My adventures building a DIY Zn/I flow battery

[danielfp248]

Not seen it, but I'll wager that he doesn't mention whether it's remotely viable.
He (quite skillfully) avoids letting users know if his suggestions are remotely viable.
I'm sure he's fully conversant with kW, kWh etc but I've yet to hear it across any of his projects. His unit of power is "wow those LEDs are really bright"
Most of his projects wouldn't charge a phone

Robert would have us believe everyone could be building 100 kWh batteries in their kitchens using 19th century technology. Sadly there are good reasons why those technologies never received massive adoption. I've always been critical of the lack of quantitative rigor and data in his videos, mainly because they do create this illusion that these things are much better than they really are. But his videos are good at sparking curiosity, which is his main goal.

 

[Patrik L]

Right. Also, the perspective matters as in laymen vs professional . I will say that some of the stuff he digs up and show can have some value if and when some of the chemicals used or components cannot be easily sourced, then it can make sense to look at an alternative even if the alternative is non ideal.

 

[danielfp248]

See this paper for a comprehensive comparison between Lithium Ion, Sodium Ion and flow batteries https://www.sciencedirect.com/science/article/pii/S0378775323008029

 

[OffGridForGood]

About pumping, the roundtrip efficiency of water pumping is usually around 70-80%.

And since the two lakes, and the generating plants are all existing - requires no new materials, space, land or construction, other than pumps running from solar/wind. low cost solution to item 1. Not a solution to item 2.

 

[danielfp248]

And since the two lakes, and the generating plants are all existing - requires no new materials, space, land or construction, other than pumps running from solar/wind. low cost solution to item 1. Not a solution to item 2.

Wherever you have the ability to pump large volumes of water and store them, this is definitely the best solution.

 

[justgary]

Wherever you have the ability to pump large volumes of water and store them, this is definitely the best solution.

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.

 

[danielfp248]

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.

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.

 

[justgary]

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.

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!

 

[Patrik L]

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 ????

 

[justgary]

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]

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!

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.

 

[Patrik L]

I agree, keep the thread to battery.

 

[Vorg]

I wonder if anyone has tried collecting together and feeding info on flow batteries into one of them new AI programs to see what it could come up with. I know they had one take a stab and a fusion reactor.

 

[danielfp248]

I wonder if anyone has tried collecting together and feeding info on flow batteries into one of them new AI programs to see what it could come up with. I know they had one take a stab and a fusion reactor.

I have given it a try, it definitely sucks at chemistry or I suck at prompting AI.

 

[danielfp248]

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.

 

[OffGridForGood]

as well as allowing you to have a hands-on experience putting a flow battery together.

I may have to change my definition of 'DIY-Battery' Build!

 

[danielfp248]

More information about the DIY flow battery on my blog : https://chemisting.com/2024/03/15/an-open-source-diy-flow-battery/