As H2 grows in popularity, there will need to be somewhere to put it until it’s used

Hydrogen storage doesn’t get the same headlines that its production methods have seen, but it is just as important, as the fuel needs to be held somewhere until it can be transported or used, once it has been produced or captured.

As an extremely light gas in its natural form, this is easier said than done

Hydrogen storage faces a number of challenges, as H2 as a gas is light enough that if it is released into the atmosphere, it rapidly floats away and is lost into space. It is for this reason that production methods are focused on capturing it from where it is trapped in other molecules or finding caches of it underground, instead of trying to obtain it from the ambient air.

Still, it isn’t simply a matter of bottling it up.  While can be a great renewable energy fuel, it is inherently difficult to store. This is because of its low volumetric density when compared to other gases. In fact, it is the lightest of all gases. This means that in its gaseous state, it requires notably more space, even when compared to natural gas.

Moreover, H2 has a boiling point that is near absolute zero and must be stored cryogenically if it is to be compressed into a liquid.  Though its essential lack of corrosive properties is promising for container storage, it can cause metals to crack under certain circumstances.

Top hydrogen storage methods to overcome those challenges

As a result, there has been a substantial focus on hydrogen storage methods.  Though this is not an exhaustive list, it does comprise the four main methods currently in use or being considered for use.

1. Caverns – This often includes old mines such as salt mines that can allow the hydrogen to be stored deep underground, as is the case in the US where Mitsubishi Power and Texas Brine are expected to use massive underground caverns for this purpose.
2. Liquification – Though it does require the H2 to be stored at under -253ºC in special insulated tanks to keep its temperature and reduce evaporation, it keeps the fuel in a small space that can be transported. This is the form used for rocket fuel and in space launches. Currently typically considered cost prohibitive for most purposes, it is helpful in areas where space is at a premium.
3. Compressed gas – This method uses special fortified tanks to hold the gas under pressure. This allows more of it to be contained in a smaller amount of space.
4. Materials-based hydrogen storage – This form uses solids and liquids that are chemically able to absorb the H2 or react with it so that they bind together.

Decision based on the use

Each of these methods has its strengths and weaknesses, so it is likely that several hydrogen storage methods will be popular in the future, instead of just one or two that will take over.