A new startup will use thermal storage -- specifically, glowing hot bricks of graphite -- to compete with lithium-ion batteries in the grid-scale storage market. This is an earlier-stage startup than I usually mess with, but the team behind it is extremely impressive and, let's face it, I'm a sucker for thermal storage.
Great interview! Would it be possible by any chance to share the three studies Ase mentions, regarding the characteristics of storage and how cost matters more than efficiency?
I think it's time to look at other solutions as well, and not focus solely on electricity.
It is extremely important to change todays need for and consumtion of oil. That is not likely to happen if electricity from wind, solar and different kinds of electricity storage devices is predetermined to be the only solution.
Why? Because the electricity produced from these devices is approx. 1% of the worlds total energy demand, and has been over the last few years. That is no threat to Big Oil.
Float glass, invented in 1950, uses a bed of molten tin to produce a flat window in a continuous process. It replaced rollers and before that casting and cutting. A great, boring, manufacturing material to start from. You worry about sulfur, but you always do because it poisons common electrode materials. At the temps here it is a closed system (graphite would oxidize otherwise), and bob's yer uncle - sorted with no worries about degradation in service (just use all graphite components - everywhere).
The heat vs. electricity choice is a market risk challenge. There will be cases where heat and electricity are co-located, but at the scale of desired impact you are talking about a few facilities around the world, facilities the size of Manhattan, with significant readiness expectations on first deployment. At that point you can't repeat the process and get onto the good learning curves (and you've maximized your time to market and company risk). The heat here, 2400C, is also too hot to hold... even for industrial processes. You could run a steel blast furnace at 900-1,300C, 2,400 is really quite toasty.
This is a great interview and the product seems really good. But one thing that confused me: if the TPV cells are only 50% efficient, where does the other 50% of the energy go? With a large facility like this, that would be a lot of heat. Do the TPV cells have to be cooled with cooling pipes, pumps, cooling towers, etc.? There was no discussion of this, but it seems like it might be important.
Looking at the schematic, there is a heat sink, so that would lead to some of the heat loss. Another factor is that once the graphite cools, the panels become less efficient. So hypothetically, you could put in electricity and heat up the graphite to 2400C, but the panels might stop producing electricity once the blocks cool to <1000C, so you can’t recover that leftover heat.
The Gallium Indium Arsenide layer is (can be) a terrible thermal conductor, which is great here. The efficiency is going to be an interesting computation, do you count it as loss if it passes through the cell, reflects off the backplate mirror, and returns to service inside the heat source where you can take a second bite at conversion?
The hot side of this McDLT is problematically warm for anything required to speak to both sides of the house. Looking at the NREL paper the continuously cooled backplate preserves your electronics letting you pull power out of the system/cells and only draws off the heat that makes it through the cell and past the mirror. The interconnects and power extraction are still going to pose challenges? The back of the junction can be a terrible thermal conductor (great here) and one could do even more with the microstructure (ala porosity frustrating phonon modes) but the demands from pulling off the electrons are probably going to constrain options here leading to storage leakage in practice. A GPHS-RTG pattern with many small cells working in tandem to produce power around the bright core speaks to the same requirements, though at much reduced temperatures. Smaller cells also puts you on a path to a learning curve in a single unit (572 thermoelectric unicouples per GPHS-RTG).
There will be a nontrivial volume of water and this will pull a non-trivial quantity of heat so long as the unit is active. The calculus on drawing down the heat reservoir will factor in how much energy it takes to recharge and re-establish efficient conversion and if it is reasonable to do that before the next draw down opportunity - because you'd be trying to maximize use and profit from the cell rather than operational efficiency (you might continue to generate below 1,000C where efficiency has fallen off if the spot price is high enough, you have a contractual obligation, or you know the next recharge spike will be free/curtailed energy).
Is the heat coming off the cooling side hot enough to make a bottoming cycle worthwhile? Or is it not enough to cost-justify adding all the extra equipment required? Is the current plan to just blow that heat out a cooling tower?
Incidentally, any idea what the cooling water requirements are for this type of system? One of the big advantages of PV/wind over thermal (fossil or nuclear) power generation is the low water consumption, so if this system has a high water footprint that is something to bear in mind (very much a regional issue).
Great interview! Would it be possible by any chance to share the three studies Ase mentions, regarding the characteristics of storage and how cost matters more than efficiency?
Followed up with Dr. Henry, here are the papers he had in mind:
1. https://www.nature.com/articles/s41560-021-00796-8
2. https://www.sciencedirect.com/science/article/pii/S2542435119303009
3. https://www.cell.com/joule/fulltext/S2542-4351(19)30539-2?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2542435119305392%3Fshowall%3Dtrue
Great, thank you so much for doing that!
I think it's time to look at other solutions as well, and not focus solely on electricity.
It is extremely important to change todays need for and consumtion of oil. That is not likely to happen if electricity from wind, solar and different kinds of electricity storage devices is predetermined to be the only solution.
Why? Because the electricity produced from these devices is approx. 1% of the worlds total energy demand, and has been over the last few years. That is no threat to Big Oil.
The Only Solution is Replacing Oil. See www.enenergy.net
Hi. Great pod as always. When you talk hot rocks batteries, though, I always find myself wondering about safety.
Is having 2,400 degree rocks sitting around safe?
Float glass, invented in 1950, uses a bed of molten tin to produce a flat window in a continuous process. It replaced rollers and before that casting and cutting. A great, boring, manufacturing material to start from. You worry about sulfur, but you always do because it poisons common electrode materials. At the temps here it is a closed system (graphite would oxidize otherwise), and bob's yer uncle - sorted with no worries about degradation in service (just use all graphite components - everywhere).
The heat vs. electricity choice is a market risk challenge. There will be cases where heat and electricity are co-located, but at the scale of desired impact you are talking about a few facilities around the world, facilities the size of Manhattan, with significant readiness expectations on first deployment. At that point you can't repeat the process and get onto the good learning curves (and you've maximized your time to market and company risk). The heat here, 2400C, is also too hot to hold... even for industrial processes. You could run a steel blast furnace at 900-1,300C, 2,400 is really quite toasty.
This is a great interview and the product seems really good. But one thing that confused me: if the TPV cells are only 50% efficient, where does the other 50% of the energy go? With a large facility like this, that would be a lot of heat. Do the TPV cells have to be cooled with cooling pipes, pumps, cooling towers, etc.? There was no discussion of this, but it seems like it might be important.
https://www.nrel.gov/news/program/2022/capturing-light-from-heat-at-40-percent-efficiency-nrel-makes-big-strides-in-thermophotovoltaics.html
Looking at the schematic, there is a heat sink, so that would lead to some of the heat loss. Another factor is that once the graphite cools, the panels become less efficient. So hypothetically, you could put in electricity and heat up the graphite to 2400C, but the panels might stop producing electricity once the blocks cool to <1000C, so you can’t recover that leftover heat.
The Gallium Indium Arsenide layer is (can be) a terrible thermal conductor, which is great here. The efficiency is going to be an interesting computation, do you count it as loss if it passes through the cell, reflects off the backplate mirror, and returns to service inside the heat source where you can take a second bite at conversion?
The hot side of this McDLT is problematically warm for anything required to speak to both sides of the house. Looking at the NREL paper the continuously cooled backplate preserves your electronics letting you pull power out of the system/cells and only draws off the heat that makes it through the cell and past the mirror. The interconnects and power extraction are still going to pose challenges? The back of the junction can be a terrible thermal conductor (great here) and one could do even more with the microstructure (ala porosity frustrating phonon modes) but the demands from pulling off the electrons are probably going to constrain options here leading to storage leakage in practice. A GPHS-RTG pattern with many small cells working in tandem to produce power around the bright core speaks to the same requirements, though at much reduced temperatures. Smaller cells also puts you on a path to a learning curve in a single unit (572 thermoelectric unicouples per GPHS-RTG).
There will be a nontrivial volume of water and this will pull a non-trivial quantity of heat so long as the unit is active. The calculus on drawing down the heat reservoir will factor in how much energy it takes to recharge and re-establish efficient conversion and if it is reasonable to do that before the next draw down opportunity - because you'd be trying to maximize use and profit from the cell rather than operational efficiency (you might continue to generate below 1,000C where efficiency has fallen off if the spot price is high enough, you have a contractual obligation, or you know the next recharge spike will be free/curtailed energy).
I wish I could show you my head exploding as I realized that this is how they got to 50% efficiency
Great comment Saahir, Volts is giving you 6 months of the paid subscription as thanks!
Is the heat coming off the cooling side hot enough to make a bottoming cycle worthwhile? Or is it not enough to cost-justify adding all the extra equipment required? Is the current plan to just blow that heat out a cooling tower?
Incidentally, any idea what the cooling water requirements are for this type of system? One of the big advantages of PV/wind over thermal (fossil or nuclear) power generation is the low water consumption, so if this system has a high water footprint that is something to bear in mind (very much a regional issue).
😤