[ams6110]

Worth being clear that splitting water into hydrogen gas for use as a fuel, no matter how efficient, is still just another form of battery. If they really are achieving >80% efficiency that's getting up there with the best Li ion batteries, but hydrogen still presents a lot of handling and transport complexities for use as something like a motor vehicle fuel. Probably best used in large industrial scenarios, e.g. storing excess energy from solar or wind, and fueling gas turbine generators at night or low-wind periods.

[spiritplumber]

The good thing is that you get a lot of energy density this way. The bad thing is that hydrogen is difficult to store, and you basically have a fuel-air bomb on your hand if anything goes wrong with your tank.

[ars]

> The bad thing is that hydrogen is difficult to store

True, because it's hard to make materials that will hold it. It tends to damage metal and leak through other things.

> and you basically have a fuel-air bomb on your hand if anything goes wrong with your tank.

No you do not, there is no air in your tank. Hydrogen is much safer than gasoline, if released it rises up in the air almost instantly. So a hydrogen fire would put itself out pretty quickly, and would not burn much that is around it.

[redblacktree]

Serious question: What happened with the Hindenburg then? Why didn't that fire put itself out quickly?

[ars]

It did. The hydrogen fire burned for only about 35 seconds. And if you look at photos you see almost all the flame is high above the airship.

[leoc]

> Probably best used in large industrial scenarios, e.g. storing excess energy from solar or wind, and fueling gas turbine generators at night or low-wind periods.

That's burying the lede a bit surely? If this process could actually be cheaper than nat. gas power plants as a backup for solar or wind grid electricity generation—or, of course, ideally if it could be cheaper than just forgetting about solar or wind and simply generating all that grid power using natural gas—then that would be big news, right? Any viable application to transport would just be icing on the cake.

[userbinator]

but hydrogen still presents a lot of handling and transport complexities for use as something like a motor vehicle fuel

With this efficiency, it could be feasible to just split the water at the point-of-use.

I'm reminded of the "run your car on water/save fuel" scams which involved "HHO generators" - basically the same thing - located in the intake manifold and connected to a source of water and electricity from the car's electrical system. This time, it might actually do something interesting...

[LordKano]

With this efficiency, it could be feasible to just split the water at the point-of-use.

If you have the power source at the point of use, it's still more efficient to just use that for propulsion.

There has to be a way to store the hydrogen for later use.

I'm reminded of the "run your car on water/save fuel" scams which involved "HHO generators"

I used to work with a guy who was convinced that his HHO generator would yield all kinds of increased fuel efficiency on his gas guzzling pickup truck.

He didn't have the background to understand why it's not possible to get more energy out of burning the brown's gas than he used to create it.

While increased efficiency in the splitting of water molecules is a great thing, there's still basic thermodynamics.

[knodi123]

> With this efficiency, it could be feasible to just split the water at the point-of-use.

Isn't it still a pretty slow process? Efficiency doesn't matter if it generates a trickle of H, and you need a large fixed volume.

Splitting at point of use is silly anyway- why use power to split water into hydrogen you can use for a fuel cell to generate power, at the point of use?

[bane]

The engine could draw on a smallish stored reservoir of H2 for normal operation. That reservoir could then be continuously supplied with H2 from the process until it hits some pressure metric after which the system temporarily turns off until the pressure in the reservoir dips below some threshold.

[knodi123]

okay, so if we need a fixed volume X, and we have a reservoir of (1/2) X, then we only have to wait on the slow trickle of the remaining 1/2 instead of the full amount.

Plus, what do you think the H2 is for? Generally, we think about using it in a fuel cell. Which generates electricity. And the idea of using electricity to split out H2 in order to generate electricity, all in one place....

You're adding complexity, but I'm not sure you're actually improving on simpler approaches.

[ars]

That doesn't make much sense. How are you going to make H2 inside a car? You need lots of electricity. Why not just have an electric motor?

[toast0]

> With this efficiency, it could be feasible to just split the water at the point-of-use.

You need electricity at the point of use, which is mobile for a motor vehicle. If you have mobile electricity, using it to get hydrogen out of water, so you can run your hydrogen powered generator to get electricity doesn't make a lot of sense.

[ars]

> With this efficiency, it could be feasible to just split the water at the point-of-use.

Hu? Why? You have electricity, you use it to make hydrogen, then burn the hydrogen and power something?

Why not just use the electricity directly?

[stephengillie]

I thought the 80% efficiency metric meant they were successfully converting 80% of the water into gas.

Edit: I guess they mean they are producing enough hydrogen that they could burn that hydrogen (recombine it with water) to generate a constant 1.2v of electricity.

Also, what amperage is required for this to work?

[ansible]

Water is cheap, so converting X% of it to gas isn't the issue.

The main issue is how much energy are you putting in to get how much hydrogen gas. That hydrogen gas can be used to power a fuel cell (for example) which generates electricity.

Historically, the amount of electricity you get out of that conversion cycle (through the production of hydrogen gas) isn't great (don't have numbers in front of me). If they're improving that ratio, that is good news. If they're doing it with a cheap and durable catalyst, that's even better news.

[monochromatic]

My guess is that they're saying 20% of the input electricity is wasted.