The heat right next to the rods is easier to access. With less dirt per rod, you can also get more watts per rod, so the number of rods doesn't need to scale directly with the cycle time.
Yes, fair.
Readit NewsVeedrac commented on Standard Thermal: Energy Storage 500x Cheaper Than Batteries austinvernon.site/blog/st... · Posted by u/pfdietz
Veedrac commented on Standard Thermal: Energy Storage 500x Cheaper Than Batteries austinvernon.site/blog/st... · Posted by u/pfdietz
You would need more rods if you're cycling more of it at once... but you can add 25x as many rods and it'll still be 20x cheaper than a battery, right?
I don't think losses would be immense. You'll spend a few months warming up the neighboring dirt, but after that the amount of heat escaping per day will look about the same as the seasonal system.
I'd assume the design as proposed isn't overbuilt, so we'd need to go from, say, 4 months cycle times to 8 hour cycle times, which is maybe 350x.
While that's not going to increase the cost by 350x directly, it is going to change the character of the pile from a bunch of dirt to a bunch of dirty pipes. This makes a lot of the simplifying assumptions no longer work; like you can no longer ignore the heat losses through the rods, or the lower thermal mass of the rods.
And to be clear, you can do this. There are faster-cycling thermal storage solutions out there. It's just not implied from the claim that these solutions would be so much better than batteries.
Veedrac commented on Standard Thermal: Energy Storage 500x Cheaper Than Batteries austinvernon.site/blog/st... · Posted by u/pfdietz
If we're looking at bare minimum cost then batteries are 10x cheaper than batteries.
And being capable of seasonal storage doesn't stop you from using it for daily storage. It's less efficient than batteries, but you can overcome that.
Let's say you can make a 24 hour power source with $10M in solar panels and $20M in batteries, including the other equipment and costs. $30M total. If we need twice as much solar for thermal storage, but the storage only costs $1M, then that's $21M for an equivalent system.
What stops systems like that from being built right now? I was under the impression that batteries were most of the cost if you want them to last more than a few hours.
I meant ‘bare minimum’ in the sense of what's needed for the system to be profitable, not in the sense of ignoring costs.
The problem with using this approach for daily cycled loads is that it relies on passive heat transfer to distribute heat through substantial regions of dirt. This simply doesn't work for daily storage.
You can overbuild, but then your energy losses are going to be immense, because you never saturate or drain the bulk of the material, and are just losing energy to it.
You could build faster cycling systems instead, and active systems especially can cycle reasonably fast, but then your dominant costs no longer reduce down to a pile of dirt with a few rods stuck into it.
Veedrac commented on Standard Thermal: Energy Storage 500x Cheaper Than Batteries austinvernon.site/blog/st... · Posted by u/pfdietz
Finland has an operational "sand battery", which primary purpose is heating. That was discussed in HN few months ago [1].
When it comes to this article, I doubt the 500x cheaper statement, we would see these already everywhere if that were the case.
500x should be conceptualized as the bare minimum, not evidence of massive low-hanging fruit.
A battery that cycles daily makes revenue on its capacity about 350 times in a year. A seasonal energy store makes revenue on its capacity about once in a year.
A battery arbitrages between the most expensive and least expensive energy generators in the system. A seasonal energy store arbitrages between seasonal price averages.
A battery smoothing out solar production is operating on the difference between how much sun there is in the day, and how much sun there is at night. A seasonal energy store in the same role averages between summer and winter.
A factor 500 cheaper plus a significant quantity of solar energy production is about where you'd expect this kind of thermal storage to start making economic sense.
Veedrac commented on Building ultra cheap energy storage for solar PV austinvernon.substack.com... · Posted by u/theptip
The only place where you could conceivably store this without having another conversion or lossy transport loop is under the house. It's not exactly trivial to excavate that much space under an existing structure without having the whole thing come down. I think I've figured that part out but it would still be legally quite shaky and it might destroy the resale value of the house unless it can be made compact enough that it would fit within a standard basement. Insulation is the key problem to solve here.
The article never frames this as off-grid storage for individual homeowners. They say
> A typical site is a factory, power plant, or town with a large earthen mound at the edge. The mound might be the size of a house for a smaller factory, and up to many football fields for a large power plant. Surrounding the earthen mound will be high-density, low-profile solar arrays.
I agree that trying to give every suburban house its own rock pile would not be very practical.
Deleted Comment
Veedrac commented on Building ultra cheap energy storage for solar PV austinvernon.substack.com... · Posted by u/theptip
I've done a lot of spreadsheets on this kind of solution, but on a slightly smaller scale: a single family home. While it will work for a while it is not enough to meaningfully offset the seasonal cycle which is the thing that needs solving. Storing energy for a few days up to two weeks is (relatively) easy, storing it cheaply for up to 6 months is very hard unless you are willing to invest massively offsetting much of your savings. The pile of rock required to heat an average home for a couple of weeks handily outweighs the house itself. And that's without a double conversion, it is used and stays as heat, the idea was to moderate the leakage upwards as a source of heat by blowing air in a controlled manner rather than to convert it again.
So I really hope these guys will succeed where I can't even get it to work on paper, sometimes scale really is a requirement to make something work and this could very well be one of those.
> The pile of rock required to heat an average home for a couple of weeks handily outweighs the house itself.
Maybe I'm failing to follow the intended argument here, but I do not see what is expensive about this. Houses are hollow; they do not weigh all that much. Dirt is cheap, especially when sourced locally.
You can pry the walrus operator from my cold dead hands.
m = re.match(pattern1, line)
if m:
do_stuff(m.group(1))
else:
m = re.match(pattern2, line)
if m:
do_other_stuff(m.group(2))
else:
m = re.match(pattern3, line)
if m:
do_things(m.groups())
else:
m = ...
I run into something like this all the time. Not many times per program, and I don't actually use the walrus all that often, but when it's the right thing it's so very nice.
FWIW another way to handle this is a local function with early returns. In this example you can also just use a single regex and most likely win performance too.
:= is so common in other languages, or even other Python statements, that it doesn't bother me at all, but Python is such an imperative-first language that its presence is rarely felt.
Veedrac commented on OpenAI claims gold-medal performance at IMO 2025 twitter.com/alexwei_/stat... · Posted by u/Davidzheng
Off topic, but am I the only one getting triggered every time I see a rationalist quantify their prediction of the future with single digit accuracy? It's like their magic way of trying to get everyone to forget that they reached their conclusion in completely hand-wavy way, just like every other human being. But instead of saying "low confidence" or "high confidence" like the rest of us normies, they will tell you they think there is 16.27% chance because they really really want you to be aware that they know bayes theorem.
There is no honor in hiding behind euphemisms. Rationalists say ‘low confidence’ and ‘high confidence’ all the time, just not when they're making an actual bet and need to directly compare credences. And the 16.27% mockery is completely dishonest. They used less than a single significant figure.
Veedrac commented on In a First, Solar Was Europe's Biggest Source of Power Last Month e360.yale.edu/digest/sola... · Posted by u/Brajeshwar
> Replacing the whole system every 20 years still seems really wild to me, especially in worlds where price doesn't fall past the cost of maintenance, because the only wear part is the battery, and batteries are modular.
It may be pessimistic. At the same time, you amortize things based on history.
Things like substations are amortized over 30-40 years. Battery banks don't have the history; a 20 year timeframe seems like a reasonable amortization time. Indeed, if technology improves and costs reduce like people are advocating for here, it'll be thrown away and replaced. If it wears out in ways that don't justify refurbishment, same. And refurbishment/recycling/etc are not well understood processes at scale, yet, nor are future usage patterns well enough understood to know if we will have those resources at the right places.
Again, we could get lucky: batteries could last longer than expected; we could use technologies that are close enough cousins and have a really good time at refurbishment; we could not hit any kind of scaling limitations with battery storage; etc. I agree battery storage is great. And I agree it could be sufficient alone (well, combined with other storage options) if we hit the top third of possible scenarios.
I just am concerned about the other scenarios. I can't rule them out. And if we're going to have insurance against them, it's time to buy it now.
I'd much rather face a future where people say that we wasted a few tens of billions on nuclear power plants than to face a future where people shake their head that we wasted the opportunity to save the climate by foregoing nuclear.
I'm not really following. You said, "I don’t think we can scale up storage enough at any reasonable cost." We checked the math. The math said that even with pessimistic numbers, that assume no cost improvement and that everything deprecates as fast as the batteries, the amount of storage needed was readily affordable. You agree that there's a reasonable chance the price could go down, and agree that parts other than the battery chemistry do indeed last much longer.
Isn't that the whole debate? What are we arguing about at this point?