Although most energy storage solutions on a grid-level focus on batteries, a group of researchers at MIT and Harvard University have proposed using supercapacitors instead, with their 2023 research article by [Nicolas Chanut] and colleagues published in Proceedings of the National Academy of Sciences (PNAS). The twist here is that rather than any existing supercapacitors, their proposal involves conductive concrete (courtesy of carbon black) on both sides of the electrolyte-infused insulating membrane. They foresee this technology being used alongside green concrete to become part of a renewable energy transition, as per a presentation given at the American Concrete Institute (ACI).
Putting aside the hairy issue of a massive expansion of grid-level storage, could a carbon-cement supercapacitor perhaps provide a way to turn the concrete foundation of a house into a whole-house energy storage cell for use with roof-based PV solar? While their current prototype isn’t quite building-sized yet, in the research article they provide some educated guesstimates to arrive at a very rough 20 – 220 Wh/m3, which would make this solution either not very great or somewhat interesting.
The primary benefit of this technology would be that it could be very cheap, with cement and concrete being already extremely prevalent in construction due to its affordability. As the researchers note, however, adding carbon black does compromise the concrete somewhat, and there are many questions regarding longevity. For example, a short within the carbon-cement capacitor due to moisture intrusion and rust jacking around rebar would surely make short work of these capacitors.
Swapping out the concrete foundation of a building to fix a short is no small feat, but maybe some lessons could be learned from self-healing Roman concrete.
Previous article on the same subject:
https://hackaday.com/2023/08/01/mit-crack-the-concrete-capacitor/
The biggest difference here is that there’s a direct link to the research paper. In the Hackaday article from August, 2023 you have to follow a link to somewhere else that then provides a link to the research paper.
Interesting idea, but hard to see where it would actually be useful.
Concrete (i.e., high cost cement mixed about 1:5 with a bunch of low cost filler) runs about $200 per cubic meter, and weighs 2.5 tonnes.
Pure Portland cement, retail, runs around $1000/ cu. m
For the same cost I can buy 1000 watt-hours of LiFePO4 battery (5x the capacity), and it weighs one thousandth as much.
True, but then the longevity of a LiFePO4 battery vs a supercap would also come into question. I dont have the numbers, but zo van imagine there may be a usecase here still. Caps have different charge/discharge rates than lithium cells, it’s not impossible that that might outweigh cost in some applications. But reading the article, it’s too early to call any of this.
There is just about zero probability that this tech will have a useful 50% life of more than five years, and you can’t replace it. You just end up with a building-sized brick (and since the structural value is less, you have to use more concrete to build it, and concrete is decidedly not carbon neutral).
Yet another green tech that can’t even displace itself
The longevity of said capacitor must yet be proven.
I’m trying to find where you’re getting $1000.00 for a cubic meter of Portland cement. My local hardware store sells it for $18.00 a bag (Portland cement and not concrete). 35 cubic feet in a cubic meter which would roughly be 12 bags at $219.60. Maybe I’m missing a variable somewhere or something has been left out. Maybe the cost is higher where you’re located?
A 94 lb bag is one cubic foot, and costs about $18-20 retail where I am, so there would be 35 per meter. 1 cubic meter (36 cubic feet), as bags not bulk, would be about $700 where I live.
A bane of higher education is the necessity to publish research and put a spin on the data such that the underlying rules of nature appear to be exposed in some new light. Extra points are awarded if the data can be presented to benefit mankind, even if the proposal seems hopeless weak for actual implementation.
Yeah, academic pressure to cater to bourgeois moralities/luxury beliefs for a head-up in grants/notoriety is an understudied phenomenon. Regardless of how you feel about those goals, such a creep of obvious bias into science isn’t going to help anybody
I follow the same logic when reading articles about (breakthrough) battery technologies: I appreciate research and creative ideas, but statistically the vast majority of these technologies never leave the lab. As long as it is not coming to the market I assume it is not technically or economically feasible to implement (yet). We are left with slow incremental improvements (no Moore’s law for batteries). Like with every technology there are always tradeoffs: energy per unit of volume, energy per unit of weight, longevity, cell voltage, safety (fire/explosions), reliability, maximum continuous/peak charge/discharge current, charge/discharge efficiency, charge/discharge complexity, cost, environmental impact, ambient conditions (temperature, humidity, vibration, etc.), form factor, etc.
Making better energy storage devices is hard.
>(no Moore’s law for batteries)
You couldn’t have one anyways, unless you somehow construct your batteries out of transistors. It just doesn’t apply – like with all the other things where Moore’s Law is misapplied to say “something doubled”.
Of course I meant a Moore’s law *equivalent* (i.e. exponential growth), not an application of Moore’s law.
Unfortunately hackaday has a primitive forum that doesn’t allow editing posts so I cannot edit my original post for clarification.
I assume this is not your normal concrete? Concrete can “explode” under the right conditions. (Don’t weld close to concrete without a protective barrier.)
I don’t think it would get above the boiling point of water (but could it in a short condition?)
A little knowledge is dangerous.
Don’t cast metal over ‘crete, but weld away.
Also: Don’t repeat advice about things you don’t personally know.
That’s what got us ‘The Anarchists Cookbook’.
I wonder if it would work properly with graphene additives instead of carbon black. I’ll have to go read the paper now.
No.
*Green cement* isn ‘t cheap tho.
And I”d hate to have to tear down my house in order to change the foundation battery if something happened to it.
And would the energy savings cover one new foundation pour–cement represents a lot of carbon.
It would sure add a lot of insult to injury if one day your foundation cracked and then you suddenly couldn’t use electricity at night as well. But I would assume this is for big industrial buildings or parking garages, not residential. Or it’s just for the blackboard. Who knows.
“…could a carbon-cement supercapacitor perhaps provide a way to turn the concrete foundation of a house into a whole-house energy storage cell for use with roof-based PV solar?”
Me: “What happened?”
Saint Peter: “Truthfully, we’re not sure. It seems you were drilling holes in a concrete slab to bolt down your floor safe, there was a big flash of light, and the next instant you were standing in our lobby.”
Why not build the house on pile foundations with motorized jacks built in, so you can store and release energy by raising and dropping the building? Raising a 100-tonne house by 1m would store 1MJ (278Wh).
You could have most of the machinery accessible for replacement, it could potentially save concrete (by using piles), it might cost less, and when climate change happens anyway you can just lift your house above the water.
Or build a 10 meter tall water tower and lift 10 cubic meters of water (W = 10 tonnes * 10 meters = 100 tonnes * 1 meter).
Then the only major mechanical components that you have to maintain is an off-the-shelf pump and a relatively simple hydro turbine.
That brings to mind early 20th century cartoons with houses that dance to the music.
Don’t drop out of middle school earth science.
The ‘kindest and most respectful’ comment possible!
Assume the idiot is a child.
I found this idea interesting the previous time I read it. Not the ‘as a foundation..’ that seems unlikely and unwise, but my thought was building these in 55 gal plastic drums with removable tops. Those are easy to get, ground moisture wouldn’t deplete your electrolyte, cause you to rip up foundation to service etc. you could bury/partially bury/not bury outside your house, but is has to be a lot better than the stated capacity for me to try, and there has to be a way to safely discharge for removal etc
So how much DEI is added to regular gray concrete to make it “green”?
The “green” refers to the funding they’re getting. The only environmentally friendly concrete is no concrete, a.k.a. “stop building things”. The infinite growth cult won’t allow that though.
I think the scalability is the key here, a concrete pour in a large basin would quickly create a huge capacity when it’s scaled up to full scale production for a small village or a city neighbourhood.
Not sure if it requires maintenance, that would be as hard as concrete ;)