Heating things up is one of the biggest sources of cost and emissions for many industrial processes we take for granted. Most of these factories are running around the clock so they don’t have to waste energy cooling off and heating things back up, so how can you match this 24/7 cycle to the intermittent energy provided by renewables? This MIT spin-off thinks one solution is thermal storage refractory bricks.
Electrified Thermal Solutions takes the relatively simple technology of refractory brick to the next level. For the uninitiated, refractory bricks are typically ceramics with a huge amount of porosity to give them a combination of high thermal tolerance and very good insulating properties. A number of materials processes use them to maximize the use of the available heat energy.
While the exact composition is likely proprietary, the founder’s Ph.D. thesis tells us the bricks are likely a doped chromia (chrome oxide) composition that creates heat in the brick when electrical energy is applied. Stacked bricks can conduct enough current for the whole stack to heat up without need for additional connections. Since these bricks are thermally insulating, they can time shift the energy from solar or wind energy and even out the load. This will reduce emissions and cost as well. If factories need to pipe additional grid power, it would happen at off-peak hours instead of relying on the fluctuating and increasing costs associated with fossil fuels.
If you want to implement thermal storage on a smaller scale, we’ve seen sand batteries and storing heat from wind with water or other fluids.
What we really need is seasonal energy storage. Eg. capture excess solar energy during the summer to use for heating during the winter.
That’s a harder problem to solve, at least economically, as it implies a chemical change such as creating biofuel from just electricity. When that becomes possible, it opens the door for households to truly be off-grid, rather than using the electric utility as their “battery” for excess energy.
We need seasonal energy storage. We also need daily/off peak energy storage. We have neither. Tackling off-peak energy storage is still viable and can lead to better solutions for seasonal storage.
I feel like the simplest technical solution to off-peak energy is connecting power grids around the world. If everyone was connected then excess solar from day areas could power night areas and summer area/winter areas.
Resistive voltage drop already makes long distance transmission lines (something like >500mi) very difficult to justify economically. It can be justifiable for resilience, but eventually inefficiency becomes unavoidable.
Not really. China have longer than 3000km HVDC line, and several >2000km line.
Not to mention that many of these lines would have to be laid underwater.
Recent history in the Baltic sea shows the issues that can arise when you run your important energy and data links through areas vulnerable to (checks notes) “accidental anchor drags” and “inadvertent mystery explosions”
These are point-to-point connections that don’t exactly connect the communities in the middle. You can’t just tap into the middle of a HVDC line.
Smelt aluminum. Oxidise it to release the energy.
It’s great idea, but pretty hard to control. Better idea and already trialled is to oxidise and reduce iron. Seems like iron is also a little more environmentally friendly, when you have some small emissions from furnace.
For that you probably want phase change materials. Particularly ones like sodium acetate trihydrate that stay melted until you trigger their recrystallisation. That’s the same stuff in some instant heat packs with the click-disk to trigger them. Melts at 61C. I’ve seen a paper investigating SAT for this purpose and it seemed plausible.
The hardest part is popping that absolutely massive metal disc that sits in the liquid to start the heating process.
In 1980, there was an article on a chemical heat pump in Popular Science that used hydration and dehydration of sodium sulfide to store energy. The system was called “Tepidus” because charged salt remained at room temperature. Introducing humidity to the salt released the heat. The salt could also be “charged” and used onsite or sealed and transported elsewhere.
There was a 30 year pilot project in Sweden to prove durabilty over a typical lifecycle. 20 years in, I found the author’s email and asked if there were any updates. He said that the pilot was stopped because the rehydrated salt tended to form a skin and prevent the underlying salt from releasing its heat.
I think the problems are solvable and this is still the best seasonal energy storage I’ve seen.
I did the calculations once and found that for the most plausible heat storage materials, much like the sodium sulfide, a regular household would need a full size shipping container full of stuff to bridge the heating season. The energy density compared to combustible fuels is just too low. It’s technically possible, but logistically implausible.
How many cubic meters of natural gas would be required to heat the household through the same season? What does the volume of that work out to when liquified? A shipping container sounds pretty reasonable to me.
Why does it matter when the gas is delivered by pipe?
If you wanted to make a more comparable case, a typical household using an oil burner would need about 275-300 gallons of heating oil, which would fit in little more than 1 cubic meter. If you were heating with wood, 5-10 cubic meters would be plenty.
A 20-foot shipping container is 33 cubic meters and a 40-foot container is 67 cubic meters. That would be a significant expansion to the size of your home, instead of a small garden shed or a buried oil tank.
Bury your household. done.
I would like to, but constuction code has a different opinion than me about it.
Look into local codes and being disconnected from the grid, even intermittently. In some areas that interferes with your “certificate of occupancy”. This triggers a loss of homeowner insurance, which can trigger your bank to cancel your mortgage. Then the city inspector(s) tend to arrive.
Oh and being off grid (and above listed issues) also flags your address to child protective services, etc.
I spent some time in a coastal region and the boating people were always thinking this would be a handy idea. Usually coastal areas are tourist areas and typically no one in local Govt wants to let any potential revenue stream to become unpredicable or reduced. Very much is planned around, generally having a, steady income from the user base.
Then change it.
Or do it the other way : build a normal house then amass ground on 3 faces
You can’t beat the NIMBYs, HOA grifters, and corrupt politicians. Too much money involved.
Coober Pedy is way ahead of you there :)
So electricity -> heat
and then ? heat up water and run a turbine to produce electricity ?
Half of fossil fuels are burned for heat, not electricity. So, yes, you could do that… Or you could just use the heat directly (or use it to make steam that will be used in a factory).
More than half of all primary energy is used as heat.
The bigger problem is that electricity is 3-4x more expensive than direct heat from fossil fuels, and renewable energy tends to be 5-7x, so the only way that storing intermittent renewable energy into heating bricks makes sense is if you basically get it for free. Relatively speaking.
It means you’re capturing renewable energy at peak when the producers have to sell it at a substantial loss, and the producers are covering that loss by collecting subsidies. That means someone else is paying for the energy. If you generalize this as a system, it would mean huge transfers of money from the public to the private industries, which makes the whole deal politically volatile and risky to invest in – unless you can make sure that the subsidy policies continue and the public keeps paying you free energy.
But, if this scheme spreads as a practice, then the overall demand would start matching supply even at peak, and the prices during the peaks would no longer dip down to virtually nothing, so the system would cannibalize its own point anyways.
it only works for now, if only a handful of companies are doing it, while the subsidy policies favor it and the public isn’t protesting being taxed for private benefit.
You just use the heat. e.g. a large industrial baking oven which uses 250kW continuous gas firing, can be powered for 16 hours by a block of preheated bricks approx 300mm square x length of the oven (50m).
There are a bunch of issues of course, but the basic heat store is a surprisingly practical size, and very cheap material cost.
The practical issues come from being able to turn the heat on and off.
You can heat a bunch of bricks to red hot glow, but how do you direct that heat to the actual process you intend to run? As in, you want to heat something but then it also needs to cool down, like firing a bunch of pottery in a kiln. You can’t move the pottery when they’re hot lest they break, so you can’t use a rolling oven type of setup.
The solutions require a heat transfer medium, like blowing air through the hot bricks, but then you get energy loss along the transmission path where the hot air loses heat to the pipework.
The feasibility depends on whether the intermittent energy is cheap enough to cover the losses, which depends on whether the actual energy is subsidized, so it can be sold below the cost of production to collect the subsidies, which means the heat storage system depends on whether someone else is paying for the energy. That makes the whole thing politically volatile – you don’t know if it’s going to remain economically viable ten years from now.
My assumption is that this is for “process heat” in industry, given how much electricity or other energy is burned to create heat for processes.
..or invest in nuclear.
AND invest in nuclear.
Makes me think of this project in Alberta, Canada: https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community
It seems to be considered a mixed success, perhaps neglecting to plan for the long-term sustainability of the system.
Funny. High-energy bulk resistors are fairly specialized and expensive (boutique, even) parts today.
Imagine having a commodity of extremely large (10s, 100s kJ? MJ?) resistors, of fairly narrow range of values, suddenly added to that market :)
Seems odd for that to be an expensive item, when a long enough wire suspended on insulators will do the trick. Is it some licensing thing? I’ve made a resistor that handled 10kJ by dropping a wrench on a car battery. It’s not rocket science.
You are likely to be heating bricks into the range of 1000C – 1700C. The heaters must be hotter again for any heat flow to happen. You need to do it for 6hours a day for 15 years. Metallic/wire heating elements only go to the lower end of that range, above that you need something ceramic like silicon carbide heaters.
Making the bricks themselves conductive is a neat idea. We looked at inductive heating of magnetite bricks. to avoid heater elements.
Like the other guy said, conventional resistor heaters can’t really handle the temperatures for long.
The heat storage medium has to be significantly hotter than the heat you intend to apply, because you need to transfer the heat from the storage body to the target – e.g. an oven – using some medium like hot air. Each step introduces losses and drops in temperature to allow the heat exchange to happen: the more power you’re transmitting, the larger the drop in temperature becomes, so the hotter the source has to be.
For example, a Tungsten wire melts at 3,400 C but it will start oxidizing above 400 C when exposed to air. That complicates the whole setup. If used as such, you’d be replacing the heating elements continuously.
US Patent Application 2023/0029346 A1 proposes a solid state device converting electromagnetic radiation, thus also heat, into electricity …
Yeah, THE only thing I can find for “2023/0029346” is your other comment. No one will look at this patent until you provide a link, because it’s not findable.
https://www.freepatentsonline.com/y2023/0029346.html
Seems very interesting, thank you!!! But if my math is right, it makes 2000uA/cm2, which means 2mA/cm2, which is 20A/m2, at 0.7V it’s 14W/cm2. (In sunshine, through the focal spot of a magnifying glass directed onto the cathode K, values of around 2000 μA/cm2 are achieved. Where the open circuit voltage VOC is measured immediately after an ISC measurement of this kind, VOC values of around 0.7 volt are obtained.) But maybe doable as a research project for dyi concentrated solar cell.
How do you turn the hot bricks into electricity?