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Old 07-19-2017, 04:15 PM   #26 (permalink)
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I see it as a lost case, but I will have another try:

From what I read, you are intendig:
1) build a "gas station" that will sell pressurised hydrogen to fellow neighbours
2) these fellow neighbours will use their present cars with kind of conversion kit - about the same way as many people here in Europe are buying LPG conversion kits

I will try not to mix energy and currency to the very end to save further confusion

Part 1 - "fuel" and producing it

"fuel" does not produce energy. It rather releases it, the energy stored in mollecular bonds. "Fuel" is anything that can release energy when you fiddle with it - you can break it to chemically simpler materials - for example burning wood is oxidizing cellulosis, and that produces water, carbon dioxide and some energy. Oxidizing hydrogen also releases some energy. (Many apologies to anyone who reads it, I know its very crude simplification).
Now, I repeat, the energy is only released. I was not created, it was "invested" into the matter when it was created. There is hidden energy of all these days Sun was shining apon mentioned tree in the campfire wood. In crude oil we release energy, that was "hidden" in it eons before we pumped it to the surface, so we can burn it. When you "make" hydrogen gas, it is you who "invests" energy to break bonds in water to break it to oxygen and hydrogen.
This article states you need about 50 kWh to make 1 kg of hydrogene (with current state-of-the-art technology). I am not going to verify it, you can do it if you want. That same article states you need additional 15 kWh to compress it so it is usable as automotive fuel. You cannot produce it for less, because it is the energy you MUST to invest into the water to break it. Do not ask about pressure you compress it, it is irrelevant. 1 kg of hydrogene is 1 kg at any meaningful pressure.
So - even if you have your gas station built for free and functional, every 1 kg of hydrogen you produce will add these 65 kWh to your electric bill. If price of electricity you buy is $0.1 per kWh, than for every kg of hydrogen you produce you pay $6.50. ymmw.

Part 2 - "fuel" and using it

As stated above, fuel is any matter that releases energy it is stored in its chemical bonds. You can find amount of the energy released by oxidation under term "enthalpy" in chemistry books. Wikipedia states it is 286 kJ/mol, what equals around 39,7 kWh in 1 kg of hydrogene. That means that if you oxidize 1 kg of hydrogene, you get ideally 39,7 kWh regardless how you make from oxygen and hydrogen water again.
So, your customer buys one kilo of hydrogen in order to release energy stored in. He can burn it, he can stream it through platinum mesh in fuel cell, he can take tweezers and manually join atomes one by one to form H2O mollecules (just kidding there). In doing so you get 39,7 kWh from 1 kg of hydrogen, and neither God nor your customers can get more because no more energy is stored in.

I am customer, who now drives a 40 MPG car. According to ecomodder converter I need rougly 1 kWh to move my car for 1 mile.
So - under ideal circumstances, if I managed to harvest all 39,7 kWh of energy hidden in 1 kg of hydrogene, I could move my car for 39,7 miles.

So - as a customer - I need to buy either 1 gallon of gas, or 1 kg of hydrogen

Now: Can you sell me 1 kg of hydrogene at the price of 1 gallon of gas?
It depends where you live, and your gas price and electricity price. - where did you get that 5 cents per kWh??

As - according to that article - current fuel cells can "harvest" 23,3 kWh and this is industry-proven most efficient way, I doubt you get more by simple burning the hydrogen in your engine. My estimate is that you get around 13 kWh, that means 13 miles per kilogram of hydrogene.

-- If anything is unclear, feel free to ask.
-- if anyone finds an error in my estimates, let me know please.

Last edited by seifrob; 07-19-2017 at 04:53 PM..
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