Eli5: Why do automobiles operate with diesel or petrol but not with water?

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Eli5: Why do automobiles operate with diesel or petrol but not with water?

In: Physics

13 Answers

Anonymous 0 Comments

Water is not flammable. In order to have combustion, you need a fuel source, oxygen and an ignition source. Water is none of them.

Anonymous 0 Comments

Because water is not a fuel source. You can use the hydrogen and oxygen that water is composed of as a fuel source, but it takes just as much energy to split the molecule using electrolysis as you get out of it when you burn the hydrogen and oxygen back together in to water.

Anonymous 0 Comments

As much as I know about combustion engines and hydrogen, I have encountered so many different reasons as to why they never took off.
So I’m following to see if there is a proper answer. Fingers crossed.

Anonymous 0 Comments

Internal combustion engines use fuels that explode so that small explosion drives the pistons in the engine.

Water doesn’t readily expel its energy like that. The energy required to break the bonds of the water molecule are much higher than the energy it would release.

Anonymous 0 Comments

To be a usefull fuel stuff has to be able to burn.

There is no chemical reaction that would release energy from water, as water is already a very stable molecule.

When you burn diesel or petrol one of the results is actually water. So running a car on water is like trying to run a campfire on ashes.

Anonymous 0 Comments

Vehicles with traditional engines use a chemical process called combustion to generate power.

They take a fuel molecule and react it with oxygen to release heat and generate pressure.

Now consider water – H2O. It already contains oxygen – it’s actually mostly oxygen by weight. It’s not combustible, it’s hydrogen that has already been combusted.

You can’t burn it again, so no more energy can be realistically extracted from a water molecule unless you have something much more dangerous than oxygen around to react it with.

Anonymous 0 Comments

-Water molecules are very very stable

-hydrogen is extremely dangerous

– even if you derived a system that splits up the oxygen and hydrogen and does end up producing energy? The entire energy required for the process would be far greater than the energy you produce for the water engine

Anonymous 0 Comments

Both diesel and petrol are combustible, which means that as a liquid they burn and as a gas they explode.

Car engines are called internal combustion engines (think explosion inside engine) because they take a fuel, like petrol, and make it to explode inside a small space.

When the fuel explodes it releases energy that moves parts of the engine and makes the wheels of the car turn.

Water isn’t combustible. It doesn’t burn or explode when it touches fire, so it won’t release energy, and won’t move the parts of the engine that turns the wheels.

Anonymous 0 Comments

Water cannot “burn” like traditional (fossil) fuels, but any hope of extracting energy from it at all, in some other way, can only be crushed by chemistry. A water molecule contains three atoms: an oxygen atom and two hydrogen atoms, which bond together like magnets. Breaking those bonds will always take more energy than you get back. A water molecule is very stable. The energy needed to separate the atoms is greater than what you get back. Plus there’s a more volatile problem: hydrogen is dangerously flammable. Without the right safety measures, things can go kaboom very fats.

Anonymous 0 Comments

Explaining like you’re five:

Water is stubbornly lazy and doesnt want to change using it’s own energy.

It only changes into other things when something else helps. Such as electricity helping the bonds between hydrogen and oxygen break. Doing all the work.

Other fuels are full of energy and only either needs a little nudge to work (for petrol), or works well under pressure (with diesel). They then release all that stored energy (by burning), change into a different form with a lower energy state.