6 ms·

I am not a fan of hydrogen, because I once worked with a former NASA robotics engineer. We were looking for a way to power terrestrial robots, and we asked him

by ekidd 4y ago

I am not a fan of hydrogen, because I once worked with a former NASA robotics engineer. We were looking for a way to power terrestrial robots, and we asked him about hydrogen. He told us there were extremely high efficiency hydrogen systems at the time. But they all suffered from similar problems: - Hydrogen is highly flammable (or explosive) in an oxygen atmosphere. - Hydrogen has truly awful power storage density—unless you compress it to a couple of hundred atmospheres pressure. Nobody wants to store potentially explosive fuel at 200+ atmospheres. I'm not aware of current hydrogen technology at all, but that's a fundamental physics challenge that needs to be addressed somehow. And it needs to be addressed in a cost-effective way at each step of the distribution chain. The problem with high density energy storage is that you're putting a huge amount of energy in a tiny space. Gasoline is flamable, lithium-ion batteries are notorious for ugly fires, and even flywheels can fail catastrophically. A good power storage system needs to manage this risk somehow. (There was some really interesting work being done with carbon-fiber flywheels and maglev bearings in a vacuum about 20 years ago. Apparently that had decent power density, and it could charge off electric charging infrastructure. But car insurance companies weren't convinced it was safe. Which would also be a problem for hydrogen.)

6510 4y ago
The internet says storing hydrogen in metal hydrides is safe and offers similar kwh/kg as lithium ion batteries. It seems to me Japan is going all in on their new high-temperature gas-cooled reactor (which supposedly cant melt down)it transports the heat with helium in stead of water which allows for temperatures that allow for hydrogen production. Just repeating what I read and hear online. This isn't an endorsement and I have no idea if it lives up to the hype. If it does it would be quite the game changer.
- ekidd 4y ago
  Yes, bonding the hydrogen with something could really change the tradeoffs dramatically. For example, the main ingredient in gasoline is C8H18. It has good energy density at atmospheric pressure, and the fire risks are manageable. We already use carbon/hydrogen systems today! I think one of the candidates for metal hydride fuel cells is MgH2? It apparently also has decent energy density. Of course, magnesium poses some risks of its own. And I personally have no idea what a complete supply chain and refueling system would look like, or what it would cost. Still, I fully expect that any portable energy storage is going to come with tradeoffs: cost, pollution, rare materials, and always the risk of catastrophic discharge (via fire, explosion, or messy kinetic failures). We should pursue multiple alternatives and invest in basic science, because portable energy is incredibly useful.
  - jnsaff2 4y ago
    I would also guess bonding and then using that adds two conversions worth of losses to the equation and are not free.
cactusplant7374 4y ago
I totally get the risk. As a consumer I feel similar fear about EV car batteries. Even if you can find the escape hatch in a pinch (some EV doors aren't normally manually opened), your house could still burn down or there could be other life changing property damage. It's a small risk but still feels like a real risk.
- Tade0 4y ago
  This problem is mostly solved by LFP batteries, which have a much lower risk of fire. So much so that you're more likely to have a petrol car spontaneously combust.
- red-iron-pine 4y ago
  > (some EV doors aren't normally manually opened) That screams regulation waiting to happen. like, have a lever or something on there. there is no more obvious or easily accessible place to flee a vehicle than the door. also, which "some". is this just another tesla quirk?
  - p-schultz 4y ago
    Yes, Teslas have buttons to open the doors, but there are also mechanical releases as a backup [1]. The backups unlock the doors "no questions asked", so to speak, which includes possibly damaging the windows (because they don't get lowered out of their seals). For the front doors they are so intuitively placed that pretty much all of my first-time passengers have already used them before I can tell them to press the button instead. Models other than 3 also have mechanical releases for the rear doors, apparently, but using those involves removing floor mats (according to the owner's manuals, no personal experience). [1]: https://www.tesla.com/ownersmanual/model3/en_us/GUID-7A32EC01-A17E-42CC-A15B-2E0A39FD07AB.html https://www.tesla.com/ownersmanual/model3/en_us/GUID-7A32EC0...
flavius29663 4y ago
There are ways to work around those limitations, basically removing the "very small and very reactive" part of hydrogen. You can bind it with Nitrogen to gen ammonia - which is till very dangerous, but much easier to contain or work with. The problem with H2, ammonia, biofuels and other synthetic fuels is not that they have some limitations, it's that they are not accepted by the green energy dogma. Some green energy activists would like to see the gas stations go away, for example, and that is not going to happen if you keep needing to go somewhere to re-fuel, with any fuel.
- schiffern 4y ago
  The problem isn't "dogma," it's inefficiency. Throwing energy away is counterproductive, and Energy-to-Hydrogen-to-Energy throws away lots of it. If there were no alternative long-term storage plans this might be acceptable, but that's simply not the case. If you're using hydrogen to smelt steel or make ammonia fertilizer, then there's no energy loss (beyond what's needed to decarbonize petrochemicals anyway). The article aptly refers to these as "no regrets" uses. Gas stations (ie ground vehicles) are fighting a losing battle. BEVs will eat the sector. They're simply so much less expensive [than hydrogen]: for the vehicles themselves, for the infrastructure, and then of course for the wasteful energy use in operation.
  - theshrike79 4y ago
    > Throwing energy away is counterproductive, and Energy-to-Hydrogen-to-Energy throws away lots of it. The current process needs 55kWh of electricity to produce 15kWh of electricity on the other end. Not very efficient at all.
    - flavius29663 4y ago
      Look at how much energy is on the other end of the oil flow: 20% efficiency and still the ICE car is king, without subsidies, EVs would go nowhere. The hydrogen back and forth is still better than that. Talking about efficiency is a losing battle, people don't care about that, they care about total cost, safety and convenience.

by ekidd 4y ago

6510 4y ago

The internet says storing hydrogen in metal hydrides is safe and offers similar kwh/kg as lithium ion batteries. It seems to me Japan is going all in on their new high-temperature gas-cooled reactor (which supposedly cant melt down)it transports the heat with helium in stead of water which allows for temperatures that allow for hydrogen production. Just repeating what I read and hear online. This isn't an endorsement and I have no idea if it lives up to the hype. If it does it would be quite the game changer.

ekidd 4y ago
Yes, bonding the hydrogen with something could really change the tradeoffs dramatically. For example, the main ingredient in gasoline is C8H18. It has good energy density at atmospheric pressure, and the fire risks are manageable. We already use carbon/hydrogen systems today! I think one of the candidates for metal hydride fuel cells is MgH2? It apparently also has decent energy density. Of course, magnesium poses some risks of its own. And I personally have no idea what a complete supply chain and refueling system would look like, or what it would cost. Still, I fully expect that any portable energy storage is going to come with tradeoffs: cost, pollution, rare materials, and always the risk of catastrophic discharge (via fire, explosion, or messy kinetic failures). We should pursue multiple alternatives and invest in basic science, because portable energy is incredibly useful.
- jnsaff2 4y ago
  I would also guess bonding and then using that adds two conversions worth of losses to the equation and are not free.

cactusplant7374 4y ago

I totally get the risk. As a consumer I feel similar fear about EV car batteries. Even if you can find the escape hatch in a pinch (some EV doors aren't normally manually opened), your house could still burn down or there could be other life changing property damage. It's a small risk but still feels like a real risk.

Tade0 4y ago
This problem is mostly solved by LFP batteries, which have a much lower risk of fire. So much so that you're more likely to have a petrol car spontaneously combust.
red-iron-pine 4y ago
> (some EV doors aren't normally manually opened) That screams regulation waiting to happen. like, have a lever or something on there. there is no more obvious or easily accessible place to flee a vehicle than the door. also, which "some". is this just another tesla quirk?
- p-schultz 4y ago
  Yes, Teslas have buttons to open the doors, but there are also mechanical releases as a backup [1]. The backups unlock the doors "no questions asked", so to speak, which includes possibly damaging the windows (because they don't get lowered out of their seals). For the front doors they are so intuitively placed that pretty much all of my first-time passengers have already used them before I can tell them to press the button instead. Models other than 3 also have mechanical releases for the rear doors, apparently, but using those involves removing floor mats (according to the owner's manuals, no personal experience). [1]: https://www.tesla.com/ownersmanual/model3/en_us/GUID-7A32EC01-A17E-42CC-A15B-2E0A39FD07AB.html https://www.tesla.com/ownersmanual/model3/en_us/GUID-7A32EC0...

flavius29663 4y ago

There are ways to work around those limitations, basically removing the "very small and very reactive" part of hydrogen. You can bind it with Nitrogen to gen ammonia - which is till very dangerous, but much easier to contain or work with. The problem with H2, ammonia, biofuels and other synthetic fuels is not that they have some limitations, it's that they are not accepted by the green energy dogma. Some green energy activists would like to see the gas stations go away, for example, and that is not going to happen if you keep needing to go somewhere to re-fuel, with any fuel.

schiffern 4y ago
The problem isn't "dogma," it's inefficiency. Throwing energy away is counterproductive, and Energy-to-Hydrogen-to-Energy throws away lots of it. If there were no alternative long-term storage plans this might be acceptable, but that's simply not the case. If you're using hydrogen to smelt steel or make ammonia fertilizer, then there's no energy loss (beyond what's needed to decarbonize petrochemicals anyway). The article aptly refers to these as "no regrets" uses. Gas stations (ie ground vehicles) are fighting a losing battle. BEVs will eat the sector. They're simply so much less expensive [than hydrogen]: for the vehicles themselves, for the infrastructure, and then of course for the wasteful energy use in operation.
- theshrike79 4y ago
  > Throwing energy away is counterproductive, and Energy-to-Hydrogen-to-Energy throws away lots of it. The current process needs 55kWh of electricity to produce 15kWh of electricity on the other end. Not very efficient at all.
  - flavius29663 4y ago
    Look at how much energy is on the other end of the oil flow: 20% efficiency and still the ICE car is king, without subsidies, EVs would go nowhere. The hydrogen back and forth is still better than that. Talking about efficiency is a losing battle, people don't care about that, they care about total cost, safety and convenience.