Building a tall tower and hoisting heavy blocks to the top would probably be a bit more efficient, but very tall and very heavy get hard to manage pretty quickly.
At least blocks should stay where you put them for a long time without evaporating.
My adventures building a DIY Zn/I flow battery
- Thread starter danielfp248
- Start date
At least blocks should stay where you put them for a long time without evaporating.
danielfp248
Battery researcher
- Joined
- Sep 7, 2020
- Messages
- 430
There are many problems with gravity batteries that use weights, in the context of towers it has never worked so far due to basically problems with keeping weights stable in the wind. The only viable trials up until now are using mine shafts, at least to the best of my knowledge. Water has decent density at 1 ton per cubic meter, so you will never be able to achieve using blocks what you can achieve with even a regular pool full of water. The water evaporates but it also can collect from rain, so you can also gain energy you didn't put in.
Last edited:
It all depends on what you make your blocks from. Lead, for example, is 11.3 times more dense than water. A visit to the Flint, MI scrapyard should provide plenty.
Around here, you can't pump water very far up a hill because the land is flat, and you can't dig a hole very deep without hitting water. A tower would be the only way to gain the height needed, but a hurricane would push it over. I guess I'll stick with batteries!
So, are anyone of you actually saying that storing excess energy in the form of mechanical work (kinetic energy) done during the day when there is a surplus and later tapped into this potential when there is a need and that at the same time, such a system can be scaled to such a level there is enough energy stored to last a standard household for 2-3 months when excess input is too low ????
That would depend entirely on the "excess input" you speak of. Considering that 1kW is 1,000N-m/s, you need to let a 102kg mass (near earth's surface) fall 1 meter in 1 second to get 1kW (excluding losses). So now, 1kWh of power is that same 102kg mass falling 1m/s for an hour (3,600 seconds). Or it could be (3,600*102) = 367,200kg falling 1/3600m/s for an hour.
Put another way, each MWh of stored energy converted to power would need ~102,000kg capable of falling 1m/s for an hour. I think a 3,600 meter high tower is impractical, so I would have no choice but to build a much lower one. A 36 meter tower would need 100 times the mass moving 100 times slower, so now we're talking about lifting about 11,230 tons (sorry for the units system change) and letting it dangle in the air until you need it. That is per MWh, so if you need more power you need more towers. You also need a safe cable and gear arrangement on each tower to lift the masses and harvest the power.
The amount of solar energy that hits the earth is truly amazing (roughly 1kW per square meter at the surface). Do what you can with it and let the rest grow flowers. Saving it in a bottle for months at a time is somewhat impractical.
danielfp248
Battery researcher
- Joined
- Sep 7, 2020
- Messages
- 430
The problem is not hurricanes. Even normal wind speeds are very problematic in these approaches. I would suggest watching these videos, which summarize a lot of the technical problems with this idea. Also note the titles of the videos are overly antagonistic for views, I don't view the idea as "dumb", but do recognize it has problems that make it mostly impossible in practice.
Also I would like to keep this thread dedicated to its main subject, so feel free to open a separate thread if you would like to continue discussing gravity storage.
danielfp248
Battery researcher
- Joined
- Sep 7, 2020
- Messages
- 430
I have given it a try, it definitely sucks at chemistry or I suck at prompting AI.
danielfp248
Battery researcher
- Joined
- Sep 7, 2020
- Messages
- 430
If you are in the Neatherlands or close in the EU, we will be holding a free workshop in Eindhoven in April, it would be great if you can attend (https://www.eventbrite.com/e/flow4u...utions-tickets-851447120257?aff=oddtdtcreator). We will be explaining our DIY flow battery design as well as giving away some kits - potentiostat included - as well as allowing you to have a hands-on experience putting a flow battery together. Let me know if you have any questions!
Note these are small flow batteries, for research and characterization. Also free lunch, so make sure you only register if you do intend to come.
Note these are small flow batteries, for research and characterization. Also free lunch, so make sure you only register if you do intend to come.
Last edited:
OffGridForGood
Catch, make or grow everything you can.
I may have to change my definition of 'DIY-Battery' Build!
danielfp248
Battery researcher
- Joined
- Sep 7, 2020
- Messages
- 430
More information about the DIY flow battery on my blog : https://chemisting.com/2024/03/15/an-open-source-diy-flow-battery/
ttrongtung
New Member
You can make your own lifepo4 battery with materials purchased from 1688 for ~30$/kwh not including shipping and tax.
kirkpsmith
New Member
Hi all, I'm Kirk, I've been collaborating with Daniel on this battery project. We set up a website https://fbrc.dev/ and just got a small grant to continue the work. I'll be working on mostly the engineering of the stack design.
In contrast, flow batteries are safer to produce and use (aqueous, no risk of fire/explosion), have fewer degradation pathways and longer cycle life, tolerate wide SOC ranges, can be made from more sustainable materials (ie. Zn, I, Mn, Fe... I'm not counting V) and as far as manufacturing them... well, we can test and assemble small-scale ones in our apartments. The same cannot be said for Li-ion, where you would have to handle anhydrous propylene carbonate solvent and fluorinated salts. This general barrier of having expensive equipment (like a glovebox, Karl-Fisher titrator, etc) scales up to the manufacturing line in terms of the strictness and purity required. Flow batteries, on the other hand, are more similar to building a small chemical reactor, and water is always easier to work with than hazardous solvents. There are still plenty of challenges, of course...
These are some reasons why I think it's still interesting to work on flow batteries even though Li-ion has come down a lot in price. I think it's possible to eventually get to something cheaper than Li-ion or lead-acid, with longer cycle life, safe, and more sustainable - the main downside being less energy density.
For flow batteries? Or for Na-ion?
Yes, LFP is cheap, and benefits massively from economies of scale right now. Beyond just up-front cost, I think it's important to consider safety, cycle life, and the sustainability of the materials needed to make the battery, as well as how easy it is to recycle them at the end of life. Also, the cost of clean/dry rooms, solvent handling, calendaring equipment, etc. to produce nonaqueous intercalation batteries like Li and Na-ion means the upfront capital investment to build a factory is massive - which is why we see so many "gigafactories" being announced - the capital expenditures must be huge to get to the scale where one can profitably make Li-ion batteries. And even then, the profit margins are not that large. Recycling for Li-ion is coming around, but unmixing a slurry electrode is a big battle with entropy.
In contrast, flow batteries are safer to produce and use (aqueous, no risk of fire/explosion), have fewer degradation pathways and longer cycle life, tolerate wide SOC ranges, can be made from more sustainable materials (ie. Zn, I, Mn, Fe... I'm not counting V) and as far as manufacturing them... well, we can test and assemble small-scale ones in our apartments. The same cannot be said for Li-ion, where you would have to handle anhydrous propylene carbonate solvent and fluorinated salts. This general barrier of having expensive equipment (like a glovebox, Karl-Fisher titrator, etc) scales up to the manufacturing line in terms of the strictness and purity required. Flow batteries, on the other hand, are more similar to building a small chemical reactor, and water is always easier to work with than hazardous solvents. There are still plenty of challenges, of course...
These are some reasons why I think it's still interesting to work on flow batteries even though Li-ion has come down a lot in price. I think it's possible to eventually get to something cheaper than Li-ion or lead-acid, with longer cycle life, safe, and more sustainable - the main downside being less energy density.
Last edited:
Looks like Sodium mostly, and Li-ion. Seeing it mentioned more and more in regards to new battery tech. It looks like it can be in liquid form, soooo...
averagejoe13
New Member
This discussion intrigued me. After some Googling I found interesting paper promising solution to dendrites formation https://www.nature.com/articles/s41467-024-50543-2 - I have no chemical experience whatsoever, so no idea how accessible that will be to diyers.
danielfp248
Battery researcher
- Joined
- Sep 7, 2020
- Messages
- 430
The chemistry is not super easily accessible due to the synthetic requirements (the zinc pyrophosphate complex must be synthesized), which requires heating under vacuum to concentrate the product.
However the main issue here is solubility. Zinc pyrophosphate has a solubility of only 0.9M, so a flow battery of these characteristics is limited to around 32Wh/L, which is quite low compared to other Zinc iodide chemistries, which can reach almost 6.5x this energy density. This is the reason why the paper doesn't mention Wh/L but only mW/cm2.
Similar threads
