Air as energy storage

a reply to: rnaa

This is not an efficient process. You will lose a LOT of energy compressing the air, a lot more than you will get back in fact. Compressing air generates a LOT of heat and that is energy that is going to waste.

Yes there is loss but there is already much loss in pv systems.

The beauty is that the loss comes from the sun which is lost already anyhow.

No unnecessary emissions except for the making of the panels.

As others have pointed out in wind zones you could convert wind mills to gather the air also.

The loss is no big deal in this case.

Furthermore, maintenance is going to be very high, pressure vessels require constant monitoring and testing. Trust me, you don't want to be anywhere near when one fails under pressure.

I am talkin bout less than a thousand psi.
Nothing more than current air compressors.
The bigger the tank the longer the run time.

a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

a reply to: moebius

There's some really interesting combination regenerative HVAC / compression setups being developed for the manufacturing industry which apparently reduce energy use by pretty staggering amounts.

Now, the thing is that to get best results from these systems you really do need a custom site specific solution, ideally one that could factor in availability pricing and etc of components locally.

Sounds like a show stopper right?

It's not though!

If you look into some of the stuff autodesk Inc and others are working on with automated design solutions, this could actually be very possible if you can cut through the red tape on a bunch of laws and basically rewrite them to factor in new technological advances etc...

Unfortunately, that's proving to be nearly impossible.

Realistically, we could build infrastructure and our homes etc to be much better and much less energy intensive very easily if it weren't basically illegal to do so.

That's the great and the absolutely maddening thing simultaneously.

We have the technology and then some, but we lack the power needed to smash the entirely man made obstacles preventing implementation.

Be careful too because otherwise CAES will end up like hydroelectric and get killed by the so called environmentalists!

a reply to: roguetechie

makes one wonder why it is not already being used more.

everything needed for home system is found at local hardware store in most cases.

a reply to: howtonhawky

To really do it the better ways legally would be pretty expensive AFAIK for one.

For two though, you would basically have to live on unincorporated county land in a handful of US states to even do these legal but very costly installs.

In a majority of the US you very simply couldn't even get permits or variances in most residential zoned areas PERIOD to build anything other than a baby system too small to even be worth bothering with.

The more I've looked into a lot of this stuff the more it's become very apparent that pretty much everything worth doing from a payoff perspective etc is already illegal or will be made so the second someone tries to commercialize or even just stupidly tells the whole truth on permit applications.

There genuinely is a very firmly entrenched monolithic and hyper aggressive power structure and web of existing interests that effectively collude to make building better more efficient and most especially anything resembling self sufficient homes, businesses, and etc as close to impossible as can be managed.

Note: when I said that there is effective collusion when it comes to this, what I'm saying is that while that may not be the actual goal of most or even ANY of the separate entities in play here... By default, that is what is happening anyway whether it's intentional or not.

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

originally posted by: pteridine

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

no not all batteries are recycled

no this is not hard for the average person

we are talking less than 1000psi

most commercial air compressors could be adjusted and used

small scale

the larger the tank the longer the run

air motor doesn't require but 10-100psi to run at 1hp+

originally posted by: roguetechie
a reply to: howtonhawky

To really do it the better ways legally would be pretty expensive AFAIK for one.

For two though, you would basically have to live on unincorporated county land in a handful of US states to even do these legal but very costly installs.

In a majority of the US you very simply couldn't even get permits or variances in most residential zoned areas PERIOD to build anything other than a baby system too small to even be worth bothering with.

The more I've looked into a lot of this stuff the more it's become very apparent that pretty much everything worth doing from a payoff perspective etc is already illegal or will be made so the second someone tries to commercialize or even just stupidly tells the whole truth on permit applications.

There genuinely is a very firmly entrenched monolithic and hyper aggressive power structure and web of existing interests that effectively collude to make building better more efficient and most especially anything resembling self sufficient homes, businesses, and etc as close to impossible as can be managed.

Note: when I said that there is effective collusion when it comes to this, what I'm saying is that while that may not be the actual goal of most or even ANY of the separate entities in play here... By default, that is what is happening anyway whether it's intentional or not.

it works for me

yes many places suck like florida where they will not let you have off grid systems

it does require some space to have panels but beyond that it is not that tough for most. most of this could be hidden under a standing array.


think of this
a 5gallon propane tank like at most big box stores will put out about 12 hrs+ at 10 psi and you can run a .5-1hp air motor with that same amount of pressure of air for about 8-12 hrs depending on use. running at 2000-2500w it will take about 1 hr. to produce that amount of volume of air with a compressor from panels
my figures are from actual experience and not a pen so your maths may vary.

one has to remember that over a period of 24 hrs the average electric usage of a person is very low when compared to the peak of a user. Since batteries will still be used it is not necessary to have an air motor that peaks out at high output. slow and steady will win the race in this case.

originally posted by: howtonhawky

Yes there is loss but there is already much loss in pv systems.

The beauty is that the loss comes from the sun which is lost already anyhow.

What loss in pv systems? Excess generation that is not used immediately? That is what you are looking for a storage medium for.

No unnecessary emissions except for the making of the panels.

As others have pointed out in wind zones you could convert wind mills to gather the air also.

Yeah, but that is true no matter what storage medium you use.

The loss is no big deal in this case.

Yes it is, when there are cheaper, more efficient storage mediums, it is a very big deal. You could easily be using 100% of your available generation to just pressurize the tank. No household electricity available during that time - is that what you want?

I am looking at a decent quality compressor (I assume you want good quality - there are better and worse examples) available in Australia. Its motor is rated at 5.5kW (20A at 500V !) and has a 220 liter receiving tank.

In Oz, most rooftop systems being installed these days are right around 5kW, big ones are around 10kW. You should be able to see that running a compressor to fill a HUGE tank is going to take up most of the output for the day, not just the 'excess'. You will be losing energy at every conversion step, and there are lots of conversion steps. A practical size compressor for your HUGE tank will use a corresponding high energy conversion.

I am talkin bout less than a thousand psi.
Nothing more than current air compressors.
The bigger the tank the longer the run time.

Current air compressors pressurize to about 115-125 psi and safety pop at 160psi.

The bigger the tank the longer the time to pressurize, you'll be using everything to power the compressor and have nothing left over to run the refrigerator and computer and lights and...

Furthermore you aren't going to get anywhere near 1000psi without spending more money than your house is worth. And that pressure vessel will be subject to constant safety monitoring by government. Don't forget your pressure vessel will have to be inspected and hydro tested at regular intervals (according to standards specified by your state law), and this can be expensive. Private folks often find this expensive put off the tests, (heck its only 120psi), but they really need to be inspected periodically, by law. You are going to have trouble getting a permit for your 1000psi tank full stop, I doubt the authorities will let you get away with keeping a giant untested time bomb in your back yard.

Batteries are easily the safest, least expensive and most efficient storage medium by a factor of 100.

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

no not all batteries are recycled

no this is not hard for the average person

we are talking less than 1000psi

most commercial air compressors could be adjusted and used

small scale

the larger the tank the longer the run

air motor doesn't require but 10-100psi to run at 1hp+

Storage batteries that would be used for this scheme are recycled.

Some people could build this system but most would have to buy a system. How would one heat the gas to use it? Commercial plants use natural gas. [See Joule–Thomson effect]
It would probably be better to use the capital outlay for solar heating and cooling and passive efficiency improvements. One could begin easily by replacing all light bulbs with LED's and improving insulation of the house.

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

no not all batteries are recycled

no this is not hard for the average person

we are talking less than 1000psi

most commercial air compressors could be adjusted and used

small scale

the larger the tank the longer the run

air motor doesn't require but 10-100psi to run at 1hp+

Storage batteries that would be used for this scheme are recycled.

Some people could build this system but most would have to buy a system. How would one heat the gas to use it? Commercial plants use natural gas. [See Joule–Thomson effect]
It would probably be better to use the capital outlay for solar heating and cooling and passive efficiency improvements. One could begin easily by replacing all light bulbs with LED's and improving insulation of the house.

i just do not think we are on the same page here

there is no gas

i used that for comparison cause most people have used a 5 gallon propane can before

imagine one already has a working pv system off grid

currently when the batteries are full then the excess solar is burnt off in order to not overcharge the batteries

what i purpose is that instead of burning off that excess you just use it to run a compressor that fills a large tank to 200-300psi then put an outlet on the tank run it to an air motor that powers an alternator that is switched on at night when your battery bank is low

that would be one design

less than 1000$ and you could also benefit on those cloudy days

a reply to: rnaa

yes it can take some space and is not right for every set up

i am not familiar with every gov. rule and where i live if you can build it you can use it

you can use whatever size storage tank you want the bigger the tank the less pressure you have to have

yes they sell some big compressor out there but you can use what ever size you want

to me it sounds like in your case i would make a small scale system just so you could get a feel for it and find your own benefits if any

a 1hp air motor is cheap and so are most air pumps (you can adjust most pump output) but be careful

do not let your negativity get in the way of your progress


think of it as an on demand wind turbine

Seems to me you should be able to use the air pressure to fuel a chemical reaction to make liquid fuel. Energy is energy, converting it using pressure as a catalyst might be feasible, we do not need oil to make energy or manmade catylists to make potable energy.

a reply to: pteridine

Right you'd pretty much have to dive into pre 1940's compressed air locomotive design to get your basic inspiration since they were very much using heat recovery and even passive tank heating schemes to get more bang per buck.

Now if you had some freaky hybrid solar thermal / PV array that had something like a pressurized ammonia coolant loop to work with that was nice and modular you might be able to do some pretty cool stuff.

a reply to: roguetechie

you guys are way past my purpose and i hope maybe i sparked some imagination cause yall are more educated than i as it sounds.

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

no not all batteries are recycled

no this is not hard for the average person

we are talking less than 1000psi

most commercial air compressors could be adjusted and used

small scale

the larger the tank the longer the run

air motor doesn't require but 10-100psi to run at 1hp+

Storage batteries that would be used for this scheme are recycled.

Some people could build this system but most would have to buy a system. How would one heat the gas to use it? Commercial plants use natural gas. [See Joule–Thomson effect]
It would probably be better to use the capital outlay for solar heating and cooling and passive efficiency improvements. One could begin easily by replacing all light bulbs with LED's and improving insulation of the house.

i just do not think we are on the same page here

there is no gas

i used that for comparison cause most people have used a 5 gallon propane can before

imagine one already has a working pv system off grid

currently when the batteries are full then the excess solar is burnt off in order to not overcharge the batteries

what i purpose is that instead of burning off that excess you just use it to run a compressor that fills a large tank to 200-300psi then put an outlet on the tank run it to an air motor that powers an alternator that is switched on at night when your battery bank is low

that would be one design

less than 1000$ and you could also benefit on those cloudy days

In the link you provided, a large scale unit uses gas to heat the air because of the J-T effect.

I understand the concept of using a household propane tank as a storage vessel. A common low pressure 1000 gallon tank [about 133 cubic feet] which could be charged to 300 psi. This could get an hour or two of generator time.
What will the air powered generator do? It will be charging the battery bank when it is depleted. You will lose between 30 and 50 % of the energy if you have to go through this cycle. It is far more efficient to increase the size of the battery bank while eliminating all the mechanical moving parts that can cause trouble.
Heating water would be a good way to dump extra energy from a mismatched solar power/battery pack. If you use hot water, that is an easy thing to do. You could also use existing systems as an energy sink such as a heat pump.

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

no not all batteries are recycled

no this is not hard for the average person

we are talking less than 1000psi

most commercial air compressors could be adjusted and used

small scale

the larger the tank the longer the run

air motor doesn't require but 10-100psi to run at 1hp+

Storage batteries that would be used for this scheme are recycled.

Some people could build this system but most would have to buy a system. How would one heat the gas to use it? Commercial plants use natural gas. [See Joule–Thomson effect]
It would probably be better to use the capital outlay for solar heating and cooling and passive efficiency improvements. One could begin easily by replacing all light bulbs with LED's and improving insulation of the house.

i just do not think we are on the same page here

there is no gas

i used that for comparison cause most people have used a 5 gallon propane can before

imagine one already has a working pv system off grid

currently when the batteries are full then the excess solar is burnt off in order to not overcharge the batteries

what i purpose is that instead of burning off that excess you just use it to run a compressor that fills a large tank to 200-300psi then put an outlet on the tank run it to an air motor that powers an alternator that is switched on at night when your battery bank is low

that would be one design

less than 1000$ and you could also benefit on those cloudy days

In the link you provided, a large scale unit uses gas to heat the air because of the J-T effect.

I understand the concept of using a household propane tank as a storage vessel. A common low pressure 1000 gallon tank [about 133 cubic feet] which could be charged to 300 psi. This could get an hour or two of generator time.
What will the air powered generator do? It will be charging the battery bank when it is depleted. You will lose between 30 and 50 % of the energy if you have to go through this cycle. It is far more efficient to increase the size of the battery bank while eliminating all the mechanical moving parts that can cause trouble.
Heating water would be a good way to dump extra energy from a mismatched solar power/battery pack. If you use hot water, that is an easy thing to do. You could also use existing systems as an energy sink such as a heat pump.

your figures are off

1hp air motor requires 10-40psi to run

the size tank you mention would run most houses for a day or two

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

no not all batteries are recycled

no this is not hard for the average person

we are talking less than 1000psi

most commercial air compressors could be adjusted and used

small scale

the larger the tank the longer the run

air motor doesn't require but 10-100psi to run at 1hp+

Storage batteries that would be used for this scheme are recycled.

Some people could build this system but most would have to buy a system. How would one heat the gas to use it? Commercial plants use natural gas. [See Joule–Thomson effect]
It would probably be better to use the capital outlay for solar heating and cooling and passive efficiency improvements. One could begin easily by replacing all light bulbs with LED's and improving insulation of the house.

i just do not think we are on the same page here

there is no gas

i used that for comparison cause most people have used a 5 gallon propane can before

imagine one already has a working pv system off grid

currently when the batteries are full then the excess solar is burnt off in order to not overcharge the batteries

what i purpose is that instead of burning off that excess you just use it to run a compressor that fills a large tank to 200-300psi then put an outlet on the tank run it to an air motor that powers an alternator that is switched on at night when your battery bank is low

that would be one design

less than 1000$ and you could also benefit on those cloudy days

In the link you provided, a large scale unit uses gas to heat the air because of the J-T effect.

I understand the concept of using a household propane tank as a storage vessel. A common low pressure 1000 gallon tank [about 133 cubic feet] which could be charged to 300 psi. This could get an hour or two of generator time.
What will the air powered generator do? It will be charging the battery bank when it is depleted. You will lose between 30 and 50 % of the energy if you have to go through this cycle. It is far more efficient to increase the size of the battery bank while eliminating all the mechanical moving parts that can cause trouble.
Heating water would be a good way to dump extra energy from a mismatched solar power/battery pack. If you use hot water, that is an easy thing to do. You could also use existing systems as an energy sink such as a heat pump.

your figures are off

1hp air motor requires 10-40psi to run

the size tank you mention would run most houses for a day or two

It will run on 10-40 psi but what volume of air will it use? How much power will it produce? Why wouldn't the solar array and the storage batteries be matched to output?

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky

originally posted by: pteridine

originally posted by: howtonhawky
a reply to: pteridine

For an individual household, it is probably more economical and efficient to get a bigger battery array.

Batteries are producing much chemical waste.

This would be like a battery but without the waste.

Are you aware that storage batteries are recycled?

The scheme you propose is complex and expensive to build and maintain for an individual household. A high pressure compressor is expensive and requires a significant amount of power to operate. High pressure gases must be handled and stored safely. From your own link, commercial power plants have to burn fuel to heat the compressed air.

Unless you have a household of engineers and a large budget, this is a bad idea for an individual.

no not all batteries are recycled

no this is not hard for the average person

we are talking less than 1000psi

most commercial air compressors could be adjusted and used

small scale

the larger the tank the longer the run

air motor doesn't require but 10-100psi to run at 1hp+

Storage batteries that would be used for this scheme are recycled.

Some people could build this system but most would have to buy a system. How would one heat the gas to use it? Commercial plants use natural gas. [See Joule–Thomson effect]
It would probably be better to use the capital outlay for solar heating and cooling and passive efficiency improvements. One could begin easily by replacing all light bulbs with LED's and improving insulation of the house.

i just do not think we are on the same page here

there is no gas

i used that for comparison cause most people have used a 5 gallon propane can before

imagine one already has a working pv system off grid

currently when the batteries are full then the excess solar is burnt off in order to not overcharge the batteries

what i purpose is that instead of burning off that excess you just use it to run a compressor that fills a large tank to 200-300psi then put an outlet on the tank run it to an air motor that powers an alternator that is switched on at night when your battery bank is low

that would be one design

less than 1000$ and you could also benefit on those cloudy days

In the link you provided, a large scale unit uses gas to heat the air because of the J-T effect.

I understand the concept of using a household propane tank as a storage vessel. A common low pressure 1000 gallon tank [about 133 cubic feet] which could be charged to 300 psi. This could get an hour or two of generator time.
What will the air powered generator do? It will be charging the battery bank when it is depleted. You will lose between 30 and 50 % of the energy if you have to go through this cycle. It is far more efficient to increase the size of the battery bank while eliminating all the mechanical moving parts that can cause trouble.
Heating water would be a good way to dump extra energy from a mismatched solar power/battery pack. If you use hot water, that is an easy thing to do. You could also use existing systems as an energy sink such as a heat pump.

your figures are off

1hp air motor requires 10-40psi to run

the size tank you mention would run most houses for a day or two

It will run on 10-40 psi but what volume of air will it use? How much power will it produce? Why wouldn't the solar array and the storage batteries be matched to output?

it depends on the style of air motor you use. There are many types.
please clairify what you mean by matched output in relation to the array and batteries.

Keep inmind this air system would indeed require double the number of panels as would normal set ups but the gain would be you would only need one or two batteries to run the system all day vs now you would have to have very many batteries to do such.

Yes there would be loss but the loss would only be on the solar side and that is already being lost everyday even as we speak.

@OP,

a reply to: moebius


^^^^ This, right here.

It is called your "working fluid" (even if it is not a fluid), it is what you store energy into, to retrieve out later. Regular good old air is not dense enough. Which is why you add heat (diabatic storage), and/or pressure. Which is why geothermal is promising as a closed-loop system.

At some point, it only make sense to switch over to supercritical CO2 (SCO2) as your working fluid: it is denser so is more efficient. That is what the concentrated solar power towers are trying out. That one stores solar to heat these pebbles that converts CO2 to SCO2 for release later. There is a plant in Texas about to come online that uses SCO2 to generate electricity so you will see this in action soon.

Here is one you may never have heard of: GTM.com - Startup Says Molten Silicon Will Make Lithium-Ion Storage ‘Uneconomic.’ Here’s the Full Story.

They want to take any energy source's excess, heat a block of silicon until it melts (1414 degrees, where their name comes from), then use heat exchangers to extract energy long after the sun sets, or the wind stops blowing (but like I said, any energy source can be used). It is half as cheap as lithium batteries and more environmentally friendly.

Anyway, glad to see somebody thinking about energy storage in unconventional manners!