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I remember going to the science museum as a kid and they had device the split water into hydrogen and oxygen. I wonder if we could use wind and solar when the s

I remember going to the science museum as a kid and they had device the split water into hydrogen and oxygen. I wonder if we could use wind and solar when the sun is shining to do this and burn these gasses when we renewables aren't producing.

gpm 7y ago
Sure, you could. Batteries are more efficient though.
- new_realist 7y ago
  Also extremely expensive to use for long term storage; costs grow linearly with storage size, as opposed to sublinear for hydrogen.
  - dilekz 7y ago
    But hydrogen has huge maintenance cost. - Filters need to be replaced. - Moving parts need to be serviced like the Hydrogen pressure pump. - The fuel cell itself has degradation and will lose it's efficiency. (funny thing is, it already has a very lower efficiency) I have worked with hydrogen in school. And it's so funny how much details people forget which actually impact the WHOLE idea of hydrogen solutions. I am sure it will never take off, just because it's already against the limits of the laws of nature. Unlike chemical batteries. Also to store energy, most efficiënt and cheap way to store mass ammounts of energy is in gravity. Current applications have a back and forward efficiency (Charging/decharging) energy of 85%. While hydrogen probably has a maximum of back and forward efficiency of maybe 20%-30%. While waisting the other 70%. Please. Don't read hydrogen propaganda. Read implementations and read the math. And then do the math yourself instead of following the hype of fake hydrogen news.
the8472 7y ago
Several pilot plants already exist in Germany (some produce methane instead of hydrogen). https://de.wikipedia.org/wiki/Power-to-Gas#Liste_der_Anlagen_in_Deutschland https://de.wikipedia.org/wiki/Power-to-Gas#Liste_der_Anlagen...
- _ph_ 7y ago
  I think methane generation for storage purposes has a place in going towards zero CO2. methane is relatively easy to store - currently Germany has reserve of 90 days of methane - and it can be very easily used in gas power plants. If they are combined electric and heating power plants, their efficiently is really good. In total, the energy losses are higher than with batteries and pumped water storage, but the relative cheap long-term storage of the methane will make this attractive.
ethbro 7y ago
Yes. It's called hydrolysis (albeit somewhat inaccurately), and is mentioned in the article. https://en.m.wikipedia.org/wiki/Water_splitting https://en.m.wikipedia.org/wiki/Water_splitting
jjoonathan 7y ago
Or we could use corn plants and sunlight to capture atmospheric CO2 and convert it into easily produced, transported, and consumed liquid fuel that's already largely compatible with existing infrastructure. What ever happened to ethanol anyway? It seemed like it was about to be a thing ~10 years ago -- a similar position to electric cars today -- and then it vanished without a trace. Did it die or was it murdered?
- lucb1e 7y ago
  > we could use plants to put CO2 into easily stored liquid fuel that's largely compatible with existing infrastructure Are you suggesting we spend resources to get CO2 out of the air and then burn them, releasing it again? We could capture it again (which is easier when there is a high concentration, such as at the exhaust of any such plant), but that seems like double the effort. You probably have a reason why this is a good idea or you wouldn't be suggesting it, so I'm interested to hear your thoughts on it.
  - jjoonathan 7y ago
    The argument that capturing a CO2 molecule (by growing corn) and then releasing it (by burning EtOH in a car) is fundamentally different from not capturing it in the first place is alien to me. AFAIK atmospheric CO2 molecules are fungible. Would you mind explaining? "Flex fuel" cars were very much a thing, mass production of ethanol as fuel was very much a thing, and it was supposedly at nearly price-parity with gasoline. No dreaming necessary. Something happened, though. Saudi oil price cuts? The great recession? Subsidy politics? Some combination of those? I'd love to hear from someone who knows more.
    - danans 7y ago
      There are significant petroleum derived inputs to corn farming, which combined with the low energy yield of corn ethanol, result in it not being a net carbon zero energy source at all: https://www.pnas.org/content/pnas/suppl/2006/07/05/0604600103.DC1/04600Table1.NEW.pdf&ved=2ahUKEwiRipz2q-jjAhVTu54KHZyhAvsQFjAAegQIAhAB&usg=AOvVaw1bVi11h4YRYP7s-d9DjTst https://www.pnas.org/content/pnas/suppl/2006/07/05/060460010...
simonebrunozzi 7y ago
We can and we've been able for quite some time, but the problem is that doing that is very inefficient, and you would end up with a very inefficient and expensive way to store energy. Can't find a proper reference, but one of the most efficient way to store energy is pumping water up and storing it there, in which case the efficiency is close to 90%, and the cost of storing large amounts of energy are low. Doing what you are proposing should have an efficiency below 50% - or more than 5 times worse -, without considering much higher energy storage costs.
- EForEndeavour 7y ago
  How is 50% efficiency five times worse than 90%? Isn't that a factor of roughly two? 90% efficiency: spend 100 joules to get 90 useful joules, wasting 10. 50% efficiency: spend 100 joules to get 50 useful joules, wasting 50. You could say that 50% efficiency is five times more wasteful than 90%, but that doesn't strike me as a useful metric. More useful is to observe that spending 100 units of energy at 90% efficiency gets you roughly twice as much usable energy compared to 50% efficiency (9/5 = 1.8 times, to be precise).
  - simonebrunozzi 7y ago
    10 -> 50 : 5 times worse.
    - EForEndeavour 7y ago
      In my opinion, that's the less useful way of measuring efficiency. By that metric, 99% efficiency is twice as good as 98%, since the former wastes only 1% of input compared to 2%. Isn't it more useful to recognize that 98% efficiency is almost the same as 99%?
- reitzensteinm 7y ago
  Whether or not it's a good idea, the numbers you're quoting aren't really an argument for it. A low efficiency solution with high storage capacity absolutely has a role in the transition to renewables. Solar and wind are going to necessarily be overbuilt in terms of peak capacity. If you have enough to power your country on a relatively calm overcast day, what happens on a windy clear day?

gpm 7y ago

Sure, you could. Batteries are more efficient though.

new_realist 7y ago
Also extremely expensive to use for long term storage; costs grow linearly with storage size, as opposed to sublinear for hydrogen.
- dilekz 7y ago
  But hydrogen has huge maintenance cost. - Filters need to be replaced. - Moving parts need to be serviced like the Hydrogen pressure pump. - The fuel cell itself has degradation and will lose it's efficiency. (funny thing is, it already has a very lower efficiency) I have worked with hydrogen in school. And it's so funny how much details people forget which actually impact the WHOLE idea of hydrogen solutions. I am sure it will never take off, just because it's already against the limits of the laws of nature. Unlike chemical batteries. Also to store energy, most efficiënt and cheap way to store mass ammounts of energy is in gravity. Current applications have a back and forward efficiency (Charging/decharging) energy of 85%. While hydrogen probably has a maximum of back and forward efficiency of maybe 20%-30%. While waisting the other 70%. Please. Don't read hydrogen propaganda. Read implementations and read the math. And then do the math yourself instead of following the hype of fake hydrogen news.

the8472 7y ago

Several pilot plants already exist in Germany (some produce methane instead of hydrogen). https://de.wikipedia.org/wiki/Power-to-Gas#Liste_der_Anlagen_in_Deutschland https://de.wikipedia.org/wiki/Power-to-Gas#Liste_der_Anlagen...

_ph_ 7y ago
I think methane generation for storage purposes has a place in going towards zero CO2. methane is relatively easy to store - currently Germany has reserve of 90 days of methane - and it can be very easily used in gas power plants. If they are combined electric and heating power plants, their efficiently is really good. In total, the energy losses are higher than with batteries and pumped water storage, but the relative cheap long-term storage of the methane will make this attractive.

ethbro 7y ago

Yes. It's called hydrolysis (albeit somewhat inaccurately), and is mentioned in the article. https://en.m.wikipedia.org/wiki/Water_splitting https://en.m.wikipedia.org/wiki/Water_splitting

jjoonathan 7y ago

Or we could use corn plants and sunlight to capture atmospheric CO2 and convert it into easily produced, transported, and consumed liquid fuel that's already largely compatible with existing infrastructure. What ever happened to ethanol anyway? It seemed like it was about to be a thing ~10 years ago -- a similar position to electric cars today -- and then it vanished without a trace. Did it die or was it murdered?

lucb1e 7y ago
> we could use plants to put CO2 into easily stored liquid fuel that's largely compatible with existing infrastructure Are you suggesting we spend resources to get CO2 out of the air and then burn them, releasing it again? We could capture it again (which is easier when there is a high concentration, such as at the exhaust of any such plant), but that seems like double the effort. You probably have a reason why this is a good idea or you wouldn't be suggesting it, so I'm interested to hear your thoughts on it.
- jjoonathan 7y ago
  The argument that capturing a CO2 molecule (by growing corn) and then releasing it (by burning EtOH in a car) is fundamentally different from not capturing it in the first place is alien to me. AFAIK atmospheric CO2 molecules are fungible. Would you mind explaining? "Flex fuel" cars were very much a thing, mass production of ethanol as fuel was very much a thing, and it was supposedly at nearly price-parity with gasoline. No dreaming necessary. Something happened, though. Saudi oil price cuts? The great recession? Subsidy politics? Some combination of those? I'd love to hear from someone who knows more.
  - danans 7y ago
    There are significant petroleum derived inputs to corn farming, which combined with the low energy yield of corn ethanol, result in it not being a net carbon zero energy source at all: https://www.pnas.org/content/pnas/suppl/2006/07/05/0604600103.DC1/04600Table1.NEW.pdf&ved=2ahUKEwiRipz2q-jjAhVTu54KHZyhAvsQFjAAegQIAhAB&usg=AOvVaw1bVi11h4YRYP7s-d9DjTst https://www.pnas.org/content/pnas/suppl/2006/07/05/060460010...

simonebrunozzi 7y ago

We can and we've been able for quite some time, but the problem is that doing that is very inefficient, and you would end up with a very inefficient and expensive way to store energy. Can't find a proper reference, but one of the most efficient way to store energy is pumping water up and storing it there, in which case the efficiency is close to 90%, and the cost of storing large amounts of energy are low. Doing what you are proposing should have an efficiency below 50% - or more than 5 times worse -, without considering much higher energy storage costs.

EForEndeavour 7y ago
How is 50% efficiency five times worse than 90%? Isn't that a factor of roughly two? 90% efficiency: spend 100 joules to get 90 useful joules, wasting 10. 50% efficiency: spend 100 joules to get 50 useful joules, wasting 50. You could say that 50% efficiency is five times more wasteful than 90%, but that doesn't strike me as a useful metric. More useful is to observe that spending 100 units of energy at 90% efficiency gets you roughly twice as much usable energy compared to 50% efficiency (9/5 = 1.8 times, to be precise).
- simonebrunozzi 7y ago
  10 -> 50 : 5 times worse.
  - EForEndeavour 7y ago
    In my opinion, that's the less useful way of measuring efficiency. By that metric, 99% efficiency is twice as good as 98%, since the former wastes only 1% of input compared to 2%. Isn't it more useful to recognize that 98% efficiency is almost the same as 99%?
reitzensteinm 7y ago
Whether or not it's a good idea, the numbers you're quoting aren't really an argument for it. A low efficiency solution with high storage capacity absolutely has a role in the transition to renewables. Solar and wind are going to necessarily be overbuilt in terms of peak capacity. If you have enough to power your country on a relatively calm overcast day, what happens on a windy clear day?