[HN Gopher] Advancing electrolysis: Splitting water to store ene...
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Advancing electrolysis: Splitting water to store energy as hydrogen
Author : elorant
Score : 22 points
Date : 2020-04-23 12:12 UTC (10 hours ago)
(HTM) web link (inl.gov)
(TXT) w3m dump (inl.gov)
| triceratops wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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.
| tln wrote:
| "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 wrote:
| Shouldn't you take into account the voltage. From the graphs
| they don't look like they were symmetrical.
| tln wrote:
| 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
| rrmm wrote:
| 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 wrote:
| 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.
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