
Open source all-iron battery for renewable energy storage - stevewilhelm
https://www.sciencedirect.com/science/article/pii/S2468067219300318?via%3Dihub
======
philipkglass
A fundraising appeal for this project was posted to HN in 2017:

[https://news.ycombinator.com/item?id=15618494](https://news.ycombinator.com/item?id=15618494)

I contributed. It's great to see the results published.

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Animats
Actual paper.[1] This looks like someone's science fair project. This
chemistry has lower energy density than nickel-iron (Edison, 1901). Iron
batteries are commercially available.[2] Not much of interest here.

[1]
[https://reader.elsevier.com/reader/sd/pii/S2468067219300318](https://reader.elsevier.com/reader/sd/pii/S2468067219300318)
[2] [https://www.essinc.com/energy-storage-
products/](https://www.essinc.com/energy-storage-products/)

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Causality1
Lithium ion battery prices are currently below $0.17 per watt-hour and
expected to drop below $0.10 by 2024. Does the all iron battery have any
advantages aside from being more environmentally friendly and not requiring
lithium? I must admit, the "safe for DIY" description makes me want to give it
a try.

~~~
dredmorbius
Iron is extremely abundant. It's too heavy for most mobile applications, but
might serve stationary needs.

~~~
solarkraft
Lithium batteries from EOL cars are also going to become extremely abundant.

~~~
majewsky
Maybe in 20 years. As usage of electric cars is still ramping up, demand for
new batteries is going to outstrip supply of old batteries by far. And that's
before we ask how difficult it is to extract raw materials from old batteries.

~~~
solarkraft
FWIW, my city (Lünen, Germany) has 2 Multi-MWh storages built from them (1
from batteries from Smart cars, 1 possibly from i-MiEV batteries). Without any
material-level recycling, just simple reuse, as energy density is a lot less
important than for cars.

Maybe having 2 of those (admittedly pilot) projects in my backyard biases my
estimations of their availability.

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kragen
Certainly iron is the metal to look at if you're going for the lowest cost,
but the results so far are not inspiring.

There are about nine orders of magnitude in between these results and utility-
scale energy storage, but it doesn't seem like that's what they're aiming
for—the existing flow batteries they mention in the paper would be a better
fit. They seem to be aiming at home applications, but they are seven orders of
magnitude away from even the “tens of kilowatts” they cite in their abstract
as typical for such applications.

However, both the negative results they mention in passing and the positive
ones are major contributions to the progress of such low-cost battery designs.

Iron costs around US$0.03 per kg, while lithium is more like US$300 and nickel
is US$30. In the intervening 3 orders of magnitude, cheaper than nickel but
not as cheap as iron, are aluminum, antimony, arsenic, cadmium, carbon,
cerium, chromium, copper, lead, manganese, samarium, silicon, tin, titanium,
vanadium, and zinc.

Some of these are unpromising precisely because they are too electronegative;
zinc, as they said, cannot be reduced electrolytically in water; the same
problem applies to titanium, aluminum, and carbon—but maybe a different
electrolyte could solve that problem. Others, like lead, are already in common
use for batteries.

Chromium, titanium dioxide, vanadium, tin and tin oxide, copper, manganese and
its oxides, cerium, samarium, and of course lead seem like plausible
candidates. Indeed at least zinc-cerium batteries exist.

~~~
tim333
I'm not sure their materials even sound all that cheap. From the article

"The total cost of materials is $0.1 per watt-hour"

Or presumably $100/kWh

On the other hand with Zinc Air "our fundamental raw material cost of zinc is
just $2-$3/KWh." from [https://www.altenergymag.com/article/2019/03/zinc-air-
batter...](https://www.altenergymag.com/article/2019/03/zinc-air-battery-
technology/30652) talking about NantEnergy's rechargables.

~~~
maxerickson
Yeah, the interesting comparison is the energy storage per dollar, not the
cost of the raw materials.

~~~
tim333
Indeed. Nant have been talking $100/kWh all in which is cheap but I think
that's projected rather than that you can actually buy them for anything like
that. Though the material cost is interesting as a potential end point if you
got super automated production. A problem with Vanadium flow for example is
that the materials are like 60% of the cost of the battery so it's hard to
drop much. With LiCo the materials are quite a big % of the battery cost
though these things vary with time and may drop. I think Telsa are reducing
the amount of Cobalt used dramatically for example [https://qnovo.com/82-the-
cost-components-of-a-battery/](https://qnovo.com/82-the-cost-components-of-a-
battery/)

~~~
maxerickson
Sodium ion batteries that don't use much in the way of exotic materials seem
feasible. It's the sort of thing where someone has to be successfully selling
them to prove that they are reasonably competitive though.

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blacksqr
+1 for discovering that a polymer used in diapers for absorbing moisture is a
cheap and effective ion-permeable separator membrane.

~~~
benj111
Unfortunately only mentioned once. Are we talking about the granules inside
the nappy here?

Also doesn't seem to have instructions for processing it beyond the short
description.

------
edent
This looks amazing - and great to see such detailed instructions.

One thing to note is that this probably isn't yet ready for home storage of
solar power.

"Our iron battery has sufficient capabilities for practical use in low power
devices and projects. The cell’s internal resistance is high, and so the
discharge rate is limited."

At the moment it could be useful as a backup for high efficiency lighting. The
bill of materials doesn't cover any electronics to monitor and maintain the
cells as the charge/discharge.

But all pretty nifty!

~~~
kragen
No, it doesn't provide enough power for high efficiency lighting, or any
lighting. Yet.

~~~
chabes
In the article, it describes keeping an LED lit for 350 continuous hours. Lots
of room for improvement too

~~~
kragen
An LED with 0.5 mA going through it is definitely visually distinguishable
from one that's off, but it's not “lighting” either, except maybe for
Borrowers in a romantic mood, or ants.

~~~
chabes
A single LED emits plenty of light. Just not compared to daylight. And this
was for many days..

~~~
kragen
A single LED can emit enormously varying amounts of light. With some
quantities of current, it can emit plenty of light. (Unless it's a low-power
LED and burns up first.) With other quantities of current, it emits very
little light, all the way down to no light when the current is zero. The
brightness at a given current varies by the type of LED, but not all that much
(unless you're dealing with infrared or ultraviolet LEDs). And at 0.5 mA, all
LEDs are very dim, more like “barely visible”.

I suggest you try the experiment. Grab a 7805 and a 10kΩ resistor; you can
find these in any discarded electronic device (from 1980 to 2005, anyway) or
you can buy them at any electronics store. Connect the resistor between the
“output” and “ground” pins of the 7805. _Do not connect the “ground” pin to
ground._ Connect an LED between the “ground” pin ( _not_ the “output” pin) and
_actual_ ground. (The negative pin of the LED goes to ground.) Connect a
positive DC voltage relative to ground to the “input” pin of the 7805; any
voltage between 10 volts and 35 volts will work. Now you have a regulated 0.5
mA going through the LED; if you want to confirm this, replace the LED with a
1kΩ resistor and measure the voltage across it with your multimeter. Try
different LEDs.

Do they emit “plenty of light”? No, they do not. None of them.

If you want variable current regulation, you can use a variable resistor, but
you should probably put it in series with a fixed resistor. You aren’t going
to burn up the 7805 without great effort, but you might burn up whatever
you're driving with it.

------
dcahill-ieee
It made 1mA of current, 0.5mW of power. Pretty long bow to draw linking this
to renewable energy storage. A kettle uses a kW or 2 just to boil water. You
would need a million of them to make a packet of noodles.

~~~
tsroe
"just to boil water" has got to be the biggest understatement that I've heard
in a while. There is a reason we use water in radiators: It's because water
has a very high heat capacity.

I think this battery is meant to be used in small electronics projects. Like
powering an arduino or even just an ATTINY.

~~~
ninkendo
> "just to boil water" has got to be the biggest understatement that I've
> heard in a while.

It’s also a good illustration of how much we depend on extreme energy
densities for everyday use cases. Coming up with a good storage solution for
renewable fuels is going to be a defining challenge for our generation.

~~~
smt88
This is my favorite method so far:

[https://qz.com/1355672/stacking-concrete-blocks-is-a-
surpris...](https://qz.com/1355672/stacking-concrete-blocks-is-a-surprisingly-
efficient-way-to-store-energy/)

Works well, portable, space efficient (could house it in the center of a
skyscraper), and easy to disguise as something aesthetically pleasing

~~~
maxerickson
A much larger battery (129 megawatt-hours) can fit into a similar footprint:

[https://hornsdalepowerreserve.com.au/](https://hornsdalepowerreserve.com.au/)

(it takes ~1 hectare, which maybe the tower of blocks won't have quite that
footprint, it'll be at least that imposing)

~~~
smt88
But aren't the drawbacks of a Lithium ion battery going to outweigh the
benefits of saving the space?

~~~
maxerickson
In a literal sense, apparently not. There's a real actual 100 megawatt-hour
lithium-ion grid battery and (concrete?) pie in the sky ideas for using dry
mass for gravity storage.

~~~
smt88
I wouldn't say it's "pie in the sky" when the technology already exists and
has been demonstrated. It's a really simple system.

In a sense, you're right that any technology currently in use is better than a
technology that isn't, but if every discussion ended there, we'd have no new
technology.

My question was assuming someone is choosing between lithium ion and gravity
storage. My understanding is that lithium mining is pretty awful for humans
and the environment, the batteries can explode easily, and their lifespan is
limited.

Besides being a weird shape, what are the drawbacks of storing energy in
concrete blocks?

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xvilka
Curiously, the article has a link[1] to the sources, located at OSF (Open
Science Foundation), but it asks for the login first, not allowing to view
without registration. Doesn't look like open science to me.

[1] [https://osf.io/4jvr9/](https://osf.io/4jvr9/)

~~~
lazypenguin
Clicking the "download" link with the pdf icon at the top gave me access to
the entire pdf

[https://www.sciencedirect.com/science/article/pii/S246806721...](https://www.sciencedirect.com/science/article/pii/S2468067219300318/pdfft?md5=9b80bd4a023bb227ff43f2dc066b936b&pid=1-s2.0-S2468067219300318-main.pdf)

------
0wis
Great detailed publication ! Makes me want to build one.

Curious to know how much efficient this battery can become without using too
hard to source material ! And for which kind of cycles.

Even if components are environmentally friendly, electricity production is
never footprint free, so if you need to 2x it to compensate...

------
crispyambulance
It makes me think of the Acquion project from Pittsburgh
([http://aquionenergy.com/](http://aquionenergy.com/)). That was an
interesting attempt to commercialize environmentally safe batteries intended
for uses where low power density isn't a problem-- eg underground energy
storage for windfarms or solar arrays. They went bankrupt a couple years ago,
but the concept was really exciting.

The immediate technical challenge with these kind of batteries at scale is the
electronics to monitor and maintain the battery banks as well as deploying
these things. It would take a truckload to set-up something usable for a
house, I think.

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nickcw
To put the costs intro perspective, an 83 Amp Hour car battery (typically a
small car might have a 40-60 AH battery and a large car >100 AH) holds 1 kWh
(kilo watt hour).

An 80AH battery can be had for about $100 on eBay.

The article states that the cost of materials might be $100/kWh.

So you could get the storage for about the same price using a car battery.

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cagenut
I skimmed through looking for some key numbers but didn't find them. I bet
someone who knows how to read the many numbers they did share would be able to
hazard a guess:

what would the $/kWh look like?

how many cycles until you hit 90%, 80%, 50% capacity?

~~~
std_throwaway
100 $/kWh

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s_Hogg
This reminds me of the cheap water purification thing that got rolled out
across poorer bits of Africa. Any cost reduction possibilities for this
design?

------
kator
What are the odds the steel wool could catch fire on these?

~~~
rini17
Only if the electrolyte dries out, and even then it will be probably covered
by salt crust.

