Oh hey, this is the Energy Superabundance guy.

Overall it's a good idea but I'm skeptical that random "dirt" will reliably withstand the temperatures required for

> the stored heat creates steam on demand for the turbines instead of burning coal

but mostly-quartz sand without any calcite and crushed granite surely can, and those are widely available for barely more than the cost of driving a truck to your construction site, because those are the main ingredients in concrete. (As he says in his white paper https://findingspress.org/article/141340-thermal-energy-stor..., US$20–50 per tonne.)

From perusing https://www.eia.gov/analysis/studies/powerplants/capitalcost... I'm also skeptical that the turbines (especially steam turbines rather than gas turbines) will have a low enough cost to make this worthwhile.

If your random dirt is good enough I'd think you'd want to trench into the existing dirt to lay pipe, the way most ground-source heat pumps are done, rather than hiring a bulldozer. But I haven't done it; maybe the cost structure is different than what I imagine.

I wonder why he says

> Surrounding the earthen mound will be high-density, low-profile solar arrays.

What's stopping you from putting the solar arrays on top of the earthen mound (or sandpile) too?

Sand or feolite thermal "batteries" on the daily rather than seasonal timescale are eminently economical for even household thermal storage for heating. With TCES energy storage, which I expect to be barely more expensive at the household scale, you can get cooling too. TCES also scales down to small systems and long storage times in a way that sensible and phase-change thermal energy storage can't, while also bettering them on density.

Incidentally, energy superabundance is apparently becoming a reality in the PRC, and CO₂ emissions are falling:

https://fortune.com/2025/08/14/data-centers-china-grid-us-in... “#AI experts [#Rui-Ma] return from #China stunned: The U.S. grid is so weak, the race may already be over. (...) In the U.S., surging AI demand is colliding with a fragile power grid, the kind of extreme bottleneck that Goldman Sachs warns could severely choke the industry’s growth. ¶ In China, Ma continued, it’s considered a “solved problem.”” because “China has an oversupply of electricty [sic]”. “In China, renewables are framed as a cornerstone of the economy because they make sense economically and strategically, not because they carry moral weight. Coal use isn’t cast as a sign of villainy, as it would be among some circles in the U.S. It’s simply seen as outdated.” #energy #USA

https://xcancel.com/ruima/status/1955040979259650267 #Rui-Ma’s account of her trip to #China to go to the World #AI Conference (#WAIC) and see investors and renewable #energy. "We met with companies ranging from Baidu, Alibaba, and Tencent (BAT) to unicorns, as well as young startups founded less than a year ago. (...) Energy is considered a solved problem. The Chinese government’s investment in sustainable energy — from advanced hydropower to next-generation nuclear — means that, relative to many other markets, electricity supply is secure and inexpensive. Everywhere we went, people treated energy availability as a given. This is a stark contrast to the U.S., where AI growth is increasingly tied to debates over data center power consumption and grid limitations."

https://xcancel.com/ruima/status/1955372325970514161 #Rui-Ma on #energy in #China: “China: Electricity generation jumped from roughly ~5.6 PWh (2015) to ~10.1 PWh (2024), which is +80% in less than a decade. And 2024 alone grew ~7%, accounting for ~HALF of the world’s increase. China now produces ~1/3 of global electricity. That’s what “supply went up a lot” looks like, so yeah even if coal as a % of total went down, the total will still increase but the increase is QUICKLY PLATEAUING (...) Multiple independent analyses now show China’s CO₂ fell year‑on‑year across the last 12 months (and in Q1’25), driven by the clean‑power surge rather than an economic slump.”

Another minor note as I read the rest of the page:

> the resistor material itself is $1-$2/kilowatt. (...) There are only a few materials that are even acceptable as resistors.

This depends strongly on your target temperature and conditions. Nichrome may cost US$2/kW but galvanized barbed wire doesn't. It can kill you with the fumes, and in oxidizing conditions it won't last long above 200°, but zinc fumes inside a dirt pile won't hurt anybody, and you can probably maintain reducing conditions by mixing some humus into your dirt initially and keeping the pile dry. If process heat or climate control is your objective, you don't need temperatures high enough to oxidize iron rapidly even in an oxidizing environment.

(Incidentally, reducing conditions will destroy nichrome at the temperatures people use nichrome for. Maintaining oxidizing conditions inside your dirt pile over the years is going to be a lot more challenging, I suspect.)

I suspect keeping the pile dry is the reason for not just trenching in existing soil. Dryness is essential for maintaining temperature over 100°.

My intuition is that you could probably scale the seasonal-sensible-TES-in-dirt approach further down from the few megawatts he's talking about if you can use real insulation instead of dirt. But insulation is expensive at this scale, even things like perlite and vermiculite.

Spitballing, suppose we want to withdraw 100kW energy for 4 months (1TJ) and can deal with a time constant of 8 months, so leakage is ballpark 50kW. Suppose we have 1J/g/K sand and ΔT = 200K. Then we need 5300 tonnes of sand; at US$20/kg that's US$100k, a dollar a watt, cheaper than power from a coal plant but not really competitive. A larger ΔT can save you but might shorten the life of your barbed wire. But at those low temperatures you pretty much can use any old dirt, US$5300 of it by Vernon's embankment figure.

But that's about 2000m³, whose minimum insulated surface area would be as a 7.8m sphere with 800m² of surface area. 50kW of leakage over that area would be 70W/m², or 0.3W/m²/K, or 3K·m²/W.