[HN Gopher] An open-source flow battery kit
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An open-source flow battery kit
Author : idamantium
Score : 108 points
Date : 2024-08-13 14:25 UTC (8 hours ago)
(HTM) web link (dualpower.supply)
(TXT) w3m dump (dualpower.supply)
| Workaccount2 wrote:
| I cannot see how this is useful outside of being a fun student
| learning program.
|
| From the data it appears a battery with 1L of electrolyte
| provides about 18Wh of energy. Mind you this is at ~1.2V, which
| isn't especially useful without a boost converter. With a boost
| converter though you would need a low internal impedance from the
| battery, which I highly doubt is any good with a paper membrane
| (from what I understand it already isn't great for flow
| batteries).
|
| Meanwhile a pair of 18650 lithium ion batteries can be had for $5
| and can provide 24Wh at a very usable 7V with no power
| conditioning or a range of voltages with more than enough ability
| to source current. And it is a fraction the size, weight, and
| complexity.
|
| I don't mean to tear apart the project, perhaps there is a key
| detail I am missing, but I just don't see what this is trying to
| do outside being a learning experience for students.
| msandford wrote:
| Typically if you want to DIY something you first start with the
| smallest prototype possible and work your way up from there.
|
| This demo cell isn't super interesting on its own but to
| validate the chemistry it's super helpful. Once you got that
| done you'd then work on a stack of cells, say 10 or 20 or 40 to
| get up to normal system voltages.
|
| Once you have that working it's just a matter of making the
| tank as big as you want for your storage. Provided the initial
| chemistry is reasonable you could probably use a pair of IBC
| totes and really go somewhere.
| Gravityloss wrote:
| Yeah! The thing about flow batteries is that if we manage to
| find good chemistries, they have the potential to be very
| cheap energy storage compared to ordinary batteries. High
| energy, low power, low cost.
|
| Ie the small electrodes cost something but the big bag of
| fluid might be cheap.
|
| Say, vitamin- like substances consisting of extremely common
| elements like hydrogen, oxygen, nitrogen, carbon etc could be
| used to store energy in a flow battery. Even with quite low
| performance, they could be very cheap compared to things like
| cobalt, nickel, manganese or lithium.
|
| Or what about quinones? And sodium, sulphur, sodium are cheap
| too. There are a lot of very cheap chemistries that could be
| explored!
| pjc50 wrote:
| "For some scientists doing flow battery experiments in their
| respective homes/apartments, we've got some solid preliminary
| results"
|
| Obviously it's a research project not a commercial product.
| What do you expect?
| Tade0 wrote:
| Personally I would find it useful for applications where there
| needs to be little to no self-discharge and fire safety - like
| a remote shed with some kind of sensor.
| Workaccount2 wrote:
| You still need something to power the pumps. And we already
| have long term low power batteries. And solar + battery has
| filled this role for decades.
| heeton wrote:
| Not a battery expert, but this seems the right ballpark for
| useful batteries.
|
| Back of envelope stuff:
|
| 1liter for 18Wh.
|
| 1k liter 18KWh (this is an average hot tub).
|
| 10k litre for 180Kwh. This is a ~$1000 farming tank.
|
| ~100KWh lithium batteries are around the $20-30k. (Used Tesla
| pack for reference)
|
| Quick google shows flow electrolyte in the neighbourhood of
| $100 per KWh. Or $10k for a ~100KWh battery.
|
| All this is nothing definitive, but it's not showing any 10x or
| 100x differences that would rule out an interesting idea.
| Workaccount2 wrote:
| In order to really make a determination though you need to
| know what the internal resistance characteristics looks like.
|
| 18kWh becomes near useless if it can only source enough
| current to power your TV at any given time. Or to put that
| another way: 18kWh doesn't do you much good if you can only
| draw 200W from it at a time.
|
| Given that flow batteries are known for their virtually zero
| self-discharge, and this project is aiming for a cheap/easy
| membrane, it seems very likely that internal impedance will
| kill most use cases here.
|
| Mind you I don't think flow batteries themselves are useless
| to pursue. It's just that I believe a viable flow battery is
| almost certainly going to be something that requires complex
| chemistries and advanced manufacturing. In the same way you
| can build an open source EV from scratch, but you really
| wouldn't want to ever take that thing on the street.
| ajford wrote:
| Why wouldn't you take a scratch-build EV on the road?
| People build kit-cars all the time, and an EV has a much
| simpler control system.
|
| This is a very simplified project to prove the concept and
| provide a test bed for further exploration, not an end-
| product by any stretch. This seems like the perfect project
| to test various membranes and electrolyte solutions.
| Workaccount2 wrote:
| >Why wouldn't you take a scratch-build EV on the road?
|
| Because you don't want to snap your spine in a minor
| fender bender.
|
| Scratch built is not the same thing as an EV conversion
| kit, where all the hard stuff (like a frame and body
| panels) was already made by commercial manufacturers.
|
| This flow battery is from scratch (well except for the
| pumps and electronics, but the cell itself is). They are
| not using off the shelf electrolyte and electrochemical
| cells like a flow battery kit would.
|
| It's a neat project and would teach a lot, but I just
| cannot find a scenario in my head where I would want this
| (even a scaled up version) over another solution.
| marcosdumay wrote:
| You are missing that this is just some salts dissolved in
| water, while the 18650 is a highly complex device.
|
| How much does it cost to store 10m^3 of water? And hos much
| does it cost to store the same energy in 18650 batteries?
|
| Also, the internal resistance depends entirely on how many
| cells you have. But a practical battery wouldn't use paper.
| Workaccount2 wrote:
| >Also, the internal resistance depends entirely on how many
| cells you have.
|
| Right, from the one study I can find, commercial flow
| batteries have about 10-20x the internal resistance of a
| lithium ion battery, so the match the power and energy
| capabilities of a single li-ion cell you would need a liter
| of electrolyte and about 30 (!) cells (3 for voltage x 10 for
| power).
|
| And that is for a commercial quality flow battery. And
| lithium ion batteries are wholesale in the $2 a piece range.
|
| I'm not trying to say flow batteries are stupid or dumb, but
| their use cases are going to be very limited without some
| huge breakthroughs that will probably dramatically increase
| the complexity too.
| entropicdrifter wrote:
| Their use cases would become extremely relevant to people
| trying to rebuild society from scratch, I'd imagine. This
| device is so simple you could probably build one in the
| woods with nothing but a basic survival kit given a year or
| two alone.
|
| So that's something. Learning how to build one from scratch
| seems worthwhile, much like learning to build a radio from
| scratch
| Dylan16807 wrote:
| Unless you're flying a drone, you don't need to match the
| power and energy capabilities of lithium ion.
|
| On top of that, you don't have to match the internal
| resistance to match power. If you have plenty of material
| to absorb the heat, then you can tolerate more percentage
| points of loss.
|
| In particular, while lithium ion batteries can be built to
| sacrifice discharge rate for a bit of extra capacity,
| something like a 3C discharge rate is easy enough to reach.
| And if your use case is powering a building for several
| hours, you might only need a .2C discharge rate. That would
| mean lithium ion as a technology is 15x overqualified, and
| a flow battery that gives you 10x less power would still be
| overqualified.
| Workaccount2 wrote:
| I see what you are saying, in reality the right energy
| storage is very application dependent. The crux of my
| argument is that I cannot think of many applications
| where a commercial grade flow battery is the best choice,
| much less a single application where a DIY flow battery
| is the best choice.
| Dylan16807 wrote:
| My main point is that while it definitely has to compete
| on price, it doesn't have to compete on price _while
| also_ making you buy ten times as many cells.
|
| Many elements of being the "best choice" are thresholds.
| Excess performance doesn't make it better. Price is
| extremely important, but power density is not so
| important for most use cases. So if it's even slightly
| cheaper, expect to see a lot of it.
| EricE wrote:
| A flow battery isn't going to burst into extremely high
| temperature flames in a self-sustaining not easily
| extinguishable fire that also spews toxic fumes in mass
| quantities.
|
| I'll take a basement (or garage) with a flow battery over
| lithium ion ANY day of the week if I want battery backup
| for my house.
| mschuster91 wrote:
| > I'm not trying to say flow batteries are stupid or dumb,
| but their use cases are going to be very limited without
| some huge breakthroughs that will probably dramatically
| increase the complexity too.
|
| The largest use case is going to be grid scale storage, and
| for that one a bunch of dumb tanks and a bank of cells are
| far easier to handle and less risky than a bunch of li-ion
| cells that can go into runaway for whatever reason.
| Workaccount2 wrote:
| The thing is that there are like 50 other options for
| energy storage, it's not just lithium-ion that flow
| batteries have to out compete. Everything from
| electrolyzed hydrogen, to hot sand, to air pressure
| tanks, to sodium-ion and zinc air and LiFePo batteries.
|
| Flow batteries are cool because the storage element is
| extremely easy to scale. But its not even that great
| because you also need to scale the amount of cells
| dramatically to make it useful outside of edge cases. At
| which point it probably makes more sense to just use
| another storage mechanism.
| Retric wrote:
| 1 liter of electrolyte is nothing for a flow battery, the
| smallest scale they become a serious competitor is ~10m3
| (10,000L) tanks which are ~(7 foot X 7 foot X 7 foot).
|
| Start taking GWh of storage and lithium ion technology gets
| really expensive and has a lot of associated risks. Flow
| batteries on the other hand don't need to worry about a
| single cell failure resulting in a fire which then spreads.
| Workaccount2 wrote:
| The amount of electrolyte doesn't scale the available
| power though, only the available energy.
| almostnormal wrote:
| Energy storage is the problem that needs a solution,
| e.g., storage from summer to winter.
| marcosdumay wrote:
| Annual and long-tail storage are both problems that need
| solving, and fuel cells do look like a possible solution.
| But it's not clear at all what the winner will be for
| those applications.
|
| Even hydrogen is competitive here. IMO, more competitive
| than that battery chemistry on the article.
| Retric wrote:
| That just means you get to scale it independently.
|
| While they both need to scale the amount of DC<>AC
| inverters based on peak power demand. If you want to
| discharge over 16 hours you're using 2% of lithium ion's
| peak power output and need a huge mess of wiring to move
| power from each internal cell to that inverter.
|
| Flow batteries on the other hand can use a single pump (+
| redundancy) and fat pipe to supply a huge array of ion-
| exchange membranes which then sit next to the inverters.
| K0balt wrote:
| This is awesome!
|
| Obviously we'd need a real ion exchange membrane and put 40 of
| them in series, but it looks pretty scalable even in its
| present form. This looks very practical to me, once a few more
| years of tinkering is done.
|
| I'd love to have more information about electrode fluid cost,
| life and reconditioning/reprocessing, as well as power
| densities for membrane area.
|
| I'd love to be able to add capacity just by adding tanks and
| electrode fluid! For microgrids like ours, this is a
| longstanding goal.
| KennyBlanken wrote:
| Flow batteries are optimized for cost and capacity. Not weight,
| nor volume/energy density, nor instantaneous power delivery. In
| the case of some iron flow designs, add in "dirt-cheap, non-
| toxic materials."
|
| A pair of 55 gallon drums equals 7.4kWh, and I'm guessing a
| _lot_ of us could easily find that much space in our basements.
| That 's enough to power 300W of load 24x7 (a modern fridge is
| about 60W. 100W will get you _really_ far in terms of LED
| lighting given that most "60W" bulbs are well under 10W these
| days.)
|
| One "car battery" sized LiFePO4 battery is about 1400Wh, and
| costs anywhere from $100 to $500+ depending on the
| manufacturer/reseller.
|
| I'm a little mystified why they didn't go with a simpler iron-
| flow design as it is very cheap, and can be nearly completely
| non-toxic.
| ForOldHack wrote:
| There are two key details you are missing:
|
| 1) Its scalable to dishwasher size, ( enough to power a tiny
| house )
|
| 2) If you shot it with a bullet, it would just leak salt water.
| That is all. Lithium Ion will explode:
|
| Now here is the quiz: If you have a cell phone that is
| inflating, do you A) Dunk it in water? or B) Toss it in a full
| document safe? or c) Quickly empty your document safe, and toss
| it in?
|
| If a flow battery leaks, you can toss in a chicken into the
| delightful brine.
|
| Since you cannot scale this easily to Utility sized batteries
| easily, the D.O.E. is not interested. i.e. if you are looking
| to scale this to a couple of hundred megawatts, just stop
| reading and thinking about this now. This is NOT mobile. Its
| not useful for cars or cities. Its right sized for homes.
| 0cf8612b2e1e wrote:
| ... if you are looking to scale this to a couple of hundred
| megawatts, just stop reading and thinking about this now
|
| I thought that was one huge appeal of flow batteries is that
| you can basically infinitely scale them. China has a 100MW
| installation (potentially more since this 2022 report)
|
| https://www.pv-magazine.com/2022/09/29/china-connects-
| worlds...
| briffle wrote:
| These guys in the US make a 500kwh version, that can run at
| 75kw of discharge power across 3 phases, and its a single
| shipping container: https://essinc.com/energy-warehouse/
|
| It doesn't seem like it would take up that much space to
| have 200 shipping containers sitting somewhere, i'm pretty
| sure the Home Depot distrubution center in our town already
| is close to that in their parking lot (yes, you would want
| them not on wheels, and farther apart)
| 0cf8612b2e1e wrote:
| That's incredible. I wonder what are the costs relative
| to a grid scale battery of equivalent size.
|
| I only wish they made one that were barrel sized and fit
| for consumers. Worst case, you have a leak vs a home
| battery fire.
| gwbas1c wrote:
| > I just don't see what this is trying to do outside being a
| learning experience for students.
|
| Perhaps one of those students will figure out how to make a
| useful large scale flow battery? I have solar, and the missing
| piece is being able to store electricity for the winter.
|
| Perhaps the person who figures it out learned something from a
| project like this?
| perlgeek wrote:
| Lots of software started this way: as a toy, a proof-of-concept,
| a learning opportunity for the programmers. I really hope that
| they find interested people who join their experiments, and build
| something awesome and open together.
| ForOldHack wrote:
| This looks like a toy, but its INSANELY COOL! You build a proof
| of concept? This technology is cool.
|
| I was at a tiny house competition, and we were using golf cart
| batteries, and the winner: The University of Santa Clara, CA:
|
| "The house stores its energy using saltwater batteries, the
| only batteries in the world to be Cradle to Cradle certified."
|
| https://www.tinyhousebasics.com/revolve/
| smallerize wrote:
| That article is from 8 years ago. Saltwater batteries are
| hard to find right now since Aquion quit making them and I
| don't know of anyone retailing Salgenx yet.
| RobotToaster wrote:
| Home 3d printers started as repraps that could barely print a
| shot glass.
| moffkalast wrote:
| That wasn't because it was a proof of concept tech, but
| because Stratasys was effectively patent trolling it since
| the 80s.
| kragen wrote:
| it's possible the necessary inventions would have happened
| earlier without the patent problem, but the minimug era of
| reprap was not simply reproducing existing fdm machines;
| they were having to figure out a lot of things nobody had
| figured out before, like parts cooling fans, pla to use
| lower temperatures and avoid the need for a heated build
| chamber, threaded rod truss gantries, avr g-code
| interpreters, and eventually auto bed leveling, pla pinch
| extrusion, etc. there are things people could have told
| them, but if they'd done everything in the safe
| conventional way they would have ended up with a two
| thousand dollar machine
| kleton wrote:
| What is the Coulombic efficiency? A paper membrane probably leaks
| a lot, but a state of the art ion exchange membrane probably runs
| $1k/m2.
| KennyBlanken wrote:
| It's in the blog. The author mentions finding that matte inkjet
| paper worked fairly well.
|
| There are much cheaper membranes; ESS for example uses a
| membrane that is used by lithium ion batteries (I think) and
| thus is commonly available and very inexpensive.
| kragen wrote:
| where in the blog?
| KennyBlanken wrote:
| I've been watching ESS (they make a non-toxic iron flow battery
| system) for years and been really frustrated that they have made
| essentially zero progress deploying the technology, with less
| than half a dozen deployments.
|
| The technology looks great, but they seem annoyingly incompetent
| at marketing/selling their product...or are just holding out for
| "whale" customers, refusing to work with anyone except microgrid
| (ie college campus) and utility scale customers.
|
| So many promising products and technologies die because the
| inventors/developers hold out for huge customers while ignoring
| the huge demand from retail/small/medium corp customers.
|
| "We won't talk to anyone except corporations with deep pockets.
| Once we find a couple of those, we'll be filthy stinking rich!"
| instead of "if we sell the components at a price that undercuts
| LiFePO4, we'll have as many customers as we can handle, and
| there's plenty of margin for distributors and retailers, so we
| don't have to be B2C."
| hlieberman wrote:
| The author actually talks about ESS in a comment to the linked
| blog post from the article. Apparently their battery generates
| a ton of H_2 that needs to be managed. That could easily be the
| sort of thing that only is possible/realistic at large scales,
| thus eliminating sizing the battery down indirectly.
| https://chemisting.com/2024/03/15/an-open-source-diy-flow-ba...
| kragen wrote:
| you can just vent h2 to the atmosphere
| _alex_ wrote:
| I dont know anything about flow batteries, but some quick
| searching leads me to believe that there are two tanks of
| electrolytes with pumps that pump them along a membrane and then
| you get power across the membrane. In this small battery kit, is
| the idea that the battery provides enough power to both operate
| all its own pumps/electronics, and then output usable power? Does
| anyone know how much power you'd be able to get out of a small
| setup like this?
|
| Looks like a cool project!
| moffkalast wrote:
| Definitely looks like a great idea, fuel cells with something
| that doesn't outright explode if you look at it wrong. The
| shortcoming would be the energy density I would expect. But
| even so if there's something that can maybe be half as good as
| lithium but can be refuelled in seconds by just filling up a
| tank there's definitely a market for it.
| hosh wrote:
| Flow batteries have some fantastic properties. Their energy
| output and capacity can be scaled independently. They are safer
| and can be made from material that are easier to source.
|
| They are also have high upfront costs and poor energy density,
| so there have not been much application outside of grid-scale
| deployments. Getting something practical for onsite commercial,
| residential, and vehicular applications have been something
| aggressively pursued. (Solid-state batteries being another
| battery tech that is also pursued).
|
| So for someone to make a open-source DIY flow battery that can
| scale well can change a lot of things.
|
| https://www.wevolver.com/article/what-is-a-flow-battery-a-co...
| mikewarot wrote:
| It's my understanding that iodine is one of those things watched
| very closely by the TLAs enforcing prohibition. Be careful, lest
| you end up unable to move about freely because this gets you on a
| list.
| sterlind wrote:
| Iodine used to be commonly used to reduce pseudoephedrine to
| meth, but these days most meth comes from superlabs in Mexico,
| who use a very different process. I doubt you'll catch much
| heat for it these days, especially since it has a number of
| legit uses. And even if it gets you on a "list" you're more
| likely to just get raided once rather than no-fly'd.
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