Storing Renewable Energy in Boxes of Air

[kristopher]

Storage is needed to harvest the full yield available from intermittent sources of energy like wind and solar. One of the options is compressed-air storage; till now only possible in underground caverns. But SustainX Energy Solutions; a Dartmouth College start-up that got $4 million in VC funding from Polaris Venture Partners and Rockport Capital this year is working on compressing and storing air in cheap off-the-shelf shipping containers.

Over the next two years SustainX will try to develop a way to cram 4 megawatt-hours worth of stored energy into each 40-foot long container and to reduce the energy that it currently takes to compress and release air by about 70%.

The goal? A renewable energy storage system with the portability and scalability of a battery and the economy and capacity of a cave. Make that a portable cave....

http://cleantechnica.com/2009/11/20/storing-renewable-energy-in-boxes-of-air/

[madokie]

1. I like the idea of a use for the shipping containers

my brother has a couple 40 ft ones for two sides of his shop. I've seen others use them to make living quarters, anything is better than letting them go to waste.

I believe the metal is parkerized so it has a resistance to rust

http://www.adjunct.diodon349.com/Attack_on_USA/parkerized_definition.htm

[joshcryer]

3. Yeah, they're super cheap, people build houses out of 'em.

Though the houses I have seen are not targeted at a lower priced market that they could be. You can get 'em for $2,000.

[joshcryer]

2. This relates to an energy density by mass to about 3.8MJ/kg.

Mass doesn't include the mass of the compressed air, which I am too lazy to calculate. Just the mass of a 40' container. A marginal improvement upon lithium ion batteries.

[joshcryer]

4. Ahh, the real improvement is cost, $546/kg for li-ion, $1.50/kg for this.

That's an incredible, mind boggling improvement.

edit, for my sources for the calculations:

li-ion: http://www.allaboutbatteries.com/Battery-Energy.html

storage container: http://www.storagecontainers.net/specs.html

Assumed $2500 for the container, they go for $3500 new, but I assumed a lower bound for a commercialization of this concept, and for recycling, you can actually get them for less than $2000, I've seen as low as $1400 for ones in very good shape.

[GliderGuider]

16. For once I'm going to agree with kristopher.

Energy density is only significant if the energy source has to be mobile. The energy density of a hydro reservoir is pretty lousy, but it's also irrelevant.

I don't think we'll be seeing railway locomotives based on this technology any time soon.

[joshcryer]

18. I only calculated energy density out of curiosity.

It so happened that my lithium numbers did come in MWh so I could have done cost comparisons by MWh. Sorry people here seem to place so little relevance on energy density even though I feel it makes a valid comparison between energy sources.

[kristopher]

24. It isn't the relevance of energy density

It is the use of mass (weight) instead of volume. Again - your comparison would only be apt for applications where weight is a consideration. Comparing a storage container to cellphone/laptop batteries or batteries that power portable hand tools and autos is just think.

[joshcryer]

27. It is clear that to ease your senses, I should have used MWh rather than MJ/kg.

Sorry.

[kristopher]

29. Damned you sound just like another poster

who is confused about the significance of units of measurement; joule or watt is irrelevant. Volume and mass are the variables of consequence.

Maybe this will help.

If this keeps up I'm going to start charging you tuition.

http://www.fuelcellsforpower.com/Energy-Density.html

[joshcryer]

33. The only variable of consequence is which is cheaper.

You expect consumers to magically buy enough EVs in the coming future to solve the problem. They won't until the oil starts running out. Simple.

[kristopher]

38. Not only

...are you fixated on the use of joules, you also share the same problems with understanding basic logic. That was your attempt at an analysis to present negative information on EVs. It isn't my fault you screwed it up.

... joule or watt is irrelevant. Volume and mass are the variables of consequence.

Maybe this will help.

If this keeps up I'm going to start charging you tuition.

http://www.fuelcellsforpower.com/Energy-Density.html

Whatever you're making, it is waaaay too much.

[joshcryer]

40. That's if you just want to calculate external energy density, without regards to components.

I am explicitly talking about the true energy density of a system, in which case the mass of the container should be included, plus of course the mass of the air.

You are picking at trivialities.

[kristopher]

44. I'm not "picking at" anything

With no knowledge of any of the operating characteristics capabilities (what they hope to achieve isn't a capability) and costs of the system you did a "comparison" of storage capacity by weight between a stationary, large scale energy storage container and one kind of lithium batteries.

Using the the weight and price of a shipping container as a basis you then pronounce the empty, used shipping container (no system to operate it included) to be superior to lithium batteries and decide this is the technology we need to dedicate all of our efforts to.

Since the use of weight is really not much of an issue for fixed storage, and since the role of lithium is primarily for mobile applications were scalability and round trip efficiency are as important as energy density by mass it is just puzzling that you feel it is nit picking to point out that the comparison isn't apt. Indeed, given the circumstances, the charge of "nitpicking" is as bizarre as the original confusion you offered.

Have you been kicked off DKos lately?

[joshcryer]

48. It makes a useful comparison, I'm sorry you don't see it that way since you don't believe they...

...should be compared. :hi:

[kristopher]

50. Useful for what?

[joshcryer]

52. For a cost comparison, I admitted comparing with MWh/$ would be better.

Sorry!

[kristopher]

5. How does the mass of the container relate to the energy density of the contents?

Josh wrote, "This relates to an energy density by mass to about 3.8MJ/kg. Mass doesn't include the mass of the compressed air, which I am too lazy to calculate. Just the mass of a 40' container. A marginal improvement upon lithium ion batteries."

[joshcryer]

6. That's the true energy density, the energy density of air can be much higher if you can compress it.

That's a simple approximation of energy density of the storage system itself. It's a little lower because the compressed air will have density, too. Probably wouldn't even factor into the calculation if you rounded.

[kristopher]

7. What?

Josh wrote, "That's the true energy density, the energy density of air can be much higher if you can compress it. That's the energy density of the storage system itself."

Josh V.2.0, ""That's the true energy density, the energy density of air can be much higher if you can compress it. That's a simple approximation of energy density of the storage system itself. It's a little lower because the compressed air will have density, too. Probably wouldn't even factor into the calculation if you rounded."

Please explain that in detail.

[joshcryer]

9. What in detail? I was admitting that I approximated the true energy density.

Do you know what energy density means?

[kristopher]

11. Yes, I know what energy density means

That's why your post needs a detailed explanation.

Exactly what are the variables and values you used?

[joshcryer]

12. Read post #4.

I explained the variables. Do you think the mass of the container shouldn't be counted? This isn't ground storage compression, it's a container that has to be manufactured.

[kristopher]

13. Post 4 does not provide the requested information.

This is something from grade school - just show us your work.

[joshcryer]

14. OK.

A storage container is 8278 lbs according to: http://www.storagecontainers.net/specs.html

8278 pounds = 3754.83764 kilograms according to Google unit conversion.

4 megawatt hours = 14400 megajoules according to Google unit conversion.

14400/3754 = 3.835 MJ/kg

Happy?

Note this calculation is easily derived from post #4.

[kristopher]

15. I just like it clearly laid out for examination before remarking on the validity...

Josh wrote, "A storage container is 8278 lbs according to: http://www.storagecontainers.net/specs.html

8278 pounds = 3754.83764 kilograms according to Google unit conversion.

4 megawatt hours = 14400 megajoules according to Google unit conversion.

14400/3754 = 3.835 MJ/kg"

You first post on energy density made this as a comparison to Lithium batteries.

Ahh, the real improvement is cost, $546/kg for li-ion, $1.50/kg for this.
That's an incredible, mind boggling improvement.

edit, for my sources for the calculations:

li-ion: http://www.allaboutbatteries.com/Battery-Energy.html

storage container: http://www.storagecontainers.net/specs.html

Assumed $2500 for the container, they go for $3500 new, but I assumed a lower bound for a commercialization of this concept, and for recycling, you can actually get them for less than $2000, I've seen as low as $1400 for ones in very good shape.

Comparing the energy density of lithium batteries to this storage system by weight seems like a peculiar endeavor. Energy density by mass in batteries is usually a concern only because of the relevance of mass to motion and the potential of the battery as an alternative for transportation.

What is the relevance you see in that comparison? I can understand the price comparison (more below) and could understand (perhaps) how one based on volume might have applicability for some purposes but I need some help in the significance of the weight.

As for the price (and weight I suppose) what about the cost of the device for compression and decompression? In a simple system like this it is bound to be the largest cost issue, so speculation such as you've offered seems... odd.

[joshcryer]

17. It helps with the calculation, there may be better ways to do it.

The energy density comparison was out of my own curiosity, since it makes it easy to compare relative technologies (they both store energy). And since the only good calculation I could find for Li-Ion cost/storage is in kg it allows me to do the math easier.

The cost comparison obviously doesn't include the compressor, but even if the compressor was 100 times the cost of the container, it would still come out favorable.

Li-Ion is $546.56/kg and for easy calculation let's assume 1 MJ/kg for lithium (it ranges from .46 to 2.54). Since from earlier calculations we know that 4 megawatt hours is 14400 megajoules, we just multiple $546.56 times 14400, that's about $7,870,464

Now, let's assume $5000 for the container, at 4 megawatt hours. The compressor equipment is 100 times more, that's $500,000. For $505,000. That's a factor of 15 times cheaper.

If we build this kind of storage we can more quickly and economically produce the storage necessary rather than rely on BEVs.

[kristopher]

25. About the BEV link you push

There is plenty of room for both, but the advantage of PHEVs is that the capital costs are ALREADY being made for transportation. Essentially the value of the storage accrues to the owner of a car to offset part of their transportation expense - get it?

In one case we pay to build storage, in the other we use something we've already bought for another purpose and find another use of it. Thus the capital outlay for the BEV storage is essentially zero. Your comparison would only apply if you were to buy batteries for the exclusive purpose of storing energy from the grid for resale.

Somewhere you have to account for the value of the transportation.

[joshcryer]

26. Of course I know where you are coming from.

It takes longer to do it that way, and it would obviously be more expensive than utilizing other, cheaper, storage technology.

[kristopher]

28. What "other cheaper storage technology"?

You are once more choosing to just ignore the facts. The grid storage aspect of plug in EVs is a free bonus to the efficiency improvements of electric drive.

$0 < any price above $0.01.

[joshcryer]

31. The costs of the time it takes to deploy millions of EVs relying on consumers vs...

...the time it would take to build a few hundred million of these at some small added cost to the electric grid.

Climate change is a problem that must be solved soon, not in 50 years from now when you're dead and your grandchildren are dealing with the problem you gave them because you foolishly believed EVs would solve it.

[kristopher]

39. Ahhhh

The costs of the time it takes to deploy millions of EVs relying on consumers vs...
Posted by joshcryer


...the time it would take to build a few hundred million of these at some small added cost to the electric grid.

Climate change is a problem that must be solved soon, not in 50 years from now when you're dead and your grandchildren are dealing with the problem you gave them because you foolishly believed EVs would solve it.

The odor of undiluted ignorance....

[joshcryer]

42. Yes, chosing a power source 10 to 15 times cheaper is really "ignorant."

What's ignorant is thinking that magically something 15 times more expensive is somehow magically going to solve the problem. It's not.

[kristopher]

46. ROFLMAO - "a power source"????????????

You wrote: "Yes, chosing a power source 10 to 15 times cheaper is really "ignorant." What's ignorant is thinking that magically something 15 times more expensive is somehow magically going to solve the problem. It's not."

So lets get this straight.
In post 31 you admit that EVs for grid storage is a free by-product we get when we switch to electric drive for reasons of efficiency, carbon management, and energy security: "The costs of the time it takes to deploy millions of EVs relying on consumers vs the time it would take to build a few hundred million of these at some small added cost to the electric grid."

Using the $550,000 dollar figure you pulled out of your rectum in post #17 and the "few hundred million of these" you posit in post 31 and we can quantify the "small added cost to the electric grid you allude to as $550,000 X 300,000,000 (three is "a few" right? Could have used 4 I suppose...) and we get the pittance of $165,000 trillion.

Now that is you recommending we spend 165,000 trillion dollars to provide a solution which is largely there without spending anything more than will already be spent for transportation anyway.

With $165,000 trillion we might be able to do a few other things; I leave the possibilities to your very vivid imagination.

[joshcryer]

47. Oh, you're right, we don't need 400 trillion watt hours of power.

Feel free to actually plug the numbers in since you like doing math today. Hint, it'll still be cheaper than Li-Ion. In fact, the costs would be something around a dollar a year added to peoples light bill. Big deal.

[kristopher]

49. The point is you are talking out of your ass.

[joshcryer]

51. I threw a number out there, sorry it was too high.

:shrug:

[shiftingbaselines]

22. As the author of the piece at cleantechnica

Do you mind adding that entire calculation all laid out like that to the cleantechnica story as a comment?

Ahh, the real improvement is cost, $546/kg for li-ion, $1.50/kg for this.
That's an incredible, mind boggling improvement.

edit, for my sources for the calculations:

li-ion: http://www.allaboutbatteries.com/Battery-Energy.html

storage container: http://www.storagecontainers.net/specs.html

Assumed $2500 for the container, they go for $3500 new, but I assumed a lower bound for a commercialization of this concept, and for recycling, you can actually get them for less than $2000, I've seen as low as $1400 for ones in very good shape.


It really IS a staggering difference in cost. Great work on that math.

[joshcryer]

23. Note that kristopher is right that it doesn't include the compressor/decompressor tech!

The other calculation did a rough estimate for it though so it's still crazy cheap compared to other storage methods.

edit: I'd be interested if you contacted the people who you interviewed for the article and asked them how much it would cost from their estimates, how much the compressors are, etc. :)

[shiftingbaselines]

35. Wish it was that easy! It is still at the pie in the sky stage

[joshcryer]

36. True, that. I'm sure the physics work. Now if they can engineer it.... :)

[kristopher]

8. Crickets...

[joshcryer]

10. Nah, responding in another thread.

:hi:

[Fledermaus]

34. Do you two understand that a unmodified shipping container can not hold that amount of energy?

The shipping container is going to hold some sort of device/process. The whole idea is that it would be modular, scalable, and transportable. Thats why they show images of shipping containers.

The device/process is not even described in any detail.

[joshcryer]

37. They have to be modified, but they *are* using shipping containers.

Shipping containers are very tough, they just have to make the welds air tight, or alternatively, coat the inside with some substance, possibly an epoxy or rubber compound. It's not a big of a deal as you make it out to be. Even if the coating was 20 times the cost of the container, it's still far far cheaper than other sources that have been considered.

edit: now that I think about it, coating the inside is probably what they plan to do, that way they can use those tens of thousands of shipping containers that sit and do nothing except for wait to be recycled. Those go very cheap, too. Either that, or some sort of bladder system that can be put into a container (which would otherwise expand and burst if it wasn't contained). But I don't know about that last one.

[Fledermaus]

41. You think so?

SustainXs innovative storage/conversion system is easily scalable and is designed to be modular, fitting compactly into shippable containers that can be delivered via truck, ship and rail.
http://cleantechnica.com/2009/11/20/storing-renewable-energy-in-boxes-of-air/

Perhaps you oould provide a linke supporting your claims?

[joshcryer]

43. Selective quote much?

But SustainX Energy Solutions; a Dartmouth College start-up that got $4 million in VC funding from Polaris Venture Partners and Rockport Capital this year is working on compressing and storing air in cheap off-the-shelf shipping containers.

Over the next two years SustainX will try to develop a way to cram 4 megawatt-hours worth of stored energy into each 40-foot long container and to reduce the energy that it currently takes to compress and release air by about 70%.

[Fledermaus]

45. You think so?

The primary difference with SustainX's approach is that it doesn't need an underground salt dome or limestone cavern to store the compressed air. Instead, it proposes storing the compressed air in off-the-shelf tanks. Its technical goal in two years is to cram 4 megawatt-hours worth of stored energy in a 40-foot long container, said Kepshire. The tank-filled container would be able to deliver 1 megawatt of power.

http://news.cnet.com/8301-11128_3-10396756-54.html

Theres a reason why compressed gas tanks are round and not square.

XOXOXO :loveya::smoke:

[joshcryer]

53. They're at least keeping the components simple, so I think the costs would be similar.

Thanks for the link, sorry for assuming.

[kristopher]

54. Now you've got it.

:toast:


Learning to not go off half cocked is a pretty big step.

[Fledermaus]

55. You didn't know either

:dunce:

[joshcryer]

56. Now if only we knew what *kind* of compressed air containers...

...we could get a more accurate cost.

[kristopher]

57. Know what?

[GliderGuider]

19. Has anyone done a comparison with pumping water up into a high water tower?

Or several hundred feet up a hill into a tank? Essentially small-scale pumped hydro.

[GliderGuider]

20. I just did the calculations.

4 MWh is the potential energy of 16,000 cubic meters of water with a 100 meter height differential. Essentially a tank 40x40x10 meters, at the top of a hundred-meter hill.

Not quite as flexible as a storage container and a compressor.

[joshcryer]

21. I have wondered if it would be possible to include one of those in a wind turbine design.

Somewhere at the top of the structure or inside it. The 5MW turbines are freakin' huge, and I've wondered if you could pull it off.

Then again you could probably fill the whole inside of the structure with air bladders.

But, storage is probably better used at localities at the end of transmission lines rather than at the beginning, due to losses.

[kristopher]

30. They're starting to put "watchsprings" on the rotor shaft.

It stores the gusts mechanically and smooths out the generating profile quite a bit as I understand it.

Not exactly what you are talking about but it's the only match I know of on-tower storage and wind turbines.

Another interesting concept is to replace the generator in the nacelle with an air pump that goes to a larger, integrated compressed air system on (or under) the ground. http://cleantech.com/news/node/910

"Customers don't want power when the wind blows. They want it when they want it."

So noted the CEO of a new startup that thinks it's found a way to make wind power "dispatchable"—utility jargon for being available on-demand—using turbines to compress air and store it underground.

Boston-based General Compression today announced an initial round of funding of $5m to help accelerate development of its wind energy capture technology, meant to address the major criticism of wind power: that it's rarely available when it's really needed.

The company's system is to have three components: special proprietary compressed air wind turbines, a pipeline network that collects and stores compressed air and a power plant of expanders and generators.

General Compression intends to put its compressors in conventional-type wind turbines, high in the air.

"If you're going to compress air, you've got two choices: either make electricity in the turbine and put the compressors in the ground, or put compressors in the turbine and pump the air into the ground," said General Compression CEO David Marcus today to the Cleantech Group.

"We've found it's much cheaper and efficient to put compressors in the turbine."

When the wind blows, General Compression compressors inside turbines are to pump air to over 100 atmospheres of pressure and send the air down the towers into an underground network of high-pressure pipes.

The pipeline network is to collect and store 6-12 hours of energy. If the project is sited near a geologic feature such as a salt dome, aquifer, limestone cavern, or depleted gas field, the company projects energy storage times of weeks, or even months.

"There have been some small experimental turbines putting compressors or hydraulic motors or direct drive shafts that powered water pumps underground. But those have been small scale irrigation pumps, old fashioned windmills. There's been very little work on utility-scale wind turbines that have been non-electric," said Marcus.

[joshcryer]

More things to consider for my wind turbines.

Thanks for the info.

[DU GrovelBot]

32. ## PLEASE DONATE TO DEMOCRATIC UNDERGROUND! ##

This week is our fourth quarter 2009 fund drive. Democratic Underground is
a completely independent website. We depend on donations from our members
to cover our costs. Please take a moment to donate! Thank you!