5 ms·

Advancing electrolysis: Splitting water to store energy as hydrogen

37 points by elorant 7y ago

tln 7y ago
"the cell was firstly operated at an electrolysis mode with a constant current density of 0.6 A cm−2 for three minutes to generate hydrogen, which was instantly consumed by switching to a fuel cell mode at 0.2 A cm−2 for two minutes" So, 22% round trip efficiency
- rrmm 7y ago
  Shouldn't you take into account the voltage. From the graphs they don't look like they were symmetrical.
  - tln 7y ago
    Doh! Fig 6c[0] shows ~1.6 in and 0.4v out so... 5% round trip efficiency? [0] https://www.nature.com/articles/s41467-020-15677-z/figures/6 https://www.nature.com/articles/s41467-020-15677-z/figures/6
rrmm 7y ago
Interesting: I had no idea there was an Idaho National Lab. The new electrode is a perovskite which is a crystal structure tangentially related to superconductors among other things. The electrode allows for reversible operation in the 400-600 degC range.
- shodan666 7y ago
  World's first nuclear power plant (BR-I) was located in IDAHO. That why there are some serious NO-FLY zone in Idaho. NAVY is doing some reasearch out there as well.
- BuffaloBagel 7y ago
  INL (the site) put food on our family's table during my childhood in Idaho Falls.
- aYsY4dDQ2NrcNzA 7y ago
  Home of a deadly reactor explosion. https://en.wikipedia.org/wiki/SL-1 https://en.wikipedia.org/wiki/SL-1
  - rrmm 7y ago
    I did know about the SL-1 which makes it an even more glaring oversight. Maybe I associated it more with Argonne? I dunno. But that SL-1...dang.
- elcritch 7y ago
  It's involved in a lot of nuclear work. One of the first nuclear reactors in the work like was there. They also have strong ties to Boise State's Micron School of Material Science and engineering (Micron as in Crucial RAM brand) [1]. Yes, I'm biased, as I did PhD work there. Fun to watch talks on nuclear engineering. I'll have to look up the group behind the perovskite. No one ever seems to commercialize perovskite tech. Maybe small applications, but nothing large scale? 1: https://www.boisestate.edu/coen-materials/ https://www.boisestate.edu/coen-materials/
triceratops 7y ago
Does anyone know if coal or nat gas power plants can burn hydrogen too? Or be retrofitted to burn it? Then you could store excess solar or wind energy generated during the day as hydrogen and burn it at night.
- ChuckMcM 7y ago
  Sure, since the lab is running their perovskite at 600 C anyway, just add CO2 in a chamber with some nickel and get methane out via the Sabatier reaction. Send the methane to where ever its needed.
  - eloff 7y ago
    So many problems are solved so easily by "just" doing simple thing X. Maybe this really is a simple fix. It doesn't sound that way to me though.
    - ChuckMcM 7y ago
      It's not. The response is 'accurate' not 'easy' :-) The biggest challenge is getting a source of CO2 using less energy than you are going to get back by burning the methane. Thermodynamics doesn't let you cheat sadly. When evaluating these sorts of things you follow the energy consumption of each step and remove it from the initial pool of energy. Energy out over energy in will give you a way to compare methods for "goodness" regardless of complexity. Processes that have net negative energy are clearly in the "bad" category. Any positive is something. Localized schemes like hydro pumping do quite well in this equation. It is distance schemes that suffer. Distance schemes are hard because pushing electrons through a wire spends power just getting through the wire. Eventually its all gone. This is why you can't just cover 1/3 of Nevada with PV solar cells and power the grid from that one state. So distance means transforming electricity into some other energy (chemical, potential, kinetic, thermal), moving it physically somewhere else (ideally without much loss) and then converting it back into electricity at the destination. One of the more fanciful ideas I heard was train cars full of Tesla powerwall packs. If you've ever seen an operating coal fired power plant you may have seen the long line of coal cars in a train that pulls in each day. Once at the plant the cars are slowly pulled through the plant, dumping coal when they need to into the feed mechanism. Eventually a string of empty cars is on the other side to take back to be refilled. Imagine doing that with powerwalls. Cars pull up, connect electrically to the plant and start discharging. Once they are down to their "empty" level the car disconnects and moves on. I think it would be fascinating to watch.

37 points by elorant 7y ago

tln 7y ago

"the cell was firstly operated at an electrolysis mode with a constant current density of 0.6 A cm−2 for three minutes to generate hydrogen, which was instantly consumed by switching to a fuel cell mode at 0.2 A cm−2 for two minutes" So, 22% round trip efficiency

rrmm 7y ago
Shouldn't you take into account the voltage. From the graphs they don't look like they were symmetrical.
- tln 7y ago
  Doh! Fig 6c[0] shows ~1.6 in and 0.4v out so... 5% round trip efficiency? [0] https://www.nature.com/articles/s41467-020-15677-z/figures/6 https://www.nature.com/articles/s41467-020-15677-z/figures/6

rrmm 7y ago

Interesting: I had no idea there was an Idaho National Lab. The new electrode is a perovskite which is a crystal structure tangentially related to superconductors among other things. The electrode allows for reversible operation in the 400-600 degC range.

shodan666 7y ago
World's first nuclear power plant (BR-I) was located in IDAHO. That why there are some serious NO-FLY zone in Idaho. NAVY is doing some reasearch out there as well.
BuffaloBagel 7y ago
INL (the site) put food on our family's table during my childhood in Idaho Falls.
aYsY4dDQ2NrcNzA 7y ago
Home of a deadly reactor explosion. https://en.wikipedia.org/wiki/SL-1 https://en.wikipedia.org/wiki/SL-1
- rrmm 7y ago
  I did know about the SL-1 which makes it an even more glaring oversight. Maybe I associated it more with Argonne? I dunno. But that SL-1...dang.
elcritch 7y ago
It's involved in a lot of nuclear work. One of the first nuclear reactors in the work like was there. They also have strong ties to Boise State's Micron School of Material Science and engineering (Micron as in Crucial RAM brand) [1]. Yes, I'm biased, as I did PhD work there. Fun to watch talks on nuclear engineering. I'll have to look up the group behind the perovskite. No one ever seems to commercialize perovskite tech. Maybe small applications, but nothing large scale? 1: https://www.boisestate.edu/coen-materials/ https://www.boisestate.edu/coen-materials/

triceratops 7y ago

Does anyone know if coal or nat gas power plants can burn hydrogen too? Or be retrofitted to burn it? Then you could store excess solar or wind energy generated during the day as hydrogen and burn it at night.

ChuckMcM 7y ago
Sure, since the lab is running their perovskite at 600 C anyway, just add CO2 in a chamber with some nickel and get methane out via the Sabatier reaction. Send the methane to where ever its needed.
- eloff 7y ago
  So many problems are solved so easily by "just" doing simple thing X. Maybe this really is a simple fix. It doesn't sound that way to me though.
  - ChuckMcM 7y ago
    It's not. The response is 'accurate' not 'easy' :-) The biggest challenge is getting a source of CO2 using less energy than you are going to get back by burning the methane. Thermodynamics doesn't let you cheat sadly. When evaluating these sorts of things you follow the energy consumption of each step and remove it from the initial pool of energy. Energy out over energy in will give you a way to compare methods for "goodness" regardless of complexity. Processes that have net negative energy are clearly in the "bad" category. Any positive is something. Localized schemes like hydro pumping do quite well in this equation. It is distance schemes that suffer. Distance schemes are hard because pushing electrons through a wire spends power just getting through the wire. Eventually its all gone. This is why you can't just cover 1/3 of Nevada with PV solar cells and power the grid from that one state. So distance means transforming electricity into some other energy (chemical, potential, kinetic, thermal), moving it physically somewhere else (ideally without much loss) and then converting it back into electricity at the destination. One of the more fanciful ideas I heard was train cars full of Tesla powerwall packs. If you've ever seen an operating coal fired power plant you may have seen the long line of coal cars in a train that pulls in each day. Once at the plant the cars are slowly pulled through the plant, dumping coal when they need to into the feed mechanism. Eventually a string of empty cars is on the other side to take back to be refilled. Imagine doing that with powerwalls. Cars pull up, connect electrically to the plant and start discharging. Once they are down to their "empty" level the car disconnects and moves on. I think it would be fascinating to watch.