It takes more energy to electrolyze water than you get from burning the hydrogen. And burning hydrogen is just reacting with oxygen to turn it back into water. Electrolyzing water: 2 H2O —> 2 H2 + O2 Burning hydrogen: 2 H2 + O2 —> 2 H2O

by Bechtelarbrayan 4 days ago

Never forgot to sanitize my database inputs though.

by Annual_Cranberry_350 4 days ago

Ah I see! Thanks :)

by Anonymous 4 days ago

Also, O² levels in the air are not a concern, CO² levels are; electrolysis isn't desirable because it adds O² but because it doesn't add CO².

by Miserable_Subject114 4 days ago

Also, Hydrogen is very hard to contain effectively. It is an extremely small molecule and will leak from almost any container eventually. Not something you want happening with your explosive gas fuel.

by Anonymous 4 days ago

I would befriend all the most dangerous animals.

by Ok-Plan 4 days ago

Maybe you missed the exam

by Anonymous 4 days ago

You would need a pretty big battery to make enough hydrogen from water to run a car. Bigger than what you need to run a EV of similar size. The process of turning water into hydrogen isn't 100% efficient, so you lose some energy at this point. The engine burning the hydrogen isn't 100% efficient either so you lose some energy here as well. Then the weight of the water plays a roll in the amount of energy needed to move the car, so that's another loss. Plus the weight of the hydrogen engine as adds to this loss. So in the end, just running the car off the batteries instead of losing all that energy is the better choice. It all comes down to thermal dynamics being a bitch.

by Anonymous 4 days ago

Because of the laws of physics, electrolyzing the water MUST use up at least as much energy as you can recover by burning the hydrogen. It would be free energy otherwise. Like, if you use 10 Ah of electricity splitting water, there is no physical way to get more than 10 Ah of work back from that hydrogen in an engine or fuel cell. And you would only break even if every step was 100% efficient, which is also physically impossible. So you'll always be able to drive farther by just using that electricity to drive the car itself rather than electrolysis....which is what an electric car already is. >and pumps oxygen back into the air? Also, hydrogen powered cars don't run on just hydrogen, they draw oxygen from the air. It uses one oxygen atom for every 2 hydrogens burned, because the product of a hydrogen engine is water. So if you are getting the hydrogen from splitting water in the first place, then using that hydrogen in a hydrogen car is going to consume the exact amount of oxygen from the air you just made when splitting the water. There will be no excess "oxygen back into the air" (besides the fact that you will get less power from the hydrogen engine than you spent splitting the water...).

by Alone_Vacation 4 days ago

Thanks:)

by Anonymous 4 days ago

Maybe when they also have a nuclear plant build in.

by Anonymous 4 days ago

Water is the exhaust product. It'd be like trying to power a car by turning CO2 back into petrol.

by Slight_Advantage_365 4 days ago

Electrolysis will always be less efficient than solar, wind, geothermal, and nuclear. It is a really cool piece of technology that is just not good enough to compete with alternate forms of generation.

by Anonymous 4 days ago

Hydrogen really is just liquid electricity storage. You would be better to use hydrogen run through a hydrogen fuel cell which makes electricity directly instead of burning it for propulsion. The biggest energy loss in a combustion engine is the waste heat which is why cars run at about 20% efficiency

by chelsie54 4 days ago

Water is an ash. Water is what is left when you burn hydrogen in an oxygen atmosphere. And, another great way to look at it is this: if it takes 1 unit of energy to break the oxygen hydrogen bonds, you'll never get 1 unit back and your system need to get over 1 unit back.

by Alert-Specialist-922 4 days ago

There already are hydrogen powered cars. The Toyota Mirai is the one that comes to mind. It's kind of the opposite, though in that water vapor is the by-product.

by Dependent-Remote 4 days ago

25 years ago, my dad had an old Dodge Durango in the garage. He built a hydrogen electrolyzing unit that added hydrogen into the combustion chamber with the regular fuel air mix. The idea was not to build a car that only burned hydrogen but to use hydrogen to greatly improve the fuel efficiency. I remember it did run but there were constant issues. It was very difficult to get the mixture right. It definitely didn't work with the emissions sensors and the computer. He was having issues with the electrolyte mixture in the water tank as well. I always wondered if it would work on a carburetor car. Maybe someday I'll get around to trying it.

by hullrich 4 days ago

It would be relatively negligible but also just pumping presumably O2 into the air isn't necessarily a positive like it's probably better than pumping co2 but it's not like there's an oxygen shortage

by MudNo9731 4 days ago

Hydrolysis is a great way to store solar energy in a form we can more easily transport: liquid hydrogen. But the resulting hydrogen would be created off-site and then loaded into the car, just like gasoline. It takes more energy to hydrolyze water than your get from burning the hydrogen, so it makes no sense to do the hydrolysis on board.

by Mental-River3786 4 days ago

But there's no reason for it to be inside the car. It would be more effective to have electric cars that get their energy from hydrogen, wind, nuclear, or solar energy. Not everything needs to be done "in house"

by Anonymous 4 days ago

My thinking was the release of oxygen before taking an L :)

by Anonymous 4 days ago

electrolysis needs energy to be done. where are you getting that energy from in the first point? electrolysing hydrogen and then using that hydrogen to make energy gets you at best right where you started. if you have perfect machines that have no losses

by Anonymous 4 days ago

This is basically the principal of operation for hybrid hydrogen fuel cell vehicles, where you produce hydrogen on-site and then use it as a "rapid fill" fuel. We could also use it to create hydrogen during periods that are low grid consumption and convert it back. Unfortunately, the limitations of storing and transporting hydrogen mean existing battery technology is a significantly more reasonable option.

by Anonymous 4 days ago

Aside from the terrible grammar (I truly don't know exactly what you're trying to say sorry), this is a flawed idea. Where does the power come from to electrolyze the water? Converting that energy to hydrogen back to energy will have loss. It's better to just take that energy and run the motor.

by SignalWaltz 4 days ago

That's assuming you have the motor near the electrolyzing plant. With cars that's not 5he case. The motor goes near the plants and then it consumes the fuel away from the plant. Hydrogen is basically just any other fuel that can be burned, just that it's exhaust fumes are only composed of water.

by veumdorothy 4 days ago