Fluidized Sand Thermal Energy Storage

tahanson43206 · 2024-09-30 19:34:01

For SpaceNut .... we did not seem to have a topic that captures this announcement by an Italian company....

https://www.yahoo.com/tech/storage-solu … 29555.html

thermal technology: 'Critical to reach net-zero'
Innovators from Italy's Magaldi Green Thermal Energy Storage plan to fight planet warming with an unlikely ally: heat.
It's part of a unique method to store intermittent renewable energy using fluidized sand. Fascinatingly, the system has the crucial steps familiar to batteries — charging, storing, and discharging — without the expensive metals needed for power-pack chemistry to work.
The sand collects heat generated from surplus renewable energy, with a heat exchanger to manage the process. A well-insulated tank keeps the sand packs inside hot with little energy loss.
To discharge, the heat exchanger reverses, releasing superheated steam at up to 752 degrees Fahrenheit. The hot air can make electricity by powering a turbine, according to Magaldi and Renewable Energy Magazine.
"Our storage technology can be used in the steam section of existing thermoelectric power plants … or combined cycle gas turbine plants," Letizia Magaldi, Magaldi's executive vice president, said in a 2021 PV Magazine article on the patented tech.
Heat generation is an energy

This forum contains a number of suggestions for storing thermal energy using a great variety of materials.

I'm hoping a member (or two perhaps) will compare this method to others in the archive.

(th)

tahanson43206 · 2024-09-30 19:34:58

This post is reserved for an index to posts that may be contributed by NewMars members over time.

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tahanson43206 · 2024-09-30 19:50:14

in opening this topic, I had no idea what "fluidized Sand" might be .... Google came up with a couple of snippets...

Search Labs | AI Overview
Learn more
…
Fluidized sand is a phenomenon that occurs when a solid, like sand, behaves like a liquid when pressurized air is forced through it. This happens because the air pressure balances out the weight of the sand grains, making them less dense and easier to move around.
Fluidized sand has many uses, including:
Fluidized sand beds
These beds can be used to demonstrate how sand can act like a liquid, and how objects can sink and float in it.
Fluidized sand baths
These baths use a fluidized mass of fine particles, like aluminum oxide, to distribute heat evenly. They are a safer, cleaner, and more cost-effective alternative to other types of baths.
Fluidized sand heating beds
These beds use sand to gently clean industrial metal components, grease, and grime. They are efficient, safe, and environmentally friendly.
Fluidized bed powder coating
This process uses a fluidized bed to suspend finely ground powder particles in air. A preheated part is dipped into the powder bath, and the melted particles fuse to the object.
Liquidized Sand Machine - YouTube
application was created in 1922 to burn coal more efficiently the process combines a pressurized fluid a liquid or a g...

Nick Uhas ·
YouTube · 6y
Design and management of conventional fluidized-sand biofilters - ScienceDirect
ScienceDirect.com
Fluidized Sand Heating Bed Work - What is it? - Schaus-Vorhies, Co.
Dec 9, 2020
Schaus-Vorhies Companies
Show all
Show more
A fluidized sand bath consists of a loosely packed mass of fine solid particles (aluminium oxide ) through which an upward flow of air is passed. In the fluidized state, the aluminium oxide particles become mobile, and the bath displays many of the properties of a liquid.Jun 27, 2023
Fluidized Sand Bath Selection Guide - Cole-Parmer

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Calliban · 2024-10-01 07:14:16

This idea would certainly work. It has the advantage of a high technological readiness, given that steam plants, resistance heaters and thermal storage in sand are all well understood technologies. This is an idea that could be developed into a practical solution quickly. In fact, this is probably the easiest grid electricity storage solution to develop quickly and at scale.

The problem with it is that the steam powerplant has to buy already generated electricity off the grid, turn it into heat, store it and then reconvert the heat into electricity. At 752 farenheit (~400°C), a large steam plant could realistically convert about one third of the heat into electricity, with the rest being low grade waste heat that we may or may not have a use for. Ignoring all other costs, the plant will need to sell electricity for three times the price they buy it for just to break even. Including capital, operating, maintenance costs and profit, the price will need to be several times higher. Not necessarily an unworkable idea, but it clearly faces obstacles.

It would work a bit better from an efficiency standpoint if it could be integrated into a town district heating system. Such a plant could avoid the construction of cooling towers, which would marginally reduce construction costs. The problem is that waste heat is worth a lot less than electricity. So the plant wouldn't get much compensation for selling the heat. To a certain extent, we may need to accept this as a fact of life. To turn intermittent electricity into dependable electricity is going to cost money and require capital equipment. There is no solution on the cards that avoids that reality. One other advantage that a steam plant offers that may cushion its cost impact, is long system life. With good water chemistry control, a steam plant can live for 80 years, perhaps longer. So it is in many ways a gift to future generations. After 30 years of operation, capital costs are mostly gone. But a well cared for plant could operate for another fifty.

Last edited by Calliban (2024-10-01 07:18:43)

SpaceNut · 2024-10-03 18:54:23

We have talked about sand but adding liquid now creates internal tank storage pressure. Sand battery was discussed in the Geothermal and Geothermal Battery (Changed Title 12/21/23) a Void started topic.

SpaceNut · 2024-10-04 17:26:16

An image to go with words

afbd98359b74b360ede6abab22fb1c7b

heat exchanger imbedded in the sand

SpaceNut · 2024-10-05 18:02:31

I take the word sand as sand being crushed grains that are fine from earth soils and rock. The pipes extend in through the sand and come out the other side. The heat is coming from exhaust heat or from heated air or any other working fliud, or gas that is pumped through the system.

Magaldi's website states that its thermal unit is sustainable, made with silica sand and steel.
charging, storing, and discharging
To discharge, the heat exchanger reverses, releasing superheated steam at up to 752 degrees Fahrenheit.

tahanson43206 · 2024-10-05 18:44:56

For SpaceNut .... we (in NewMars) are never going to get anywhere if we keep thinking new announcements are the same as previous ones.

The only thing I ** know ** is different about this concept is that air is used to move the sand particles.

The advantage would appear to be increased thermal storage capability.

You've shown us old fashioned sand storage, in which the sand does not move.

If you can (somehow) find a bit of time to investigate, please see if the Italians have improved upon the ancient sand pile concept you showed us in Post #6.

Let's see if we can accomplish something useful with this topic.

(th)

kbd512 · 2024-10-05 19:39:54

SpaceNut,

If you've ever been to the Middle East, they have lots of sand there, but it's nothing like the "beach sand" I think of as a child from swimming in the Gulf of Mexico or in the Pacific near San Diego. It's as fine as talcum powder. It's every bit as hard and abrasive, but much finer, with a consistency closer to flour than what I think of as "beach sand".

If you put that flour-like consistency sand into a highly pressurized container with say, CO2, then I would assume if you tried to stir-up the sand that you could more uniformly inject or extract thermal energy. This "stirring action" doesn't need to be performed using a mechanical device. It could be performed by pumping or circulating CO2 from the bottom to the top of the container. Thus, you have "fluidized" sand that is constantly churning about inside the container, either soaking up or releasing heat.

If you were intent on extracting stored heat, then because sand is also a reasonably good insulator, the sand surrounding the heat transfer pipe becomes cooler, so the sand further away from the heat transfer pipe (which is most of it) cannot efficiently re-radiate heat to uniformly draw-down the temperature as heat is extracted. If the sand was fluidized, then you're able to continuously stir up the sand, so any temperature decrease or increase is more uniformly distributed across all of the sand inside the pressure vessel. This means you can have a simplistic stationary "heat pipe" inside the container for thermal power transfer, because the gas is constantly mixing up the sand is keeping your temperature uniform. You don't create "hot spots" or "cold spots" near the heat pipe.

I haven't read anything about what they're doing here, but just looking at that photo you posted, that's what it looks like to me. I would guess that you could also use water or oil or wax or molten salt for thermal power transfer, but CO2 would allow for the highest temperatures. Molten salt is the only high temperature heat exchange medium which would operate at atmospheric pressure, unless temperatures are kept relatively low, in which case oil or wax would also operate without pressure.

Sand can store about 290J/kg°C, so it needs to go to high temperatures to be mass and volume efficient.

Desert sand can be thermally stable between 650°C and 1000°C. However, the first heating cycle can cause the sand to lose mass and transform calcium carbonate into calcium oxide, which can negatively impact its solar absorption.

Foundry sand has a low volatile content and its main components are stable at high temperatures. It doesn't readily evaporate.

Sand has a melting point of roughly 1,700°C (3,090°F). It's also chemically stable and has no vapor pressure.

Sand can also be used as a thermal energy storage (TES) material. For example, Hitec®-saturated sand can be used to store and extract more energy than concrete at thermal storage temperatures ranging from 400°C and 500°C.

Water, oil, and paraffin wax are not going to survive 400°C, never mind higher temperatures. CO2 molecules begin to thermally dissociate around 1,727°C. Steel melts around 1,370°C. Concrete will melt near 1,150°C. Alumina / Aluminum oxide refractory ceramic vessels will melt around 2,072°C. Sand is about 1,500kg/m^3, so 1.5X denser than water, but even across a 1,000°C temperature delta, sand can only store 290kJ/kg or 435,000,000J/m^3 or 120,833Wh/m^3. If you're about 50% efficient at extracting the heat energy, then your actual storage density is half of that.

According to rough estimations, the Earth is estimated to have around 2.5 x 10^15 cubic meters of sand

That's 2,500,000km^3 of sand on the Earth's surface, thus there is no shortage, nor is there ever likely to be a shortage. We would need about 19.726km^3 of sand to store energy for 90 days, to account for our seasonal energy demand. That's quite a lot of sand, but such a system would be remarkably stable over a very long period of time. As long as you don't subject the ceramic storage containers to thermal shocks or impact loads, it's almost immortal.

However, you could store a lot more energy at much lower temperatures

Al2O3: 880J/kg⋅°C * (800°C - 200°C) = 528,000J/kg
Fe2O3: 750J/kg⋅°C * (800°C - 200°C) = 450,000J/kg

Al2O3 is stable in air, up to 1,650°C.
Al2O3: 880J/kg⋅°C * (1,500°C - 500°C) = 880,000J/kg

Al2O3 is 3,890kg/m^3, so it would require far less volume, at 3,423,200,000J/m^3 or 950,889Wh/m^3. It has 7.87X greater thermal storage capacity than sand over the same temperature range. Aluminum oxide is almost 7% of the weight of the Earth's crust, so no shortage of that stuff, either. Turning it into Aluminum metal requires a crazy amount of energy, but Alumina is much easier to obtain from far less energy input.

tahanson43206 · 2024-10-06 06:16:27

For SpaceNut ... taking the post #9 as a guide, and if you have the time and this topic is of interest, please compare what the Italians are doing to the system you showed us, which does NOT use the "fluidizing" process.

My guess is that the fluidizing process is ONLY needed when the operator is adding or withdrawing thermal energy from the store.

After all, it is going to take energy to fluidize the store, so you'd only use it when you are adding energy or withdrawing it.

Otherwise, the store would sit quietly at whatever temperature it was given, for extended periods due to the poor thermal conductivity of the unfluidized material.

It would be ** really ** interesting to see actual numbers for the new process compared to the traditional one.

(th)

kbd512 · 2024-10-06 14:39:10

tahanson43206 wrote:

After all, it is going to take energy to fluidize the store, so you'd only use it when you are adding energy or withdrawing it.

That would essentially be "all the time", assuming you're building the device to use it. You're either adding energy into the device to keep it hot, or removing heat to produce power. The sand itself has poor thermal conductivity, but it's inside an above-ground metal box with a bunch of metal pipes penetrating into the box. It's going to lose heat, just not as fast as if the sand inside was fluidized. I don't think anyone is going to circulate gas through the box except to charge or discharge it, but conduction and convection still do what they do at all times. Maybe it's a double-wall design, which would help minimize heat losses. The process of "cooling down" might only take a week or two without those design improvements, or it could take a month or two with improvements to retain heat, but keeping the sand hot will require continual energy input, because it's much hotter than the surrounding environment.

Here's an interesting tidbit of knowledge:

Coating sand with quartz can improve its thermal stability and solar absorption. This can increase the energy storage efficiency of coated sand by 60–80% compared to raw sand.

Calliban · 2024-10-07 06:35:56

Alumina costs about $500 per metric tonne.
https://www.focus-economics.com/commodi … s/alumina/

Which is cheap. Not quite as cheap as dredged sand or aggregate, but still cheap. Alumina heated to 800°C will store about 150kWh/tonne. So we are talking about $3.30/kWh as a one time purchase cost. The material is reusable indefinitely. It cannot wear out.

The only question is whether to use it as it comes (i.e as powder) or fuse it into some kind of stackable block. The second might be easier. Mix it with about 30% iron oxide rich clay and then fire it in a CO rich atmosphere. The Iron (III) Oxide will partially reduce and polymerise, given an extremely hard and strong brick that can be stacked into a pile. The alumina will be chemically uneffected.

Last edited by Calliban (2024-10-07 06:36:34)

tahanson43206 · 2024-10-07 11:05:20

For Calliban re #12

Thank you for posing the question that is at the heart of this topic.

This topic is about fluidized sand thermal energy storage.

The Italians reported in the opening reference appear to claim superior performance compared to brick such as you have suggested.

The difference (as kbd512 points out) is that it takes energy to sustain the fluidized state by forcing air through the mass of the alumina.

What I would like to see is a cost/performance comparison of the fluidized system vs the brick.

kbd512 has suggested that the fluidizing system might be needed all the time, but I think this might be missing a business opportunity.

If the goal is to save energy in order to get the best possible price on the spot market, then you woud NOT run the fluidizer when you are waiting for the best price. When the best price appears and your company is able to snag the contract, then it would make sense to pour energy into the fluidizer in order to pull stored thermal energy out.

The regular members of the forum are (understandably) not versed in business practice. I am repeating guidance from FriendOfQuark1, who is.

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kbd512 · 2024-10-07 22:55:55

tahanson43206,

I don't have any idea about how much energy is required to fluidize the sand. It may be a minor input, or it might not be. A rheologist should know. It should be based upon particle size, moisture content, gas velocity and pressure, and probably some other factors I don't know about. Either way, charging and discharging energy is the entire reason this energy storage device was built. Therefore, I presume the device will be "turned on" (either charging or discharging) most of the time. That's a fairly reasonable assumption, is it not?

Calliban · 2024-10-08 04:24:47

Why use sand instead of larger particles? The article doesn't say. I can only assume it has something to do with heat transfer rate into and out of the material. Smaller particles have greater surface area per unit mass and hence will heat up and cool down more quickly.

The problem with trying to blow a heat transfer fluid through sand is the viscous drag resulting from the tortuous path around all of those sub-millimetre grains. It suggests to me that pumping power may be greater than we would like. Particle size is a design choice based upon the balance between heat transfer rates and blower power. Other thermal storage ideas have used gravel or larger lumps of rock to store heat. Either way, the principle is the same. You are blowing a fluid through a bed of solid material and either transfering heat into or out of the material depending upon the relative temperatures.

Fluidising suggests to me the need to levitate the particles against gravity to allow heat transfer fluid to pass through. That implies pumping power, using viscous drag forces to prevent particles from wedging together. Unless there is a strong reason behind using particles that small, I think a better solution is to use larger particles, like gravel. These have enough pore space between particles to allow heat transfer fluid to pass through without having to suspend the particles within the fluid. The cost of stone chips is quite low in bulk, maybe $100/m3. You could probably get it for even less if your powerplant is close to a mine, as it is often a waste material from mines and quarries.

Whether sand, gravel or hardcore are used, this is a very simple and cheap way of storing energy. Really the only cost that we are paying is that of the steel or concrete container that keeps the material in the required geometry and provides insulation. But we will never find cheaper energy storage materials than graded rock that we have dug from the ground or dredged from the sea. In one form or another, sensible heat storage looks like a winner to me. Fine, dry sand is a fairly good insulation material, with a thermal conductivity of about 0.1W/m.K at room temperature. If we have a steel inner liner containing crushed rock and a concrete outer shell to keep rainwater out, then dry sand would be a good insulating material to put between the steel and concrete. The steel container would be something like a grain silo but on a larger scale. It doesn't need to contain any significant internal pressure, because the contained rock particles will transfer load to the base. The base itself can be reinforced concrete, maybe with an additional layer of sand to protect the concrete from thermal damage.

Last edited by Calliban (2024-10-08 05:53:09)

New Mars Forums

Announcement

#1 2024-09-30 19:34:01

Fluidized Sand Thermal Energy Storage

#2 2024-09-30 19:34:58

Re: Fluidized Sand Thermal Energy Storage

#3 2024-09-30 19:50:14

Re: Fluidized Sand Thermal Energy Storage

#4 2024-10-01 07:14:16

Re: Fluidized Sand Thermal Energy Storage

#5 2024-10-03 18:54:23

Re: Fluidized Sand Thermal Energy Storage

#6 2024-10-04 17:26:16

Re: Fluidized Sand Thermal Energy Storage

#7 2024-10-05 18:02:31

Re: Fluidized Sand Thermal Energy Storage

#8 2024-10-05 18:44:56

Re: Fluidized Sand Thermal Energy Storage

#9 2024-10-05 19:39:54

Re: Fluidized Sand Thermal Energy Storage

#10 2024-10-06 06:16:27

Re: Fluidized Sand Thermal Energy Storage

#11 2024-10-06 14:39:10

Re: Fluidized Sand Thermal Energy Storage

#12 2024-10-07 06:35:56

Re: Fluidized Sand Thermal Energy Storage

#13 2024-10-07 11:05:20

Re: Fluidized Sand Thermal Energy Storage

#14 2024-10-07 22:55:55

Re: Fluidized Sand Thermal Energy Storage

#15 2024-10-08 04:24:47

Re: Fluidized Sand Thermal Energy Storage

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