Are there any large investments being made to desalinate ocean water and turn the purified water into hydrogen fuel like NASA’s plan to do with lunar ice water? eli5
In: 69
Hydrogen isn’t a source of energy, it’s just a storage medium. There’s not really any reason to do this since you just end up losing energy in the conversion process.
Hydrogen is not used as a fuel for several reasons:
Cost: It is expensive to produce hydrogen, which requires processes like electrolysis of water.
Storage: Hydrogen is difficult to store because it takes up a lot of space when compressed, soaks through metal, and must be extremely cold to be liquified.
Safety: Hydrogen is extremely flammable, so it is risky to store and transport.
Availability: Hydrogen is not readily available in the atmosphere.
Energy: It takes more energy to turn hydrogen into fuel than you get out of the fuel itself.
Carbon dioxide: The cheapest way to make hydrogen also makes lots of carbon dioxide.
Infrastructure: There are not enough refueling stations.
Fuel cells: Hydrogen fuel cell technology is complicated.
One note on what others are saying:
It takes more effort to split water into hydrogen and oxygen than you get back out due to inefficiencies, that much is true.
It would still be absolutely worth it when using renewables, because that process is clean and as near to free as you can get, you zap water with electricity and get two gasses, both of which are very useful (we do use pure oxygen for more than just breathing).
So the energy loss isn’t really important. It’s something to minimise purely for economics, but it’s not a fundamental problem.
But the other problems are currently deal breakers.
Hydrogen is a real bastard to store, it can leak through solid metal (the molecules are THAT small), it embrittles everything you try to encase it in, it is VERY dangerous due to how explosive it is etc.
That makes any mass utilisation of hydrogen unfeasible until storage can be resolved. The production capacity can follow after. There’s no point in making loads of it if it’s not going to get used.
On the moon they’ll just use it for rocket fuel, so it’s less of a problem, it’ll get used up pretty much as soon as it’s made, and it’s on the moon, i.e. in vacuum. So you’re avoiding like 90% of the issue.
Sort of. If you read up on the clean energy plans of several countries like Japan or the UK you’ll find a lot of them want to produce so called “green” hydrogen by breaking down water using renewable electricity through a process called electrolysis.
The reason why it hasn’t gotten off as far is because it takes a massive amount of electricity to do that. Right now it’s 10 times cheaper to produce hydrogen by breaking down methane (1 carbon and 4 hydrogens) through a different process called steam reforming, and dumping the carbon as CO2 in the atmosphere. 99% of hydrogen today is produced this way and mostly goes into chemical production.
The big problem with using hydrogen as a fuel as it is today is that when you run it through a fuel cell you get a little less electricity out of it than what you used up to produce the hydrogen in the first place. Hydrogen is also difficult to handle because it damages metal and it needs to be compressed and cooled to some ridiculous low temperature to be transported. That process takes up electricity. With the whole process in mind, you only get back about 30% of the energy you put into producing the hydrogen originally.
This shouldn’t be a problem if we have unlimited clean electricity, but unfortunately we don’t at the moment. This also wouldn’t be a problem if we manage to find free natural hydrogen sitting in the ground, and that is actually being looked at right now and seems promising.
You don’t need to desalinate sea water before splitting into hydrogen and oxygen. It actually works better with the salt for conductivity.
Yes but hydrogen has limited uses. As other have pointed out producing hydrogen does not release energy; the energy released when we burn hydrogen is less than the energy required to produce hydrogen. Therefore hydrogen isn’t an energy source.
Despite that, hydrogen can be useful as a way to store and transport energy. If we have one area with an abundance of energy production, for example a desert with thousands of solar panels, and we need energy far from that source, we could produce hydrogen in the desert and transport it wherever the energy is needed. The simplest most direct way to do this is with power lines and batteries, but there are situations in which hydrogen could be better. For example, some people think that hydrogen powered airplanes could be better than battery-powered planes. Assuming we move to a net zero carbon economy we will need to retire all oil powered planes, which could create a market for hydrogen powered planes. However hydrogen has lots of disadvantages compared to electric power: higher cost, lower energy density, and the risk of leaks, which could cause significant injury or death. People are working to fix these problems so we can produce safe hydrogen powered planes. People are also working to make better battery powered planes. I don’t know who will win, but if I had to bet, I would choose batteries. Someone could have a breakthrough with hydrogen and prove me wrong though.
Because of the limitations I mentioned above, there aren’t many safe, cost-effective uses of hydrogen right now. If that changes and our economy suddenly requires much more hydrogen, we might see much more interest in learning how to make it from seawater. For now, it’s a niche market and projects to produce it are on the smaller side.
NASA turning water into fuel is only economical because that water is already in space. It costs NASA $10k to get 1 pound of water into space, and a similar cost for each pound of fuel they bring to space. Using water and fuel that’s already in space would be significantly cheaper.
Here on Earth, that’s almost never the case. Making hydrogen fuel is a potential way to store energy here on Earth, but we always get less energy out of it than we put in due to inefficiencies.
Desalination has its own issues. It takes a lot of energy, and it creates a lot of extremely salty brine that you can’t just release into the environment without reeking havoc on the ecosystem.
Yeah, in Australia, specifically south, we’ve been using hydrogen to create various chemicals like ammonia and using it like natural gas. Think it’s around half a billion dollars investment.
https://www.environment.sa.gov.au/goodliving/posts/2022/06/green-hydrogen-south-australia
The US Navy has been working on a couple of different methods.
Nuclear powered ships have enough excess power, but even with various catalysts, it’s not commercially viable.
Hydrogen is really difficult to store and transport for a few different reasons, of which the risk of explosion doesn’t even top the list. The most convincing way to use it, that I’ve read about, is as a reactant.
For example, creating steel from iron ore, in a traditional blast furnace, creates ~2 tons of CO2 per ton of steel. By using hydrogen as the reactant instead of coke (which is densified coal), the process instead creates steam. There’s been at least some discussion of building a local hydrogen generator at a steel mill to do this and avoid the issues of storage and transportation.
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