needs to be produced, but it also needs to be transported and stored in the place of consumption. Such activities are particularly difficult due to the characteristics of hydrogen. It is flammable, has a low density and is easily dispersed into the air. Preservation and transport still make a widespread use of hydrogen quite difficult. In the last few years different storage systems have become more and more efficient and suitable for many applications. Hydrogen can be built-up and transported in gaseous, liquid state or absorbed by special materials. Each way has some pros and cons. Anyhow it is necessary to make significant progress in terms of R&D in order to make hydrogen more reliable and economically competitive (i.e. to build a suitable network for car supply). Storage of compressed hydrogen The simplest and cheapest way to stock up hydrogen is to use it as compressed gas at 200-250 bar pressure (or more). Compressed gas bottles are the simplest way to transport it, although they are limited by the fact that hydrogen needs very big containers, up to three times bigger than the ones used for methane and ten times a big as those for petrol. Therefore this technology is not suggested for traditional cars, due to the weight and the size of tanks, which represent a limit for the autonomy and load capacity of the vehicle. Recently big progress has been made with the introduction of metallic tanks or reinforced thermoplastic tanks with carbon fibre, glass and other materials, that weigh 3-4 times as much as ordinary tanks and allow to overcome many problems linked to the use of traditional bottles. These tanks are able to operate until 350 bars (potentially until 700 bars) and allow to obtain suitable hydrogen densities according to the use on board of the vehicle. Safety is normally very high thanks to the robustness of tanks and the introduction of anti-blast fuses in case of fire, and circuit interruption valves in case of crash.