Vacuum plus Water Gravity plus Air Compression Energy Storage

tahanson43206 · 2024-09-05 08:49:23

For SpaceNut ... we had four topics with "vacuum" in the title, but none were a good match for this initiative by Calliban.

This topic is inspired by recent work by Calliban, which itself appears to have been inspired (in part) by a YouTube video showing a home workshop demonstration of a practical vacuum energy storage system that uses mechanical belts to store and retrieve energy.

Calliban improves upon the YouTube presentations by substituting water for air as the working fluid.

Here is a link to the original post: https://newmars.com/forums/viewtopic.ph … 99#p226299

Please note the enhanced appearance of the hand drawn sketches!

Update 2024/09/06 This topic is renamed to include these energy storage elements in a single package:

1) Vacuum storage as suggested by Calliban based upon a demonstration on YouTube
2) Water gravity storage as suggested by Calliban using a figure of 10 meters elevation and one ton of water (1 cubic meter)
3) Air compression in the water receiving chamber at the top of the column.

In the scenario that is shaping up, the system would reside in a well that is less than one meter in diameter and which extends 10 meters below the surface. The vacuum chamber would reside at the base, and the water reservoir would be at the top.

Energy would be supplied from renewable sources as much as possible.

Energy could be stored directly by mechanical means where that is practical, but otherwise using electricity to drive equipment.

(th)

tahanson43206 · 2024-09-05 08:50:37

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

If there is an investor who would like to fund one of the designs Calliban has offered, please see the Recruiting topic for contact information.

Update 2024/09/07 ... https://newmars.com/forums/viewtopic.ph … 44#p226344
Specifications for a system that might be constructed on Earth in 2024.

(th)

tahanson43206 · 2024-09-05 09:00:46

I would like to see this topic develop into a demonstration project.

The energy storage density is low, but the investment required times the longevity of the proposed system implies a superior evaluation.

I would like to see evaluation performed in a professional manner, so that a potential investor is reassured about the risks to be faced.

There is a massive need for adequate housing for the greater part of the human population, and the energy storage system described by Calliban in the post linked at the top of this topic would appear to have value if implemented on a massive scale, in combination with well chosen renewable energy systems.

(th)

Calliban · 2024-09-05 09:44:46

Pasted from other thread
**************************

This man has produced a video on a concept that I have toyed with in the past: storing energy in vacuum.
https://youtu.be/1D9LUaYYnrE?si=e1GzXyFQliO0mJPZ

This is a kind of inside out CAES system, with a maximum pressure difference of 1 bar. The resultant energy density of a vacuum vessel is limited to 100KJ per cubic metre. That is far too low to be useful as a vehicle energy source. But could have uses for home energy storage.

Vacuum tanks are vulnerable to buckling instability. So the best materials to use for their construction are things like concrete, stone or rammed earth. These are energy cheap, strong in compression, but weak in tension. Their low energy cost allows them to be made thick enough to resist buckling instability without becoming unaffordably costly. To store 1kWh, a vacuum tank would need a minimum volume of 36m3. Assuming a spherical tank, inner diameter would be 4.1m. That is about the size of a bedroom.

The thing that might make this worth doing is longevity of compressive structures. If this is part of a house and remains in use for a couple of centuries, it would provide excellent energy return on investment. But the amount of energy that can be stored in this way is limited to a few kWh. Otherwise your energy store starts to rivalnthe size of your house. A 1kWh store is none the less useful in buffering the output of a home PV or wind power system. My back of the envelope calcs tell me that energy payback time will be on the order of 5 years for this concept, assuming that the tank is made from concrete and is charged and emptied once a day. That is 5 years for ESoEI to exceed 1. Using rammed earth the time will be much shorter. The key to achieving high ESoEI is using low embodied energy masonry type materials and using the store intensively for long periods. I cannot see any mechanisms that would cause it to wear out.

Calliban · 2024-09-05 09:47:02

Very simplistically, maybe something like this:

Or maybe this for the vac tank, using concrete with a clay and rubble filling.

Or maybe the tank can sit within a weather proof enclosure, like a shed. This ensures that the clay providing the compressive strength is kept dry. You may notice that I am trying to use as little concrete as possible, as the tank needs to be cheap.

Pumping water instead of air allows greater energy efficiency overall, because water is an incompressible medium. Pumping water therefore minimises heat generation. But it is also presents a problem as concrete and cob, rammed earth and adobe, all lose a great deal of compressive strength when wet. So a good waterproof lining is important.

Calliban · 2024-09-05 09:59:47

The weakness of vacuum energy storage is its very low effective energy density. An energy density of 100KJ/m3 is the same as 1m3 of water stored at a head height of 10m (33'). In fact, vacuum energy storage and low head pumped storage are both very similar. The vacuum is replacing the pressure resulting from the head height of water in an elevated reservoir. Using vacuum, we can build a small scale pumped storage system on a flat site. But we introduce complications associated with a tank that is vulnerable to buckling instability, thereby requiring thick walls. Like small scale pumped hydro, a lot of work and space is needed to store a relatively small quantity of energy. But this is at least something that someone can build for themselves out of common materials, using unskilled labour.

Last edited by Calliban (2024-09-05 10:01:22)

tahanson43206 · 2024-09-05 17:22:44

For Calliban and all readers interested in this topic....

In post #6, Calliban has given us the volume of 1 cubic meter of water to consider for a vacuum storage system.

I am interested in doubling the storage capacity of the system by combining the vacuum chamber with a 10 meter gravity storage device.

It should be possible to design an energy storage system that is designed as a well that is 10 meters deep, with a 1 cubic meter vacuum chamber at the bottom and a 1 cubic meter water reservoir at the top. This system would effectively double the energy storage capacity of either system working alone. The cross section of the pipe need not be a meter. It could be substantially less.

In the scenario I am imagining, the system would be constructed by a professional organization, and not built by a homeowner with minimal tools and experience.

What might the components of such a system look like, and what energy storage capability might it achieve?

(th)

tahanson43206 · 2024-09-05 17:41:35

There is a third potential energy storage option available for the system described in Post #7.

If the system is sealed, then the receiving chamber at the top can be used as a third energy storage component, by compressing the air above the water. When water is pumped out of the vacuum chamber at the bottom, the water would be pushed up the pipe to the receiving chamber, where the water will attain potential energy due to gravity.

If the upper chamber is sealed, then the arriving water will compress the air inside the chamber.

I would appreciate someone working out the numbers for such a system.

Let's stay with the 1 cubic meter and 10 meters of elevation suggested by Calliban, so we can achieve a shared set of numbers we can all agree upon.

The total of water in the system would include the 1 cubic meter in the vacuum chamber to start with, plus some amount of water in the stand pipe. The upper reservoir needs to be large enough to accommodate the 1 cubic meter of water pushed up from the vacuum chamber, plus sufficient room for air to be compressed.

(th)

tahanson43206 · 2024-09-06 08:23:15

There is enough talent assembled in this forum to take Calliban's idea, as amended, all the way through to a set of specifications for installation of a test article.

Let's stay with the mass of water of 1 ton (1 cubic meter) and elevation of 10 meters for the lift.

The actual article would (presumably) be a bit longer to accommodate chambers at the bottom and the top.

The diameter of the shaft need not be a meter, because the volume of water can be stored in a cylinder that is less than a meter in diameter.

The entire system would be sealed, except for access to bays where equipment would reside.

The lifetime of this energy storage concept should be long, except for mechanical components which will have to be replaced periodically.

I would like to know how much energy could be stored in this hybrid system, and what a reasonable estimate of cost might be in various locations on Earth.

Let's NOT assume this is a Do It Yourself project. We are potentially talking about a mass produced installation that would be useful to millions of humans around the world.

(th)

Calliban · 2024-09-06 10:55:35

I decided to solve the buckling equation for several different materials, for a vacuum chamber with radius 2m. This equation is valid for a cylinder, so should be bounding for a sphere. For regular concrete, with a minimal youngs modulus of 20GPa and poisson ratio of 0.2, the minimum wall thickness needed to avoid implosive buckling under full vacuum, is 5.38cm, which is just over 2". Some 2.78m3 of concrete is needed to create a shell this thick. No reinforcement is needed, as cracks tend to close under compressive pressure. I estimate a materials cost of £400, which is about $500. This vessel will store 0.93kWh of energy. It turns out concrete is probably the best material to use. It is cheap in terms of money and energy and has much greater compressive strength that soil based materials like cob, adobe or rammed earth. These materials may be technically free in a DIY project. But they magnify the labour neededin construction and need to be kept dry to retain their strength. So they probably aren't worth bothering with.

We also need a receipt pond. This is nothing more complicated than a hole dug into the soil, polymer lined and covered to prevent contamination.

The turbine, generator and pump will cost at least as much as the vacuum tank. It is difficult to cost these. If the pump is powered by wind energy then a small positive displacement pump is something that a hobbyist could make. The same is probably true of the turbine. The generator is something that needs to be purchased.

tahanson43206 wrote:

There is a third potential energy storage option available for the system described in Post #7.
If the system is sealed, then the receiving chamber at the top can be used as a third energy storage component, by compressing the air above the water. When water is pumped out of the vacuum chamber at the bottom, the water would be pushed up the pipe to the receiving chamber, where the water will attain potential energy due to gravity.
If the upper chamber is sealed, then the arriving water will compress the air inside the chamber.
I would appreciate someone working out the numbers for such a system.
Let's stay with the 1 cubic meter and 10 meters of elevation suggested by Calliban, so we can achieve a shared set of numbers we can all agree upon.
The total of water in the system would include the 1 cubic meter in the vacuum chamber to start with, plus some amount of water in the stand pipe. The upper reservoir needs to be large enough to accommodate the 1 cubic meter of water pushed up from the vacuum chamber, plus sufficient room for air to be compressed.
(th)

TH, the positive pressure storage tank that you describe is a hydraulic accumulator. If we assume that this device has volume of 72m3 and some 36m3 of water is pumped into the tank (out of the vacuum chamber) the additional energy stored would be 1kWh. If the tank is on the ground, this doubles the energy stored, though unfortunately would triple the system volume. But a sealed system has other advantages.

Last edited by Calliban (2024-09-06 11:03:19)

tahanson43206 · 2024-09-06 11:04:39

For Calliban re #10

Thanks for adding details to the topic, and for confirming the compressed air (hydraulic accumulator) system would allow for additional energy storage. I deduce from the figures you've provided that if we stay with the 1 cubic meter concept you gave us a few posts back, then the stored energy in the hydraulic accumulator would be much less that the 1 kWh you computed for the 72 cubic meter store.

If you have time and the subject remains of interest, please put all the elements together, and stay with the 1 metric ton of water to be moved. I am looking for a vertical stack that descends into the Earth for a minimum of 10 meters. The diameter of the bore hole can be less than one meter, since the vacuum tank and the receiver tank need not have a diameter as great as a meter.

Please steer toward a professional, mass produced product. The home build concept is interesting and it might appeal to one or two human beings alive on Earth today, but I'd be greatly surprised (perhaps even astonished) if such a person were to show up and actually take on this project.

What I'm trying to get a sense of is how much energy storage this extremely simple, ultra reliable system might offer.

(th)

Calliban · 2024-09-06 12:54:24

I don't think I ever refered to a 1 cubic metre concept. That would be too small to be practically useful. The energy density of vacuum is quite low. To store meaningful amounts of energy, substantial volumes are needed. One advantage that vacuum offers over positive pressure is the opportunity to use low embodied energy ceramic materials, notably concrete. Buckling instability dillutes this advantage somewhat, but a vacuum tank may still be cheaper than a pressure tank. More later.

tahanson43206 · 2024-09-06 13:04:18

For Calliban re #12

Let's design the 1 cubic meter version, and discover what it's capability may be. If we speculate about huge projects they will never be built, and this topic will out of gas as have so many other topics in this forum.

A one ton mass of water is just ** barely ** within the realm of possibility. We have three modes of storage.

We have the vacuum with which you started. We've added gravity, and now we've added hydraulic accumulation.

All that storage will amount to ** something ** although at this point I'm not sure what.

Related questions are how long a wind generator would take to "charge" the store, or a solar panel for that matter.

(th)

kbd512 · 2024-09-06 13:11:40

tahanson43206,

How do you mass produce something that is fabricated onsite and tailored to provide for the energy needs of a specific end user?

kbd512 · 2024-09-06 15:25:12

I found a company which makes pre-fab concrete tanks:

ACT Concrete Water Tanks

Only their 10,000L capacity tanks are pre-fabricated. Their larger capacity tanks are poured onsite. They're intended to be buried, so presumably the force of an accidental implosion would be well-contained and not a hazard to human life so long as people and structures are not permitted above the tanks. However, the ground unevenly increases compressive forces applied to the tanks, so they require a shallow burial or perhaps earthen HESCO barriers around them. The geometry of said tanks would need to be optimized to evenly distribute compressive forces over the surface area of the tank.

It appears as though a semi-truck can deliver 2 to 4 of the 10,000L capacity tanks. From looking at other manufacturer websites in America and the UK, it appears as though truck-transportable concrete pre-fab stops well before 20,000L capacity is reached, and thereafter they pour onsite.

Someone asked the "who dunnit" question, and it appears that these people have made their own tanks:
Ferro-cement Water Tanks an Affordable DIY Solution

There are steel industrial vacuum tanks fabricated used for oilfield services, sewage / waste water removal, and removing powdery substances like fly ash from coal fired power plants or ground up slag from steel mills. Some are apparently used in concrete work as well, for reasons I'm not aware of. I'm not aware of any pre-stressed concrete vacuum pressure vessels, but I have not doubt they could be fabricated.

Calliban · 2024-09-06 15:35:51

I would suggest a standard 1kWh unit. That can be provided by a spherical vessel with 4.1m inner diameter. We could use a fibreglass mould that is bolted together on site and then filled with ready mix concrete. After a few days, the mould can be dismantled and sent to another site. The cost of pumps, turbines and generators can be reduced through economy of scale.

This link provides the equation for buckling pressure, Pb.
https://physics.stackexchange.com/quest … snt#497571

The youngs modulus of concrete is 30-50GPa and poisson ratio is 0.2. I used a modulus of 20GPa in my first calculation.

Last edited by Calliban (2024-09-06 16:04:17)

kbd512 · 2024-09-06 16:02:44

Calliban,

It looks like we get just shy of 3Wh/L as our energy density. That seems kinda low, but how long can this system last before the concrete starts to crack?

I've been trying to figure out how to tie solar thermal, compressed air from trompes and mechanical wind turbines, and now vacuum energy storage together into a coherent energy generating and storage system that provides some kind of synergy where the components either work together or they fill-in some niche role that we need for sake of practicality.

I think we've worked out reasonable and cost-effective natural energy solutions for residential power, home air conditioning / heating / cooking / cleaning, short range vehicles, and trains. We need to work out how to power industrial agriculture and mining with natural energy. I believe we've both concluded that pipelines, trains, and cable cars are the most viable natural energy solutions for long range transport and bulk delivery of goods and raw materials.

I don't think we're going to devise practical non-hydrocarbon energy solutions for shipping or aviation. Maybe we could use compressed air powered pipelines spanning thousands of miles, but that seems like another wildly impractical solution in search of a problem to solve. The world's longest natural gas pipeline spans 8,707km, but that's for delivering a gas. Perhaps cable cars can use compressed air and vacuum tanks to raise or lower the height of the floating platforms the cables are strung between to move the cars along?

Calliban · 2024-09-06 16:54:17

It is 27.8Wh per cubic metre - a measly 0.0278Wh/litre - just 100J. That is low energy density. By contrast, a 100Ah 12v deep cycle lead acid battery, will store 1.2kWh and occupy a volume of about 2 US gallons. The lead acid battery has over 5000x the volumetric energy density. The only thing that makes vacuum energy storage feasible at all is the fact that concrete has low embodied energy and the storage vessel is easy to make. But it isn't clear to me that a vacuum is a viable energy storage option with such low energy density.

Cracking of the concrete shouldn't be a problem so long as compressive stress remains beneath yield stress. So the concrete vessel should have a life measured in many decades.

Last edited by Calliban (2024-09-06 17:00:51)

tahanson43206 · 2024-09-06 20:07:35

For Calliban re #18

In Post #18, you gave a figure of 27.8Wh per cubic metre for what I assume is the vacuum portion of the energy storage system.

If the water removed from the vacuum tank is pushed up 10 meters to the receiving tank, then I assume the 27.8 Wh will be doubled to 55.6 Wh.

If the water is pushed into the receiving tank against pressure inside the tank, then I assume the storage will be increased again to 60+21+2.4 or 83.4 Wh.

But the pressure in the receiving tank does not have to be limited to 1 bar.

I wonder how high the receiving tank pressure might be raised, and what effect that would have on the storage capacity of the system.

A detail I have not seen discussed is the nature of the pump that is going to move the water in this system. I would expect a piston pump to be the best choice, because water can be forced through a one-way valve, and the piston retracted to reload for the next push.

(th)

kbd512 · 2024-09-06 21:20:27

tahanson43206,

Since cable cars require so very little energy per ton-mile of cargo moved, I was thinking that some combination of vacuum and trompes would supply the power to move them by providing a gravity assist by way of raising or lowering the towers / pylons relative to each other, causing gravity to do the work. They won't be very fast, but they're using so little energy that they don't represent a meaningful energy draw to move great masses of cargo great distances.

Imagine that China or India is shipping Pig Iron ingots to the US or Mexico, or Australia is shipping Aluminum to China if you like, and the US is shipping cold rolled steel to Europe so that the Europeans don't need heavy industry to obtain their high energy materials. Shipping a lot of heavy metal increases the cost of the metal, but the only thing the end users want to pay for is the metal itself. They don't want to pay for any fuel they don't absolutely have to. How fast the product arrives is irrelevant to receiving a steady supply in huge quantities. So long as massive coils of metal keep coming in the door, nobody cares if their shipment proceeds at 5 to 10mph across the Atlantic and Pacific.

Reliable delivery schedule is critical, and a cable car system will reliably ship low value but stable materials for pennies on the dollar, even after factoring in the infrastructure costs. Recall that cable car systems used in mines in the UK have been running continuously for more than 100 years. It now costs a small fortune to ship things between continents. The only long-term reliable way to cut the cost is to cut the fuel bill to zero. We'll still need ships for transporting people, food, medicine, and other consumer goods that aren't stable, but there's no reason why we cannot ship low value goods without burning any fuel.

tahanson43206 · 2024-09-07 05:52:03

For kbd512 re cable transport .... Thank you for the inspiration to create a new topic dedicated to cable transport!

This topic is dedicated to an attempt to define an energy storage system that incorporates three mechanical storage elements:

1) A vacuum chamber as originally described by Calliban, based upon a YouTube video that used fabric belts to store and retrieve energy

2) A gravity based energy storage system using water as the working fluid

3) A compressed gas energy storage system into which water is pumped as it is removed from the vacuum chamber

While the energy density of all three of these systems is low, they act together to increase the total amount of energy stored.

I am still waiting for a clear presentation of the amount of energy store that can be expected from a system designed to use these three elements.

For the study, I am offering these specifications:

1) Mass of water to be moved: 1 metric ton

2) Elevation of receiving tank above vacuum tank: 10 meters

3) diameter of shaft to hold system: Less than one meter

The actual system will be deeper than 10 meters, because the receiving tank and the vacuum tank are cylinders with a volume of one cubic meter.

The advantage of such a storage system is that it should last for centuries, except for periodic replacement of the pump that moves the water into storage, and the system that generates electricity as water returns to the vacuum chamber.

I am hoping this topic will provide a structure for development of a design that could be constructed and tested on Earth.

(th)

SpaceNut · 2024-09-07 07:58:20

Reminds me of the tank for the artesian well that keeps pressure of the out flowing water as it draws down at the same flow rate until the low limit pressure tells the water pump turns on to refill it.

The top of the tank has an air-filled Blatter that is pressurized to push the water, and it expands as the water goes out of the tank and compresses back as the tank is refilled.

tahanson43206 · 2024-09-07 13:12:55

For SpaceNut re #22

Thanks for engaging with this topic, and for showing us the interesting design from real human history.

For Calliban re topic development ....

It would be understandable if the storage capacity of the proposed one ton system is disappointing, when we have the example lf a lead acid battery to compare.

However, a lead acid battery will not last more than four years on average, and it's quality will deteriorate rapidly from there.

The proposed system has the potential to last for an extended period, taking into account the planned replacement of the two mechanical components that will inevitably wear out.

I would like to see a design for a system that might be constructed of available materials in 2024, in most advanced nations. We don't need to worry about do-it-yourself enthusiasts at this point. I am looking for a design that can be mass produced and installed by the thousands.

We have a set of dimensions and specifications that provide a framework for calculations, so potential investors can understand the proposed system, and evaluate the potential storage capability.

For anyone who may have missed the earlier posts, i am asking for calculations on a system that includes:

1) Water as working fluid: 1 ton
2) Vacuum chamber at bottom of shaft large enough to hold 1 cubic meter of water
3) Vertical structure through which water passes to and from the reservoirs: 10 meters
4) Sealed reservoir at the top where gas/air will be compressed as water is forced up from the bottom of the apparatus.
5) Pump able to move water against the opposing forces
6) Turbine? or other suitable mechanical device to capture energy from water flowing from storage to the vacuum tank

Energy is stored in three ways:

1) Vacuum formed in bottom tank
2) Gravity yields to force applied from below
3) Compression at the top requires work to overcome (also called hydraulic accumulator (by Calliban))

It should be noted that the pressure in the top tank is NOT limited to 1 BAR, so the upper limit of storage is dependent upon how that part of the system is designed.

(th)

Calliban · 2024-09-08 09:17:35

Let us start with consideration of the need we are attempting to meet. For large, grid scale energy storage, there are better options than vacuum. Pumped storage for example, will outperform vacuum for head heights greater than 10m. Compressed air at pressures greater than 1 bar(g) will outperform vacuum energy storage in terms of volumetric energy density. But CAES requires a pressure vessel, which means welded steel. And pumped storage requires a change in elevation, which cannot easily be achieved on a flat site. In spite of its low energy density, vacuum can be stored in relatively cheap vessels made from ceramics like concrete, stone or even dirt. This is something that is useful for storing small quantities of energy, no more than a few kWh.

In the UK, an average household uses about 12kWh of electrical energy per day. In the US, average is about double that. So a 1kWh unit will power a US home for 1 hour and a UK home for 2 hours. But that power consumption is an average, not a constant. Energy hungry appliances like air conditioning, dish washing, clothes washing, can be timed for periods when energy production exceeds their load. Air conditioning and water heating can likewise be on floating switches, as both can store thermal energy if appropriately designed. The vacuum energy store needs to provide enough energy to finish cycles, if RE generation drops midway through say a clothes wash cycle. Refrigeration can be designed to store thermal energy in ice, as can freezers and air conditioners. But lighting needs electric power on demand. Ideally, we would like a little more for things like laptops that allow people to work from home.

Is a 1kWh energy store enough to do those things for a dwelling, given some combination of wind and solar generation? A 36m3 vac store can store 1kWh. It will be smaller if we can store the water at height. We could also invest in a small DG or petrol generator, that activates if the level in the store drops beneath 10%. The vac store would reduce the demand on the DG, most of the lifetime cost of which will be fuel. Under this arrangement, there is no minimum size requirement for the energy storage system. The 1m3 system described by TH would be better than none. But bigger is better, because it reduces the demand on the DG and gives users more time to shed unnecessary loads. So we could offer a small 1m3 unit for users with little space and larger units for users with more space.

As a compressive masonry structure, the vac store has no hard limit on operational life. It does not need steel reinforcing. So its lifetime could be measured in centuries.

Last edited by Calliban (2024-09-08 09:27:27)

SpaceNut · 2024-09-10 20:50:20

image post 5, is the water flow from the high-level tank through the generator into the vacuum tank?

Also, power for the pump must come from stored energy to keep the system in a flowing mode from what I can see as once the low tank is full there is no more flow which mean power generation stops.

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