Due to its high binding affinity, hydrogen performs excellent as energy storage. The most common way of binding is the oxidation with oxygen, which sets energy free. This oxidation occurs at about 3200 ° and the end product is pure water (H2O). Currently, however, a large-scale application has not yet been successful due to the following three aspects:
1. The production of hydrogen from renewable energy sources (green or blue hydrogen) is currently less productive than the production of hydrogen from fossil energy sources as a waste product of petroleum refineries.
2. The storage of hydrogen is difficult because of the low energy density of hydrogen at room temperature. The compression of the gas by liquefying it is vastly energy intensive, nonetheless results in improved storage capabilities. Storage in the so-called metal hydride is currently technically advanced, yet has not taken a large commercial scale. Alternatively, however, methanol would be available as a hydrogen carrier, though the production of methanol as of today should not be done from fossil fuels but from renewable energy sources.
3. Although hydrogen absolutely leaves no combustion residue other than water, the following presently existing applications are not yet technically mature.
- Gas turbines
- Aircraft engines
- Internal combustion engines
Hydrogen as energy storage
As shown in the graph below, hydrogen can be stored in two different ways, either physically in its pure form or chemically bound.
In addition to the storage options described above, there is a possibility of temporarily storing hydrogen in an existing natural gas distribution network. Currently, there are worldwide efforts, including large renowned vehicle manufacturers, to store hydrogen in tanks with the aim to reach similar or the same comfort levels as with storage of gasoline or diesel.
In particular, the following aspects play a role:
- High storage density
- Minimal down-time losses
- Charging and discharging times
- Safety issues of the energy storage (tanks)