Most of the hydrogen fueling stations being built and put into production today dispense compressed H2 gas in the range of 5,000 to 10,000 psi. This has become the standard over the past few years.
But, there are some scientists who wish to rewrite this standard by working on hydrogen storage tanks that don’t require this much pressure. Researchers in Denmark, for instance, are developing hydrogen fuel tanks that absorb H2 using porous magnesium borohydride.
According to , “Researchers in Europe have developed a hydrogen storage material based on porous magnesium borohydride that can safely adsorb large quantities of the gas. They used infrared spectroscopy and other techniques to investigate this material. The team, led by Filinchuk and Torben Jensen at the University of Aarhus, in Denmark, developed highly porous magnesium borohydride so that it can store large amounts of hydrogen gas via two distinct mechanisms – chemically bonded hydrogen and physically adsorbed.
“Borohydrides have been investigated previously as hydrogen storage materials and have various advantages and disadvantages as do porous materials in which hydrogen is adsorbed physically but is not incorporated chemically into the storage medium. The researchers state that their material is the first light-metal hydride that is porous like a metal-organic framework (MOF) and is capable of storing molecular hydrogen. The researchers suggest that their porous magnesium borohydride is rather promising in that it can release hydrogen gas at relatively low temperatures but holds on to the gas at a high proportion of the material’s mass, about 3 percent (18-percent of hydrogen, in total).”
Now, I’ve talked about using both magnesium and borohydride in the past for hydrogen storage. I’ve also talked about the mechanical absorption and release of hydrogen in tanks using various methods and materials. What is interesting about this latest discovery is that both processes may be used in conjunction with one another to store and release a higher volume of hydrogen than one method alone.
And if hydrogen fueling tanks based upon porous magnesium borohydride do become the norm in H2 autos and vehicles, this may mean that modifications at the hydrogen fueling stations will need to be made to accommodate the lower pressures needed at the pump.
One of the aspects that have been holding metal hydride tanks back in the past has been the weight of the tanks themselves. So for magnesium borohydride tanks to become a commercial success they will need to be lightweight and strong as well.