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04221970 t1_jarmy6e wrote

I'd like to see the advantages of a hydrogen energy storage system over conventional battery storage systems.

Hydrogen as energy storage lacks energy density, and suffers some serious safety issues (very high pressure flammable gas). Conventional batteries are heavy, take longer to recharge, but have much higher energy density.

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Ok-Sweetums t1_jasfiw1 wrote

..what if we use the hydrogen to charge the batteries D:

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Rav99 t1_jaxkhb7 wrote

That's like using a battery to charge another battery. It takes energy (ie electricity) to make free hydrogen which can then be burned for energy. It's storage.

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meineThoughts t1_jasorda wrote

Battery technology currently is just a bit too heavy for airplanes. There are some electrics flying but their range is good for only short missions. Fuel cell technology is also emerging as a possible alternative in other transport areas such as heavy trucks. Lots of stuff gets more efficient when you don't have to drive pistons up and down.

As to safety, I think all fuel supplies have risk. Gasoline, propane, LI batteries, you name it, it's always a disaster when it goes wrong.

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SufficientLime_ t1_jay0aj8 wrote

Batteries are too heavy for aviation. Hydrogen flammability can be mitigated due its tendency to escape very quickly into the atmosphere (lots of tests on ruptured tanks floating around).

Hydrogen can also produced as a form of storage when the grid is producing more than it consumes which is not uncommon with renewables. Yes batteries are denser and more efficient but they are expensive and lithium is still a problematic resource to mine. Water electrolysis is cheap and easy to deploy.

It's a decent stop-gap solution for low emissions until battery technology becomes dense enough for aviation.

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Fonky_Fesh t1_jbbzddh wrote

There is no advantage, at this point in time. It's expensive to make, dangerous to store, and can't compete even with solar power yet

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micabobo t1_jb07ora wrote

Amazing demonstration! Hydrogen will shape out to be one of the best transition/long term combustion fuels we have as it's prinary by-product is simply water vapor in addition to the fact that hydrogen can be made using zero-emission energy sources.

In the case of transportation (hydrogen-powered vehicles), it might not be too practical however. Storage of the fuel is a major design considerations. The article was not too clear about the form of hydrogen the aircraft used (gaseous or liquid hydrogen). Liquid hydrogen (LH2) is somewhat practical as it occupies a fairly small volume, but it is cryogenic. A storage tank must be well-insulated as well as contain boiloff bleed valves (very similar design to the fuel tanks on a rocket). High-pressure gaseous hydrogen (GH2) is another option where the fuel is stored as compressed hydrogen gas (upwards to 6000 psi if not higher). Big issue is that you are then contending with hydrogen embrittlement (the hydrogen will quite literally seep into the metal of the pressure vessel and reduce the strength of the metal. This can be prevented through careful choice of material.

Regardless, this is fascenating and a great step forward to making air travel more environmentally friendly. The aforementioned design considerations will be dealt with and hydrogen will be a clean and dependable option to fuel combustion engines with.

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