Hot Sand

Guest Post by Willis Eschenbach

I live up at the top left of the map in Figure 1, in Northern California between Santa Rosa and the Pacific Ocean. Down the coast on the far side of San Francisco from me is Monterey Bay, and the town of Moss Landing.

Monterey Bay is famous for fish and fishing because there is a submarine canyon that runs all the way in to the shore at Moss Landing. This brings in the deepwater currents with loads of nutrients, which feed a rich marine ecosystem.

Half a century ago, I fished commercially for three years in Monterey Bay, two of them fishing out of Moss Landing. There was a huge old power plant in Moss Landing that was the friend of everyone who fished those waters, because it had two giant chimneys. We fished nights, not days, and at any time of the night, it was infinitely comforting to see the rings of red lights on the chimneys, visible from all over the Bay. They marked home, and land, and safety. Here are the stacks during a full moon.

Now, fifty years later, the power plant is shut down but the chimneys still remain, mute obelisks of an earlier time. You can see their shadows in the upper right of this aerial view of Moss Landing.

And what are the white boxes up at the tip of the shadows of the chimneys? They’re one of the subjects of this post. Those make up one of the largest battery installations on the planet. It’s comprised of hundreds of Tesla Megapack batteries. It stores on the order of 7.3 gigawatt-hours of electric energy (GWh, or 109 watt-hours). Here’s a photo from the ground.

So … what’s not to like about lithium megabatteries?

Well, the first thing not to like is cost. The Tesla Megapacks cost about $327 per kilowatt-hour of storage, a huge amount. And with lithium prices skyrocketing, that will only go up. So building them at grid-scale is stupendously expensive.

Next issue is environmental damage. Lithium mines are not very pretty and are destructive to the environment without special procedures … procedures that are unlikely to happen in the countries where lithium is mined.

Next issue is safety. Here’s a recent story

Second battery malfunction in less than 6 months reported at Moss Landing power plant

7:11 PM PST Feb 14, 2022: MOSS LANDING, Calif. — In Moss Landing, firefighters responded to another battery meltdown at the Vistra Energy Storage Facility Sunday night, when they arrived roughly 10 battery racks were melted.

It’s the second incident at the plant in the last five months alone.

Firefighters say the two incidents should provide a learning opportunity to make any needed adjustments or improvements.

One concern is this plant is going to get bigger.

A Tesla Megapack costs about one million dollars … and ten of them went up in smoke. That’s an expensive “learning opportunity”.

And a final issue is lifetime. Lithium batteries can only be cycled a certain number of times before they wear out and need to be replaced.

With that list of the issues with lithium batteries as prologue, folks that know me know that I’m very skeptical about new technologies. I’ve seen lots and lots of “stunning breakthroughs” announced with great fanfare that never made it off of the drawing board.

But today, I came across an energy storage technology that might actually work. Here’s a drawing of the idea. It’s being developed both privately and by the National Renewable Energy Laboratory (NREL). NREL calls its incarnation of the technology the “Enduring” system.

ORIGINAL CAPTION: In a new NREL-developed particle thermal energy storage system, silica particles are gravity-fed through electric resistive heating elements. The heated particles are stored in insulated concrete silos. When energy is needed, the heated particles are fed through a heat exchanger to create electricity for the grid. The system discharges during periods of high electricity demand and recharges when electricity is cheaper. Image by Patrick Davenport and Al Hicks, NREL.

TL;DR Version: Electricity is used to heat sand. When you need electricity, the hot sand is used to boil water to drive steam turbines for electricity.

So why do I think this one is possible? Several reasons:

First, it is very cheap. Instead of using expensive lithium for storage, it uses cheap silica sand. This brings the cost down from the $327 per kilowatt-hour (kWh) of lithium batteries to an NREL estimated cost of $2 – $4 per kWh. And even if the final cost is three times that, it’s still only a few percent of lithium battery cost.

Next, it’s safe. Sand can’t catch on fire. Lithium can, and does, and is very hard to put out once it starts burning.

Next, it’s scalable, and it’s cheap to scale. Add more insulated tanks of sand and you add more storage capacity.

Next, it can be built on the sites of closed coal-fired power plants. All the infrastructure is there—train tracks to bring in the sand, turbines, generators, substations, transmission lines, and the like.

Next, it doesn’t require any new or unproven technology. We know how to heat sand, and how to build boilers and steam turbines, and how to do all the things shown in the drawing above.

So will this be the secret technology that sets solar and wind loose to make an actual difference in the real world? Because up to now, solar and wind ain’t doing diddly squat.

Seems doubtful that it will change things that much. Storage is only one small problem with sun/wind. A much larger problem is that most of the electricity from sun/wind is used immediately, and so there’s not a lot left over to put into storage. Next, both technologies require dangerous/rare/poisonous materials, are short-lived, and are hard to recycle. Plus, wind turbines massacre raptors, for a curious reason discussed here.

And there’s another big problem … there’s not a lot of solar/wind energy there to harvest because it’s so spread out, and many of the good sites are already in use. So this storage technology could help at the margins, but won’t be a revolution.

However, sand storage would still be useful for load balancing on the grid, and should be quick to ramp up and down to meet variations in demand.

There’s already a Finnish company that is commercially testing the technology. It’s called Polar Night Energy, and they’re using the heat directly, not for electricity, for district-wide heating of towns in the far north. Here’s their test installation:

Store heat in the summer when it’s not needed, and release it in the winter when it is needed … works for me.

Anyhow, that’s the good news for today … yeah, I know that compared to the ongoing global lunacy it ain’t much, but it’s what I’ve got.

My best wishes to all,


PS: As always, I politely ask that when you comment you quote the exact words you’re discussing. This lets us all know exactly what and who you are responding to, and it avoids endless misunderstandings.

Technical Note: I ran some numbers to see if this all pencils out … seems like it does. R computer language code and results below. Lines starting with “[1]” are the computer output. Anything on a line after a hashmark (#) is a comment.

(us_electric_consumption = 3.9e15)# watt-hours Wh
[1] 3.9e+15
(moss_landing_battery = 7.3e9)
[1] 7.3e+09
(enduring = 26e9) # enduring storage, watt-hours Wh
[1] 2.6e+10
(ca_electric_consumption = 280e12) # Wh
[1] 2.8e+14
(sf_electric_consumption = 5e12) # Wh
[1] 5e+12
(ny_electric_consumption = 51e12) # Wh
[1] 5.1e+13
(enduring/ny_electric_consumption*secsperyear/3600/24) # days of NY City supply [1] 0.19 (moss_landing_battery/ny_electric_consumption*secsperyear/3600/24) # days of NY city supply, Moss Landing Battery
[1] 0.05225152
(degrees_temperature_swing = 900) # °C
[1] 900

(sand_specific_heat = 800e3) # joules/tonne/°C
[1] 8e+05
(storage = degrees_temperature_swing*sand_specific_heat) #storage joules/tonne
[1] 7.2e+08

(storage_whr = j2wh(storage)) # storage wh per tonne
[1] 2e+05
(tonnes_needed = enduring/storage_whr) # tonne
[1] 130000
(sand_density = 1.6) #tonnes/m^3
[1] 1.6
(volume_needed = tonnes_needed/sand_density) # cubic metres
[1] 81250
(tank_num = 5) # number of tanks
[1] 5
(cube_side = volume_needed^(1/3)) #metres per side
[1] 43.31196
(cube_side_per_tank = (volume_needed/tank_num)^(1/3)) #metres per side
[1] 25.32899
(cube_side_ft = m2ft(cube_side)) #metres per side
[1] 142.0993
(sand_per_ton = 40) # sand cost, $/tonne
[1] 40
paste0("Sand cost = $",format(sand_cost,big.mark=","))
[1] "Sand cost = $5,200,000"

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Kevin kilty
July 7, 2022 10:24 am

Thermal storage feels the full limits of the second law not only with every round trip through the system, but during the idle period too. The needed storage might be cheap but is immense in terms of mass, land space, and so forth.

Reply to  Kevin kilty
July 7, 2022 11:19 am

Gas is best. CO2 is good. There is no man made warming.

Reply to  HenryP
July 7, 2022 1:04 pm

Yes, it’s certainly better to avoid storage at all by eliminating the problems it’s trying to solve that are being caused by the mitigation efforts targeting a problem that doesn’t exist.

Julian Flood
Reply to  HenryP
July 7, 2022 11:35 pm

Henry, if you coat the surface of a lake with light oil it will warm as evaporation is reduced and albedo is reduced. (See Benjamin Franklin’s experiment at Mount Pond in the UK.)

Now imagine doing that to a semi-enclosed sea by run-off from surrounding settlements. At the extreme you end up with the Sea of Marmara which is warming at twice the average oceanic rate.

MHI is happening, it’s warming and it’s anthropogenic.


Reply to  Willis Eschenbach
July 8, 2022 1:00 pm

Just a couple of idle thoughts.
1) It looks like your data starts and stops at different times of the year. Did you adjust your running average to account for this? Of course that would only impact the ends of the graph, not the bulk of it.
2) I suspect there are a lot of other factors that would impact this hypothesis. For example changes in economic activity could impact how much oil is released into the lake. Changes in environmental regulations, both state and federal could have an impact as well.

Frederick Michael
Reply to  Kevin kilty
July 7, 2022 1:37 pm

Yes. The second law of thermodynamics is a huge problem here. The systems that use gravity, moving mass up and down, are much more efficient. Not many places where you can do that with water, but you can do it with heavy blocks anywhere.

Reply to  Frederick Michael
July 8, 2022 1:23 pm

Moving Mass up and down:

An electric machine roughly 75% efficient can generate one horsepower output for each kilowatt input. To store the daily usage of one average US home (1000kWh / 30) would be 3.3 kWh which gives us 3.3 HP for an hour. 

A HP is 550 pounds lifted a foot every second, or about one tonne lifted a foot every 4 seconds or about one tonne lifted five meters every minute or 300 meters up per hour.

So to store one day of average US home power, you would need to lift 3.3 tonnes of weight 300 meters overhead or 10 tonnes 100 meters overhead or 100 tonnes 10 meters up if you want to keep things within a residential scale. Most people have no idea how much work can be done by one cheap little kWh. This is why electrification changes everything within a society. And why it takes a frightening amount of suspended mass to store meaningful amounts of electrical power.

Reply to  Kevin kilty
July 7, 2022 3:32 pm

Plus attrition of sand, erosion of all surfaces, including heaters, ceramic brick insulation and be ready for unexpected water chemistry challenges. By all means, build pilot and demo plants for testing and evaluations.

Tim Gorman
Reply to  Scissor
July 7, 2022 3:47 pm

If you heat that sand hot enough to boil water after an extended storage interval will it tend to clump up? Perhaps even see some of it melt together? How would you clean out the storage container?

Reply to  Tim Gorman
July 7, 2022 6:28 pm

Depends on temperature and chemical condition. Usually, particles are readily vacuumed out.

Silica’s water solubility is low but it’s pH dependent (higher at higher pH). There’s always something.

Reply to  Tim Gorman
July 10, 2022 9:37 am

Sand melts at 3000F.

Tim Gorman
Reply to  mellyrn
July 10, 2022 3:29 pm

Sand usually has more in it than just silica. Not all of it melts at 3000F.

I guess if you want absolutely pure sand you could just pulverize glass but where does the glass come from and how much energy does it take to make it plus pulverize it.

old mike
Reply to  Kevin kilty
July 7, 2022 4:36 pm

Sand is a very very abrasive material, annual maintenance costs wil be way higher than the usual 3% of capital cost rule of thumb, think more like 15% or even 20%. The materials of construction that can withstand severe abrasion are usually not good heat transfer candidates.

Those simplistic diagramatic boxes that represent heat transfer points are going to be very big problems.

I base my comments on over thirty years experience in the oil sands industry where every tonne of oil sands processed consumes circa 1-2 pounds of steel from abrasion.

Last edited 1 month ago by old mike
Reply to  old mike
July 7, 2022 6:29 pm


Rick Kargaard
Reply to  old mike
July 7, 2022 6:48 pm

The sand would be very abrasive if it was moved, but that should not be necessary. A few pipes through the sand carrying hot water or other fluid would work to do the heating and the energy could be extracted by a simple reversal through heat pumps so that boiling water or other liquids would not be necessary. Certainly possible but the economics may be another mater

Rainer Bensch
Reply to  Rick Kargaard
July 8, 2022 3:38 am

This solves also the problem of where to store the whole lot of cool sand after use to heat the water. You haven’t the energy handy to move it up and heat it again at this times.

Tim Gorman
Reply to  Rainer Bensch
July 8, 2022 10:21 am

It doesn’t solve all problems. The diameter of the storage tube means not all sand will be in contact with the tube carrying the fluid to be heated. This means either the sand has to be very much hotter than it would have to be if there was a narrow band of sand that was moving or it would greatly expand the amount of time needed to allow the proper amount of heat to enter the fluid via conduction in order to boil it.

You have problems either way.

Rick Kargaard
Reply to  Tim Gorman
July 10, 2022 8:02 am

Boiling the water is a problem only if boiling is required. Other solutions include using the heat to replace electricity. Examples would be heating homes or factories or preheating water to be boiled for whatever reason. Many processes require warming material but not necessarily to higher temperatures.

July 7, 2022 10:25 am

While the sand thermal storage idea may sound good on paper, I would be concerned about the massive waste of energy that takes place in any thermal power plant where steam is produced to drive a turbo-generator.

The standard efficiency of a rankine cycle thermal power plant is the problem. In a modern technology steam power plant – which is the method by which the stored energy in the sand plant is converted back to electrical energy – the maximum thermal efficiency is only about 33%. Meaning, only 1/3 of the thermal energy produced by the heat source – be it a nuclear reactor or a conventionally fired steam generator or heated sand – is converted to mechanical energy produced by a turbo-generator. Then there is additional loss involved in converting the mechanical energy of the turbo-generator to electrical energy produced by the electrical generator. The overall efficiency of thermal energy out to electrical energy input is just 29%.

The energy losses result from the change in state and enthalpy of feedwater transforming to steam, and then condensing again to form recycled feedwater … and also results from thermal losses to the atmosphere or cooling water from the plant itself. These losses are inevitable and cannot be avoided unless one uses a once through system where all of the steam after it exits the turbine is simply discharged to the atmosphere. Which would amount to a tremendous consumptive use of water.

Compare that system efficiency of a rankine cycle thermal power plant (regardless of the source of the thermal energy input) to lithium ion battery storage, which enjoys an efficiency – electrical output to electrical energy input – of 99% or better.

Thermal power plants make a great deal of sense when one is converting chemical energy or nuclear energy to electrical energy. But not for storing electrical energy.

Last edited 1 month ago by Duane
Gordon A. Dressler
Reply to  Duane
July 7, 2022 11:45 am

“Compare that system efficiency . . . to lithium ion battery storage, which enjoys an efficiency – electrical output to electrical energy input – of 99% or better.”

Not true.

The round trip efficiency of battery storage for electrical grid use is actually much less, around 90-92%, when taking into account that the grid is based on using AC electricity whereas chemical batteries are based on using DC electricity. The necessary use of rectifier circuitry (for AC-to-DC conversion) and inverter circuitry (for DC-to-AC conversion) adds substantial inefficiency to the round-trip process.

G Yowell
Reply to  Gordon A. Dressler
July 7, 2022 1:05 pm

Agreed furthermore, in Heavy Duty Electric Vehicles the Altoona Bus Laboratory measures 85% round-trip efficiency.

Reply to  G Yowell
July 7, 2022 4:53 pm

Electric buses seem to to be going Roman candle. Granted there haven’t been hundreds of busses every week burning up, just two is enough to produce much unforced skepticism about Li batteries and large or high-powered electric vehiicles.
The interesting alternative is a hybrid fuel vehicle. They have been finely honed by several manufacturers. They are in the same range as a good diesel engine without all the excess small particle pollution. No large lithium ion batteries are needed.

Reply to  Philo
July 8, 2022 4:32 am

Not true – for every EV bus that catches fire there are nearly a thousand diesel fueled buses that catch fire. In 2021, there were reported (meaning likely significantly less than the totals) bus fires of more then 2,600 in the US alone vs. what, one or two EV bus fires?

Note that most of the occurrences of EV bus fires are overseas. With US-only reported bus fires of 2,600 in just one year, that implies probably tens of thousands of bus fires world wide last year.

Last edited 1 month ago by Duane
Reply to  Duane
July 8, 2022 8:55 am

For every electric bus on the road, there are 10’s of thousands of diesel buses.
The average age of those diesel buses is also decades older than your electric buses.
Secondly, the diesel buses usually only catch fire after an accident or somebody tosses a molotov at them.
Electrics on the other hand can go up pretty much any time.

You have been corrected on this lie of yours many times.

Andrew Wilkins
Reply to  Duane
July 8, 2022 11:44 am

You’re not very good with the concept of percentages or ratios, are you?

Reply to  Duane
July 8, 2022 5:24 pm

Fire departments can put out a diesel fire.

Reply to  G Yowell
July 8, 2022 4:29 am

Nope – not true

Reply to  Duane
July 8, 2022 8:55 am

Completely and utterly true. You just can’t deal with reality, can you.

Reply to  Gordon A. Dressler
July 8, 2022 4:28 am

Your “not true” is not true. The efficiency of lithium ion batteries exceeds 99%. Fact. Your are enttled to your own opinion but not to your own “facts”.

Reply to  Duane
July 8, 2022 8:57 am

Gordon presented facts, you on the other hand present nothing but carefully culled propaganda that ignores 90% of the other factors dealing with battery efficiency.
If battery charging and discharging was 99% efficient as you so desperately want to believe, the Electric car makers wouldn’t have to install dedicated cooling systems to keep those batteries from burning themselves up.

Reply to  Duane
July 7, 2022 12:31 pm

Unfortunately, DuhWayne, your explanation of why there are efficiency losses is completely bogus – just like everything you’ve ever written about thermodynamics (and many other things too). Look up “Carnot Efficiency”. Carnot figured this out in 1824 – you’re only about 200 years out of date. The efficiency is limited by the high and low temperatures used and can be no greater than a reversible engine – one with no irreversibilities. The higher the input temperature and the lower the output, the higher the efficiency. Unfortunately, you can’t get lower than ambient temperatures, – even in a once-through steam cycle. Steam trains which do exhaust directly into the atmosphere are still very inefficient – about 6%.

However, you are correct that the efficiency in converting heat to electricity is limited. Use electricity to heat sand and then later make electricity out of the hot sand then and you’ll get about 45% of the input electricity back (the efficiency of a highly efficient steam turbine), plus or minus, depending on how hot you get the sand. As you use the heat in the sand the sand will cool down and the efficiency will get worse.

To get a equal amount of electricity at night as you can get from one solar farm during the day would require that you build ~3 more solar plants just to heat the sand.

You would be much better to use the sun to heat the sand, but we already know that solar concentrators can’t compete economically even at the very high temperatures (and thus high efficiency) achievable with Liquid Sodium.

I don’t think that Willis did his normal due diligence in calculating the cost of such an inefficient system to provide load leveling.

Reply to  meab
July 8, 2022 4:38 am

Dude, unlike you I was a qualitied reactor plant operator for years, both military and civilian, and I am a degreed engineer, so I know the rankine cycle quite well, unlike you and Willis. Ask any qualified steam power plant operator and they know exactly this

Go ahead smart boy, look it up – there are only thousands of articles on the rankine cycle on the internet – a technology that has been well established for centuries.

The rankine cycle cannot be overcome – the efficiency losses are simply built into any steam power plant.

Likewise the efficiency if lithium ion batteries (energy out minus energy in) is also well established ever since they were invented. Even the extremely old low tech lead acid batteries can, depending upon design and use, be up to 95% efficient.

Reply to  Duane
July 8, 2022 8:38 am

Like always, DuhWayne, you’re full of shit. You are talking to a PhD Nuclear Engineer who taught thermodynamics at a major university for years. You can’t BS me with your “qualified reactor plant operator” stuff. It’s a world away from being taught to follow procedures written by someone else and designing systems from scientific and engineering principles. You constantly prove that with your ignorant drivel.

Andrew Wilkins
Reply to  Duane
July 8, 2022 11:48 am

You claim to be a degreed engineer, but don’t understand the concept of percentages. I think you’re telling porkies.

Reply to  Duane
July 7, 2022 5:12 pm

Even if your claimed battery efficiency of 99% were true, you are ignoring the inefficiencies of the charging and discharging circuitry which includes AC/DC and DC/AC conversions.

Secondly, If you are going to move more than a trivial amount of energy into or out of those batteries, you have to deal with a significant amount of heat. There’s a reason why Tesla adds active cooling to the batteries themselves.
That cooling consumes power, and the heat that is being removed constitutes lost energy as well.

Last edited 1 month ago by MarkW
Reply to  MarkW
July 8, 2022 4:41 am

It is true. Electrical energy storage is simply vastly, vastly vastly more efficient than any kind of thermal or mechanical energy storage, always has been, always will be, it is unavoidable with any thermal power plant.

Last edited 1 month ago by Duane
Reply to  Duane
July 8, 2022 8:59 am

One of these days Duane will come to the realization that just because he wants something to be true, doesn’t make it true.

Reply to  Duane
July 8, 2022 1:07 pm

While it is technically true that electrical storage may be more efficient than most mechanical forms of storage, so what.
1) Electrical storage is nowhere near as efficient as you have been claiming.
2) What matters is total cost, and on that factor, batteries loose, by several orders of magnitude. There’s a reason why people are still looking for affordable storage schemes despite the fact that battery systems already exist.

Reply to  Duane
July 8, 2022 9:01 am

I have to give Duane credit. He usually scurries off and hides whenever one of his missives on the wonders of batteries gets shredded. This time he actually came back and tried to defend his nonsense. Of course his “defense” amounted to little more than screaming “I’m right, you’re wrong”. One does have to account for basic ability and intelligence after all.

Last edited 1 month ago by MarkW
Reply to  Duane
July 9, 2022 11:12 am

Having on done the cost estimate for a phase change glauber salt system at some point in the past, I found that long term storage of heat results in the cost of INSULATION and the heat loss through the insulation to be a significant factor. Even geothermal storage of summer heat underground (“free” insulation) requires the use of backup gas boilers of 100% capacity in case of failure. Here is an example a few miles from where I live….note “not competitive with natural gas heating”

Last edited 30 days ago by DMacKenzie
July 7, 2022 10:29 am

Willis: I like the idea. Simple is better. But scalable is debatable. Alberta, with 2 million homes, would need 1-2 billion tonnes of sand, or more, to heat through a moderate winter.
My mental calcs are quite conservative, too.
1 tonne of bulk sand (kudos for getting the bulk density right), would warm the air in a small apartment (100 m3, about 500 ft2) about 16 times, reducing the sand temp by 30 C deg each time (assumes 100% efficiency), starting at 500 deg C.
Assuming the furnace kicks in once an hour, means 16 hours of heat. So about 1.5 tonnes/day of sand is needed for a small apartment. A winter heating season in Alberta is 6 to 8 months.
180 days*1.5 tonnes =270 tonnes per season per small apartment.
For a cold winter, it could approach 1000 tonnes per unit. The furnace runs near constantly when its -40. For a larger home, double, treble or more.
For scale, 1000 tonnes of sand is used on a VERY large fracture job. This would require 25 field silos to store. Insulated, of course. The footprint of these silos would be about 1000 sq ft, if packed tightly, and two stories high. All for one 500 sq ft apartment. The volume of 1000 tonnes of bulk sand alone is 625 m3, which is over 6 times the volume of a 500 ft2 apartment with about 7 foot ceilings. Watch your head.
Yes, a larger silo would work better, but I am just trying to show the scale needed, using equipment I am familiar with.
I think the tech has potential, but its niche. The sheer weight of the sand, and volume of storage, makes it impractical for any large urban area.
I also think the round trip efficiency will be less than 40%. But that is another issue.

Last edited 1 month ago by Les Johnson
Reply to  Willis Eschenbach
July 7, 2022 11:47 am

And I see my error. I misplaced a decimal point AND used the same specific heat. All my numbers are high by over an order of magnitude (nearly 2!). Close enough for government work, but not engineering.

Using your numbers, roughly 1 or more tonnes of sand (initial temp 1000) would heat a 500 sq ft apartment over a mild winter. Air source temp and whether it replaces or recirculates unit air, gives a wide range.

Much more manageable.

Last edited 1 month ago by Les Johnson
Reply to  Les Johnson
July 7, 2022 11:27 pm

I’d be more comfortable with your numbers if you compared them with the typical KWh/BTU usage of an Albertan home (if it works in Alberta, it’ll work most anywhere else!)

Reply to  Willis Eschenbach
July 7, 2022 11:50 am

So in this case we are heating sand near the end user and blowing air through it to warm their house? I’m not sure how you would plan on heating the sand locally to 1000C efficiently.

Way back in my early academic days and my ceramic engineering classes, I remember ideas to heat ceramic materials that have a higher specific heat than pure sand and use them in passive solar homes. The issue was winter Sun didn’t heat it up much, so you had to add extra heat from somewhere. I suppose with some technical refining, you could get it to work somewhat.

I certainly think what Willis is proposing has more merit than Li-ion batteries. Sand or a better ceramic won’t wear out, although the infrastructure ultimately will. Ceramics are not a good heat conductor which is why sand can store a bunch of heat, so you have to address heat transfer in and out. Lots of technical issues would need addressing to get the more efficient solution.

Last edited 1 month ago by rbabcock
AGW is Not Science
Reply to  rbabcock
July 7, 2022 1:58 pm

I can’t help but picture an electric car hauling a semi trailer with insulated sand silos plus a turbine setup, and a windmill to generate power to hear the sand.

In my mental cartoon, the driver turns to the passenger and says “We’re just waiting for the sand to heat up. Should be on our way in a month or so.”

Peter Muller
Reply to  Willis Eschenbach
July 7, 2022 3:00 pm

OK has anyone thought about the rheological properties of quartz sand at 1000 C? I would think that it behaves in at least a somewhat ductile fashion and especially if its under pressure from the weight of overlying sand. Seems like it might even start to recrystallize and flow creating a solid mass, not a low-cohesion granular material that can be easily recycled over and over. Structural geologists think about this kind of stuff….

Reply to  Peter Muller
July 7, 2022 7:46 pm

Reports I read about the solar mirror setups that heated a salt of some sort in a central tower, for underground storage, had a big fail in that the salt would not stay hot enough to be pumped back out at night when it was supposed to be used to generate electricity. If I remember correctly, the system required at least 8 hours per day of natural gas heating to keep the underground salt fluid.

The mechanics of this sand particle idea might be a little different but it still seems like the storage period would be very short before heat loss to the surrounding environment would make the once heated sand useless for producing steam.

Tim Gorman
Reply to  Peter Muller
July 8, 2022 1:56 pm

That’s what I called “clumping” in another sub-thread.

Reply to  Willis Eschenbach
July 7, 2022 7:38 pm

The higher the temperature of the storage media, the greater the gradient to the outside, thus the faster heat will be lost from storage.

The Dark Lord
Reply to  AndyHce
July 7, 2022 11:39 pm

yeah big urban heat island right there … millions of BTU’s per hour … all lost …

Reply to  Les Johnson
July 7, 2022 4:42 pm

Alberta, with 2 million homes, would need 1-2 billion tonnes of sand,”
No, this shouldn’t be replacing all other electrical production, just added to or to supplement.

Reply to  Les Johnson
July 8, 2022 10:09 am

Greenhouses in Alberta using passive heat storage. It gets damn cold there which makes this even more impressive.

July 7, 2022 10:31 am

Great post as always Willis – inviting us all to look into a topic and further inform ourselves through our own research efforts.

Monterey Bay – wasn’t that where John Denver ditched his plane?
When I visited there, one of the local tour guides told us that J.D. was the ultimate greenie – wouldn’t pollute his plane by putting gas in it.

Michael in Dublin
July 7, 2022 10:34 am

As a non-technical person I am trying to comprehend how this would work. As an analogy will it be something like a Pumped-storage hydroelectricity dam? Excess electricity is used to fill the upper dam from a lower one. In times of higher demand this will then supplement the normal supply with hydro. This works well with peak demand and uses electricity available during low demand but I do not believe it as economical as electricity produced from natural gas power plants – if this is available.

AGW is Not Science
Reply to  Michael in Dublin
July 7, 2022 2:01 pm

My first question with these pie-in-the-sky scams, er schemes is “where is all this “excess” electricity coming from?! Wind and solar can’t even produce enough energy to replicate themselves.

Chris Hanley
Reply to  AGW is Not Science
July 7, 2022 3:12 pm

As with all alternatives to establish energy sources the ratio of energy returned to the energy invested is the fundamental problem.

Last edited 1 month ago by Chris Hanley
Willem post
Reply to  AGW is Not Science
July 7, 2022 5:31 pm

Fossil fuels are the best that ever happened to civilization.
They have so many benefits, it would take a long list to display all of them

Last edited 1 month ago by Willem post
Reply to  AGW is Not Science
July 8, 2022 9:12 am

Power plants are most efficient if they can be run at the same level, 24 hours a day.
Unfortunately demand is not constant throughout the day, their are peaks and troughs in demand. The exact timing of these peaks and troughs will vary throughout the year and will also vary due to latitude, or the geography of the plant location.

It would be very expensive to build your baseline plants big enough to handle the biggest peak of the year, and then have a portion of your power plants at idle the rest of the time. Many electricity producers handle this by having “peaking” power plants, that only get run when the baseline units can’t keep up. This is an expensive solution.
Other solutions such as pumped storage have been tried, and have been successful. The problem is that the number of places suitable for pumped storage are limited.

Batteries have been proposed, but batteries are hideously expensive. If this idea turns out to be economical, it could help with this problem. I don’t see it having any potential for anything other than that.

July 7, 2022 10:38 am

Despite the oft repeated claims by WUWT writers that lithium is mostly produced in backwards undeveloped third world backwaters with child labor, it’s simply not true.

Here is the list of worldwide production of lithium by nation, of which only one nation, Zimbabwe, can be characterized as claimed by WUWT, and Zimbabwe produces only 1,000 tons per year, as of May 2022.

Here’s the list:

The Top Lithium Producing Countries In The World
Australia – 13,000 metric tons
Chile – 12,900 tons
China – 5,000 tons
Argentina – 2,900 tons
Zimbabwe – 1,000 tons
Portugal – 570 tons
Brazil – 400 tons.

So the only third world backwards country allegedly using child labor produces 1,000 tons out of the 32,870 tons of lithium produced by the worlds top seven producing nations … accounting for a mere 3% of production.

Reply to  Duane
July 7, 2022 11:10 am

I think most people are concerned with the safety of lithium.

G Mawer
Reply to  Derg
July 7, 2022 12:46 pm

Anybody know why they are not using the flat blades as opposed to the round wrapped batteries? I have seen demonstrations indicating they are much safer, much less prone to fires.

Reply to  Derg
July 8, 2022 4:47 am

So most people” included the idiots here at WUWT? … so what about the concerns or non-concerns of the other 8+ billion people in the world.

You apparently do not realize that the laptop computer or mobile device that you and billions of other people use every day are somehow not the problem, only EV s that violate your sense of anti-EV religious radicalism?

Reply to  Duane
July 8, 2022 9:15 am

Wow, Duane really gets his panties in a wad whenever someone points out some of the many problems with lithium and his precious electric vehicles.
One EV has more lithium in it than do a thousand lap tops or a 100,000 cell phones.

Reply to  MarkW
July 8, 2022 12:38 pm

ANY simpleton would have thought of that before comparing EV batteries to small phone or laptop batteries.

Well not EVERY simpleton.

Reply to  Duane
July 7, 2022 11:14 am


Reply to  Rob_Dawg
July 8, 2022 4:48 am

China has technology and an industrial base that is better than in most advanced first world nation, and rivals that of the US.

What, do you still think the Chinese are a nation of peasants starving in rice paddies? SMH

Reply to  Duane
July 8, 2022 9:16 am

Large portions of Chinese are still peasants working in rice paddies.

Barry Malcolm
Reply to  Willis Eschenbach
July 7, 2022 4:12 pm

Can you stop with common sense and facts, be kind to detractors.

Reply to  Willis Eschenbach
July 8, 2022 5:06 am

Your entire existence as a human depends upon mining of ALL kinds, none of which is ever “pretty”. Everything from the tools you use, the electronics you possess and use to compose and post your articles on the internet, the internet itself, to the electrical wiring in your home, to your mode of transportation, to the medicines and medical devices and medical facilities that keep you alive, the the concrete in your home’s foundation, to the materials used to build and power the fishing boats you used to work on, to the jewelry and watches you and your wife wear, to the national defense hardware that keeps the entire nation safe …

Every damn bit of your life and my life depends upon mining that is NEVER pretty. And that has been true for all of humanity ever since mankind progressed beyond the stone age.

And do NOT pretend you aren’t talking about child labor Virtually every post on WUWT, of which you are a regular contributor, including one posted just a few day ago, include pictures of child laborers in Africa – which all of you cry so many crocodile tears over. Oh PULEEZE, get serious.

Nearly all of the world’s lithium is produced in ugly mines, operated by sophisticated mine operators working under their respective mining rules. The US has never been any more sophisticated or modern in our mining rules – after all, every US mine is still operated under a 19th century mining law – 1872 to be exact – that exempts the mine operator from most environmental laws and regulations that every other industry is compelled to comply with.

How about all the articles you rarely pay attention to about mine spills or mine waste mis-management in the US? I know personally, having worked at one time as an engineer on the Uranium Mill Tailings Remedial Action (UMTRA) program that spent hundreds of millions of US tax dollars trying to clean up the mess left behind by 50 years of US uranium extraction and processing. That’s just a single mineral, and one that is very tiny in terms waste volumes compared all the others that are still being mined today.

In the State of Colorado alone, a huge area in the southwest part of the state was declared a Super Fund site a few years ago – much of the mining activity dating back to the late 19th century, but also a good deal of it in the modern era post WW Two. Remember that mine blowout a few years ago that made all the headlines? That was part of the EPA response to that massive mess left behind by totally legal (and still legal) US mining that was never “very pretty”.

Stop it with the crocodile tears and the feigned concerns over mining that weirdly only applies to one mineral that it extremely tiny in volume compared to the massive volumes of mine operations all over the world that are never “very pretty.”

I am with WUWT all the way on its campaign against warmunism … and I am equally totally opposed to the mindless Luddism that is unfortunately also rampant on WUWT. The future of the world is electrical power, better get use to it, and it has nothing to do with global warming and everything to do with cleaner, cheaper, less environmentally impactful, and safer infrastructure and machines.

Reply to  Duane
July 8, 2022 8:32 am

Virtually every post on WUWT, of which you are a regular contributor,

So, guilt by association is your argument then? That makes you guilty too. It’s a wide net you cast, too bad you got caught in it too.

Reply to  Duane
July 8, 2022 8:48 am

The oil and gas industry is cheaper, has a smaller footprint, and produces products for both stationary and transport devices. IT. IS. THE. BEST. By far. PS I have no interests monetarily, in any way beyond common sense, with the fossil fuel industry. Energy density by weight? Better X 7. That’s a high bar…

Reply to  Duane
July 8, 2022 9:25 am

And do NOT pretend you aren’t talking about child labor Virtually every post on WUWT, 

Willis is responsible for what every other poster posts? Really?

As to your claims that you know what Willis is talking about better than Willis does … I just have to consider the source.

Willis treats you much better than you deserve.

Reply to  Duane
July 8, 2022 9:26 am

You readily admit that mines are ugly and dangerous, so why do you want to increase the total number of mines by such a huge amount?

Perhaps you aren’t the saint that you believe yourself to be?

Reply to  Duane
July 7, 2022 12:49 pm

Nice move there combining cobalt, lithium, and other commodities and then making the argument based on lithium alone. Is that part of the weekly troll instruction manual or a rogue effort?

Tony Sullivan
Reply to  ResourceGuy
July 7, 2022 2:20 pm

Likely a combo of the two when Duane is involved.

Reply to  Tony Sullivan
July 8, 2022 5:12 am

Likely a combo of common sense, engineering education and experience on real world projects (not banging the keyboard in someone’s mother’s basement), including decades of experience specifically in steam power plants and also mining waste and petroleum waste cleanup, among other areas of expertise, that nobody else on this thread or the the former commercial fisherman authoring this post possesses.

Reply to  Duane
July 8, 2022 9:28 am

Wow, so much ego, so little actual accomplishments.

Duane the picture you paint of yourself is that of a pathetic little soul that can’t find any other way to get the attention that you so desperately crave.

Reply to  ResourceGuy
July 8, 2022 5:10 am

Citing relevant facts is not trolling. Calling such trolling is trolling.
You like all other humans on the planet are dependent upon “not pretty” mining To single out lithium as the whipping boy is just plain effing weird and only something that a Luddite like you would embrace.

Reply to  Duane
July 8, 2022 9:29 am

The problem is that your facts aren’t relevant, for the reasons laid out above.

William Wilson
Reply to  Duane
July 7, 2022 2:21 pm

32870 tons does not sound much given that everybody is supposed to be driving electric cars soon.

Reply to  William Wilson
July 8, 2022 5:13 am

Certainly production will rise to meet whatever the demand will be in the future, and again, nearly all of it will come from first world modern developed industrialized nations, not jungle backwaters of the third world.

Trying to Play Nice
Reply to  Duane
July 8, 2022 9:14 am

The price of lithium today is up 424% from one year ago. Do you think if the demand for lithium goes up by a couple orders of magnitude that the price will drop or remain stable? Maybe you should have taken an economics class along with all those engineering classes that make you so smart.

Reply to  Duane
July 8, 2022 9:33 am

Why do you believe that future growth will come from developed ones and not the third world? The trend over the last 100 years or so has been for mining to be leaving the developed world. Why do you believe that lithium will be the one mineral to buck this trend?

Since EVs are still less than 1% of all cars being built, the amounts needed just to handle new car production will have to go up by a factor of more than 100. In addition to that the number of batteries that will be needed to replace worn out batteries will easily outnumber the number of batteries needed for new cars.

Face it, your religious fanaticism in favor of electrics is a pipe dream.

Dave Andrews
Reply to  William Wilson
July 8, 2022 7:33 am

A recent report for the European Commission ‘Crtitical Raw Materials in Technologies and Sectors in the EU – A Foresight Study’ said that lithium needs in the EU would increase by 108,000 tonnes by 2030 and 340,000 tonnes by 2050. This is 18 and 58 times the current usage respectively

Cobalt would increase 150,000 tonnes by 2030 and 420,000 tonnes by 2050 (5 and 14 times the respective current usage)

Now imagine the increased mining necessary with the rest of the world going down a similar path.

Reply to  Duane
July 7, 2022 7:49 pm

The clhld labor claims come from the mining of cobolt somewhere in Africa, not lithium.

Reply to  AndyHce
July 8, 2022 5:16 am

WUWT routinely conflates cobalt and lithium, blaming it all on EVs as if the entire world is not already electrified. Most cobalt is not even used in EVs – its used mostly for tools as improved steel alloys such as oil and gas drilling bits, and other machine tools. One of the largest manufacturers of tools is in fact named “Kobalt” and that is no mere coincidence.

Dave Andrews
Reply to  Duane
July 8, 2022 7:49 am

The IEA published a commentary on the supply challenges facing the EV market earlier this year (30th Jan 2022) which said

“EVs are set to enter a new phase in which raw materials and component supply come to the fore. For the first time , supply side bottlenecks are becoming a real challenge to electrification of road transport ” and
World faces potential shortages of lithium and cobalt as early as 2025″

Reply to  Duane
July 8, 2022 8:52 am

The periodic table disputes your claim. No one has ever conflated cobalt and lithium since 1817 when lithium was discovered. It is not possible for educated people to do that, as they are two different elements.

Reply to  Duane
July 8, 2022 9:34 am

As usual, Duane is unable to find support for his position in the current article, therefore he has to claim that all articles written here are part of some grand conspiracy to make electric cars look bad.

Reply to  Duane
July 8, 2022 4:44 am

Downvoting proven facts – wow, that shows that the 19 idiots downvoting here care only about their anti-EV ideology not actual, you know, real world facts.

You are exactly like the warmunists and their religious fervor for warmunism. Like two peas in a pod you all are.

SMH cubed!

Reply to  Duane
July 8, 2022 9:36 am

While they may be facts, they are unfortunately for you, not facts that are relevant to the discussion at hand. Which is pretty typical of your posts.
Though I do have to give you credit, for once your facts are actually true.

Alastair Brickell
Reply to  Duane
July 9, 2022 6:31 am

Yes, I think you’re mostly right on this one. WUWT sometimes lumps lithium production with cobalt or rare earth production which is quite different and can often be nasty (thought not so much in Australia).

I would think that yes Zimbabwe could be a problem but so could China (slave, not child labour). Most of the other Li producers are from brines or spodumene pegmatite hard rock mines so relatively clean and child free.

Rud Istvan
July 7, 2022 10:39 am

WE, agree about the Tesla megapacks. Two major fires in six months is NOT a good look despite the high cost.

As for hot sand, color me very doubtful. For one thing, NREL has NEVER produced a useful engineering development. All their spun out fancy Solar ideas have failed. All their battery ideas failed. They even dabbled in supercapacitors and failed, while my novel carbon materials idea succeeded, validated by Naval Research Labs in a $multimillion joint project involving hundreds of devices for something the Marine Corps badly needed for their electronic field equipment.

For another thing, a UK engineering company called Isentropic tried a version of this NREL ‘hot sand’ idea in the UK in 2014 at pilot scale (using UK government money for the pilot plant at IIRC about 1 Mw. They used gravel (ok, so hot rocks) rather than sand because they wanted more voids in their ‘PHES’ system, which left the gravel in place and used inert argon for heat injection/extraction.It didn’t work as planned. They went bankrupt.

Highest regards

Rainer Bensch
Reply to  Willis Eschenbach
July 8, 2022 3:48 am

When the sand is heated immediately after extracting the heat why do you even do this? Looks like perpetual motion to me.

Reply to  Rud Istvan
July 7, 2022 6:39 pm

Interesting table on various materials heat storage.
Where is “sand” (silica ?) compared to granite?
What is the cost of converting a certain specific heat of one material to the energy density of a different material ?

Reply to  Rud Istvan
July 8, 2022 5:19 am

Really, all their “solar ideas have failed”. Hmm, coulda fooled the rest of the world, given the massive growth in production of solar cells including utility scale plants using cells that have drastically been reduced in cost (90% reduction in the last decade). Here in Florida the state’s largest and most successful utility – Florida Power and Light – is also the world’s largest producer of utility scale solar, and also has nearly the cheapest electrical power rates, non-subsidized – of any utility in the US and even the entire world.

If that is your definition of “failed” then it certainly begs the question of your definition of “success”.,

Jim Gorman
Reply to  Duane
July 8, 2022 6:31 am

Given that solar is truly productive for what six hours per day, I wouldn’t call it a success for power generation.

Reply to  Jim Gorman
July 8, 2022 9:41 am

6 hours a day in the summer. Much less in the winter.
0 hours when it is cloudy or the panels are covered in snow.

Reply to  Duane
July 8, 2022 9:40 am

Yes, they have all failed.
The fact that governments continue to spend massive amounts of money to prop up failed ideas is hardly new or unusual.

If something can only “succeed” using massive subsidies and government mandates, can it really be called “successful”?

Reply to  Duane
July 8, 2022 12:45 pm

Is Florida Power and Light based on NREL engineering?

Reply to  Rud Istvan
July 8, 2022 7:00 am

NREL has NEVER produced a useful engineering development.

That’s an interesting point. Someone smart enough to come up with a useful engineering development is probably going to be keen on capitalizing and controlling it them self.

July 7, 2022 10:41 am

The cost of the bulk sand is probably trivial compared to the cost of the buildings, the insulation, and the piping needed to transfer the heat.

Rick C
Reply to  Willis Eschenbach
July 7, 2022 12:42 pm

I’m curious about what materials will be used for piping to circulate water/stream through the sand fluidized bed. Sand is pretty abrasive and hot sand more so. A ruptured water pipe within the hot sand containment would be a serious hazard. What kind of materials would last long enough in this environment to be practical?

Reply to  Rick C
July 7, 2022 1:39 pm

My guess is air is circulated through the sand and the heated air heats the water in an exchanger. I made a comment earlier above that any ceramic is a poor heat conductor and getting heat into and out of it efficiently takes a well thought out and tested process. It would be a really fun engineering design problem. You have materials, mechanical, electrical and thermo involved. Maybe Griff can chime in with some ideas since he is well versed on just about anything to do with wind or solar.

Reply to  Willis Eschenbach
July 7, 2022 9:40 pm

Clean (silica) sand for construction is about $80 /tonne in Australia, how much does that work out per kwhr?

July 7, 2022 10:59 am

The rate of heat extraction from the system may be a problem. Your are depending on mechanical systems, running at high temps to transfer sand from the bins to the boilers, or from the heaters to the bins. Gravity only helps some. Also, the transfer of heat from sand to water seems to be problematic. Boiler tubes filled with sand moving at some rate? Engineering problems, but certainly sources of more losses.

Reply to  Dbw49
July 8, 2022 9:44 am

I’m having trouble visualizing a mechanism by which sand can be transported into the boiler and dropped into the water in order to boil it. Remember the boiler has to remain air tight otherwise the steam just escapes to the atmosphere rather than turning your turbine.
The same problem exists for how to remove the wet sand from the boiler after it has given up its heat.

Steven Pfeiffer
July 7, 2022 11:13 am

The diagram is a bit disjointed and confusing. They refer to it as a “combined cycle”…does not look like a combined cycle to me. And the turbines are gas/steam turbines? What does that mean?

Gas turbines are a LOT different than steam turbines, unless they mean an “air standard” Brayton cycle with a hot air turbine.

Seem that it would require energy storage at quite high temperatures if they want to operate a stem turbine or air turbine cycle. I would like to see the fluid temperatures and pressures involved.

And lastly, this seems lie an idea similar to the idea that has been widely floated of using solar or wind generated power to store heat energy in molten salt and then use the stored energy to run a steam turbine or heat engine power cycle.

Rud Istvan
Reply to  Steven Pfeiffer
July 7, 2022 1:45 pm

In my experience, everything at NREL is disjointed and confusing.

Frank from NoVA
July 7, 2022 11:14 am

‘First, it is very cheap. Instead of using expensive lithium for storage, it uses cheap silica sand.’

Isn’t crystalline silica on CA’s (Prop 65) sh*t list?

john harmsworth
July 7, 2022 11:20 am

I have to wonder what the specific heat of sand is and how much physical work is involved in moving it around the system. Doesn’t look very efficient to me. Also, I hate energy storage in principle because it’s always used to deflect from the reality and cost of creating that energy in the first place.

Gordon A. Dressler
July 7, 2022 11:32 am


Thank you for your interesting post.

I have some related comments:

1) As to the new NREL-developed particle thermal energy storage system, it will pass or fail based on its overall cycle efficiency . . . time averaged kWh in versus kWh out. There was no mention as to engineering calculations for even maximum possible efficiency with such a concept. An expected issue in this regard is that systems based on intermediate storage of thermal energy have been notoriously inefficient due to unavoidable but significant heat losses over time.

2) Moss Landing is located in an area of high seismic activity, in relatively close proximity to several major active faults including the offshore San Gregorio Fault and the offshore Monterey Bay Fault. It is located about 15 miles west of the San Andreas fault line. Not having the details a what earthquake it was designed to survive structurally, I can only speculate that the Tesla Megapacks at the old Moss Landing power plant might not fare too well in a magnitude 8+ earthquake.

3) Being located at sea level within some 500 to 1,000 feet of the Elkhorn Slough and at a distance of one-half mile from the Pacific Ocean, I do believe any significant tsunami that results from a sizable earthquake in the area stands a good chance of significant damaging, in not totally destroying, these Tesla Megapacs.

4) “Not far from you, but out of sight, lateral spreading at the Moss Landing Marine Laboratory causes the building’s foundation to spread apart by 1 to 1.3 meters, nearly collapsing the whole structure.
“Such were the sights on Oct. 17, 1989, along the perimeter of Elkhorn Slough, during the historic Loma Prieta earthquake. The damage in Moss Landing, documented in photos on a UC Davis website on earthquake hazards, would later serve as a case study for the impact of liquefaction in seismic events. Liquefaction, according to the U.S. Geological Survey, is a phenomenon wherein ‘loosely packed, water-logged sediments at or near the ground level lose their strength in response to ground shaking.’ The fluid-like consistency of the ground cannot support structures, and is often likened to quicksand.
“No earthquake of a comparable scale has since struck this region of the San Andreas Fault, which runs through the southeastern region of Monterey County for 30 miles. But the USGS estimates that in the greater Bay Area region, which extends from Santa Rosa to Monterey County, there is a 72-percent probability of at least one 6.7-magnitude or greater earthquake striking before 2043, a forecast based on historical earthquake frequency and magnitude and the rate that tension builds along faults in the region.
“And according to a 2018 USGS long-term earthquake hazard map, most of Monterey County falls on or near the ‘highest hazard’ end of the scale, with the southwestern portion of the region around Big Sur posing slightly less than the ‘highest hazard’ designation.”

July 7, 2022 11:45 am

Have you heard of Heath Robinson?
The idea is insane, just take a step back, why are such crazy ‘solutions’ even proposed?
Any way you slice it it is pointlessly using up more manufacturing resources and energy to add more cost, complexity, and inefficiency to energy supply, futilely trying to make unworkable renewables do what they can’t. Provide cheap and reliable constant energy.
The Fin 100T silo doesn’t even store as much energy as one UK house uses for heating in a year. Obviously that is not how it will be used, but equally it tells you one such silo could only serve a handful of houses. Can you imagine what this would look like in reality?

Reply to  MrGrimNasty
July 7, 2022 12:27 pm

”…pointlessly using up more…resources and energy…to make…renewables do what they can’t…”

That sums up the entire search for energy storage. You can’t make an inefficient impractical system efficient & practical by adding more systems to it.

The solution is to get rid of renewables and operate the fossil fuel and nuclear generating systems proven to be practical & efficient.

Reply to  MrGrimNasty
July 7, 2022 12:53 pm

In the states we’re more familiar with Rube Goldberg than Heath Robinson

John Hultquist
Reply to  MrGrimNasty
July 7, 2022 12:54 pm

In the USA, the artist Rube Goldberg is the counterpart of Heath Robinson.

2% Milk
July 7, 2022 11:55 am

While I can’t quote you praising district heating (because you don’t) there is also no reference to the corrupt, expensive, capital-intensive boondoggle such systems inevitably become. Sorry no footnotes on the comment, but I speculate even with free energy district heating is a high-cost, low quality of service operation wherever it is attempted.

John Hultquist
Reply to  2% Milk
July 7, 2022 12:59 pm

District heating is used at many places, such as university campuses, with pipes running under sidewalks, and allowing for access.
In Boise, ID, geothermal energy has been used for many years to heat a large number of buildings.
Geothermal district heating in the U.S.? – actually yes, in Boise, Idaho | ThinkGeoEnergy – Geothermal Energy News

Gilbert K. Arnold
Reply to  John Hultquist
July 7, 2022 7:37 pm

Additional information about geothermal district heating can be found the websites of Geothermal Rising <> and the Oregon Institute of Technology’s Geo-Heat Center

Reply to  2% Milk
July 7, 2022 3:18 pm

” …. District heating is a high-cost, low quality of service operation wherever it is attempted.”

I don’t know if that’s true generally, but the system in Sutton, S. London, certainly merits the term boondoggle.
Sutton District Energy Network – SDEN to its friend – seems to be a plaything of the local Borough Council.


July 7, 2022 12:00 pm

Dear Willis :
I read all your articles, but do not comment, not being a scientist. But this time, after your Hot Sand piece , I went to “The Native Sun”, down in the Related . And I just loved it.

The stories you write from your life are Great.
I read the old ones in my Plaza Moyua preserved ( now that Plazaeme is no more )
I hope you publish them together as a book.

Un fuerte abrazo

July 7, 2022 12:11 pm

The idea, I gather, is to use excess wind- and solar-generated electricity to heat the sand. My question is where is this excess power going to come from? Today, in the windy Plains states (Southwest Power Pool, to be precise), coal and natural gas are providing about 83% of the load, and wind is providing about 8.2%. Solar is less than 0.5%; in other words, lost in the rounding. There has never been a day, even a moment, when wind and solar have met the full demand on the system, since the records have been made available. It will be a long time before wind and solar can fill the bill here. And if we, in the windy Plains, can’t do it, likely nobody can.

Reply to  starzmom
July 7, 2022 2:54 pm

Word salad Bob must have downvoted your post, but I gave it +1.

Tombstone Gabby
Reply to  starzmom
July 7, 2022 5:26 pm

G’Day Starzmom,

“There has never been a day, even a moment, when wind and solar have met the full demand on the system…”

A day to day graphic illustration of how California is obtaining it’s power. The bottom graph on the page is “Import”. Over the past three weeks that line has dipped below zero on just four days. Overnight the ‘Import’ ranges from 7,000 to 9,000 MW.

Reply to  Tombstone Gabby
July 7, 2022 6:24 pm

Gabby, i don’t follow California, as I don’t live there, but I do follow the SPP, since I live in its territory. We don’t have an “import” portion of our grid, at least not in the easy to find information. I look at whether or not we can meet our demand with non-fossil-fueled generation, and we never, ever have. Maybe other places are different.

July 7, 2022 12:39 pm

As others, I don’t think that the capacity of this system is adapted for a seasonal heat storage. In addition, sand is not a good material in this case (first it will begin to soften at relatively mild temperatures of 600 or 700°C and in addition the grains will erode during operation and let silica dust damage the turbine).
It should be noted that pressurized hot air storage / generator have been used for centuries in the steel industry (look for “cowper stove” on internet) with inlet / outlet temperatures of 1500 / 1200 °C and pressures of 10 bars (150 psi), which is enough to feed a “standard” gas turbine, but with a storage capacity of a few hours only !

Reply to  papijo
July 8, 2022 10:03 am

Beyond questions of storage material, I don’t know of any kind of insulation that will be able to keep that material warm for months.

Old Man Winter
July 7, 2022 12:39 pm

There is an aggregate shortage in the Twin Cities area due to demand for construction/road building
as well as fracking sand made from sandstone. They’re mining for fracking sand east of there in
Wisconsin, at least 600 miles from the oil wells in ND.

Peta of Newark
Reply to  Old Man Winter
July 7, 2022 2:09 pm

Yes and no..
Aggregate requires (UK terminology) ‘Sharp Sand’
i.e. Sand in s,mall grains as sand is but = grains with sharp edges. Picture broken glass.

The sort of sand Willis would need might be ‘Builder’s Sand’ (much softer and rounder grained) or what you would use in a children’s play-pit.

If you happen to have sandy desert near you, The Perfect Stuff exists there a-plenty.
Desert sand is wind-blown and thus polished – the grains are rounded with no sharp edges and the stuff flows like water.
Desert sand is perfect for this application.

The Anecdote:
Concerned, I think, one of the World Cup soccer tournaments held some notso little time in Kuwait (I think, somewhere round there anyway)

Of course in wherever it was, they had to build an immense infrastrure of stadiums, new roads, hotels & accommodations etc etc and that required immense amounts of concrete.

One of their biggest headaches, everybody laughed, was finding enough of the right sort of sand to make all that concrete – I think some large part of it came from the UK in fact.
Despite being in a humongous desert made of sand, it was all the wrong sort and made shit concrete…

Old Man Winter
Reply to  Peta of Newark
July 7, 2022 2:40 pm

Thanks. All sand is NOT created equally.

July 7, 2022 12:43 pm

The true test is the lobbyist count and donations list to Uncle Joe’s Party. How else do you explain looking the other way on salve labor components for silicon solar components for half the world’s production of panels? It also needs to be rebranded into names that fit the DoE mandates like Diversity Sand or Inclusive Heater Tower or Concentrating Solar Sand. Minority sand colors might help also or minority small biz sand companies.

July 7, 2022 12:45 pm

It sure sounds good as a less costly DoE distraction, but cost savings might also harm its prospects.

July 7, 2022 1:01 pm

An interesting aspect of Moss Landing topo maps showing the underwater features where the river goes into the Pacific — the underwater ravines could only have been created when the sea level was MUCH lower. All that sea level rise since the ravines were scoured was definitely not caused by manmade CO2

H. D. Hoese
July 7, 2022 1:02 pm

Good post, that’s where the failure is from lack of proper science where hypotheticals are encouraged, then to be based on reality, not models with accepted speculations.

Been up in that area, even once on a field trip collecting in the deeps of Monterey Bay. You really have rip currents, have a picture of one north of Point Reyes. Some sands have darker heavy metals, wonder if that might help some, even walking barefoot across the whitest in a hot sun is tough. “Next, it can be built on the sites of closed coal-fired power plants.” Put in a little coal dust? There is a defunct coastal carbon black plant north of Aransas Pass, TX, that still has dark sand.

As to the fossil towers, just imagine how many we will have. Had a few the first time around decades ago, guess windmill towers minus blades came down eventually. Travel up there showed us the evidence that northern California people would have better solutions, need more electoral votes.

Steve Keohane
July 7, 2022 1:11 pm

Something similar and more simple is already in use. About 10-15 years ago I had a friend who built greenhouses, and we fantasized about storing the summer heat for winter. So I made a spread sheet with inputs for average summer temperature, humidity, altitude, etc. Used to calculate the size of a stone filled chamber beneath the building. The air from the greenhouse is blown via ducts through the stone, heating them and returning cooler air to the building. The very first greenhouse built with this ‘climate battery’ made it into February at 6000′ with no auxiliary heat. Some adjustments very made in the calculations, and a viable system needing only fan blowers and thermostats for equipment.

Tombstone Gabby
Reply to  Steve Keohane
July 7, 2022 6:02 pm

G’Day Steve,

“About 10-15 years ago…”

In the late 1980’s, if the ‘green house’ was attached to the residence and was used for no other purpose than heating the dwelling, it would have qualified for a federal income tax credit.

Unfortunately the 1970’s magazine “New Shelter” (from Rodale Press) didn’t last too long. They concentrated on serious energy conservation. What’s worse, when I contacted Rodale some years later asking for a back issue, “We didn’t keep any”. Drat!

July 7, 2022 1:14 pm

Neighbor of mine is working on the hydrogen ammonia electrolysis as a fuel for IC vehicles, apparently far more energy efficient than water electrolysis.

July 7, 2022 2:02 pm

“Instead of using expensive lithium for storage, it uses cheap silica sand. This brings the cost down from the $327 per kilowatt-hour (kWh) of lithium batteries to an NREL estimated cost of $2 – $4 per kWh. And even if the final cost is three times that, it’s still only a few percent of lithium battery cost.”

With lithium, people aren’t paying for the kWh as such. They pay for the dispatchability. Frequency control, but also the ability to switch on in seconds, to cover the gaps when a generator drops out, for example. You can’t do that with hot sand.

Steven Pfeiffer
Reply to  Nick Stokes
July 7, 2022 2:49 pm

I agree…comparing lithium batteries to hot sand is an apples to sewing machines comparison.

Reply to  Nick Stokes
July 7, 2022 2:55 pm

But does the sand catch fire 😉

Reply to  Derg
July 8, 2022 1:16 pm

You can get pretty much anything to burn, if you work hard enough at it.

Reply to  Derg
July 9, 2022 10:43 pm

Just pour some chlorine trifluoride on it.🙃

William Wilson
July 7, 2022 2:12 pm

This is not revolutionary. It is just a heat exchanger which could be found in thousands of industrial plants worldwide. Outgoing hot gases heat incoming cold gases and save heating costs. Just reengineered.

Ed Zuiderwijk
July 7, 2022 2:18 pm

Sand has about 1/5th of the specific heat of water but is 3.3 times as dense, so per unit volume it has about 65% of the heat storage capacity of water. However, sand can be heated to over 500 degrees centigrade, water only to 80 or 90 degrees. Depending on the lowest temperature at which you can extract heat efficiently from the storage, say 30 or 40 degrees, a sand based heat battery can outperform a water based one by a factor up to ten.

Peta of Newark
July 7, 2022 2:38 pm

A few folks are concerned about The 2nd Law and as it applies here.

No no no.
The 2nd Law is the 2nd Law – only Climate Science can and does ride roughshod over it.

The mains concern here is the efficiency of the system and it is Carnot that tells us all about it.

Carnot says that the efficiency of any and all heat engines depends **only** on two things:

  1. The input temperature
  2. The output or exhaust temperature

Both expressed in Kelvin

The Heat Engine here is the steam turbine driving the generators.
Its input temp is the temp of the steam going in and it’s exhaust is the temp of the fluid coming away from the other end of the turbine
That is it – the steam turbine is the heat engine here

The output of the steam turbine will be as almost all steam turbines is and are and will be about equal to the temperature of the cooling tower = about 30° Celsius

The input to the turbine is limited by the mechanical strength of your system.
In that you can make steam of very high temperature but when you do, its pressure rises considerably.
Designing your turbine system then means a compromise between the temperature handling and pressure capabilities of your materials and also your fabrication skills
Thus in conventional power stations using steam turbines, the limit is set at around 200° Celsius

Running that through Carnot gives you an efficiency of 35%

And that is the efficiency of most fossil fuel powered stations

It’s mentioned that the sand can be heated to 1,000° Celsius.
Yes and very lovely but you can not feed the sand into your turbine

What is needed is something that the sand can heat to that temp and then have that as your ‘steam’

If you can find something then that’s brilliant
Keeping the cooling towers at 30°C and a turbine input of 1,000°C gets you and efficiency of 76%

Epic brilliant fantastic you’ve doubled your power station efficiency but you ain’t gonna get steam up to that – and plenty people have tried.

PS Carnot’s heat engine rule applies inside the GHGE also – where energy (infra-red radiation) interacts with matter to create a temp rise = increased mechanical/physical agitation of the gas molecules

So, run Carnot with an Earth surface temp of +15°C and an atmosphere with and average temp of -15°C…
You get a Carnot efficiency of 10%

Of all the infra-red radition emitted by Earthj;s surface, only 10% of it can go to heating the atmosphere

Now there’s a real bad brain-ache.
Where does the 90% go and how do you reconcile that with the 1st Law?

And if anyone dares ask those questions we know exactly what happens – you’re met by a torrent of personal abuse.

Everything is now wrong in this world but especially, The People are wrong, in every sense.

Reply to  Peta of Newark
July 8, 2022 10:51 pm

“Where does the 90% go and how do you reconcile that with the 1st Law?”

There isn’t much wrong with NASA’s “Earth Radiation Budget” diagram.

Jim Gorman
Reply to  DMacKenzie
July 9, 2022 7:49 am

Yes there is. From a thermodynamic standpoint, the surface is one body and the atmosphere is another body. They both radiate based upon their temperature. The S-B equation for net radiation is (BodyHot – BodyCold) NASA’s radiation budget has the BodyHot getting hotter by using the equation (BodyHot + BodyCold). That is wrong. The only reason for doing this is so you can get a massive number for the “back radiation” value. That is wrong.

July 7, 2022 2:42 pm

This article followed a pattern typical of leftists:

(1) Everything is wrong !
In this case, sola,r wind and lithium batteries are wrong.

(2) New technology is the answer

I’ve seen this story before.

How about my solution?
Produce electric power only when it is needed.
With nuclear, hydro and gas.
Don’t store anything.
This just might work.
No new technology needed.

Last edited 1 month ago by Richard Greene
Reply to  Richard Greene
July 8, 2022 3:05 am

Always amazing. How did you get that typed on that newfangled interweb from your Underwood?

Old Man Winter
July 7, 2022 2:46 pm

The EU commission just okayed nuclear & natty gas as green energy & assuming the US follows
suit, we’ll still need to replace the 22% that’s from coal. If they’re smart, they’ll use natty
gas for all of it as unreliable solar & wind (SAW) needs backup, which with batteries is very
expensive. Currently, the US averages 450 GW continuous generation- ~11k GWh/day. SAW is 12%
of it- 55 GW, 1,300 GWh/day. @ $327/kwh => $425B/day battery storage for 55 GW continuous
generation. If they replaced the coal portion also, the total for current & future SAW is $1.2T

Solar has a capacity factor of 9% in both the UK & Germany, because of bad weather & being N of
the Alps. For wind, the UK’s wind capacity factor’s >40%, which is industry average as Ireland
& the UK are the best spots for wind in Europe. Germany’s wind is 18% on land & 35% off-shore,
with most of it on land where Germany has very poor wind potential.

In the US, solar is best in the SW & poorest in the NE quarter & the NW coast. The SE isn’t as
good as the SW because of humidity & cloudier weather. For wind, the best spot on land is the
Great Plains. Unfortunately, there are no cities >1M there. Off-shore wind is great N of San
Fran, on the Great Lakes, & N Carolina northward. (With off-shore wind, the problem is a
NIMBY allergy among wealthy liberals toward wind turbines.) The E coast is subject to
hurricanes & Nor’easters.

So, the SW should use mostly solar, augmented by off-shore wind, where practical. The NW coast
should use off-shore wind & a mix of wind/solar inland, depending on local conditions. The middle
has better wind N & better solar S. SE should use mostly solar. The NE should use wind-
off-shore being best- as solar loses too much to daylight ops only & cloudy weather.

While unreliable green energy’s a scam, at least we should plan to use the best type suited
to a particular area. That would mean off-shore wind @ the Farallons, Point Reyes, Mendocino, San
Juan Islands for the whale watchers & Martha’s Vineyard, Cape Cod, … for the sailors. Enjoy!

Last edited 1 month ago by Old Man Winter
July 7, 2022 2:50 pm

I can’t see this working unless there is a considerable over supply of wind and solar production. But the idea of capturing waste heat that is being discharged to atmosphere utilizing ‘very course sand or pea gravel’ may have merit that may provide a relativity short term peak supply but not in the configuration/concept as shown in the graphic. A lot of cost for a peak load but likely much cheaper than existing battery technology.

Plus, when the current MADNESS subsides the installation could be useful in the future. The real question is how long will the MADNESS last?

July 7, 2022 2:53 pm

Umm, serious question. It occurs to me that there is considerable energy required to lift the sand, which is not recovered in any way when it falls into the silo after heating. Is this input significant, and if so, was it considered in the input energy costs?

Steven Pfeiffer
Reply to  Davidf
July 7, 2022 3:34 pm

Yes there is a lot of what I call “parasitic” power in this scheme. The usual that you find in every power plant – feedwater pumps, cooling tower pumps/fans.

And yes the energy to convey the sand most likely using electrically-driven blowers, would be significant. May be quite large given the sand quantities involved.

July 7, 2022 2:57 pm

“Sand can’t catch on fire.” True. But anything that comes in contact with those ultrahigh temperature particle silos probably will.

July 7, 2022 2:58 pm

The Gartner hype cycle is a graphical presentation developed, used and branded by the American research, advisory and information technology firm Gartner to represent the maturity, adoption, and social application of specific technologies. Following the discovery of a new technology, what follows is a peak of inflated expectations (eg solar, wind, batteries), followed by a trough of disillusionment (failure to deliver, cost blowouts etc),and then a slope of enlightenment as lessons learned are applied, and finally a plateau of productivity. Lots of technology discoveries never make it through the trough of disillusionment.

Mike Edwards
July 7, 2022 3:34 pm

The Finnish system makes more economic sense in that the sand is used as a heat store – it outputs heat to be used in a district heating system for domestic premises. There is at least the prospect of getting out a high percentage of the energy put into the heat store. They claim that they can store the hot sand for a considerable length of time – so enabling energy to be gathered in the summertime and then fed into the heating system in the winter. How effective this can be remains to be seen, but the Finns appear to have a prototype system up and running so we should get some results in the near future.

The NREL system is more aimed at storing electrical power. This is bound to be much less effective due to the inherent losses in generating electrical power from the stored heat. The overall efficiency might be between 30 and 45 percent. However, given relatively low capital costs, this low efficiency may still be economically preferable compared with Li batteries, due to the high capital costs of the batteries. It might be an effective approach for dealing with solar or wind power droughts, assuming that enough “excess” solar and wind power is built to enable charging of the heat store during times of plenty.

The NREL system probably only makes economic sense if fossil fuels are banned from electricity generation. Electricity generated using the sand heat store is likely to be relatively expensive, since the input energy must be paid for, whatever its source.

Reply to  Mike Edwards
July 8, 2022 10:12 am

I’m pretty skeptical of any claims to being able to keep something 100 degrees or more above ambient for months, without any external energy input.

David Dibbell
July 7, 2022 3:34 pm

Willis, thanks for this post. Interesting.
“TL;DR Version: Electricity is used to heat sand. When you need electricity, the hot sand is used to boil water to drive steam turbines for electricity.”

The illustration says “Brayton Combined Power Cycle”. At this link below there is more technical information. Still some choices to be made, e.g. closed or open Brayton cycle. Clearly though they intend a combined-cycle configuration similar to CCGT plants fired by natural gas. This means the thermal efficiency in the power generation section will be somewhat better than a straight thermal steam cycle plant.

David Dibbell
Reply to  David Dibbell
July 7, 2022 3:53 pm

Also found this. It says “GE 7E.03 Combined Cycle.”

Dr. Bob
July 7, 2022 3:56 pm

One scary proposal is Direct Air Capture and conversion to hydrocarbon fuels. This is incredibly energy intensive. IEA proposed capturing 84 million MT of CO2 this way. Using wind energy alone, this would require 150,000 each 2 MW wind turbines. At 70 acres/turbine, that requires 10.5 million acres of land or 16,400 sq mi of land. And then, considering the lifecycle GHG emissions for wind turbines at 8 gCO2e/MJ, for each MT of CO2 captured, 100 kg of CO2 are emitted for production and instillation of the turbines.

There is no free lunch, even with renewable power.

Steven Pfeiffer
Reply to  Dr. Bob
July 7, 2022 5:07 pm

There is no free lunch ESPECIALLY with “renewable” power.

July 7, 2022 4:00 pm

We know how to heat sand

Yes! By burning fuel, we know how to heat sand to where we can recover as much as 80% of the energy energy input to the system.

Affordable storage technologies require cheap generation technology. The sales brochure press release that I saw on the Finnish Polar Night project seemed to have very little information on how they plan to generate the 1000 degree F thermal energy to heat the sand, other than some vague mumbling about recovering waste heat from data centers. They also intended to use it for community steam heat generation within the small community — notably in winter months when solar energy available in Finland is nil (or perhaps Nils).

I’m all for storage as an integrated part of a generation system, but it has to be rated at the system output per input energy unit, and in GWh, not peak output under ideal conditions. Say an ideally sited and well maintained 6MW rated wind turbine with attached thermal storage might be able to ideally achieve 1.5 MWh output for peak years of operation. Most likely it would produce much less. A thermal “battery” of this sort might be a useful energy buffer to smooth out the peaks and valleys of wind power generation. On the cost side of the equation, the turbine, thermal storage, and steam generator will “cost” a couple megatons of fossil fuels in materials alone to build and maintain for about a 20 year life span. Is it worth it?

Jefferson’s Monticello stored heat in water pipes on south-facing walls, and generated heat by burning wood (and light by burning wax, fat, and oil). Jefferson himself out lasted the system. I rather doubt he recovered the installation cost.

Last edited 1 month ago by dk_
Tim Gorman
Reply to  dk_
July 8, 2022 1:07 pm


Kevin kilty
July 7, 2022 4:04 pm

The brayton cycle machines contemplated for this are ideally reversible, but in reality they are not. I figured the cycle efficiency for joule cycle machines to accomplish this to be around 60%. Then there are heat exchangers of various sorts. One can design heat exchangers that are adiabatic, but what can’t be made are exchangers that preserve availability, so there is further irrevesibility from this. Then there is the generator/motor efficiency.By the time one is done the actual overall efficiencies are perhaps 40% maybe worse because all the cycle inefficiencies are encountered twice — once in and once out. In a ff fired plant one encounters the irreversibilities only once.

I have looked at a similar system before and the land area required is pretty staggering.

Here is an overlooked problem. The needed storage in GWhr is one thing, but one has to build also for the needed peak delivered power and likely also some minimum slew rate. This runs costs even higher.

Fine, NREL, have at your pilot plants, but my view is these are research projects hoping for taxpayer subsidies in order to commercialize.

David Dibbell
Reply to  Kevin kilty
July 8, 2022 3:14 am

There seems to be a desperation to neutralize the obvious objections to intermittent and unreliable injection of wind and solar power into the grid. The sales pitch of “cheaper than coal” energy comes first, but folks figure out pretty quickly that it won’t work without massive inexpensive storage. So we get these news bursts about research projects to persuade the public to believe that surely a storage solution will become practical before long.

Last edited 1 month ago by David Dibbell
Kevin kilty
Reply to  David Dibbell
July 8, 2022 8:42 pm

Exactly right.

July 7, 2022 4:59 pm

I posted this in another thread a couple of days ago, it sure fits here…

Here’s a German solution: Giant Thermos Bottle to store hot water. Ya gotta wonder…

July 7, 2022 5:04 pm

You are going to need a heck of a lot of insulation to keep that sand hot from summer into winter.

July 7, 2022 5:22 pm

Why not steel shot and an inductive heater?

July 7, 2022 5:53 pm

For the sake of brainstorming: what about using large concrete cylinders mounted on magnetic bearings?

July 7, 2022 5:55 pm

Sounds like an idea for wasting less money than spending it on batteries.

July 7, 2022 6:53 pm

How long can it stay hot? With good insulation, probably at least several day…but what if you need stored energy to compensate for extended intervals of low wind/solar output…a couple of weeks, say…or, for that matter, extended periods of above-average demand….how much heat will be left in the sand?

July 7, 2022 7:27 pm

H?w is this better than storing the heat in water?

Reply to  AndyHce
July 7, 2022 9:16 pm

It’s difficult to heat water to 900 degrees.

July 7, 2022 7:54 pm

Redox flow batteries should perform much better than Tesla Megapacks in this kind of application.

July 7, 2022 9:34 pm

Hot sand? Meh. Hot jelly doughnuts? Now you’re talking!

July 7, 2022 11:17 pm

The Korean built Barakah Nuclear Power Plant cost about $25B for 5GW power, or about 44B KWh over the space of one year, which would be $.50 per KWh, but of course the reactors are good for 50 years so 1¢ per KWh. Sure, this back of the envelope calc ignores the cost of fueling every 18 months or so, maintenance, company picnics, and donations to the local environmentalists to encourage them to go glue themselves to some coal plant or far away road, but it shows how stupidly not stupendously expensive the battery backup idea is.

Julian Flood
July 7, 2022 11:27 pm

Willis, we drove near you back in the late 70s, savouring the wonderful October weather – gales, driving rain, flooded and closed roads. We felt at home.

You might be interested in the UK website SAY NO TO SUNNICA where they mention the hydrofluoric gas given off by lithium ion fires.

While I’m here… Have you thought of examining the Marine Heat Islands (MHIs) at Lakes Michigan, Superior, Tanganyika, seas Baltic, Black, Japan, Eastern Mediterranean, Red etc.

Start with the Sea of Marmara. It has added sea snot.


The Dark Lord
July 7, 2022 11:33 pm

no heat loss was calculated …

here is a stab at it for each cube …
each side – 143 ft squared = 20,449 sq ft times 6 = 122,694 sq ft of surface
times temperature difference 1,000 F
divided by R – Factor of 100

1.226 Million BTU per HOUR of heat loss … per tank

so 6 Million BTU per hour of heat loss … 24/7

I think coal gasification is a better use of the excess solar/wind electricity … and a better energy storage solution …

Reply to  The Dark Lord
July 8, 2022 2:58 am

Can’t criticize or vouch for your figures, but I think there was an attempt to adjust for heat loss in the efficiency numbers.
I agree with your final point, even though terms like “clean coal” and “coal gasification” are hysterical triggers for a lot of people. Wondering what the yeild of syngas or coal gas might be with the same energy input as the sand-based thermal battery installation? I dunno how to calculate that, but maybe a better use for the energy we were going to put into storage?
But to me synthetic gas production seems a more effective use for the real estate and electrical infrastructure of a prematurely retired coal or gas ( or nuclear) plant than thermal storage, and could provide a healty output of ammonia fertilizer and conventional battery electrolyte at the same time. If paper, plastic, agricultural, and other waste is used as feed stock it could reduce landfill volume. Direct energy-to-thermal storage seems more wasteful even if it was somehow cost-free waste energy recovery.
And this is precisely what is being done for “green” “biofuels” to produce methane, methanol, synthetic gasoline and synthetic kerosene/diesel from agricultural and natural feed stocks ( and the supply shortage is the reason that those products cost two arms and a reproductive organ at retail ).

Last edited 1 month ago by dk_
Eric Vieira
July 8, 2022 12:25 am

Any hot body, even well insulated loses heat. The hotter is is, the more losses it will have, according to the 4th power of its temperature (°K). That’s Stefan Boltzmann’s law.
Another possibility that’s been also studied is the use of latent fusion. Hollow particles with a substance that melts at a specific temperature. Below a threshold temperature, the substance solidifies and gives back its latent heat of fusion. This helps to solve, at least partially the above mentioned problem. With a mix of several types of particles, with different melting temperatures, it would even be possible to cover a certain temperature range.

Last edited 1 month ago by Eric Vieira
July 8, 2022 1:47 am

A ton of sand at 500 C stores about 100 kWh. If the storage cycle is higher than 20 % efficient I’ll be xurprised.

July 8, 2022 4:15 am

The Elkhorn battery is 730MWh = 0.730GWh. Not 7.3GWh as stated.

Sand is ok. I like liquids because they flow and are better at heat transfer. Molten salts, molten silicon, and water are good depending on your temperature needs.

See 1414 degrees, many molten salt system providers, and many thermal energy storage water heater providers for details.

D Boss
July 8, 2022 4:27 am

While technically accurate, this assessment is flawed at it’s core. We do not need man made energy storage because we cannot compete with mother nature’s own “solar energy” storage mechanism. Hydrocarbon fuels are the best energy storage available, aside from using unstable nuclear isotopes.

Sand has 0.00084 MJ/kg of energy stored per degree C. Water has 0.0042 MJ/kg per deg C. So if you raised a kg of sand by 100 C you’d have 0.084 MJ stored. Likewise a kg of water raised 100C stores 0.42 MJ. But consult the following chart for the energy stored in a kg of various hydrocarbons:

Gasoline and Diesel both store just over 45 MJ/kg, and LNG and methane store 55 MJ/kg. Coal comes in a bit lower at between 24 and 31 MJ/kg depending on flavor of the coal.

Sorry but a complicated and lousy storage method, be it lithium batteries or hot sand – simply cannot compete with the energy density and simplicity of using hydrocarbons as the energy storage mechanism which nature freely provides. (well it’s not free to extract it or refine it, but we don’t have to expend or waste energy to produce it – it was made by nature from solar energy)

Reply to  D Boss
July 8, 2022 6:51 am

Water stores more heat than sand, but you can only heat it up so much before it becomes high pressure steam. Sand and other silicon stuff can be heated to much higher temps so you can presumably use it to heat water to make steam to run generators.

July 8, 2022 6:29 am

Isn’t there a sand shortage worldwide?

Reply to  c1ue
July 8, 2022 10:21 am

Not yet

Jim Gorman
July 8, 2022 7:06 am

Willis, nice article but a couple of observations.

As Steven Pfeiffer pointed out, there will be a lot of parasitic power needed to run this system. Conveying the sand from the bottom of the system to the top will take a lot of power. Think of the horsepower it takes to power a dump truck from a dead stop to some speed, lots of torque and plain old horsepower needed.

As drawn you are looking at some complicated conveyer design to reverse direction without causing jam up of material.

Lastly, this shows no cooling towers to change the warm steam into liquid water so it can be pumped back to be heated.

This pumping also takes a lot of power to maintain pressure through the system. For megawatt power generation, much sand and water must be moved requiring a considerable amount of parasitic power which reduces the efficiency of the overall system – a lot.

Reply to  Jim Gorman
July 8, 2022 10:28 am

As always, the devil is in the details.
The biggest question I have is how do they transfer the heat from the sand to the water.

If you are going to drop the sand into the water, you need a mechanism for getting the sand into and out of the boiler, without losing any of your steam pressure.

If you are pumping sand through pipes in the water, you have to deal with issues of heat transfer out of the sand, and friction of the sand in the pipe.

If you run water pipes through a sand bed, you still have to deal with issues of heat transfer and friction, plus you have to add a mechanism to move the sand through the sand bed.

July 8, 2022 9:01 am

It matters not if this energy storage system works. Maybe it will. However, wind and solar are still unsustainable in material requirements, mining burden, material burden, maintenance burden, environmental pollution, physical foot print, unreliability, short-half-life, nonreoyclability, infrastructures, and expense. Adding batteries which would have to relatively close to these stupid installations simply increases the cost but in no way fixes the problems with wind and solar.

July 8, 2022 9:30 am

Might make sense for somewhere like the Sahara Desert where you have endless sand, and endless Sun as ‘slave’ panels become less expensive. Plus there is water available from underground aquifers. Much of the ‘plant’ could be built from local materials. But a far distance from markets to send those electrons. It does seem rather inefficient in general to be storing solar/wind, which in itself isn’t that efficient already.

Where I think this might have some application is just storing raw heat, to be released as raw heat for space heating either over night or maybe even season to season. Still a lot of sand to heat all summer, for use in winter. For that matter, I have been using rocks (and concrete) for 40 years to store thermal heat over night. Passive solar makes a lot of sense.

This is similar to using solar panels to make electricity to heat water. That is truly bizarre. But a black barrel of water on a roof, or a simple black garden hose in a box covered in clear plastic 6 mil poly will make that same hot water for 1/100 the cost of using solar panels to make electricity to make hot water. Converting electrons to heat and back to electrons seems to be a last ditch effort. Or should be. Seems to violate the laws of common sense.

This does put into perspective the massive problem we would have if we were to ‘outlaw’ fossil fuels, or when the cost of fossil fuels rises so high in the future when recoverable supplies of fossil fuels are being severely depleted in a few hundred years. I am an optimist in that regard though…the Universe is one really big free lunch and I am sure w.e will figure it out.

Last edited 1 month ago by Earthling2
July 8, 2022 9:58 am

I doubt that the boiler and turbines that were used by the coal plant will work for a hot sand system.
A boiler designed to work with hot gases from a coal fire will not work for transferring energy from hot sand into the water. A complete re-build will be necessary.

Likewise a turbine that was designed for the temperature, pressure and volume of steam coming from a coal fired boiler will be much less efficient with the lower temperature, pressure and volume coming a hot sand boiler.

July 8, 2022 11:06 am

While this idea might actually be workable, it is not because of sand. “Sand” is just a placemarker for any substance that is cheap and has the capacity to act as mass thermal storage.

The losses involved in capacitance heating and the heat recovery process make this idea silly unless one is using electrical energy that would otherwise be wasted or “thrown away”.

Waste electrical energy is solar or wind that is overproduced when not needed and must be disposed of to protect the grid.

Reply to  Kip Hansen
July 8, 2022 2:05 pm

The idea of storing excess energy in a heated medium is more simply exploited by Energy Dome ( see: and also: )

The idea is to use CO2 as the working fluid and storage medium both, compress and heat to supercritical state and store in hot pressure vessels, then feed through a turbine to generate power, saving the gas in a large gasometer structure until it gets compressed again.
The virtue of CO2 is that it liquefies easily at modest pressures and temperatures, plus it is non toxic. Note that there are still major issues dealing with heat extraction during compression and heat injection during the generating phase However, CO2 is quite stable even at 1000*C, so at least potentially a reasonable working fluid.

Reply to  etudiant
July 8, 2022 3:28 pm

etudiant ==> Storing energy as heat has a long history — thermal walls behind glass, brick floors, adobe buildings (which store cool), etc.

The repeated emphasis on “sand” in these sciencey MSM stories reveals that understanding is lacking.

Any Boy/Girl Scout knows that rocks heated in the fire stay hot — for a long time — even when dropped into the creek. Many have burned their hands proving this is true.

I would like to see a real world analysis of the efficiency (details of losses involved) in the energy in // energy out.

July 8, 2022 12:52 pm

My hometown, less than 2 miles from O’Hare airport.
The Elk Grove Village located in Illinois, not the one in California.

“About North America’s Largest Industrial ParkElk Grove Village is where great makers come together to make great things. Elk Grove is home to the largest industrial park in the United States with over 62,000,000 square feet of inventory, 5,600+ businesses, 22 data centers, and over 400 manufacturers who specialize in plastic, metal, food, tech and more.”

The remaining nuke plants still supply energy, but are getting long in the tooth.
Time for an upgrade.

July 8, 2022 5:14 pm

The problem with thermal storage is the huge loss when heat is converted to electricity.

A far more efficient and cheaper solution is the hydroelectric pumped storage principle. As an example, there is the Norwegian «Blåsjø» reservoir with a storage capacity of 7.8 TWh. That is 1000 times more than the example described above.


Reply to  Willis Eschenbach
July 8, 2022 7:50 pm

You are of course right that we need all that. However, pumped hydro is so efficient and cheap that it will usually be the best solution even if we have to add in a few hundreds, or even thousands, of kilometers of high voltage transmission lines.

The technology for high voltage lines has improved recently. DC lines are now the preferred solution. There are such lines up to 3400 km long in China.

July 8, 2022 7:37 pm

I did a quick bar-napkin cost calculation for 1-week Tesla PowerWall battery backup of the US grid:
1-week Tesla battery backup cost for average home: $40,000 (six PowerWalls)
Number of US households: 122 million
Residential power consumption as percentage of total US grid:16%
Tesla PowerWall Lifespan: 15 years (6.66 replacements per century)
Total Cost per century for US entire grid: $205 TRILLION/century or about $2 trillion/year, which doesn’t even consider the cost of building and replacing a wind turbine/solar grid which would likely be more than $200 trillion/century…

Leftists suck and math, science, logic, economics, business acumen, ethics, morals, etc.

July 8, 2022 10:16 pm

As etudiant’s comment was mentioning above, it does look promising for Supercritical properties of CO2 (sCO2) as a viable heat storage/transition medium. CO2 is the magic gas that just keeps giving and giving. 

Research is ongoing to develop a sCO2 closed cycle gas turbine to operate at temperatures near 550 C, using the Allam-Fetvedt Cycle, which is relatively new tech. 

A 50 MW pilot plant was built in Texas in 2018 (NET Power Demonstration Facility) by a consortium of companies and has now been recently commissioned and grid connected. It is also sequesters the CO2 from the nat gas combustion. It is is a demonstration plant, so doubt it is economical at this point. Would be good to see Willis dig into this a little bit deeper and provide more insight.

If I understand correctly, this would have very good implications for bulk thermal and nuclear generation of electricity, because the supercritical properties of CO2 at above 500 C and 20 MPa enable thermal efficiencies approaching 50%. Much better than steam in a coal or nuclear generator at 33%+. This could increase the electrical power produced per unit of fuel required by perhaps a 1/3 or more. This increased efficiency would be very significant in ‘fuel’ saving costs per MW/h generated, at least in coal and nuclear generation and would lower emissions per fuel/energy consumed/produced. This technology is also beneficial to CO2 sequestration, so if we can commodify CO2 for applications like additional oil production, or using the Allam Power Cycle with sCO2 instead of steam, then a win-win for everyone. 

Supercritical sCO2 could also presumably work in this application of converting thermal heat storage instead of sand to electricity, and be a much easier substance to deal with. There are still engineering challenges in getting the right alloy materials to resist corrosion and pitting etc, but is looking very promising. I expect we will be hearing a lot more about (Supercritical) sCO2 in the future. 

Last edited 30 days ago by Earthling2
July 9, 2022 7:23 pm

I bet dollars to donuts that they’ll fill those batteries when power is cheap and sell it back to the grid when it’s expensive. This is a money making scheme actually (if they do this)…

I wonder if this is the main reason for them?

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