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Since 75% of the universe is hydrogen, would it be sustainable to use fuel cell electricity generators? Fossil fuel generators won't last forever, because there is not an endless supply of fossil fuels,​ and solar power is only best when the sun is out. Fuel cell generators can be used any time of the day. So, are fuel cell generators sustainable?

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    Why is it important how abundant hydrogen is in the universe (as opposed to on Earth)? – JBentley Nov 15 at 14:07
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    To make a fuel cell work you need hydrogen and oxygen. 75% of the universe is hydrogen, but only 1% of the universe is oxygen. On Earth, oxygen makes up 46% of matter, most of it tied up in rocks, but hydrogen only 0.15%, mostly tied up in water...and rocks. How does that impact sustainability? Does it even matter? How do you propose to collect that hydrogen from the universe? – J... Nov 15 at 14:15
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    @Hobbamok Please be polite to the OP. There is no need to question anyone's knowledge. – THelper Nov 16 at 10:01
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A residential hydrogen-fuel-cell is a solid-oxide-fuel-cell which makes a lot of heat when it produces electricity.

The waste heat has obvious uses for the house or building but also the most likely source of hydrogen is to steam propane or natural-gas. So there is plenty of heat for that process once the fuel-cell is running. The only thing needed is the natural-gas feedstock but of course that's the fossil fuel use.

Here are two links to hydrogen-fuel-cells designed for RV's but that can also be used in multiple units for a house:

https://www.wattfuelcell.com/portable-power/watt-imperium/

https://www.prnewswire.com/news-releases/peoples-gas-completes-installation-of-the-first-watt-residential-fuel-cell-in-western-pennsylvania-300723773.html

Now a hydrogen fueling station for vehicles can produce hydrogen by electrolysis of water using electricity. And then the only issue is the source of electricity.

http://www.itm-power.com/news-item/new-shell-fuelling-station-opened-at-beaconsfield

It's possible that the source of electricity could be wind power, solar power, or hydro power.

https://www.newsday.com/long-island/nassau/point-lookout-hydrogen-1.16496819

Or hydrogen in general could be produced from ethanol with the ethanol produced from sorghum and that is near carbon neutral. Note that sorghum can be grown without irrigation only requires about 12" of rainfall during a growing season. Also, sorghum needs less fertilizer than corn.

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    So... what is the answer to the question? – JBentley Nov 15 at 14:10
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    I think the critical point that's missed here is that, on Earth, hydrogen is not a source of energy at all - it is a store of energy. We can take solar energy and store it by producing hydrogen from water. We can take wind energy and store it by producing hydrogen from water. We can take biomass, which has stored solar energy, and re-store its energy by extracting the hydrogen. But there is no sustainable source of hydrogen for us to exploit. A fuel cell is really just a battery - we need to "charge" it by producing hydrogen and we discharge it by consuming the hydrogen. – J... Nov 15 at 14:22
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    It is a sure bet that using the heat from the fuel cell to produce more hydrogen from natural gas will be a loss. – JRE Nov 15 at 16:51
  • But the house also uses the waste heat from the hydrogen-fuel-cell and that is a gain in efficiency. Also the solid-oxide-fuel-cell that makes the most heat is the most affordable hydrogen-fuel-cell. – S Spring Nov 15 at 17:00
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    This in no way answers the question. – R.. Nov 15 at 23:28
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No. There is no readily available supply of net-positive-energy hydrogen on Earth, where most human power usage takes place. Hydrogen fuel cells may be a useful component of a total energy system but they are not a source of generation capacity. Hydrogen is more like a battery than a supply of energy. Hydrogen can be liberated from water by using energy. Some of this energy can be recovered by using the resulting hydrogen in a fuel cell. This may be useful but the original energy to liberate the hydrogen must come from another source.

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The focus on electricity is probably secondary: Any energy source can be converted into electric energy.

The focus on fuel cells is probably secondary, too: Hydrogen can simply drive combustion engines as well; if the hydrogen and oxygen sources are sustainable, then the combustion engine will be as sustainable as the fuel cell (minus potential efficiency considerations).

Having these out of the way, the question is simply whether hydrogen can be produced in a sustainable way. Since there is almost no free hydrogen on earth, it must be produced from water in an endothermic reaction — that is, a reaction which needs an injection of energy.

This means that the focus on hydrogen is probably secondary. Your question boils down to whether there is a sustainable energy source. And the answer is:

The only virtually (for the next couple billion years) sustainable energy source on earth is solar radiation.

Hydrogen may be useful to store and transport solar energy, and a fuel cell may be an efficient method to convert it into electric energy at convenient locations in space and time.

Two remarks:

  1. Another potentially virtually sustainable energy source would be fusion, if it can be made to work on an industrial scale, including a self-sustaining Tritium production.

  2. Solar radiation provides not only just energy — energy as such is plentiful; it provides low-entropy energy which can be put to use.

  • Third remark: nuclear fission of Pu-239 created by U-238 + neutron capture is sustainable too for billions of years. Uranium can be extracted from seawater: www-formal.stanford.edu/jmc/progress/nuclear-faq.html and www-formal.stanford.edu/jmc/progress/cohen.html – juhist Nov 22 at 19:02
  • @juhist The same holds for gold and almost anything else, but: Did anybody ever calculate the energy and industrial scale requirements? Reducing entropy is costly. But fossil and nuclear are moribund anyway. Solar electricity cost is still in freefall. Remember when blank CDs were $16 apiece and remote controlled drones were James Bond issue? That's were we currently are with solar cells. Keystone etc. will be scrap metal before the first gallon has passed it. – Peter - Reinstate Monica Nov 22 at 19:56
  • Agreed, renewables make fission a bit pointless. Just wanted to point out, however, that fission is sustainable too. – juhist Nov 23 at 4:28
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So, are fuel cell generators sustainable?

Yes. The hydrogen will be generated using spare electricity when wind and/or sunshine are plentiful. It will be stored, and used later to create electricity when there is no wind and sunshine.

The key here is that the hydrogen is generated in a sustainable manner: using renewables, not from steam reforming of natural gas.

  • There are renewable sources of methane and so make hydrogen from the available methane and run the hydrogen in fuel-cells to make electricity. en.wikipedia.org/wiki/Renewable_natural_gas . Also, since a fuel-cell makes both electricity and heat it is a more efficient use of ordinary natural-gas when for a building. – S Spring Nov 23 at 0:19
  • The renewable sources of methane are not large enough to supply large-scale hydrogen usage. Also, gas turbines burning renewable methane directly can utilize waste heat in district heating networks. The only renewable source large enough for widespread use is electrolysis of water using wind/solar power. – juhist Nov 23 at 4:26
  • Every waste treatment plant could make hydrogen from methane and produce electricity with hydrogen-fuel-cells. This is a contributing system just like most other forms of renewable energy are merely contributing. But most waste treatment plants that make hydrogen set-up a vehicle hydrogen fueling station a couple of miles from the plant. – S Spring Nov 23 at 19:22

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