7 ms·
An open-source flow battery kit
- Workaccount2 2y agoI 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 2y agoTypically 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 2y agoYeah! 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!
- kirksmith 2y agoBingo, this is exactly the plan. Of course there are non-trivial engineering challenges when scaling up, but that's the rough idea.
- pjc50 2y ago"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 2y agoPersonally 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 2y agoYou 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.
- kirksmith 2y agoThe pumping cost constitutes a 1-2% total penalty on round-trip energy efficiency for a well-designed flow battery.
- heeton 2y agoNot 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 2y agoIn 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 2y agoWhy 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 2y ago>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 2y agoYou 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 2y ago>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 2y agoTheir 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 2y agoUnless 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.
- K0balt 2y agoThis 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 2y agoFlow 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.
- pfdietz 2y agoThe actor I'm mildly paying attention to is Lockheed-Martin, who have an energy systems group that's working on flow batteries. Judging by patents, their flow battery likely uses various transition element ions that are kept in solution with any of a variety of organic ligands. The wide variety of chemistries is the attractive part, since they present many knobs to twiddle for optimization.
- kirksmith 2y agoIron plating is a hydrogen evolution nightmare. It's interesting for sure, but not feasible for a simple demonstration system, due to pH issues and oxidation state drift from hydrogen evolution. We do plan to explore it in the future, and move onto larger cells/stacks that offer practical amounts of storage.
- ForOldHack 2y agoThere 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 2y ago… 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-largest-redox-flow-battery-system-to-grid/ https://www.pv-magazine.com/2022/09/29/china-connects-worlds...
- briffle 2y agoThese 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/ 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 2y agoThat’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 2y ago> 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?
- beAbU 2y agoThis website is called hacker news. I think you are missing the point of this post.
- perlgeek 2y agoLots 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 2y agoThis 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/ https://www.tinyhousebasics.com/revolve/
- smallerize 2y agoThat 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.
- ForOldHack 2y agoWow! You have totally done your homework. Totally. Yes, Aquion went out of business, and Salgenx is not on the market yet.
- RobotToaster 2y agoHome 3d printers started as repraps that could barely print a shot glass.
- moffkalast 2y agoThat wasn't because it was a proof of concept tech, but because Stratasys was effectively patent trolling it since the 80s.
- 2y ago
- kleton 2y agoWhat 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 2y agoIt'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 2y agowhere in the blog?
- jerrysievert 2y ago> where in the blog? the blog is listed in the first paragraph of the linked article: https://chemisting.com/2024/03/15/an-open-source-diy-flow-battery/ https://chemisting.com/2024/03/15/an-open-source-diy-flow-ba...
- kragen 2y agoif by 'the blog' you (or you and kennyblanken) mean https://chemisting.com/ https://chemisting.com/, which post do you mean? the post you link to in that blog doesn't say anything about coulombic efficiency or inkjet paper, and there are four years of posts in the blog
- jerrysievert 2y agohttps://www.amazon.com/Kodak-photo-paper-matte-count/dp/B0B5B7TQ3K/ https://www.amazon.com/Kodak-photo-paper-matte-count/dp/B0B5... according to the link.
- kirksmith 2y ago
- KennyBlanken 2y agoI'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 2y agoThe 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-battery/ https://chemisting.com/2024/03/15/an-open-source-diy-flow-ba...
- kragen 2y agoyou can just vent h2 to the atmosphere
- jhayward 2y agoYour local fire department will want to very closely inspect your explosive materials handling and safety procedures. Think about what big banks of lead-acid batteries have to do, and google the pictures of battery rooms with their roof blown to bits.
- 2y ago
- _alex_ 2y agoI 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 2y agoDefinitely 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 2y agoFlow 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-comprehensive-guide-to-understanding-and-implementing-flow-batteries https://www.wevolver.com/article/what-is-a-flow-battery-a-co...
- jillesvangurp 2y agoThe cool thing with flow batteries is that you can scale the amount of power they store (kwh) by simply using bigger tanks. The power output (kw) you get out of them is determined by the size and efficiency of the anode and cathode. So, in this case both are a bit underwhelming obviously. But the main point is that you can increase the kwh by simply using bigger tanks and the kw by using multiple cells in parallel or by improving the anode/cathode somehow.
- mikewarot 2y agoIt'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 2y agoIodine 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.
- pfdietz 2y agoIodine is also pretty expensive ($61/kg in 2023) so this doesn't seem scalable for that reason alone.
- kirksmith 2y agoWe are planning other electrolytes beyond zinc-iodine (including iron salts), but this one happens to be practical for getting started due to widespread availability, tolerance to oxygen (avoiding requirements of purging with inert gas), and low hydrogen evolution rates (quite unlike iron-salt systems, which are practically H2 electrolyzers!).
- jamexcb 2y agoHi! Just to say that Symantec doen not like your website! Malicious Site Blocked! Symantec Endpoint Protection blocked this website: https://dualpower.supply/ https://dualpower.supply/
- happymellon 2y agoThe solution is to avoid using Symantec. Perhaps report this issue to your malware provider rather than the site owner?
- GTP 2y agoMalware provider sounds like someone distributing malware :D
- kirksmith 2y agoYeah I am self-hosting with a VPN and following all the best practices I know (not my expertise), not surprised there's some warnings going around.
- riiii 2y agoIt would be helpful to start the article with a link to why flow batteries are amazing.
- kirksmith 2y agosome context: https://dualpower.supply/posts/motivation-OSHW-RFB/ https://dualpower.supply/posts/motivation-OSHW-RFB/
- kirksmith 2y agoWow, hi all, I am Kirk, the author of this blogpost, never thought my small ARM board home server would handle this much traffic! Currently reading through these posts, feel free to ask questions. Great to see interest. FYI, I am quitting my postdoc job in two months to work on this full-time, which should help the rate of progress, but my main source of income will stop. We hav ea small but it will only cover a few months of full-time work. If you want to support the project financially we have an Open Collective here: https://opencollective.com/fbrc/donate https://opencollective.com/fbrc/donate We'd really appreciate any support you're able to give, which we'll use to push this open technology as far as we can! We are planning to start work on a much bigger stack after the kit.
- mharig 2y ago[dead]
- kirksmith 2y ago*typo: meant to say we have a grant from NLnet https://fbrc.dev/posts/NLnet-funding/ https://fbrc.dev/posts/NLnet-funding/ , which will cover a few months of full-time work (for one contributor)
- metadat 2y agoHey Kirk, this is a neat project and I admire your high level of commitment! Question: What happens to the liquids once they have been used up and depleted? Is there a "recharge" procedure? If they can be reused, how many times before they become disposal waste?
- kirksmith 2y agoHey, thank you! The liquids are reusable, and are charged and discharged repeatedly without needing to replace the fluids. In other words the system is closed with respect to mass, only electrical energy (and minor amounts of thermal) are transferred in and out, reversibly. Flow batteries are similar to so-called reversible or regenerative fuel cells for this reason. The answer to how long it lasts depends on many factors, and we hope to provide a clearer picture of that in our work. In a well-designed system, they can last extremely long in comparison to, say, lithium-ion batteries. This is because flow batteries have different degradation pathways that are less severe and, if present, can usually be overcome through other solutions (e.g. electrolyte rebalancing, see ESS's "proton pump").
- culopatin 2y agoCan this be combined with uphill water storage so you store both kinetic and chemical energy? The pump would store water uphill as it does now, but when it flows down it goes through the membrane and also generates power this way? Of course it robs some of the momentum used for the turbines but idk, maybe it’s more efficient?
- rini17 2y agoUphill water storage has little energy density, you need huge reservoir to get useful amounts of energy.
- deleted 2y ago[deleted]