Don’t we have to burn both to produce energy/electricity?
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Hydrogen has to be produced by humans, using energy we got elsewhere. It effectively stores energy that we made earlier.
Petroleum is already around, containing energy that we haven’t already had to make through other means.
That’s because hydrogen alone can’t be found in nature, so you need energy to energy to extract the hydrogen from molecules to get pure hydrogen. It’s physically impossible to get more energy from hydrogen, than the energy needed to make hydrogen.
Petroleum can be found in the ground. Yes you need a bit of energy to extract it, but depending on the source you can still get more energy from it, than what was needed to extract it.
There are no significant sources of elemental hydrogen that we can extract. In order to have hydrogen to “burn”, we have to produce it. One of the easiest ways to produce hydrogen is to send an electrical current through water, which splits it into hydrogen and oxygen. But, this process requires energy.
By contrast, petroleum already exists in the ground. We don’t have to spend any energy to produce it. We do spend some energy to extract and transport it, but it’s much smaller than the inherent energy in the fuel itself.
Petroleum already exists underground to be harvested. There is little free hydrogen, that is not mixed with gas deposits together with methane and other gases. Hydrogen has either “burned” to combine with other elements or been lost from in space. Hydrogen must be produced by splitting it off bigger molecules with the input of energy from another source. Some of this energy is later recovered as the gas is burned.
There are no significant supplies of raw Hydrogen on Earth, so the only way we can produce it is by breaking down other compounds like Water.
That means we need to put in as much if not more energy into producing Hydrogen than we get out of it.
While Petroleum despite needing to be refined produces more energy than we put in.
Semantics.
Stricly speaking in physics, there is no such thing as an energy sorce, since energy can’t be created or list, just changed from one form to another. So petroleum is, strictly speaking, an energy bearer as well, even though you’ll probably still find it referred to as an energy source all the time among physicists as well.
I think the other commenters have it right. It’s got to do with our perspective on it. Hydrogen is a bit like a battery, we need to put the energy into it from somewhere, and we can than use it when needed for energy. Hence, we call it an energy bearer. Petroleum, we can dig up and burn, so it’s an energy source to us.
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