Using Shipping containers as compressed air 'Batteries

In summary: So, you need a way to store the energy and a way to get it from a to b. If the losses are too great then it's just not feasible as a solution.I am all for renewable energy, but let's not just say "oh it's better than burning oil". It's not that simple.1. Renewable energy sources are not always available (e.g. night, cloudy days)2. Energy demand is not constant, it varies throughout the day3. Current renewable technology cannot always meet peak demandThis is where energy storage solutions, like using shipping containers as compressed air 'batteries', come into play. It allows for the utilization of excess renewable energy during off-peak hours to meet
  • #1
matchinu
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Using Shipping containers as compressed air 'Batteries"

Just joined the site, you have a much more practical captcha system, I am surprised its not more widely implemented.

Anyway! Obviously if you have seen a peak energy demand graph you will notice that the peak energy requirement is from around 6pm to 11pm. A problem the energy suppliers face is providing that peak demand from renewable sources.

Approximately 25 Trilla(?) Watt Hours of energy produced by Wind Energy goes to waste in the U.S each year. (google it, this is my first post, i don't think i can provide links)

I have seen it suggested that renewable energy such as wind and solar can be used to power an air compressor, to compress air into things such as shipping containers. From 6pm to 11pm the air stored in these shipping containers could be released (to drive turbines) to meet the peak demand. This eliminates the problem of not being able to generate enough electricity from renewables when its needed most. This process shifts renewable energy production to a 'on demand' basis such burning fossil fuels.

I had the idea this morning that energy could be generated by pumping air into a chamber filled with water, the resulting bubbles would power a turbine. After thinking about it i realized this idea was impractical as you can't get out more energy out than that would be put into the pump to make the bubbles. This then made me remember about compressing air to generate energy at a later period in time.

Since I know next to nothing about Physics.

In regards to losses of energy, would it be better to:

1 - Release the compressed air to create bubbles in a chamber of water to generate electricity

Or

2 - Release the compressed air to drive a turbine?

Or can you think of a more efficient way to harvest the compressed airs stored potential.

Ps I saw threads about the efficiencys of energy generation in this forums so i figure this is the correct forum if not please move my post or tell me where to go =D
 
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  • #2


Hi matchinu, welcome to PF!

This is a nifty idea. As a mechanical engineer, I would next consider what the energy density is (i.e., how much energy can be stored in a given volume), how much shipping containers could be pressurized without failing, and what the total pump, container, and turbine costs would be. Then you could compare your idea to other approaches.

For example, one of my buddies down the hall is working on large (1 m3) high-temperature batteries for the same application. At night, when an energy surplus exists, the battery uses electrical current to reduce a metal oxide to metal. During the day, the metal is allowed to oxidize, producing electrochemical power. I have a hunch that the storage density is far higher than what is available with pressurized shipping containers (because solids are several of orders of magnitude denser than gases, among other reasons), but the metals required are relatively exotic and expensive.

Anyway, the practice of evaluating these figures of merit will make you a better engineer, inventor, and promoter, I believe.
 
  • #3


Hi matchinu, welcome to the board. There's been a lot of research into ways of storing energy from renewable resources and a lot of different solutions, some exotic, some conventional. Compressing air into underground caverns (not really caverns per se, but porus rock or equivalent) is just one of the methods of energy storage. The energy is then extracted by running it through a turbine. A more exotic solution is to store energy as http://www.gizmag.com/liquid-air-energy-storage/18148/". Basically, you liquify the air to store it, then heat it and expand it through a tubine to get it back. Another very low tech and perhaps the most common method is to pump water from a lower elevation to a higher one, then take the energy back out by dropping the water though a turbine. So there are lots of ways to do it, all have advantages and disadvantages. The best solution however is just to use the energy as soon as it's created, thereby eliminating the losses associated with storing energy.
 
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  • #4


From my experience you're lucky if the average shipping container is watertight let alone airtight.
 
  • #5


Jobrag said:
From my experience you're lucky if the average shipping container is watertight let alone airtight.

That was my first thought.

Why shipping containers?

Why not just design a vessel to do the job (or just pick out of the thousands available).

The problem I see is that turning wind (or whatever renewable) into electric and then driving a compressor and then extracting it again via a turbine is going to have significant losses and make the whole process fairly useless.
 
  • #6


jarednjames said:
The problem I see is that turning wind (or whatever renewable) into electric and then driving a compressor and then extracting it again via a turbine is going to have significant losses and make the whole process fairly useless.

I will never EVER understand this thought process. I have stated it in a different thread but I cannot resist saying here either. So what if there is significant loss with a renewable system? It is better to do that than the alternative which is continuing to burn more non-renewable fuels. Granted that it is always better to have as much efficiency in the system as possible.
 
  • #7


Averagesupernova said:
I will never EVER understand this thought process. I have stated it in a different thread but I cannot resist saying here either. So what if there is significant loss with a renewable system? It is better to do that than the alternative which is continuing to burn more non-renewable fuels. Granted that it is always better to have as much efficiency in the system as possible.

You are ignoring a crucial factor: meeting demand.

Renewable is certainly a better way to get power, no emissions etc, but if you have to wipe out areas the size of countries to get the required coverage to supply you then it's useless - and that's just going directly to electric and then use.

If you then add a "middle man" as per the OP's suggestion, you get even less out of the system meaning you have to increase the number of devices and subsequently land use just to meet demand.

Or, we could have one nuclear plant to do the job nicely.

I did a study for my first year electrical engineering class, for one nuclear plant in the UK (I forget which one) it would take 700 2MW wind turbines to cover it's production and even with all of those you wouldn't have a consistent supply. Just to put this number in perspective, for 16 turbines where I live it currently occupies 16,000,000 square feet of land (just over 350 acres). I understand you could probably cut that down a fair bit, but there's only so tightly they can be packed.

If the renewables cannot meet demand whilst occupying a reasonable amount of space and cannot provide a consistent supply, they are no good and not worth it.

I can't remember the exact figure I came to, but if we removed all nuclear plants from use in the UK (due to decomissioning etc) and tried to use only wind power, we'd have to cover an area the size of Wales just to meet the demand (assuming it was consistent - which it's not).
 
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  • #8


jarednjames said:
(assuming it was consistent - which it's not).

Which is the whole point of storage. I rest my case.
 
  • #9


Averagesupernova said:
Which is the whole point of storage. I rest my case.

Did you just ignore the rest of the post regarding how many renewable sources would be required to "fill" said storage to provide a consistent supply?

Assuming 1.4GW output from a nuclear plant you need 700 2MW turbines - just to cover the supply.

If you then want to store it, via the means indicated above you get X amount of losses meaning you need 700 + Y turbines to provide the input required.

Now, unless you have a hell of a lot of land to throw into it, it just isn't feasible. (The UK has ~20 nuclear plants alone, without including other forms.)

My 'case' doesn't hinge on consistency of supply, it all works around meeting demand for power. Which renewables cannot - the consistency is simply an added issue to deal with.
 
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  • #10


My point is that you cannot use the argument: Alternative energy (wind, solar, etc.) is a poor choice because it requires storage to make it reliable 24/7, so, since it is a poor choice we won't bother researching into storage devices. Do you see the circular illogic here? No one has said alternative energy can completely replace conventional energy. This is MY case. I never asked about your case. The only point I made was the storage issue.
-
I personally don't care what you do across the pond from where I live. I personally don't care that it would take bookoo wind towers to replace your however many nuke plants or whatever plants you have where you live. There are places in the world that alternative energy works and I happen to live in one of them. I haven't even touched on the issue of one conventional plant vs. the multiple smaller plants and the advantages of redundancy, and I won't since I don't really enjoy discussing this matter with you.
 
  • #11


Averagesupernova said:
My point is that you cannot use the argument: Alternative energy (wind, solar, etc.) is a poor choice because it requires storage to make it reliable 24/7, so, since it is a poor choice we won't bother researching into storage devices. Do you see the circular illogic here?

I certainly do, but that's not my problem and neither is it my argument.

EDIT: You know what, too much attitude for me, I'm done here.
 
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  • #12


I'm aware of the many methods of storing energy, however that's the first I've heard of storing it the way you describe Mapes.

Yours talking about storing it with cryogenics Q_goest?

And Jared, remember that a house with solar panels can produce enough power to meet the houses demand, since the power isn't going to be used during the day a practical solution to storing it on site in a battery of sorts for use at night, rather than the area the size of Wales. A custom built vessel to store compressed air would be one practical solution considering how little resources it uses.

Kind of dissapointed that niether of you actually answered my question lol.

I came to that conclusion myself... turbine turning in water vs thru air? I think i know which one id choose.
 
  • #13


I suppose this is obvious but is your buddy looking into more common materials or will it simply only work with the rarer ones?
 
  • #14


Hello all:

I haven't posted much on these boards, but I have read them for a while and I thoroughly enjoy them!

Without taking this thread too far off-topic, one question that I have for citizens of the UK is:

Has there been any research, development, or implementation of tidal or wave-powered generators?

It seems that it may be one way to address the issue of consistency of supply while tapping into an essentially unlimited and renewable energy source.

I admit that I haven't done much research myself on the UK's energy generation techniques, so I apologize if this question is matter-of-fact information.

Cheers!
 
  • #15


i have read about a 1.5 kw/mw? tidal generator in the uk
 
  • #16


matchinu said:
i have read about a 1.5 kw/mw? tidal generator in the uk

The one up in Orkney?

Orkney is probably the best place for tidal in the whole of the UK, as there is no slack tide, it goes around in circles and has a really high current. Ironically this is making it tremendously hard to design and install the supports, it's presented significant design challenges for how to drill the supports.
 
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  • #17


Keeping the containers air tight would be the biggest problem. If you used liquified air you may transfer a lot of energy into the container in the early morning.

I wonder if you could do the same idea with oil and gas reservoirs.
 
  • #18


xxChrisxx said:
The one up in Orkney?

Orkney is probably the best place for tidal in the whole of the UK, as there is no slack tide, it goes around in circles and has a really high current. Ironically this is making it tremendously hard to design and install the supports, it's presented significant design challenges for how to drill the supports.

Is the River Severn not a good place as well? I thought it had one of the best tidal systems for the generation in the UK?
 
  • #19


JaredJames said:
Is the River Severn not a good place as well? I thought it had one of the best tidal systems for the generation in the UK?

The Severn is too, it's just a different type of challenge of capturing the power. A high tidal range for a set time in the Severn vs a constantly flowing tide in the Orkneys.
 
  • #20


The key problem with tidal power is that the daily tidal cycle takes 24 hrs 50 mins, so peak production drifts at almost an hour a day, so needs a great hunk of storage or in-fill power to synchronise it with daily demand...

Let's not get into the issues of Spring and Neap tides...

IIRC, there *was* a scheme proposed for Severn Estuary which would have retained the natural tidal rhythms plus a neap-tide range, but it needed an immense pumped-storage ring-dam tower in mid-channel attached to the main dam. Elegant, perhaps, and eco-friendly given the outer face would be ledged for sea-bird nesting, but sadly uneconomic. It didn't even make the short-list...

Instead of a few such UK mega-projects, we're getting a rash of oft-unsightly wind turbines, plus tidal-current etc projects where they can be positioned with least interference...

Uh, IMHO, trying to store compressed air in flimsy shipping containers is a VERY BAD idea. They are not a good shape for holding over-pressure, their panels would bulge and stay bent, the whole could burst horribly along any of the seams. There's a good reason why divers' and welders' gas-tanks are shaped as they are, and really, really heavy. Also consider the shape of tanks mounted on garage compressors and truck air-brakes, the cylinders used for bottled LPG etc. Finally, consider the behaviour of vend cans and litre bottles of soda drinks...
 
  • #21


for the orkeys id suggest something like this then, maybe on a smaller scale as i have no idea what the depth is like there. also not dangerous to marine life (which is one argument against what there trying to do at the moment.

http://www.physorg.com/news192784124.html
 
  • #22


Hey, new to this forum but this chimes with an idea I've dreamt up.
Re compressed air and turbines... could you not have a totally enclosed container with sufficient height to create a big head of water.
Container divided vertically into 3 columns, all linked at the bottom, outer 2 with one-way air valves
Start off with water level in all 3 columns and air in all
Inject high pressure air into central chamber depressing water level and raising it in outer columns, expelling air to create 2 solid columns of water
Sustain air pressure

the idea is to take water from somewhere in the outer columns out through an exterior turbine and back into the central pressurised chamber to re-enter the system there just above the depressed water level?

Would this not keep the outer columns primed and passing water through the turbine under internal air pressure, which could be adjusted if necessary, thus recirculating itself back into the columns?
 
  • #23


Hi FoggontheTyne, welcome to PF.

This will not work. The water will not flow through the turbine into the central pressurized chamber because there's essentially no pressure gradient. That is, the outer chambers are at the same pressure as the inner chamber, so there's no driving force to move the turbine.
 
  • #24


ok but what about the height gradient?

Are you assuming that the water outlet from the turbine is immersed in the lower water body?

I was thinking the simple height gradient would drive the turbine, perhaps not very dynamically but even so it would run.

If the central chamber air pressure were extremely high, would that not cause an expulsive force throughout the whole body of water?

Water levels would not change because of the established air pressure.
 
  • #25


FoggontheTyne said:
ok but what about the height gradient?

Are you assuming that the water outlet from the turbine is immersed in the lower water body?

I was thinking the simple height gradient would drive the turbine, perhaps not very dynamically but even so it would run.

If the central chamber air pressure were extremely high, would that not cause an expulsive force throughout the whole body of water?

Water levels would not change because of the established air pressure.

We immediately that no such device could ever work, because it would be a perpetual motion machine. One can always show through examination how the device won't work, but this is more effort. I suggest you try it, though, to clarify the physics to yourself. For each relevant location (e.g., turbine input and output), add up the hydrostatic pressure and the pressure from any other mechanisms. Note that fluids will always move from areas of higher to lower pressure. You'll find that no turbine will ever provide net energy forever from a column of water, pressurized or not.
 
  • #26


I'll have one more go at this!

The input is the pressurised water outlet up the outer columns, but once it has all flowed through the turbine and back in, it's vented into the air body itself in the high pressure air ie above the central chamber water level where it falls into the reservoir?? My question is, would not the water flowing down from a height and under pressure from the top simply exit the turbine outlet and back into the reservoir?
 
  • #27


| w | a | w |
| ^ | v | ^ |
\ ^ \ v / ^ /
\ ^ \ v / ^ /
\_/\<>/\_/

Basically?
 
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  • #28


yes, that' right...it's a sealed system and a wacky idea but I don't know if it's Alfred E Neumann or pure genius!

The turbine is outside the unit and I envisaged two outlets spiralling in from somewhere up in the outer columns, re-entering the air chamber to discharge just above the water level!
 
  • #29


I wasn't thinking of anything quite so huge but obviously it's all at high pressure...is there not a design way out of this, such as inward-pointing cantilever walls? Like the load-bearing structure of a bridge. They could then in turn be braced against a containing structure that could sort of soak up the strain

I would think the thrust would all be directed down into the converging points of a structure like this which could be reinforced.
 
  • #30


FoggontheTyne said:
I would think the thrust would all be directed down into the converging points of a structure like this which could be reinforced.

If you really had to use a shipping container, sure you could design some way to strengthen it. But it would be cheaper and have more energy density to just use a proper pressure vessel in the first place.

Be careful talking about that water machine. Apparently they close threads for that. Perpetual motion is against the rules.
 
  • #31


so I've come to realize...all I want to know is what would happen to the circulation once it had started
 
  • #32


There is a small prob here..
Renewable energy has anyways got a higher value of $/kW produced.
Top of that using this to compress air, store, and then expand again.. Each stage has got considerable amount of losses..
Overall the net power that u get won't justify the capital required to be put in..
 
  • #33


chetanladha said:
Top of that using this to compress air, store, and then expand again.. Each stage has got considerable amount of losses..
Overall the net power that u get won't justify the capital required to be put in..

As somebody else mentioned, large losses can be acceptable for storing renewable energy because the alternative - dumping it - has 100% loss.

Whether a particular way of storing it is cheap enough is a detail that can't be decided on simply by looking at efficiency. It depends strongly on how much overlap there is between the demand and production periods. It also depends on what other power sources are available to fill in the gaps. Having a lot of coal power and only a small amount of renewable will make storing renewable less economical. But the greater the proportion of power that's renewable (and cyclic), the greater the economy of storing it can be.
 
  • #34


arent there existing industrial devices based on pneumatic technology which has been proven to store compressed air very well? at the very least you can expect good reliability, if the efficiency has not really been a focus of these technologies

come to think of it, will a giant piston be more efficient than a pump/turbine combination?
 
  • #35


carmatic said:
arent there existing industrial devices based on pneumatic technology which has been proven to store compressed air very well?

There are - air compressor reservoirs, but they're used when people want compressed air on demand. You don't want compressed air, you want electricity, so that opens up many more options.

Sure, compressed air would be technically feasible. But I think the biggest drawback would be the cost of the tanks. Calculate the energy density of an existing compressed air tank. See how many you'd need to power a city for half a day, assuming 100% efficiency.

If that shows it's impractical then there's no point trying to optimize the pump/turbine.

Turns out there's a wikipedia article onf Compressed air energy storage. It says you might as well use a battery.
 
<h2>1. How do shipping containers function as compressed air batteries?</h2><p>Shipping containers can function as compressed air batteries by using the principles of compressed air energy storage (CAES). In this process, air is compressed and stored in the container, which acts as a reservoir. When energy is needed, the compressed air is released and runs through a turbine, generating electricity.</p><h2>2. What are the benefits of using shipping containers as compressed air batteries?</h2><p>Using shipping containers as compressed air batteries has several benefits. They are cost-effective, as shipping containers are readily available and can be repurposed for this use. They are also portable and can be easily transported to different locations. Additionally, they have a long lifespan and can be used for many years.</p><h2>3. Are there any limitations to using shipping containers as compressed air batteries?</h2><p>One limitation of using shipping containers as compressed air batteries is their size. They may not be suitable for smaller energy storage needs. Additionally, the efficiency of this method may be affected by the temperature and humidity of the environment. The location of the container may also impact its effectiveness.</p><h2>4. How can shipping containers be converted into compressed air batteries?</h2><p>To convert a shipping container into a compressed air battery, modifications must be made to the container. This includes adding an air compressor, a turbine, and a control system. The container must also be insulated to maintain the compressed air at a stable temperature. It is recommended to consult a professional for the conversion process.</p><h2>5. What are some potential applications for using shipping containers as compressed air batteries?</h2><p>Shipping containers can be used as compressed air batteries in various applications. They can be used in remote areas or off-grid locations to store renewable energy, such as solar or wind power. They can also be used in emergency situations, providing a backup power source. Additionally, they can be used in industrial settings to manage energy demand and reduce costs.</p>

1. How do shipping containers function as compressed air batteries?

Shipping containers can function as compressed air batteries by using the principles of compressed air energy storage (CAES). In this process, air is compressed and stored in the container, which acts as a reservoir. When energy is needed, the compressed air is released and runs through a turbine, generating electricity.

2. What are the benefits of using shipping containers as compressed air batteries?

Using shipping containers as compressed air batteries has several benefits. They are cost-effective, as shipping containers are readily available and can be repurposed for this use. They are also portable and can be easily transported to different locations. Additionally, they have a long lifespan and can be used for many years.

3. Are there any limitations to using shipping containers as compressed air batteries?

One limitation of using shipping containers as compressed air batteries is their size. They may not be suitable for smaller energy storage needs. Additionally, the efficiency of this method may be affected by the temperature and humidity of the environment. The location of the container may also impact its effectiveness.

4. How can shipping containers be converted into compressed air batteries?

To convert a shipping container into a compressed air battery, modifications must be made to the container. This includes adding an air compressor, a turbine, and a control system. The container must also be insulated to maintain the compressed air at a stable temperature. It is recommended to consult a professional for the conversion process.

5. What are some potential applications for using shipping containers as compressed air batteries?

Shipping containers can be used as compressed air batteries in various applications. They can be used in remote areas or off-grid locations to store renewable energy, such as solar or wind power. They can also be used in emergency situations, providing a backup power source. Additionally, they can be used in industrial settings to manage energy demand and reduce costs.

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