Essay by Eric Worrall
If every house were to implement this energy storage “solution”, a single dielectric failure could lead to a sizeable chain reaction, as adjacent houses suffered mechanical shock and failure.
MIT engineers create an energy-storing supercapacitor from ancient materials
Made of cement, carbon black, and water, the device could provide cheap and scalable energy storage for renewable energy sources.
David L. Chandler | MIT News
Publication Date: July 31, 2023Two of humanity’s most ubiquitous historical materials, cement and carbon black (which resembles very fine charcoal), may form the basis for a novel, low-cost energy storage system, according to a new study. The technology could facilitate the use of renewable energy sources such as solar, wind, and tidal power by allowing energy networks to remain stable despite fluctuations in renewable energy supply.
The two materials, the researchers found, can be combined with water to make a supercapacitor — an alternative to batteries — that could provide storage of electrical energy. As an example, the MIT researchers who developed the system say that their supercapacitor could eventually be incorporated into the concrete foundation of a house, where it could store a full day’s worth of energy while adding little (or no) to the cost of the foundation and still providing the needed structural strength. The researchers also envision a concrete roadway that could provide contactless recharging for electric cars as they travel over that road.
The simple but innovative technology is described this week in the journal PNAS, in a paper by MIT professors Franz-Josef Ulm, Admir Masic, and Yang-Shao Horn, and four others at MIT and at the Wyss Institute for Biologically Inspired Engineering.
Capacitors are in principle very simple devices, consisting of two electrically conductive plates immersed in an electrolyte and separated by a membrane. When a voltage is applied across the capacitor, positively charged ions from the electrolyte accumulate on the negatively charged plate, while the positively charged plate accumulates negatively charged ions. Since the membrane in between the plates blocks charged ions from migrating across, this separation of charges creates an electric field between the plates, and the capacitor becomes charged. The two plates can maintain this pair of charges for a long time and then deliver them very quickly when needed. Supercapacitors are simply capacitors that can store exceptionally large charges.
The amount of power a capacitor can store depends on the total surface area of its conductive plates. The key to the new supercapacitors developed by this team comes from a method of producing a cement-based material with an extremely high internal surface area due to a dense, interconnected network of conductive material within its bulk volume. The researchers achieved this by introducing carbon black — which is highly conductive — into a concrete mixture along with cement powder and water, and letting it cure. The water naturally forms a branching network of openings within the structure as it reacts with cement, and the carbon migrates into these spaces to make wire-like structures within the hardened cement. These structures have a fractal-like structure, with larger branches sprouting smaller branches, and those sprouting even smaller branchlets, and so on, ending up with an extremely large surface area within the confines of a relatively small volume. The material is then soaked in a standard electrolyte material, such as potassium chloride, a kind of salt, which provides the charged particles that accumulate on the carbon structures. Two electrodes made of this material, separated by a thin space or an insulating layer, form a very powerful supercapacitor, the researchers found.
The two plates of the capacitor function just like the two poles of a rechargeable battery of equivalent voltage: When connected to a source of electricity, as with a battery, energy gets stored in the plates, and then when connected to a load, the electrical current flows back out to provide power.
“The material is fascinating,” Masic says, “because you have the most-used manmade material in the world, cement, that is combined with carbon black, that is a well-known historical material — the Dead Sea Scrolls were written with it. You have these at least two-millennia-old materials that when you combine them in a specific manner you come up with a conductive nanocomposite, and that’s when things get really interesting.”
As the mixture sets and cures, he says, “The water is systematically consumed through cement hydration reactions, and this hydration fundamentally affects nanoparticles of carbon because they are hydrophobic (water repelling).” As the mixture evolves, “the carbon black is self-assembling into a connected conductive wire,” he says. The process is easily reproducible, with materials that are inexpensive and readily available anywhere in the world. And the amount of carbon needed is very small — as little as 3 percent by volume of the mix — to achieve a percolated carbon network, Masic says.
Supercapacitors made of this material have great potential to aid in the world’s transition to renewable energy, Ulm says. The principal sources of emissions-free energy, wind, solar, and tidal power, all produce their output at variable times that often do not correspond to the peaks in electricity usage, so ways of storing that power are essential. “There is a huge need for big energy storage,” he says, and existing batteries are too expensive and mostly rely on materials such as lithium, whose supply is limited, so cheaper alternatives are badly needed. “That’s where our technology is extremely promising, because cement is ubiquitous,” Ulm says.
The team calculated that a block of nanocarbon-black-doped concrete that is 45 cubic meters (or yards) in size — equivalent to a cube about 3.5 meters across — would have enough capacity to store about 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household. Since the concrete would retain its strength, a house with a foundation made of this material could store a day’s worth of energy produced by solar panels or windmills and allow it to be used whenever it’s needed. And, supercapacitors can be charged and discharged much more rapidly than batteries.
After a series of tests used to determine the most effective ratios of cement, carbon black, and water, the team demonstrated the process by making small supercapacitors, about the size of some button-cell batteries, about 1 centimeter across and 1 millimeter thick, that could each be charged to 1 volt, comparable to a 1-volt battery. They then connected three of these to demonstrate their ability to light up a 3-volt light-emitting diode (LED). Having proved the principle, they now plan to build a series of larger versions, starting with ones about the size of a typical 12-volt car battery, then working up to a 45-cubic-meter version to demonstrate its ability to store a house-worth of power.
There is a tradeoff between the storage capacity of the material and its structural strength, they found. By adding more carbon black, the resulting supercapacitor can store more energy, but the concrete is slightly weaker, and this could be useful for applications where the concrete is not playing a structural role or where the full strength-potential of concrete is not required. For applications such as a foundation, or structural elements of the base of a wind turbine, the “sweet spot” is around 10 percent carbon black in the mix, they found.
Another potential application for carbon-cement supercapacitors is for building concrete roadways that could store energy produced by solar panels alongside the road and then deliver that energy to electric vehicles traveling along the road using the same kind of technology used for wirelessly rechargeable phones. A related type of car-recharging system is already being developed by companies in Germany and the Netherlands, but using standard batteries for storage.
Initial uses of the technology might be for isolated homes or buildings or shelters far from grid power, which could be powered by solar panels attached to the cement supercapacitors, the researchers say.
Ulm says that the system is very scalable, as the energy-storage capacity is a direct function of the volume of the electrodes. “You can go from 1-millimeter-thick electrodes to 1-meter-thick electrodes, and by doing so basically you can scale the energy storage capacity from lighting an LED for a few seconds, to powering a whole house,” he says.
Depending on the properties desired for a given application, the system could be tuned by adjusting the mixture. For a vehicle-charging road, very fast charging and discharging rates would be needed, while for powering a home “you have the whole day to charge it up,” so slower-charging material could be used, Ulm says.
“So, it’s really a multifunctional material,” he adds. Besides its ability to store energy in the form of supercapacitors, the same kind of concrete mixture can be used as a heating system, by simply applying electricity to the carbon-laced concrete.
Ulm sees this as “a new way of looking toward the future of concrete as part of the energy transition.”
The research team also included postdocs Nicolas Chanut and Damian Stefaniuk at MIT’s Department of Civil and Environmental Engineering, James Weaver at the Wyss Institute, and Yunguang Zhu in MIT’s Department of Mechanical Engineering. The work was supported by the MIT Concrete Sustainability Hub, with sponsorship by the Concrete Advancement Foundation.
Read More: https://news.mit.edu/2023/mit-engineers-create-supercapacitor-ancient-materials-0731
The idea is brilliant – using concrete to self assemble a matrix which can be used for a supercapacitor, out of cheap materials, is pure genius.
My concern is the application.
When capacitors fail they go with a bang. Old style televisions were notorious for this kind of failure, the loud bang which preceded the magic smoke was usually caused by capacitors suffering catastrophic dielectric failure, and releasing all their stored energy in a fraction of a second.
What concerns me is, if a TV capacitor explodes, abruptly releasing a few joules of energy, you spill your beer and curse a bit. But if a 10KWh household super capacitor goes, that’s 36 million joules of energy – equivalent to 8.6Kg of TNT, enough to turn your house into a sizeable crater.
10KW (10,000 watt hours) x 3600 seconds in an hour = 36,000,000 joules of energy
36,000,000 joules / 4,184 joules / gram = 8,604g = 8.6Kg of TNT
Even more interesting, brittle materials like concrete are vulnerable to mechanical shock. So that 8.6Kg of TNT equivalent, enough to utterly destroy a normal house, could trigger a chain reaction of adjacent dielectric failures, resulting in thousands or even millions of houses abruptly releasing their stored energy. And that’s not even considering the energy storage requirements of even greater concentrations of energy, like high-rise apartments and office buildings.
The failure of 115 adjacent household storage super capacitors holding 10KWh could release a kiloton of force – think the Beirut explosion in 2020.
Worse, each additional household energy storage system recruited into the chain reaction and explosion would increase the risk to the next house.
I’m thinking, that would not be a good day to visit town.
Of course, all this risk could be mitigated by using expensive spring or rubber loaded mounts and shock resistant supports, to minimise the risk of the house foundation capacitor detonating because of an adjacent explosion. I’m sure no building contractor would be tempted to cut corners and use cheap, substandard shock protection components, right?
So great idea guys, but please find another proposed use for your brilliant idea which doesn’t involve a small but non-zero risk of a nuclear scale explosion in a builtup area.
Yeah, the better the energy density, the more energetic a failure can be.
These capacitors almost make lithium ion batteries seem safe.
This whole idea is a crock. IMO it’s a spoof paper or a grant scam.
I don’t think they’ve taken into account that structural concrete constains rebar.
That depends, Charles. Strip and trench foundations rely on the compressive strength of concrete.
Concrete in tension, so beams/columns and the like, require rebar.
Civil Engineering Rebar 101
Strip & trench foundations
https://duckduckgo.com/?q=strip+and+trench+fill+foundations&t=ffab&atb=v380-1&iar=images&iax=images&ia=images
A Trench filled with concrete is= A Beam or ‘horizontal column‘
Trench foundations definitely have rebar in them. A point load pressing down from above will cause tension on the lower face, (unless the concrete is directly cast onto a stiffer material, like rock).
I have yet to see anyone build foundations for housing, using concrete and not have rebar, if not for the applied tensile loads, then to cater for the shrinkage cracks, as the concrete cures. A cracked slab/beam would otherwise result and it most probably would separate, with one portion drifting away from the other. Not good.
Yes, and our slab is also post-tensioned. There are pre-tensioned slabs around, as well.
(Sorry, this comment was supposed to be appended to Nicholas McGinley’s comment below.)
And slabs.
At the very least they require steel mesh.
Yes, ground bearing slabs require mesh
If you building on rock or gravel you may get away with just a strip foundation to level the ground.
Foundations are generally to provide a stable base and can be submitted to uneven support and uneven loads. That will require a steel armature.
Crikey, I’ve started something here, haven’t I?
All I can say is when I were a lad, a strip footing didn’t require rebar.
In the UK, a strip foundation is defined as:
This is an old image but the principle is the same:
They might not have required rebar when you was a lad.
They do now.
The purpose of rebar is not to help with compressive forces. Never has been. It’s to help the concrete to withstand everything else.
What happens to a foundation when it has to bear an uneven load?
That’s why even foundations have rebar in them.
Last word from me on this.
According to the current UK’s LABC Warranty Technical Manual, there is no requirement for rebar in a strip footing. These are one of the companies that would have to pay if if foundations failed.
It may be in your part of the world the requirements are different due to soil type or regulations, but here in Blighty, rebar is not a requirement.
Charles – spun Basalt makes good rebar material (and doesn’t rust, which considering this concrete would need to remain wet is a good thing). Costs a bit more than steel at the moment, though.
The rebar would create a better “plate” than their proposed carbon fibers. As long as the rebar in both slabs never touch, it wouldn’t be a problem. At least rebar would add strenth, rather than reducing it.
BTW, better, still doesn’t mean good.
I would be seeking advice from a civil engineer before claiming it could be used for house foundations or other elements such as concrete floors. Concrete is most commonly used in conjunction with steel reinforcing. Somehow I think the steel may interfere with their storage ability.
These guys are from the MIT civil engineering dep’t. Concrete in structures is their businass.
and there has never been a disaster caused by an ‘expert’ building something, has there?
https://en.wikipedia.org/wiki/List_of_structural_failures_and_collapses
Maybe I should have been clearer – a practising civil engineer – not an academic version.
It makes a *BIG* difference when what you do is subject to civil and criminal liability if you do it wrong!
My fear would not be capacitor failure creating an explosion but since there has to be a way of extracting that energy there would be a big possibility of accidental discharge caused by someone screwing around with the wiring. Enough people die from accidental shocks with common household wiring. I can’t imagine the potential accidents from high voltage, high current capacitor banks built into a home.
The amount of energy this capacitor would be capable of storing wouldn’t be enough to light a small LED for a few seconds. There won’t be enough energy to spark, much less explode.
Unlike other disciplines, most “academic” engineers practice prodigiously. They are mostly, fully, registered and certified. They also, often, take time off for real world projects. That’s the way it is at every “Mines” school I’ve worked with faculty from – including mine and the missus’s -, at my son’s Alma Maters, CPSLO, Stanford, and no doubt at MIT.
BoB
Yes and no. Research institutions (such as MIT) are not “Mines” schools. While civil engineering does require licensing if you intend to actually build things and, especially, sign drawings, many engineering fields don’t even have licensing requirements (such as min – aeronautics and astronautics).
Mine doesn’t, but it’s offered it optionally, state by state. I got mine a year in advance of when I was technically permitted, based on special recommendations. Oklahoma Professional Petroleum Engineering Registration #14428. Suss it out and find out my non Nom de WUWT!
But, so? Engineering professors stand for these creds just like everyone else, and use them, just like the others. Only at higher rates than non “academics”.
So you actually believe that a practical focused school like “mines” is comparable to a theoretic focused school like MIT?
Is there any swill you won’t swallow?
MIT is as “practical” as any “Mines” school. Yes, they are in a blue state, but, from the Civil Engineering Corps grads I served with in the Navy, to those on the leading edge of technologies in my line of work, they are as “practical” as they came. As a red state “Mines” grad, your ideologically biased blue state/red state distinction is fact free….
Get your assisted living Coordinator to take you and your fellow shut ins to see Oppenheimer on a field trip. Find out where General Groves got his engineering education….
Hi Nick,
What department were the MIT engineers from who wanted to build concrete spheres on the ocean floor to pressurize using windmills? That idea got properly shredded.
The simpe fact is that there is grant money out there for idiot ideas like this and researchers scoop it up. It doesn’t mean the idea is credible.
We bury power lines for the most part these days, cuts down on all the complaints from people claiming they get cancer from them when they can no longer see them. Can you imagine the complaints when a few people with electric foundations come up with health problems?
Well if you can imagine that these will pale in comparison to the first house that burns down. We store gasoline, propane, diesel and other fuels well away from our buildings because we’ve learned the hard way that storing that much energy IN the buildings is a bad idea. One of the reasons electricity is so safe is because it is generated and stored so far from our buildings. You want to make that much energy PART of the building?
LOL.
Nick,
these civil engineers know little about power enginering and they seem to believe the myth that storage is the answer to running a power system on renewables.
My dad poured concrete basements back in the 50’s. He always put rebar in, especially in the corners. Of course, he didn’t teach civil engineering at MIT.
Nick, the electrolyte they mention as being required will instantly begin corroding the steel reinforcing the concrete and rapidly destroy it.
It does not matter who they are and where they are from, concrete requires steel to be a useful building material, and potassium chloride is as corrosive as any salt can be.
When the steel corrodes it expands and the concrete is destroyed. Rapidly and completely.
“Potassium chloride is a chemical compound that is used in various applications such as fertilizers, food additives, and water treatment. However, it can have a negative effect on steel-reinforced concrete. Chloride ions can cause the corrosion of reinforcing steel in concrete. The main factor causing the destruction of reinforced concrete is the corrosion of steel reinforcement, about 80% of the damage is due to this phenomenon. Chloride-containing media are aggressive both to cement concrete and to steel reinforcement.
Tip13w.pdf (nrmca.org)
Steel expands as it corrodes, which also quickly fractures the concrete, allowing even more water in, which speeds corrosion, which …
Nick. I strongly suspect this paper is a spoof or a grant scam.
They are describing a battery, not a “super-capacitor”. They repeatedly talk about this being and “intensive property”, which would not describe energy storage or a “scalable system”. They talk of the capacitor storing “power” , when they store energy.
The whole thing reads like AI generated BS stuffed with sciency buzzwords and lots of crap about climate and “energy transition”.
This was NOT written by someone with even basic science training. If they are civil engineers they should not be designing super-caps !
How about you read the abstract of the paper and let me know what you make of it. You are very knowledgeable and I suspect you spot the BS straight away.
https://www.pnas.org/doi/10.1073/pnas.2304318120
Not a surprise that the world’s greatest expert on absolutely everything would fall for something as stupid as this. Stokes’ only filter is if an idea advances the net zero nonsense.
Nick, I graduated from the Massachusetts Institute of Technology (that MIT) many years ago. My favorite professors were those who had gone out and worked in industry, then acquired their earned doctorates and became professors. Way, way more practical than the 26-year olds who had just gone through school to the doctorate and were now professing, usually with no idea of how things actually work in the real world. The exception was my thermodynamics professor, who was just brilliant.
It is not inappropriate to give “these guys” some credit for having made the grade, as profs or grad students, at MIT, but as the comments in this thread show, “these guys” could do with some help from real engineers, who have gotten their hands dirty in the real, civil engineering world. They also really need some help with their risk analysis.
That this idiocy could come from a MIT civil “engineer” is just further evidence of how far standards at MIT have fallen.
Concrete is strong in compression, very weak and brittle in tension.
Without steel reinforcement, it is worthless as a building material.
Salt corrodes steel and causes it to expand, making the concrete into a pile of gravel.
These jackasses have no idea what they are talking about.
And what is this crap about ten kilowatt hours being a daily supply for a house?
That is less than the average EV car owner uses just to charge their car.
Over one third less in fact.
Overall, in the US, an average home uses between 500 and 1200 kilowatt-hours a month.
2 to 4 times what they state in this article, and that is with a ton of stuff using other power sources.
By the time we all have to use electricity for everything from our cars to cooking and hot water and everything else, it is gonna be way more than what it is now.
IOW, these people are either big fat liars or complete idiots who have no idea what they are talking about.
Look up some numbers, Nick Stokes, and tell me I am wrong.
Additionally, are they storing the energy in the foundation of a typical 1400 – 1800 square foot home (USA), or a 5,000 square foot MacMansion? Size matters.
And they feel content that the capacitor will discharge during the day and be able to be recharged during the night (while the cars are recharging???). What is there is a typical multi-day lull in the output of the blessed renewables, such that the foundation can’t recharge. Shouldn’ this super cap be designed for, maybe, 2 weeks’ use?
If you’re on an island in the ocean, and need to build, say, a runway so that aircraft can deliver military supplies and personnel, do you use seawater to mix the concrete? Well, not if you use steel rebar. The salt in seawater causes more rapid corrosion of the steel, which eventually causes the concrete to fail.
In order to avoid the need to import large amounts of freshwater just to make concrete, the US military developed Kevlar-reinforced seawater concrete. It works very well. And Kevlar is not electrically conductive. More recently, people have experimented with basalt fiber reinforcement, for the same reason. I believe it works fairly well.
The underlying paper is here
The potential for catastrophic failure will depend on the internal resistance, as will the usefulness of the capacitor. The paper doesn’t say much about that, and I think with such a structure they would be struggling with high resistance.
The potential will depend on the amount of energy stored, period. You can’t decide ahead of time what factor catastrophic failer will depend on. Even with rigorous testing of full scale implementations (not the tiny things they’ve built) all you know for certain is that you’re building a house on a bomb that you don’t believe is going to explode.
Waiting for Nick-wit to get one of these, to hook up to the massive wind turbines in his back yard. ! 😉
Or getting set to fry the first raccon that come by. (We lost a day of work once when a racoon decided to eat the nearby substation – the sort of practical, “lived experience” that “these guys” appear to lack.)
These are the building code regulations in the UK for oil tank siting:
It is possible to site a fuel storage tank inside a garage or out-house; however, they need to be self-contained within a 60-minute fire rated chamber.
The tanks themselves must be dual-walled, and must be footed on a concrete or paving stone base which extends a foot or so beyond the tank.
And this is for tanks containing heating oil, kerosene, which is not explosive and which doesn’t even catch fire very easily. If anyone is seriously thinking of building energy storage at this scale into the foundations of a house or block of flats, the first thing they should do is contact Oftec in the UK, or equivalent elsewhere, to get their views. I think the chances of getting approval will be few or none.
The idea of locating a 10ft cube battery storing 10Kwh in your garden will also only be allowed with quite some safety conditions. Can’t quite imagine what they would have to be, to be safe, and then to convince the agencies that it will be safe when done at scale in say a suburban neighborhood or a village with reasonably close situated houses and gardens.
Seems like another green pipe dream.
Yes, while carbon black is a conductor, it is a high-resistance conductor, typically used to make discreet resistors for electronics circuitry.
We do not want to transition to wind, solar or wave. We already have reliable, safe and affordable energy sources in fossil fuels and nuclear. Get the government out of the way and all will be well. No mandates, no subsidies, no preferential tax treatment and no bailouts for renewables.
With inexpensive and reliable storage, solar panels might be quite useful in some locations, particularly off grid or as backup to grid blackouts. UPS systems are widely used and not only because of badly unreliable grids. What if you had to keep your insulin supply stable when a major storm hits — or die?
I have no problem with individuals or groups using wind, solar or waves. That is their choice and they should pay the full cost of those systems. They should not be connected to the grid. The grid has enough problems without including the short comings of wind solar and waves.
“We already have reliable, safe and affordable energy sources in fossil fuels and nuclear”
Yes … but … it wasn’t always safe and affordable energy;
history is littered with fossil and nuclear fuel accidents & fails –
Explosions & fires
Coal mines, Steam Boilers, Gasworks & gas mains;
Oil wells, Oil pipelines, Oil Refinery’s, Oil storage;
LPG & NG ;
Nuclear meltdowns (few, but significant when they happen)
Good Engineers learn from other peoples mistakes & try to not repeat them, which is why we have reliable, safe and affordable energy sources in fossil fuels and nuclear.
Politicians have visions/agendas so think they can never make mistakes (just pass the blame down) & keep doing the same thing, but expecting a different result.
As an electrolyte KCl can be used, and would be adequate. However, at scale how are they keeping the “plates” separated, and what is the dielectric layer that makes the gap nonconductive. In Aluminum Electrolytic capacitors that is done my the oxide layer. Now I haven’t read the paper, but the article published here shows a small demonstration using an LED as a load. I would have been more impressed if they stated the efficiency of the system. Watts vs Watts out. What is the equivalent series resistance? What was the capacity in Coulombs per units volume? How long does the dielectric last? What are the structural characteristics of the carbon in the cement. What about the use of aggregate and rebar? How does the dissipation factor change over time? If the dielectric fails at full charge what happens to the electrolyte? Is it converted to steam and explode?
This sounds like a trolling for Venture Capitol activity to me.
‘I don’t think it rises to that level, more like a hunt for some research grant mula.
What is the dielectric layer thickness? I seem to recall that foundations are composed to a large extent of very nonuniform aggregate. Are they talking about depositing alternate layers of conductor and dielectric? Of course they are. Sorry, but there will be no aggregate in the capacitor foundation. It’s just another space elevator scam.
I’ve worked with capacitors for many decades, including those old tube televisions with their large leaky electrolytic capacitors. Failure due to leakage was once common but I never experienced, or heard of, an explosive failure. Shorting a large, charged electrolytic could produce a sizeable spark, however.
The idea is certainly interesting. Nothing was said about the self leakage rate. It would have to be very slow to be useful as a storage device. Concrete could contain some conductive material, aside from the carbon black, throughout it. Perhaps very stringent (and expensive) quality control would be necessary to produce devices that would store for very long.
This also raises the question whether some much lighter material than concrete could be engineered into a similar response. That might make much lighter batteries possible. Just how rapidly could a large one be practically charged?
I’ve had explosive failure happen twice on old TVs, and once on an ancient computer. Impressive snap sound when they go, like a whip crack or firecracker.
Thye do explode, but it is more of a bursting than a bomb sort of thing. They instantly discharge whatever power is in them, and that can be loud and scary and even very dangerous if it is a large capacitor.
Many of them have toxic goo inside of them.
I once was part of a maintenance dept for a major telephone company. One of the central office fires we investigated was traced to a capacitor in a relay rack of N-carrier equipment exploding and catching fire. The source was quite obvious from the smoke and soot trail going up the relay rack like a cone.
This was from a *small* capacitor being used in 24v powered equipment. Multiply that by at least one order of magnitude if not more.
They can explode and they can catch fire, yup. I have seen that many times.
But not like a bomb exploding.
It is a pressure related bursting.
A bomb is created by containing the expanding gas until the shell shatters.
Most large capacitors have a built in weak spot to release the pressure before it can get dangerous.
I once had an electrical engineers from pump manufacturer tell me (and the rest of a teleconference), that “capacitors do not fail”.
Licensed PE, no idea what the eff he was talking about, zero real world experience, never left an office in his entire career. He was sure he was saying something that was safe to say.
I walked out to my warehouse and grabbed a handful of burst capacitors from his pumps that I had had to replace.
Ebara, was the company.
Wastewater pumps that we had tried to repurpose at their recommendation.
Nothing like real world experience as a teacher of reality.
I am reminded of climate science academics that say all measurement uncertainty is random, Gaussian, and cancels.
Toxic and often corrosive. You need to get the board out and clean it as soon as possible, unless you were planning on replacing the whole board anyway.
For 17 years I was service manager for a fountain company, and most of them used single phase submersible well motors.
All large motors use capacitors, and well motors over 2 HP that are single phase use a thing called a motor control box, also known as a starter box.
Various start and run capacitors are contained in the box, along with various relays and switches, such as thermal overload relays and the relay that disconnects the start capacitors and engages the run capacitors once the motor is spinning.
The do not exactly explode like a bomb or anything, but they definitely explode. They do not last forever either. They can last a long time, but that is hardly guaranteed. They can catch on fire, and when they fail they expand to many times their original size.
Does not sound like a great idea for a house foundation.
IN any case, almost all of these new brilliant ideas go nowhere.
But the people who come up with the ideas often get handed huge fat stacks of cash to test out the idea.
Super capacitors are not a new idea for storing power instead of batteries, and all efforts have come to nothing.
Capacitors are used in various applications because they will discharge all of the stored electric charge in a very short time, fractions of a second. But they are not batteries. They will discharge spontaneously unless the two plates are perfectly insulated from each other, and there is no such thing as a perfect insulator.
The insulation on a typical electric wire or copper winding has insulation rated in the megaohms, but this is still letting in many cases quadrillions of electrons go right through it every second if voltage and amperage are large. And 1 amp is equal to 6.2 times 10 to the 18th electrons( >6.2 x 10^18th)…per second!
Just go ahead and do the math…I have many times many years ago.
The possibilities are endless. The capacitor is your garage floor. It blows and ignites your electric cars batteries. Wow!
Oh, how they yearn to see a bomber burn
Color flashing, thunder crashing, dynamite machine
Wait till the fire turns green
Ha ha, good catch – a built in BEV igniter!
Even if all it does is wreck the slab, your home is now destroyed.
And when it goes bad, even if it just stops working, how can it be fixed?
Pour a new foundation for your home?
Hah!
Oh, yes, the other thing guys with “pet rock” ideas always forget – maintenance and support, and ultimate disposition.
Seems like buzzword abuse. The specific energy is about 0.15 WH/kg, right in there with ordinary capacitors. Supercapacitors are more like 4 WH/kg.
Finding electrical ordering like this is pretty cool. The feeble energy density (770J/kg) seems to me hardly something to worry about regarding a violent failure. On the other hand I did see what the velocity of a 1kg brick needs to be to have 770J kinetic energy – about 39m/sec (!). Like it fell 75 meters. Ugh, a hard hat would not help there.
Making little pellet size models is one thing, scaling many orders of magnitude to something of useful size seems highly unlikely – I’ve a feeling the factors AndyHce mentions below will reduce the usefulness to the point of not offsetting the additional cost and structural negatives.
I wonder what an electrical failure would be like in a large capacitor slab as proposed, some 65,000 Kg of concrete? Not a high order release I’d bet. Possibly some intense local heating/cracking/melting, but I doubt you’d notice anything without some monitoring equipment, unless you saw steam or smoke coming up from the floor somewhere. I would guess (I’m not an electrical anything), there would be busbars or something to interface and conduct the power, those might be problematic. Personally, I rather not be living on top of something like this.
The number of possible chemicals that could be produced inside of a slab by electrochemical processes is large, and many of them are dangerous.
This is a rotten and awful idea.
When the thing fails, your house is destroyed and a toxic waste site.
Super capacitors have a very low voltage limit, and since energy stored is proportional to the voltage squared, (where v is (Vcharged – Vdischarged).
And SC also fail badly when the voltage limit is exceeded. Punch through leading to a short between the plates. All capacitance gone in a flash.
And what happens if there is a nearby lightning strike? Will the capacitor carry ground current, most probably in the hundreds of volts range, (based on series resistance), at that voltage, is it all over? Could we expect a suburb to lose it’s batteries as a storm goes over. If so, can you ever replace them?
Oh, and let’s site these things on a fault line in California.
dear gods what a load of crap..
They don’t understand what a capacitor is = something that uses electrostatics and NOT moving ions and electrolytesThus they’ve built a really shonky battery…,,, they claim it has an energy density of 220Wh/m³ -compare to a standard car battery of 60kWh/m³(They themselves say) You cannot apply more than one Volt to it less the water decomposes to Hydrogen & Oxygen. That’ll be nice.They describe it as being ‘porous concrete’ = something with the usefulness of a chocolate fire-guardApply any more volts and it will start generating Chlorine gas and metallic Potassium -….which will react with the water in there to make Potassium Hydroxide……. Real Hazard #1 = that reaction gets extremely hot which will boil the water and explode the concrete. THAT is your explosion hazard…..Real Hazard #2 is that Potassium Hydroxide is akin to Caustic Soda and for living critters is The Most Dangerous/Destructive Stuff EVAH….(on contact, it turns you into soap. Literally)Unless insane and impossible to maintain efforts are made to exclude water – it WILL at some future time self destruct…….by the same principle of ‘Natural Variation’ – aka Soil Erosion, all naturally occurring water will be a solution of Carbonic Acid and this is the primary destructive force for all ‘rocks’ – including concrete.So as soon as any acidic water gets into it (it is porous after all and all water is acidic), mosses, lichens and bacteria will move in to eat the nutrients within the concrete and very effectively short circuit the thingIt is more wrong that a really wong thing – it has perfctly NOTHING in its favour and is potentially an extremely dangerous and toxic device.
And these children/muppets/clowns want to build houses with it
<weeps>
edit. I’m gonna let the ‘wong’ typo ride – as a mark of respect to Chinese EV manufacturers and their valiant and increasingly successfully attempts to destroy peoples lives, homes and cities
Thanks Peta, I didn’t know about the potential chemistry (I’m not a Chemist either), but what you say sounds reasonable.
Peta,
Thanks, you’ve reinforced the impression that this was a nice science project, but an engineering non-starter.
Many, many things to consider when developing a new product. The technology is important. Next, hazard / risk analysis. Then economic analysis. Next, can it be built? Can the necessary quality issues be solved at a commercial construction site by today’s contractor community? Is training necessary. Then there are the maintenance and support issues. Ultimately, how ill it be disposed of at end-of-life? Is site remediation necessary?
Just a few issues that engineers have to deal with in fielding a product.
And from some of the comments above, including yours, is this idea even remotely good enough, technologically, to be one of those breakthroughs that the Net-Zero crowd is expecting to happen and be in production massively in time for 2050?
The Aluminium electrolytic capacitors, still used in electronics today, had the added bonus of producing hydrogen when they failed. Often the gas pressure forcing a rupture was the first event in Catastrophic failure. Often spreading electrolyte all over the electronics causing short circuit problems.
The top plate of these devices has a safety valve of one sort or another to prevent a huge pressure build up and even more spectacular failure.
Does this new technology produce a flammable gas as a byproduct of failure?
A capacitor the size of a house or street could be more of a problem to fire fighters than a row of buses.
Large capacitors usually have a case that is three-sided, sort of cup shaped, with the open end a piece of cardboard or some stiff plastic, held in place rather loosely with a metal clip designed to released very readily.
I know stories about motor capacitors and clueless over-zealous safety & health czars.
These are the type of electrolytics I worked on about 50 years ago. Things haven’t changed a great deal since.
Your pictures look like motor starter capacitors, which where a different technology*, suitable for the application. Caveat things may have changed in 50 years
*Electrolytic capacitors used in electronics are usually DC rated, with the anode “plate” in the winding made from etched and formed (electrically grown layer of oxide) the higher working voltage the thicker the oxide layer the larger plate for the same capacitance. The cathode is etched with minimal forming giving very high capacitance per unit area. The reason for this is that an electrolytic capacitor is basically two capacitors in series. the total capacitance is less than any one of the series capacitors’ individual capacitances, having a very high value means that the total is as close to the formed anode as possible. The electrolyte is liquid.
Motor Starter capacitors have no polarity, both plates are formed and the electrolyte is solid. Because these capacitors are working with single phase AC they cannot use unformed foil for either plate.
In both cases if the formed foil plate has not been created at a high enough voltage for long enough or has been damaged during manufacture then the oxide is (re)formed during use creating hydrogen and heat neither are a good thing.
I suspect that what is being proposed for a building is a polarised capacitor. Two reasons
But if a 10KWh household super capacitor goes, that’s 36 million joules of energy – equivalent to 8.6Kg of TNT
=====%
A small short range EV has a 30KWh battery. 25Kg of TNT? Same energy as one gallon of gasoline. But a gallon of gasoline weighs 3Kg.
A 1kg chunk of wood – 18MJ
The critique of the MIT concrete capacitor above is totally off base (LOL).
Beirut was 500 to 1100 tons of TNT – you would need 52000 to 127000 houses’ concrete bases worth of electricity to match, assuming 45 cubic meters of concrete/10kWh storage per house (which is roughly accurate).
Pretty clearly there is a unit calculation error above.
Plus Beirut was a single warehouse with tons of ammonium nitrate; 52000 to 127000 single family homes would not be concentrated even remotely to the same degree.
The real problems are:
1) Scale. The 10kWh is for 45 cubic meters of concrete. In order to store 1% of the US’ electricity consumption per year = ~4000 terawatt hours, you would need more concrete than the entire world produces in a year…times almost 13:
4000 billion kWh * 0.01 / 10 * 45 = 180 billion cubic meters of concrete vs. world annual concrete production of 14 billion cubic meters.
This is a huge materials problem.
2) Time Cost. Materials cost might be low, but the process above does not seem like a “fire and forget” setup. How much time does it take to “self-organize” the supercapacitor vs. a normal slab creation? Special temperature controls? Humidity controls? Mixing? Electrical Connections?
3) Repair. Stuff breaks – how do you repair a concrete slab? Tear it out and re-lay it? There’s also safety issues with things like flooding or even high humidity…
4) And related to the above 2) and 3): How much longer/difficult to create = money cost. Saying materials are cheap and abundant is pretty irrelevant if you’re building 100 ton objects (yes, 45 cubic meters of concrete weighs 100 tons or so).
And so this underscores the error in focusing on the explosive power of 10 kWh vs. 45 cubic meters of concrete; 8.6 kg of TNT would bounce off far smaller concrete objects much less the 100 tons actually involved.
Capacitors are generally made to be a self-contained unit that is inside of an accessible compartment specifically because they may need to be replaced at any time.
They are not permanent, that is for sure.
A given one may in some instances outlast the device it is part of, but they can also fail within a week.
Building it into the foundation of a house, the most expensive thing most of us will ever own, is, in scientific parlance, wack-job nutso.
I bet homeowners insurance companies will be less than thrilled with such an idear.
It seems they’ve also forgotten the problems of temperature and moisture related expansion/contraction issues. One season’s weathering, it’ll fail, if it ever worked at all.
Capacitors are sized by Farads, not by how much “energy” they contain (which varies).
One Farad is defined as being capable of storing one Coulomb of electrons at one Volt.
Double the voltage and you double the number of electrons stored. This can continue up to the limit of the dielectric.
Mark,
Just a point on electrical energy, doubling the voltage does not double the number of electrons, they stay the same. It will increase the speed or movement of the electrons, known as amperage. The number of electrons in a given length of conductor stays the same regardless of the change in voltage.
Let’s keep in mind they have no working prototype yet. So this is all at the “Hey, maybe we could…” stage.
And we know how many of those ideas go from light bulb over the head to something that is economical and actually works: Almost never.
But with trillions of dollars available for the asking for anything anyone can think of, as long as the use all the correct buzzwords, it is not like they have any incentive to be sure they have something that might work, or that might work well enough to be commercially viable.
They only need some talking points.
In other words, nothing but yet another climastrology model.
The article is more of an euphoric brainstorm session after a potentially patentable lab experiment. I don’t think I’d be willing to invest very much in this technology until some larger-scale attempts are made that can demonstrate scalability beyond a 1 mm thick, 1 volt experiment.
19 lbs of TNT isn’t going to turn your house into a smoking crater! And this explosive energy is distributed throughout the entire concrete foundation, so the energy density at any one location is very small – not at all like having 20 pounds of TNT concentrated in a small volume!!!
So the volume of actual TNT: it’s density is 1.65 g/cc x 8600 grams is 14.19 liters of actual TNT.
The volume of a home foundation, say a home with 2,000 ft² floor area is 1720 cubic feet of concrete (6″ thick, 8 foot basement height) which is 48,700 liters of concrete volume.
So concrete volume of 48700 divided by TNT volume of 14.19 liters is 3,432 times less energy density as the actual TNT, if 36 MJ is released, then the TNT energy density is 2,540,000 Joules per liter. And the concrete would be 739 Joules per liter energy density.
You might hear/feel a little “pop” or “crack” from the concrete supercap explosion…..
No I would be more worried about messing with the structural integrity of the concrete as was the case in the Florida Bridge collapse when they experimented with some special concrete formulation that “self cleaned” and absorbed atmospheric CO2…..
https://www.youtube.com/watch?v=mCuIwK2_CYo (FIU Pedestrian Bridge Collapse(
How is the energy put into the thing, and then removed?
It will have to be concentrated into some wires at some point.
Those wires will have to form a network to all the subunits of the thing.
So, when something starts to heat up for any reason, because after all, things do fail, how will that heat be dissipated? Concrete is not noted for being a good conductor of heat.
The foundation of your house is the last place you want to have any problem at all.
This entire thing will be completely inaccessible and unfixable.
Any failure mode which in any way damages the slab and now you have a destroyed house.
What could go wrong?
I was not advocating for this entirely dumba$$ idea. I was pointing out the silly knee jerk suggestion by the author that this is somehow comparable to detonating 19 lbs of TNT – is simply ludicrous and entirely implausible. The energy density of this stupid concrete as supercap idea is simply too low to create any “explosion” if it fails catastrophically.
I speak with actual experience on using both high and low order explosives in conjunction with my lawful occupation… For a taste of what 5 and 10 lbs of TNT does watch this:
https://www.youtube.com/watch?v=kq4-fGrleRU (Explosive Cancellation MiniMyth | MythBusters)
The notion of changing the structural properties of concrete to make a super cap, or to self clean or to sequester CO2 – is extremely dumb and in the case of the FAU bridge collapse, fatally catastrophic.
FFS that is NOT a capacitor, it’s a description of a battery !!
Two gold leaf films in a vacuum can act as a capacitor. No “electrolyte” needed.
That’s what happens when you let arts graduates write technical pieces for the University rag.
Having just scanned the abstract of the paper it looks like total pseudo-sceintific BS full of buzz words without actually saying anything of scientific relevance. I strongly suspect this was written by an AI. They talk exclusively about “energy” storage when quite clearly they are really talking about electricity storage. While storing electrical charge is storing energy, it is much more specific and it’s hard to see why any material scientist would talk about “energy” when specifically working on electricity storage.
They repeatedly crap on about “intensive property” of the material:
An intensive quantity is one whose magnitude is independent of the size of the system. Temperature is a common example. ( If you have twice as much of something that does not make it twice as hot. )
That does not seem to be useful property for a “scalable” energy storage system. Neither does it seem likely to be the right word since any kind of energy storage would an extensive property.
I’m not sure what is going on here but it looks like total BS. I don’t know whether its a spoof, a joke or some clown used chatGPT to write their paper and it got published because every paragraph starts with some guff about “energy transition” and climate.
If someone knows where to run this text through an AI detector , that would be interesting.
BINGO !
I just posted this snippet of their abstract into scribbr’s AI detection page and it gave it 91% AI rating !!!
https://www.scribbr.com/ai-detector/
I agree, it is total nonsense, the units they used make no sense.
We can give them an A+ for bafflegab anyhow, eh?
You are right about this not being the description of a capacitor.
A capacitor is two metal plates separated by an insulator, not an electrolyte.
The definition of a capacitor I recall from first year physics was two metal plates separated by a dielectric, and I think this is a more accurate description than calling it an insulator.
The key is polarizability, which is what a dielectric has that a ordinary insulator does not.
That polarizability is the key to the energy storage capacity.
If you place an electric charge on two opposing metal plates, with an electrically conductive material in between them, IOW an electrolyte (there are of course other types of electrically conductive materials besides electrolytes, but electrolytes by definition conduct electricity), the plates will immediately discharge because well because you have an electric potential and a material capable of conducting that charge.
That definition you quoted is very definitely incorrect and badly so.
It was the first thing I was thinking this morning when I read the article, but I had a doctor appointment and got sidetracked by the other comments.
But yeah, I was thinking, is my memory that bad, or is this definition 100% wrong…
Glad to see when I had a chance to look it up, my memory was not wrong at all.
So they got that wrong.
They got power usage for an average home way wrong.
Only home using that little power in the US would be a small apartment in a temperate climate, IOW, not much heat or AC required. And definitely no electric car. I think places that use such a small amount of power use gas for hot water and cooking.
Then they seem to think structural concrete, which they keep calling “cement”, will not be bothered by having potassium chloride chocked through it. Or that steel inside of a large diffuse power storage device will not immediately short the thing out.
But the big mystery is, which would anyone try to build something like this into the foundation of a home? Homes are meant to last a very long time, are very expensive, and need to be made to be as safe and stable as possible.
One last thing I was wondering about, is the coefficient of linear thermal expansion of this carbon? Steel works as a reinforcing material in concrete due to the two materials having very close to the same expansion coefficient. I do not think carbon does. I think carbon is much lower.
I believe there is a clear technical difference between batteries and capacitors. Batteries convert and store electricity in chemical form whereas capacitors store electricity as charge.
I can see how carbon could be used to store charge. It is the self organization part sounds highly speculative to me but the core principle is believable.
But even if the self organization really worked at the scales needed – my point is that there is no part of this solution even at ideal functionality that makes for a real world use case.
The charge stored is proportional to the dielectric constant (polarizability) of the material between the plates. An air-gap capacitor, commonly used to vary the capacitance for tuning a radio, can use air as the insulator and dielectric because the voltage is commonly low. Higher voltage require wider spacing and reduces the capacitance proportionally. One can use a vacuum for the dielectric, which is common in very high voltage applications. An over-voltage arc doesn’t usually destroy the capacitor and it doesn’t splash goo all over everything.
In designing a capacitor, there are two things to be concerned about. The capacitance, which is a function of the plate area, gap, and the dielectric constant of the intervening insulator, and the breakdown voltage, which is a characteristic of the insulator. It is possible to make a composite capacitor of a material with a very high breakdown voltage (very good insulator) and a material with a high dielectric constant, but lower breakdown voltage, to get closer spacing and hopefully have the best of both worlds.
Electrolytic capacitors are interesting animals:
https://en.wikipedia.org/wiki/Electrolytic_capacitor
This is a rather tortured definition: a capacitor is two electrodes separated by a nonconductive medium. The medium can even be air.
kiloWatt-hours is a strange unit for a capacitor size, it should instead be Farads; kWh is a unit of charge, and the charge in a capacitor depends on the voltage across the electrodes.
Error: kWh is a unit of energy not charge.
That is not “tortuous” it’s flat out wrong. That is NOT the description of a capacitor. As you say a capacitor has a NON CONDUCTIVE separation, not an electrolyte. What they describe is a battery.
This is total BS. My guess is this was created by chatGPT or similar.
It sounds like a description of an electrolytic capacitor. Electrolytics are normally two plates of alumina sitting in electrolyte. When the electricity switches on an insulating oxide layer forms. The advantage of this approach is the oxide layer is very thin but high resistance, which makes for a good capacitor.
From what I have read, a typical electrolytic capacitor has only one plate, made of one of only three metals, aluminum, niobium, or tantalum, the oxide layer it acquires is the dielectric, and the electrolyte gel is a coating on the outside of it that performs the role of cathode.
Nothing about two plates, nothing about an insulator in between.
Insulators in general are not the same as dielectrics because they are not generally polarizable, and that polarization is critical.
In any case, quibbling aside, the definition given in the article is wrong.
It says nothing about that being the definition of a certain type of capacitor.
It does not specify metal plates, just conductive, does not mention most metals will not work , only ones which form an insulating oxide layer, etc. There are only three families of electrolytic capacitors, aluminum, niobium, and tantalum.
I think an objective fact check has to call their definition false, since as stated it is simply not accurate.
As a general definition of capacitor it is wrong, and as a description of the subtype called electrolytic capacitors, it is also wrong.
It seems to be a mishmash of definitions.
The insulator (and dielectric) is the (aluminum/aluminium) oxide that forms on the anode, with the help of the electrolyte, when a voltage of proper polarity is applied.
I think that what we are looking at is a tech’ writer being replaced with AI.
I was trying to be kind.
It is just units.
Farads is amount of charge stored; kWh is discharge over time.
Farads times voltage over time = watt-hours.
Consider farads in a capacitor to be the equivalent of amps in a battery; current times voltage over time = watt-hours from a chemical battery.
farad = charge/volt . F * V / s = Q/V *V/s = Q/s = electrical current.
I*V/s = W/s = rate of change of power (whatever that is for). It is NOT power * time , which is energy. A watt-hours is a unit of energy.
If you do not understand basic physical units , stop posting giving us all a physics lecture and pretending that you do know something.
Change your pseudo to c1ue1ess 😉
Capacitors do not store “power” they store electrical energy. This NOT written by a physicist or a materials scientist.
What they are describing is a kind of electrical BATTERY, not a “super-capacitor”. Anyone making this mistake has never developed either.
Is this someone trying to spoof PNAC into publishing a fake paper to expose thier lack of genuine peer review, or someone trying to scam some public funding grant money ???
Also, the surface area of the two plates is determined by 3 factors, not one.
Size of the plate
Distance between the plates
Material between the plates.
Technically you have point, but in common parlance, electricity is frequently referred to as “power”, as distinct from other forms and sources of energy.
And since this is a technical paper, it needs to stick to proper technical terminology to be credible, not to mention accurate.
The number of factual errors is astoundingly huge, so you may be onto something here.
Hard to believe the bona fides they mention, MIT, post docs, etc.
Easy to picture them having a laugh as they get an AI to write this gobbledygook and then ask for a huge grant.
Too stoned on Bud Light and Zombie-Kush to be bothered to write a real paper?
Capacitors do store power. Power is simply current or charge times voltage over time. Generally speaking, capacitors are for high speed discharge but there is nothing that forces this to always be the case.
Cost is the limit. It’s very expensive to have a usable, long-term storage, low-leakage capacitor.
Current and charge are NOT the same thing. Power is current * voltage because current is already “over time”.
Three points.
If you want to store “energy” in concrete, thoroughly insulate it thermally and use it to store heat. Drill deep and add a heat pump.
Why mess with house foundations?
Just plug into people!
It worked in The Matrix. (At least for their AI masters.)
The paper abstract uses the term “intensive property” three times. Energy storage is an extensive property.
I’m calling this out as chatGPT generated crap.
This is climate porn, not science.
Many fine technical descriptions of what can go wrong with this ridiculous idea in the comments today. Having been an electrical engineer before I retired, I will only add that besides the dangers described, capacitors are not perfect storage devices. The smallest fault in the construction will cause them to leak off their charge rendering them useless for this purpose. Capacitors are generally used for very short time frame storage, not much more than milliseconds, such as phase shifting, AC ripple smoothing, motor start etc. Long term, not practical due to leakage. Besides, the usual building construction methods are not noted for microinch tolerances, necessary in a quality capacitor. When they say their technology is scalable, they are WAGing it, not even SWAGing.
Charging cars from the road.
They will be lucky if they manage to get 1% efficiency from that.
Actually I would be a lot more worried about people/animals getting zapped from short circuits due to rain, oil slicks etc. Road surface charge storage is utterly insane.
This article demonstrates the danger of letting social scientists try to do real science.
The capacitance of a capacitor is determined by 3 factors.
1) The surface area of each plate of the capacitor.
2) The permeability of the dielectric.
3) The average distance between the plates.
While it may be possible for concrete to serve as a dielectric, I doubt it is a good one.
By the very nature of the beast, the two plates are going to average probably 6 to 9 inches apart. (To keep that in perspective, most commercial capacitors try to keep that distance to less than a millimeter.)
Beyond that, where did these morons get the idea that there are air gaps in the concrete just waiting for carbon fiber to fill them? If you have ever watched someone laying concrete, one of the things they do is vibrate the mix in an effort to force all of the bubbles out. Air gaps mean weakness.
As to soaking the concrete in any form of salt. That’s a good way to rapidly decrease the concretes life expectancy.
The idea that such a structure is going to provide more than a few micro-farads per square meter is ludicrous.
Huge cost, decreased performance, no noticeable gain. Socialism in action.
I have an idea for using nitroglycerine as an electrolyte in a hypercapacitor. Would anyone be interested in getting in on a ground floor investment? I can assure you that your investment will explode over a short time period.
Finally the argument over licencing of academic engineers has no simple answer. At WSU (Mfg. Eng) and UW (Mech. Eng) I was the only engineer with a P.E. for a long time which is why I was assigned to senior design duties. I was an adjunct in Civil (UW), but never canvassed the department to learn who had a P.E. and who didn’t. At MIT even the ABET certification varies by department.
Academic engineers can be sufficiently narrow to not understand many design issues. Just sayin’.
as part of the paris accords, make a new UN building using this. And any government that pushes it, make their office buildings out of it
45 cubic metres for 10kWh? Pathetic. The Finns claim to manage 8MWh in 100 tonnes of sand:
https://polarnightenergy.fi/technology
I have to disagree with the destructive potential of this kind of capacitor, at least one with the energy density they project. Your calculation of 10 kW-hr = 8.6 kg TNT is correct, no question about that. But recall that this would be the energy stored in 45 cubic meters of concrete, a material whose density is about 2,400 kg/m^3. The specific energy of the entire mass would then be 36,000,000 J/108,000,000 g concrete = 1/3 J/g. The specific heat capacity of concrete is 0.88 J/g-degree C, so at worst the concrete would heat up by 0.38 degrees C. I don’t think that could lead to catastrophe.