Hydrogen storage

Hydrogen has a high gravimetric energy density (33,3 kWh/kg) but a low volumetric density (3 kWh/m3) under standard conditions. To store it in containers, it can be either compressed to high presssure (up to 700 bar in automotive tanks), cooled to make it liquid (good insulation necessary), or stored in metal hydride tanks (small but heavy). For small systems, mainly the first and third possibility are realistic options.

At the moment, fuel cell technology is still a new field and hydrogen infrastructure is just beginning to grow. But fortunately there are already a few metal hydride cartridges available on the market for small fuel cell systems. Suitable vessels are listed in the following table:


Manufacturer
Cartridge
Hydrogen content / Nl
Approx. Weight / g
Notes
H-Bank Technologies
HB-SC-0010-Q
10
150
other sizes available
Horizon Fuel Cell Technologies
Hydrostik
10
100
highest gravimetric density
Hydrogen Components
BL-20
20
307
other sizes available
Pragma Industries
MH10
10
112
other sizes available

Some of these manufacturers also sell larger tanks (up to > 600 Nl) and electrolyzer stations, where you can refill your cartrigdes. But the larger metal hydride cartridges lack in suitable filling time and heat management during filling. Hence, if longer runtimes are required, pressure vessels (like in fuel cell cars) could be a better choice, even though it is hard for private users to get such bottles in low quantities and to fill them with high pressure.
With eg. solar or wind power, you can build up a continuous sustainable zero emission supply for your Raspberry Pi! Try it and tell us all about it!