3 ms·
Hydrogen embrittlement is a problem only when you are trying to keep the hydrogen at high pressure. But there is no need for that, in most cases. Most of the b
by ncmncm 5y ago
Hydrogen embrittlement is a problem only when you are trying to keep the hydrogen at high pressure. But there is no need for that, in most cases.
Most of the bulk hydrogen storage plans involve underground storage at a pressure that would not cause trouble. Where more density is needed, e.g. aircraft fuel, liquid form is favored, again at low pressure.
- jacquesm 5y agoI think it is more accurate to say that there is a relationship between hydrogen embrittlement, pressure, material structure, hydrogen purity, temperature, duration of exposure and that depending on all of these it can be a smaller or larger problem but it never is 'no problem', you need to design around it somehow or it will get you. And for liquid storage you have to count on some H2 boiling off and for underground storage you will need to be extremely careful about possible ignition sources.
- ncmncm 5y agoThe secret to hydrogen safety is assuming everything leaks at all times, and maintaining positive airflow everywhere that hydrogen is not wanted, so the concentration cannot build up to the point where ignition is possible. You need to worry about material degradation mainly at high pressure where the material has to be very strong, and where the hydrogen is driven into the crystal structure, weakening it. At low pressure, ordinary aluminum is resistant to hydrogen degradation, and doesn't need to be strong. Whether liquid hydrogen is kept refrigerated below its boiling point, or kept well insulated but allowed to boil off, will depend on detailed engineering analysis. As the energy needed to produce it gets cheaper, the extra complication of keeping it too cold to boil gets less attractive. Maybe to refrigerate the tank, it needs to be above-ground so servicing is possible; but without, it can be wholly underground and thereby better insulated.