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Originally Posted by Captain Awesome
Tell that to the Sun!
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Hydrogen is an energy source in the sun. It's abundant and ready to use, kinda like crude oil is here.
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Sounds like you've just described the model for the battery in an electric car!
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Yes. Hydrogen as a fuel on Earth is very much like a battery.
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But technically we don't "make" hydrogen. We can use chemical reactions or electrolysis to collect it from the earth. An easy way is to pull it out of water molecules. Think of it as mining on a molecular scale. We "mine" a lot of elements out of common molecules this way, including some metals.
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We "make" hydrogen fuel by electrolysis. Electrolysis is exactly the opposite of burning. Burning is exactly the opposite of electrolysis.
Electrolysis of water into hydrogen: Separating hydrogen from oxygen by forcefully splitting water molecules. This requires at
least X amount of energy.
Burning hydrogen: Combining hydrogen with oxygen to form water molecules. This releases at
most X amount of energy.
It's not "easy" to "pull it out of water molecules". If it could be done with 100% efficiency (which is impossible), it would take exactly as much energy as you could get from burning it (if you could burn it at 100% efficiency, which is also impossible). If you want, you can replace "burn" in the previous statements with "process in a fuel cell" or any other chemical reaction that recombines hydrogen with oxygen to produce water and energy.
This doesn't mean that hydrogen is a bad fuel for cars, it just means that you still have to figure out where to get the energy. On Earth, hydrogen is a fuel but not an energy source. I'd be happy to drive a hydrogen-fueled car. I imagine that the energy source would be nuclear power, but it could just as easily be tidal, mules turning a mill, geothermal, solar, cow farts, or municipal landfill incinerators.