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.
It's in the graph image, CE: 88.7%
An open-source flow battery kit
81–90 of 111 posts
Re: An open-source flow battery kit
#82Hi! Just to say that Symantec doen not like your website! Malicious Site Blocked! Symantec Endpoint Protection blocked this website: https://dualpower.supply/
Yeah 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.
Re: An open-source flow battery kit
#83I'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…
I agree... part of that frustration is why we're working on this project! See my short post on "Why you can't buy a flow battery today"
Re: An open-source flow battery kit
#84I 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…
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 re…
Iron 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.
Re: An open-source flow battery kit
#85I 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…
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…
Bingo, this is exactly the plan. Of course there are non-trivial engineering challenges when scaling up, but that's the rough idea.
Re: An open-source flow battery kit
#86Hi! Just to say that Symantec doen not like your website! Malicious Site Blocked! Symantec Endpoint Protection blocked this website: https://dualpower.supply/
The solution is to avoid using Symantec. Perhaps report this issue to your malware provider rather than the site owner?
Malware provider sounds like someone distributing malware :D
Re: An open-source flow battery kit
#87What is the Coulombic efficiency? A paper membrane probably leaks a lot, but a state of the art ion exchange membrane probably runs $1k/m2.
I am the author of the blog (chemisting.com), working on the project with Kirk and Josh.
The Coulomb efficiency of a device with a microporous, non-selective membrane depends fundamentally on how fast you charge/discharge it, as the device self-discharges while it runs. The faster you charge/discharge, the higher the CE will be.
In the case of the photopaper device, it will be in the 85-90% range when charging to high SOC values at 20mA/cm2. The big advantage is that microporous membranes are really cheap and they still work even if dendrites pierce them. I must me clear that photopaper is meant as a DIY demonstration, a commercial unit would never use that but a polyethylene microporous separator - such as Daramic - with these memrbanes the CE and EE tend to be higher.
Re: An open-source flow battery kit
#88I'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…
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...
I am the author of the blog. The Zn/I chemistry actually generates very little H2, so that's not a problem in our current configuration.
Re: An open-source flow battery kit
#89I'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…
We hope to go from these low cost kits to home kits, to commercial kits. Out technology will always be open source. We hear you and we want to get there. We definitely want to live good lives - and have those who work with us have good lives too - but we really don't care about being rich.
We are going to start a work coop soon to build and sell the educational kits, as soon as we finish with the initial development. We also have a Hardware X paper coming, showing the initial results of the DIY kit. Things are slowly coming together, but it takes a while since we're literally doing these experiments in our houses.
Re: An open-source flow battery kit
#90Earlier quoted context omitted.
>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 shel…
Every other year, (solar-)electric cars scratch-built by high school students drive on public roads from Texas to (usually) California. This is considered a reasonable level of challenge, and something which insurers will cover (entrants are required to have vehicle liability insurance). https://www.solarcarchallenge.org/challenge/about.shtml https://www.solarcarchallenge.org/challenge/docs/rules2023.p...
And you would daily drive one of those?
You would be ok getting into an accident with one the same as you would get in an accident driving a civic?
Or maybe those are just learning vehicles meant to teach, and not meant to be car replacements? Just like this flow battery project?
Ironically your post validates my whole point: This is a student project at best, and likely worthless as a "democratization of energy storage". The same way those EV's would never be considered "democratization of EV cars".
C'mon...