3 ms·

1)The system clearly doesn't exist, or we'd see pictures and video of it. Given how simple such a system is, and that they've received tens of millions in finan

1)The system clearly doesn't exist, or we'd see pictures and video of it. Given how simple such a system is, and that they've received tens of millions in financing, why do they not have even a small scale demonstrator? 2)The video is nothing more than a dressed up zoom "interview" with the CEO and some stock video clips. Everything should be assumed to have been written by, or at least thoroughly vetted by, Rondo. 3)For example, the claim is that lithium ion batteries are expensive at grid scale...but the cost of such batteries continues to fall, there's now commercially viable recycling for them, and other technologies such as iron-flow are cheaper, do not require rare-earth metals, and are already in the commercial marketplace. So is pumped hydro, which they also don't address. 4)The immediate and pretty obvious drawback to their "dynamic insulation" concept: if you stop pumping air through the "battery", the insulation that is rated to only handle 150C is suddenly exposed to thousands of degrees...and now you have a fire, backed by an enormous thermal mass, which is a problem, as firefighting is largely based on using the phase change of water to pull more heat away from a fire than the fire can generate. 5)While this tech sounds nice for industrial processes, it's not anywhere near as practical for domestic heating, where geothermal heat pumps will be more efficient. At its core, this is a system that is fueled by resistive heating, and heat pumps are several times more efficient than resistive heating. What would be interesting is if they're able to leverage solar radiation directly via solar concentrators. You'd see a roughly four-fold increase in efficiency over solar.

SECProto 4y ago
> The system clearly doesn't exist, or we'd see pictures and video of it. > While this tech sounds nice for industrial processes, it's not anywhere near as practical for domestic heating, where geothermal heat pumps will be more efficient. A family member had a heat storage system that used electricity to heat bricks about a decade ago. Worked great for home heating with time-of-day rates (especially with some solar to offset the peak rate daytime). And the purchase cost was very low, unlike any sort of ground source heat pump.
u320 4y ago
> For example, the claim is that lithium ion batteries are expensive at grid scale...but the cost of such batteries continues to fall The rate at which they have been falling has been diminishing for quite some time, until this year when they are starting to rise (more than inflation). The idea that past price movements will always continue indefinitely has zero basis in reality. And yes li-ion batteries are way too expensive for large scale grid usage, even if they did fall at 10% yearly we would be decades away for them to be a satisfactory solution.
- Schroedingersat 4y ago
  > The idea that past price movements will always continue indefinitely has zero basis in reality. This is true. Any pretend exponential curve is at best a logistic curve near the beginning or middle. But there are good reasons to think batteries as a whole are in the class of logistic curves near the middleish. There are lots of chemistries in the 500-1000Wh/kg range with various deal-breakers making them not an option. Chemical reactions go up to about 10,000Wh/kg and some of them as yet undiscovered might resemble 'battery' more than 'fuel cell' or 'magic portable nuclear thingy'. Simple few component mass produced objects made of abundant materials once every ounce of cleverness in production is wrung out tend to cost around $1-10/kg plus their energy cost. So if we set the upper asymptote at around $1-10/kWh, old technologies are around $1000 per usable kWh and LiFePO4 is around $300/kWh for final products you can actually buy. It seems reasonable to posit that $20/kWh is achievable before going too far past the inflection point. This is in line with CATL claiming $60/kWh for SIB in the late 2020s, then having costs taper off and settle around $30/kWh in 2040 as the low hanging fruit are all gone. Maybe there'll be a new discovery around then that pushes it down to $1, but it seems unlikely.
scythe 4y ago
It's also not clear how quickly heat can be extracted from the bricks. There were decades of research on energy storage in molten sodium-potassium nitrate because it's a liquid so your output is always very close to the temperature of the salt bath. Clay is not a great heat conductor.
- SECProto 4y ago
  > It's also not clear how quickly heat can be extracted from the bricks. This is a commonly defined material property [1]. You would simply size your bricks to suit the situation - given same volume, more surface area means faster heat flow. [1] https://en.wikipedia.org/wiki/Thermal_conductivity https://en.wikipedia.org/wiki/Thermal_conductivity

SECProto 4y ago

> The system clearly doesn't exist, or we'd see pictures and video of it. > While this tech sounds nice for industrial processes, it's not anywhere near as practical for domestic heating, where geothermal heat pumps will be more efficient. A family member had a heat storage system that used electricity to heat bricks about a decade ago. Worked great for home heating with time-of-day rates (especially with some solar to offset the peak rate daytime). And the purchase cost was very low, unlike any sort of ground source heat pump.

u320 4y ago

> For example, the claim is that lithium ion batteries are expensive at grid scale...but the cost of such batteries continues to fall The rate at which they have been falling has been diminishing for quite some time, until this year when they are starting to rise (more than inflation). The idea that past price movements will always continue indefinitely has zero basis in reality. And yes li-ion batteries are way too expensive for large scale grid usage, even if they did fall at 10% yearly we would be decades away for them to be a satisfactory solution.

Schroedingersat 4y ago
> The idea that past price movements will always continue indefinitely has zero basis in reality. This is true. Any pretend exponential curve is at best a logistic curve near the beginning or middle. But there are good reasons to think batteries as a whole are in the class of logistic curves near the middleish. There are lots of chemistries in the 500-1000Wh/kg range with various deal-breakers making them not an option. Chemical reactions go up to about 10,000Wh/kg and some of them as yet undiscovered might resemble 'battery' more than 'fuel cell' or 'magic portable nuclear thingy'. Simple few component mass produced objects made of abundant materials once every ounce of cleverness in production is wrung out tend to cost around $1-10/kg plus their energy cost. So if we set the upper asymptote at around $1-10/kWh, old technologies are around $1000 per usable kWh and LiFePO4 is around $300/kWh for final products you can actually buy. It seems reasonable to posit that $20/kWh is achievable before going too far past the inflection point. This is in line with CATL claiming $60/kWh for SIB in the late 2020s, then having costs taper off and settle around $30/kWh in 2040 as the low hanging fruit are all gone. Maybe there'll be a new discovery around then that pushes it down to $1, but it seems unlikely.

scythe 4y ago

It's also not clear how quickly heat can be extracted from the bricks. There were decades of research on energy storage in molten sodium-potassium nitrate because it's a liquid so your output is always very close to the temperature of the salt bath. Clay is not a great heat conductor.

SECProto 4y ago
> It's also not clear how quickly heat can be extracted from the bricks. This is a commonly defined material property [1]. You would simply size your bricks to suit the situation - given same volume, more surface area means faster heat flow. [1] https://en.wikipedia.org/wiki/Thermal_conductivity https://en.wikipedia.org/wiki/Thermal_conductivity