Limestone-based Thermal Battery

kbd512 · 2023-05-21 14:23:32

I'm starting this thread in response to a recommendation from Calliban that we create a separate thread to discuss the topic of thermal batteries made using low-cost / low-embodied energy materials for powering an alternative type of electric vehicle that primarily uses electricity to heat up a very low cost heat energy storage medium, such as limestone, which costs $10 to $55 per metric ton.

This type of battery is primarily intended to store thermal power in a vacuum jacketed steel tank using a resistive heating element embedded in the tank, which contains powdered limestone, so that the stored heat energy can be extracted using a thermal power transfer loop with the atmosphere being the cold sink, in conjunction with a small low-cost gas turbine, possibly using supercritical CO2 or some other fluid, to perform mechanical work to propel a passenger vehicle or electric generator, if the heat has been stored to provide stationary energy storage to power homes and buildings.

This is of interest for both earthly uses and Mars exploration because it does not require high cost specialty materials or fabrication methods, the heat energy storage medium does not "wear out" over time the way all electro-chemical batteries do, and recycling the vehicle and energy storage material is so easy relative to electronics and other types of electrical machines.

It's well known that this will never be as efficient as an electro-chemical battery, but the point of development is not to compete with Lithium for efficiency, it's to find a practical way to completely replace all of the existing passenger cars without running short of Lithium or Copper or other high-energy materials long before that could ever happen. A limestone battery simply cannot fail the same way that Lithium or Sodium or microelectronics do, so it's a worthwhile technology to have if it enables us to quit burning so much gasoline, diesel, and coal.

I'm creating this topic and invite commentary on thoughts about how to do this, or any related thermal battery technology that doesn't require complex fabrication methods and expensive / energy-intensive materials. I'm willing to forego absolute energy efficiency if it allows us to arrive at a more practical electric vehicle or supplemental energy store for our existing solar, wind, and nuclear power plants. A lot of power is squandered already because there is no practical storage mechanism, so some is better than none, and perfect is the mortal enemy of good enough to get the job done.

tahanson43206 · 2023-05-21 14:44:50

Best wishes for robust development of this topic, and the underlying technology.

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

2024/08/28 Calliban renewed the possibility of actually doing something useful with this topic:
http://newmars.com/forums/viewtopic.php … 20#p226120

In this post, Calliban describes possible use of this technology for off-grid energy storage.

In a post on 2024-03-13, SpaceNut gave us a glimpse of an actual project under way in Finland:
http://newmars.com/forums/viewtopic.php … 57#p220357

(th)

SpaceNut · 2023-05-21 15:04:06

This is another twist of the sand battery that has promise as it does add delay of the peak level of heat being made use of. The difference of sand or limestone is just a heat level that can be retained.
Thermal storage topic is got lots of the details.

I would then believe that the co2 is within a double wall tubing and that the turbine is part of a closed loop system where the exiting co2 from the turbine is allowed to exchange the heat to other exchangers for heating hot water or other applications.

https://netl.doe.gov/carbon-management/sco2

https://www.energy.gov/fecm/advanced-turbine-systems

https://energy.wisc.edu/industry/techno … s-turbines

https://www.powermag.com/supercritical- … nstration/

https://www.netl.doe.gov/sites/default/ … am-144.pdf

Here is the Thermal energy storage

sand battery Geothermal and Geostored Energy

edit

another related topic is Compressed gas storage
As the heat will increase the pressure that would come out from the absorption of heat causing expansion that the turbine would make use of to create electrical energy.

I just went and searched for other topics to make use of and here is that list.

Dry ice pneumatic tool

Compressed Air by Terraformer

Running on Compressed Air?

C02 as a working fluid.

Supercritical CO2 - Useful technology?

CO2 Sublimation Heat Engine

Compressed gas energy storage.

So things we still need to have to create answered as they change everything

1 open or closed loop?
2 duration of use?
3 mobile self powered or just movable or fixed never moving?
4 heat source and sizing of capacity?
5 cooling whether active or passive with air or water or exchanger combinations

Calliban · 2023-05-21 15:53:37

Using vacuum to enhance insulation is a good idea I think. The paper below is by JPL and gives details of lunar regolith thermal properties, which I assume to be similar to finely powdered limestone in vacuum.
https://arxiv.org/pdf/1711.00977

Thermal conductivity for non-compacted surface fines in vacuum is <1mW/m.K. This is competitive with silica aerogel.

Vacuum tanks can be tricky to engineer, because they are under compressive force. This makes them vulnerable to local buckling and implosion. This is why a vacuum tank engineered to a dP of 100KPa ends up being much thicker and heavier than a tensile pressure vessel containing 100KPa of internal positive pressure. However, if the vacuum vessel contains a moderately compacted limestone powder filling, it will provide back pressure as the walls of the vacuum vessel press in against it. So you can probably get away with a relatively thin steel shell. To maximise volumetric energy density, your heat battery should contain a core of solid limestone, surrounded by an outer layer of compacted limestone powder. The powder is a waste product from quarrying, so shoukd be virtually free. Solid limestone will have some cost, but is still very cheap.

Vacuum systems do tend to develop slow leaks. But we can deal with this by periodically purging the vessel using a small vacuum pump. A 1m diameter spherical lump of limestone would have surface area of 3.14m2. Lets assume a 10cm thick layer of crushed limestone in vacuum, as insulation and a 500°C temperature difference. Thermal leakage would be:

Q = KA × dT/dX = 0.001 × 3.14 × 500/0.1 = 15.7W.

A 1m sphere of limestone would weigh 1.4 tonnes. Heated to 520°C, it would store some 194kWh of heat. It would take 124 hours for the sphere to lose 1% of its heat by conduction.

A direct cycle S-CO2 power generation loop avoids the need for additional heat exchangers. The CO2 is heated by passing it through a seemless steel pipe running through the limestone block. The turbine would be mounted on the end of the pipe.

We could avoid any other thermal bridges through the insulation by charging the limestone block inductively. The block would contain embedded lumps of iron, which would be heated inductively across the powder insulation, using a rotating magnetic field.

Last edited by Calliban (2023-05-21 16:21:20)

kbd512 · 2023-05-21 18:36:18

Calliban,

The issue I see with using a solid block of limestone is how to embed the heating element and thermal power transfer tubing. That could be tricky, to say the least. I think powdered limestone could be degassed and compacted, though. I was thinking of fabricating the tank, placing the thermal power transfer and resistive heating element inside the tank, letting gravity sift the powder into the tank like flour, degassing under vacuum in conjunction with vibration to help compact the powder, and then using mechanical force to compact in the last little bit of material, prior to welding the tank shut.

The induction heating idea is interesting, but would it require new charging equipment?

We must have a penetration in the tank for the thermal power transfer loop. When you spoke about eliminating thermal bridges, how would we accomplish that when we need tank penetrations anyway? Why not minimize the surface area of said penetrations and call it a day?

Calliban · 2023-05-22 04:58:21

A ceramic insulated cable would have only a small cross sectional area. So a straightforward resistance heater would create only a minor thermal bridging effect. We don't really need the complication of inductance heating. For ease of replacement, we would want to be able to slide the heating element into a sleeve in the block. So the heater is outside of the pressure boundary and conducts through the walls of the steel sleeve.

The reason I think that you should consider large lumps of limestone for heat storage is that you need good heat transfer rate into the heat transfer tube. With solid lumps, you can rely upon the thermal conductivity of the stone, which will be about 3 orders of magnitude greater than the evacuated powder. It won't be difficult drilling holes through soft limestone. Alternatively, you could mix limestone chunks with concrete and simply cast the holes that you need into a single spherical lump of concrete. The concrete will start to degass water vapour at high temperatures. One way of dealing with this is to have an inner steel vessel which is used for heat storage, which is filled with concrete and crushed limestone. The inner steel vessel is then surrounded with evacuated limestone powder which functions as insulation. But a single monolithic lump of limestone may be cheaper. It is relatively soft and easy to drill into with ordinary masonry drills.

Last edited by Calliban (2023-05-22 05:15:23)

Calliban · 2023-05-22 05:42:53

A few back of the envelop calculations. Let us assume a vehicle weighing 3 tonnes travelling at 30mph (50kph), or 13.4m/s. The rolling resistance of car tyres of concrete is about 0.015.
https://en.m.wikipedia.org/wiki/Rolling_resistance

Driving force needed = 3000kg x 9.81 x 0.015 = 441.45N

Power = driving force x speed = 441.45N x 13.4 = 5.915kW, which is 7.9HP.

We need to dump waste heat for the process to work. Can we do this with an ordinary radiator? Let us take the engine to be 40% efficient. For each kW of mechanical power raised, 1.5kW of heat must be dumped. So to drive at 30mph, the radiator must dump 9kW of thermal power into the air. The heat absorbed by the air would be:

Q' = V×A×rho×Cp×dT

Density of air, rho, is about 1.2kg/m3. V = 13.4m/s. A = frontal area of the radiator, which I am going to set to 0.5m2. Cp air ~1KJ/Kg.K. dT is what we need to calculate.

dT = Q'/V×A×rho×Cp = 9000/(13.4×0.5×1.2×1000) = 1.12K.

This tells us that a conventional radiator can easy provide the cooling needed for the engine at speeds of 30mph.

Estimate of effective range at 30mph without stopping:

To drive 1km would require 441,450J of energy, or 0.123kWk work. Let us assume that we charge the calcium carbonate block 750°C and keepdriving until its temperature drops to 250°C. It will release about 200kWh of heat, of which 40%, some 80kWh is converted into work energy.

Range = 80/0.123 = 650km.

I have neglected air resistance in this calculation and have also ignored energy lost due to braking. I have assumed an efficiency which may be somewhat high as the block cools to lower temperatures. And my calculation assumes flat ground. None the less, if actual range is only half what I have considered, it is still plenty for most day to day activities.

An engine like this would work very well for offgrid energy storage as well. It would power a house for about 1 week and the waste heat could provide water and space heating, allowing nothing to be wasted. If we can produce a thermal battery for vehicles, then we can capture a large chunk of the energy storage market as well.

Last edited by Calliban (2023-05-22 06:01:30)

tahanson43206 · 2023-05-22 06:33:18

For Calliban re #7

SearchTerm:Calculations in support of Limestone based thermal battery
SearchTerm:Limestone thermal energy storage for 3 ton vehicle

An observation I would offer is that this design will need a fan to move air through the radiator when the vehicle is at rest, in order to generate power. This is unlike a conventional internal combustion engine which produces heat from combustion, and needs the fan to remove heat when the engine is running, whether the vehicle is moving or not.

After re-reading the sentence above, I realized there are more similarities than differences. The Limestone engine needs a fan to generate power, and an IC engine needs a fan to remove heat after combustion has generated power.

A quick check with Google reminded me that the fan for the Limestone vehicle must be electric, since the engine will not be running when the vehicle is standing still at a stop light, also unlike an Internal Combustion powered automobile, whose engine is turning whether it is needed or not.

A mockup of this power train could be built in a garage or a basement.

kbd512 started this idea into motion, but his current project is receiving his free time.

SpaceNut, are you willing to take this on as a home(basement) project? Perhaps there are other forum members who are handy with tools and willing to invest some time and a modest budget in construction of a mock up.

How many components of the existing non-working oil furnace might be adapted to construction of a working mockup of the Limestone engine?

Hopefully ??? the fan is still working, and the current supply system might still be working after all these years. That would be a good place to start.

You've been talking about replacing the air ducts. I'd like to suggest eliminating the rustable metal and replacing the ducts with see-through material. Thin metal ducts have been favored for this application for many years for a variety of reasons, but the drawback of their use is that the home owner cannot see dust building up inside, which a see-through material would allow. A see-through design would also permit dropdown panels so that dust build-up can be removed as needed.

Insulation for the Limestone block (or packed dust as kbd512 suggests) could be ordinary wall insulation, and the enclosure for the energy store might be the walls of the old furnace if they are still intact.

If there is a reader of the forum who is not a member and who would like to participate in construction of a working mockup of a Limestone engine, please check the Recruiting topic for procedure.

(th)

tahanson43206 · 2023-05-22 06:48:53

For Calliban re Supervision of Experimenters...

Are you willing to provide guidance if we can find someone willing to tackle construction of a working mockup of a Limestone engine?

You indicated this system might work as an emergency heater for a home, and I would definitely be interested in that possibility. My guess is that there might well be a market for such a system in parts of the world not served by natural gas.

I had suggested that an old oven filled with brick might serve as a thermal energy store, and your recommendation of Limestone is not too different.

Since an old oven filled with brick is within the handy-person capability of many individual humans, I'm wondering if any useful data might be drawn from experiments performed with such a configuration.

Your design would require a higher level of technical competence than the simple bricks-in-an-oven design. Your design presumes elevation of temperature of the energy store to dangerous levels. The brick-in-oven concept might allow for measurement of performance (energy in vs out) measurements, assuming the experimenter is modestly capable.

(th)

tahanson43206 · 2023-05-22 07:39:28

I asked Google about Limestone, after NOT finding limestone in a table of thermal storage materials offered by Engineer's Toolbox

About 11,700,000 results (0.52 seconds)
Introduction. Limestone is a sedimentary rock composed principally of calcium carbonate (calcite) or the double carbonate of calcium and magnesium (dolomite). It is commonly composed of tiny fossils, shell fragments and other fossilized debris.Oct 13, 2016
Limestone: Characteristics, Uses And Problem - GSAhttps://www.gsa.gov › node
About featured snippets
•

Here is a table of thermal energy storage materials:
https://www.engineeringtoolbox.com/sens … _1217.html

Taconite is a low grade iron ore.

I note that brick is included in the table.

(th)

kbd512 · 2023-05-22 10:20:17

tahanson43206,

There's probably a reason why this thermal battery is so similar in operation to an internal combustion engine. That wasn't accidental. Assuming it's workable, automotive engineers would know how to make this technology work. It's not really "better" than combustion on efficiency, but it costs so much less to produce than the alternatives that it still allows us to make more affordable vehicles.

Mechanical valves could control the flow of sCO2 through the heat exchange loop, and possibly several loops on the same radiator dependent upon throttle setting, so it's not "running" at a stoplight, even though the radiator is still rather hot. For the radiator fans, I was thinking that residual thermal power from the CO2 could drive the fan as well, rather than another electric motor. I'm shooting for a completely mechanical engine and power train.

tahanson43206 · 2023-05-22 11:47:51

For kbd512 re #11 and interesting concept ....

In deference to your limited time due to multiple obligations, and taking into account that Calliban is not available to perform hands-on construction, we appear to be dependent upon NewMars members who we might be able to persuade to tackle this project.

The nature of the fan is not currently much of an issue, although your idea of driving the fan with lower grade heat from the thermal store is both interesting and promising. In a first cut at building a working model, I'd like to suggest you offer the builder some flexibility.

Electric now and a non-electric solution later. The fan is most definitely NOT on the critical path for this project.

The ** first ** hurdle is to find someone willing to build one of these in it's first crude garage or basement level incarnation.

I have proposed bricks in an oven as a first level doable project for someone. The total cost of such a system might well be close to zero, if a source of components at no cost is close by. A few monetary units will be needed to move the components to the work site, and perhaps some other supplies are needed.

Can we find such a person? Neither you or Caliban are available, but we very well may have a member who is inspired by this new topic, and by the caliber of the participants, to give physical manifestation of the idea a try.

Can I ask for this project to be performed at a professional level, as befits the nature of the members of this forum.

If we find a member who is willing to tackle this, it would be helpful if the person is willing to go along with some minimal reporting expectations, in return for day-to-day guidance from the assembled idea-generators.

(th)

tahanson43206 · 2023-05-22 11:59:00

Quoting from the opening of the topic:

I'm creating this topic and invite commentary on thoughts about how to do this,

I would like to see this topic move rapidly from discussion to physical construction, testing, evaluation and modification for more testing.

There's been enough "discussion" in this forum to fill several lifetimes of normal person reading time.

We've had a very small number of Real Universe activity reported. kbd512 has reported on chasing a burglar, and on several home and car projects.

SpaceNut has reported on multiple home and car projects.

if there have been any other examples I've missed them. I've probably only read 10% of the posts in the archive, and ** that ** may be way over the actual number.

This topic provides an opportunity for ** someone ** in the membership to tackle a Real Universe test project to see if Caliban and kbd512 have anything going, or if there is something lurking in the shadows to prevent success.

Alternatively, a member might be able to find an example of someone actually carrying out this experiment in the past.

(th)

Calliban · 2023-05-22 12:11:46

I am happy to help in any way that I can. Kbd512 has more knowledge of IC engines than I do. Maybe I can help with the heat transfer side of things.

Regarding the selection of limestone. There is no reason why it has to be limestone. It is simply that limestone is reasonably dense and has a higher specific heat than other rocks.
https://www.engineeringtoolbox.com/spec … d_391.html

The specific heat trends upwards from 909J/Kg.K at 30°C, to 1100J/Kg.K at 600°C.
https://www.researchgate.net/figure/Var … _325162542

Limestone is also very cheap, much easier to cut than granite and is quite easy to work with. The only downside is that calcium carbonate requires a CO2 gas cover at temperatures above about 500°C, as it begins to decay into CO2 and calcium oxide. So our limestone lump needs to be encapsulated in a steel shell, to prevent it from contaminating the vacuum needed by the insulation. I don't think this would add much to total cost. At 605°C, the CO2 equilibrium vapour pressure over CaCO3 is 300Pa. So a thin low carbon steel pressure envelope is all that is needed.
https://en.m.wikipedia.org/wiki/Calcium_carbonate

There are other options. Granite does not have a thermal decomposition problem, but only has 3/4 of the specific heat of limestone. Concrete is also an option. At high temperatures concrete suffers from dehydration, which creates pore pressure, leading to cracking and crumbling. But this would be less of a problem if the concrete is cast into a sealed steel container.

Molten salts offer better volumetric heat capacity than sensible heat stored in rock. But the problem here is chemical interaction. A vessel containing molten salt would probably need nickel alloy lining, due to the corrosiveness of salt. Nitrate salts have good compatability with steels. But they melt at relatively low temperatures and allow the manufacture of explosives. Not something you want falling into the wrong hands.

Last edited by Calliban (2023-05-22 12:28:39)

Calliban · 2023-05-22 12:57:22

One additional thing that we need to consider in designing the heat store is thermal conductivity. Whilst we want conductivity to be low in the insulation layer, we ideally want it to be high in the solid thermal storage material. This is because we need heat flux into the heat transfer tubes to be as high as possible. One way of doing this is to make a composite heat storage block. This would consist of limestone lumps, limestone shale and iron bars radiating from the central tube, all bonded together with concrete and encased inma thin steel pressure shell. The iron bars serve as thermal conduction channels from the bulk limestone into the heat transfer tube. This avoids the development of high temperature gradients in the block as the engine progressively drains it of heat.

tahanson43206 · 2023-05-22 14:26:52

For Calliban re #15 ...

In the spirit of trying to move things along away from conceptualizing and toward Real Universe demonstration of a working model, achieved by a member of this forum working in a garage or a basement, please continue developing your ideas with a view to how a person with a limited budget might build one of these.

I've suggested brick and an ordinary (used) oven as a starting point for a Real Universe demonstration. At the very least, a heated brick chamber could heat a house (or at least the basement) for a period of time in the winter when power goes out. More importantly, such a system could be a test bed for ideas that might arrive on the scene to provide electric power. in the case of a test system in a basement or garage, the output might be limited to a light bulb, but every aspect of the performance of the system should be measurable, so that projections can be made of performance if improvements are made.

(th)

kbd512 · 2023-05-22 17:33:43

tahanson43206,

How well does wiring insulation hold up to a radiator exhausting 500C heat behind it? Ever notice all the thermal shielding to keep ignition wires away from hot exhaust manifolds? 500C isn't the absolute hottest that an exhaust manifold can get, but it's up there.

The issue with electric motors is the extreme heat of the thermal power transfer components. That's why it has to be all-mechanical. There are practical considerations at play. A fan is required to remove heat by drawing enough cold air through the radiator, especially at low speeds. We're not going to have much rubber or plastic under the hood, especially if it's directly behind the vehicle's radiator, because the heat will melt it. Parts that can take the heat most definitely are on the critical path here.

How about we kick off testing using a concrete block with some powdered Iron or Iron pellets or ball bearings mixed into the aggregate?

We can use A36 steel tubing because that's easy to weld and readily available. It doesn't need to last forever or meet specific performance targets. It's a basic technology demonstrator project. We'll use whatever materials we can get from the local hardware stores. If the demonstrator can be made with materials of nominal value, to illustrate basic function, then we can worry about scaling up and building integrated prototype vehicles.

I can't afford to build a full-sized prototype without proper funding, but I can use my own money and fabrication skills to make a small demonstrator device. That much is doable. This should also require less fabrication time, perhaps 3 weekends.

tahanson43206 · 2023-05-22 18:07:39

For kbd512 re Limestone Energy Storage demonstration system.

Something the size of a concrete building block ** sure ** does sound feasible for a home garage/basement demonstration.

It is ** good ** to see your interest in participating in development of a small demo system for testing, and I hope you will have time to follow through. I understand that your time is limited due to all your other activities and obligations.

What I am hoping will happen is for the first time in the history of this forum, we might have a small project that several members might want to tackle.

The forum structure is cumbersome, but our members have demonstrated supplementary capabilities for project communication. We have Dropbox, Google Docs, imgur.com and other supporting free online resources. In addition, both Void and Dr. Johnson have demonstrated the ability to create images that help to explain otherwise complex ideas.

Since you created this topic, you have an opportunity to help potential participants to understand what a small Demo project might entail.

Measurements of inputs and outputs would seem needed, to lift this above a science fair level activity.

Please take a few minutes to write a first draft of what a project plan might look like, using a concrete block as the enclosure for an energy store. It is highly likely that if members decide to support your initiative, they will be able to help by finding needed components or supplies at the lowest possible prices.

Because your concept appears to involve high temperatures, this would be an adult level project, but kids could help with assembly.

(th)

SpaceNut · 2023-05-22 18:46:53

200 kwhr is the 40% or dead battery value so a fully charged would be 500 kwhr
1 first full charge is 500kwhr at $0.22 kwhr = $110 for 650km. is 404 miles
2 second and follow-up charges of possibly 400 kwhr = $88 for 650km. is 404 miles

normally a 4.3 litter = 1 gallon at current $3.50 typical 20 to 40 miles
404/20 x 3.50 = $70.70 on the low side of milage 404/40 x 3.50 = $35.35

So, would it take an hour to get back up to temp then most will not be happy as they are with the EV cars already.

edit repost

Calliban wrote:

We can get a first estimate of power requirement by calculating rolling resistance. On Earth, car tires driving through sand have rolling resistance factor of 0.3.
https://en.m.wikipedia.org/wiki/Rolling_resistance
For each kg of vehicle mass on Mars, the required driving force to overcome rolling resistance will be:
F = W x Crr = 1 x 9.81 x 0.38 x 0.3 = 1.12N
Travelling at 5km/h (1.39m/s), the amount of mechanical power needed is:
P = F x v = 1.12 x 1.39 = 1.56W/kg.
If we take vehicle mass to be 10,000kg, then we need a minimum power output of 15.6kW to drive the vehicle. With minimal hotel requirements, we can bump that up to 20kW.

https://en.wikipedia.org/wiki/Gasoline_ … equivalent

The MPGe metric was introduced in November 2010 by EPA in the Monroney label of the Nissan Leaf electric car and the Chevrolet Volt plug-in hybrid. The ratings are based on EPA's formula, in which 33.7 kilowatt hours of electricity is equivalent to one gallon of gasoline (giving a heating value of 115,010 BTU/US gal), and the energy consumption of each vehicle during EPA's five standard drive cycle tests simulating varying driving conditions.[5][6] All new cars and light-duty trucks sold in the U.S. are required to have this label showing the EPA's estimate of fuel economy of the vehicle.[7]

kbd512 · 2023-05-23 06:53:20

SpaceNut,

You seem to be more than doubling the amount of heat that the thermal battery can actually hold. That's probably why the recharging cost looks so high. 200kWh is the maximum capacity of the battery, not the 40% charged state of the battery.

Edit:

200kWh * $0.22/kWh = $44.00 <- California prices
200kWh * $0.1463/kWh = $29.26 <- Texas prices

If you drove at a constant speed of 30mph on a flat concrete roadway, which nobody does, then Calliban asserted you'd get about 80kWh of usable mechanical work energy back out of the 200kWh of stored heat energy. Cost per mile is about $0.108/mile if the range is 406.25 miles / 650km. In reality, range will be somewhere between 1/2 of 3/4 of that theoretical value, so it costs about $0.216 per mile.

Texas prices will be $0.072 per mile at the theoretical range you could drive, or $0.144 per mile if reality is half of theory.

If gasoline is $3.50/gallon (Texas prices) and a gallon will take you 40 miles, then cost per mile is about $0.0875.

If gasoline is $7.00/gallon (California prices) and a gallon will take you 40 miles, then cost per mile is about $0.17.

Our 2018 Toyota RAV4 is theoretically capable of 36mpg on the highway and 26mpg in the city. My real-world mpg is 10mpg driving around town. The best I've achieved out of it is 13mpg to 15mpg (driving on long streets without a lot of lights). It does great on the highway, and gets about 35mpg. So, theory vs reality, reality is about 1/2 of theory, which means $0.17 per mile, and we now pay about $3.50 per gallon at the local Shell station.

The Lithium-ion battery electric car may out-perform the combustion engine on energy efficiency in operation, but not in production, since it's also double to triple the price of a gasoline powered car with equivalent interior volume and carrying capacity.

This also tracks well with how expensive it is to use an electric furnace vs a gas furnace. The electric furnace's operating cost, in reality, is about twice as expensive as the natural gas furnace, because the gas is so cheap, none is lost in transit to resistance, and pumping low-pressure gas vs transfer of electricity is cheaper.

There are no free lunches to be had here. You will pay the energy piper, regardless of what you use. The difference is in how you pay. The thermal battery is very cheap in terms of up-front costs, which means more vehicles can be made in a single year and more people can afford to buy them, but then they pay about the same amount that they pay for gasoline, maybe a little less over time without so many oil changes and components to fail that don't exist on the thermal battery car, assuming the tires are big enough to handle the weight without undue wear and tear, and the battery electronic car, you hope that the battery lasts for at least 6 years and preferably 10 years, or you never get your money back out of it.

We distorted the market to make batteries and electronics appear cheaper than they really are, but without the distortion, only very wealthy people can afford to own and operate them, because they're not very cheap without a bunch of subsidies (making your neighbors pay for you to drive a battery electronic car).

Last edited by kbd512 (2023-05-23 08:39:55)

tahanson43206 · 2023-05-23 09:46:51

An option that might help to bring this concept (Limestone Energy Storage) into the market sooner rather than later is to retrofit existing IC powered cars.

The history of this forum is that nothing every happens. This is a good idea, just like all the others.

It ** should ** be possible for members of the forum to build a working model of a thermal energy storage system.

A comparison might be made to a steam engine .... steam is raised in such an engine (looking at the history) by liberating stored energy from fuel. The energy is absorbed by water which is energized to the point that it can do useful work in moving a piston.

There are model steam engines on the open market. I note with dismay that pricing is ** way ** out of my league. My guess is that prices reflect the amount of machining that goes into them, because there is not a mass market.

pmmodelengines.com offers a kit for $159.00 ... the web site has a date of 2015 ... Copyright PM Research 2015, All Rights Reserved.
Apparently the site is in Wellsville, New York ...
Email is pmrgang@pmrresearchinc.com

The site is not responding smoothly, but that could be a reflection of my equipment and not theirs.

In any case, this appears to be a starting point for someone to think about feeding water through an energy store, generating steam, and driving a small generator to light an incandescent bulb to a modest glow.

There may well be model steam engines on the used market.

What I'd very much like to see is some physical manifestation of these worthy energy storage ideas.

(th)

tahanson43206 · 2023-05-23 09:48:28

Update a few minutes later:

The Newmars forum is part of the Mars Society. A small set of forum members are thinking about thermal energy storage. Thermal energy storage is not a new concept, and I understand large commercial installations are in development. The forum members would be interested in small scale proof-of-concept projects that might be carried out by individuals working in the garage or a small workshop. Your web site Copyright is 2015. Is anyone still there?
tahanson43206
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If anyone in your membership/client list is interested in discussing this project idea, I am responsible for admission of new members. See Recruiting Topic for procedure.
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tahanson43206 · 2023-05-23 10:11:30

I went looking on eBay and found this tiny twin cylinder steam engine ....

Twin Cylinder Marine Steam Engine Model
Condition:
NewNew
Time left:
4d 21h|Sunday, 10:02 AM
Starting bid:
US $99.00
[ 0 bids ]

I can't tell if this is a working model.

Shipping cost appears to be $20, which seems reasonable to me, considering the weight and the distance.

If anyone in the group has time to investigate further, it would be good to know if this is a working model.

A detail that would be useful to know is the temperature/pressure of the steam needed, and the flow rate for whatever performance is possible.

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tahanson43206 · 2023-05-23 10:29:25

The Stanley Steamer brand has been defunct since 1924, it would appear.

Stanley Steemer is a carpet cleaning brand that started ca 1947.

I would be surprised if anyone still holds the Stanley Steamer trademark, but someone might.

Trademarks expire (I think the term is five years) so someone would have to invest a modest amount to keep the trademark in force.

I bring this up because a thermal energy store was not on the thought scape of anyone involved in early automobile design.

We now have a reasonable looking concept for dense thermal energy storage, made possible by modern technology.

https://en.wikipedia.org/wiki/Stanley_M … ge_Company

I asked Google how many IC engine powered vehicles are in the United States:

Internal combustion engines provide outstanding drivability and durability, with more than 250 million highway transportation vehicles in the United States relying on them.Nov 22, 2013
Internal Combustion Engine Basics | Department of Energy
Department of Energy (.gov)
https://www.energy.gov › eere › vehicles › articles › inte...

Some percentage of those might be candidates for conversion to a Thermal Energy Storage Stanley Steamer drive train.

Fillup at a station would include water and electric power to heat the store.

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kbd512 · 2023-05-23 22:56:23

I guess I need to know what to buy...

Thermal Energy Store Materials

Thermal store will be powdered limestone - I'm sure it's not the best, but I can get it in bulk from a local farming supply store. I'll vibrate the container to settle / pack it as well as I can. I'll weld in a bung to vacuum out the tank. We're going with 100kg of limestone as a 10% scale demonstrator. At 2.4g/cm^3, 100kg of limestone should be equal to approximately 11 US gallons of internal tank volume.

Thermal store jacket - 304L sheet with a 0.024 or 0.025 thickness - This will not be some highly optimized geometry like a sphere, rather a tank that looks a lot like the diesel tank slung under a train. I'll use ribbing for reinforcement of the tank. A 55 gallon stainless steel drum is $900 to $1,500 before shipping, so that's out of the question.

Thermal store insulation - rock wool - It's definitely not as good as a vacuum jacket, but no complex engineering is required for that and I can get it from local hardware stores. If Calliban or GW can come up with the calculations required to ensure that the vacuum jacket doesn't implode, then I'll attempt to fabricate a vacuum jacket. Try to devise something that uses simple geometry that I can actually weld and have welded before, like bits of angle Iron welded to a sheet, or something like that. If we do use a vacuum jacket, I'm not spending money on more 304, so it needs to be made from A36 (basic automotive sheet metal).

Thermal Power Transfer Loop

In-tank plumbing - 0.25" OD 304L seamless pipe / tubing with 0.065" wall thickness - My back-of-the-envelope math says 304L has about 50% to 55% of room temperature yield strength between 500C and 600C, so 0.65" wall seamless stainless pipe / tubing exceeds the 2.5X ASME safety factor for expected sCO2 pressure after the strength reduction is accounted for. Again, I'm sure it's not ideal, but I can get the material.

Radiator - 0.125" OD 304L seamless tubing. I'm having a brain fart and can't remember the wall thickness I intended to use. My browser crashed, so I'm redoing this form memory. I'll make sure the 2.5X safety factor is adhered to. I intend to use some thin 304L sheet to make fins for the radiator. I've never brazed stainless before, so not sure how well that'll go. Maybe we can get away with a press-fit. I've seen press-fit stainless electric strip heating elements built that way.

Heating element - FeCrAl wiring - It's cheap, can be formed easily, and can withstand the temperatures required.

I'm not sure what to use for the power turbine. There may not be anything off-the-shelf we can use. This is where one of our engineers should jump in and tell me what to use.

I'm still looking at valves and gauges.

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#1 2023-05-21 14:23:32

Limestone-based Thermal Battery

#2 2023-05-21 14:44:50

Re: Limestone-based Thermal Battery

#3 2023-05-21 15:04:06

Re: Limestone-based Thermal Battery

#4 2023-05-21 15:53:37

Re: Limestone-based Thermal Battery

#5 2023-05-21 18:36:18

Re: Limestone-based Thermal Battery

#6 2023-05-22 04:58:21

Re: Limestone-based Thermal Battery

#7 2023-05-22 05:42:53

Re: Limestone-based Thermal Battery

#8 2023-05-22 06:33:18

Re: Limestone-based Thermal Battery

#9 2023-05-22 06:48:53

Re: Limestone-based Thermal Battery

#10 2023-05-22 07:39:28

Re: Limestone-based Thermal Battery

#11 2023-05-22 10:20:17

Re: Limestone-based Thermal Battery

#12 2023-05-22 11:47:51

Re: Limestone-based Thermal Battery

#13 2023-05-22 11:59:00

Re: Limestone-based Thermal Battery

#14 2023-05-22 12:11:46

Re: Limestone-based Thermal Battery

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Re: Limestone-based Thermal Battery

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Re: Limestone-based Thermal Battery

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Re: Limestone-based Thermal Battery

#18 2023-05-22 18:07:39

Re: Limestone-based Thermal Battery

#19 2023-05-22 18:46:53

Re: Limestone-based Thermal Battery

#20 2023-05-23 06:53:20

Re: Limestone-based Thermal Battery

#21 2023-05-23 09:46:51

Re: Limestone-based Thermal Battery

#22 2023-05-23 09:48:28

Re: Limestone-based Thermal Battery

#23 2023-05-23 10:11:30

Re: Limestone-based Thermal Battery

#24 2023-05-23 10:29:25

Re: Limestone-based Thermal Battery

#25 2023-05-23 22:56:23

Re: Limestone-based Thermal Battery

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