Not just blowing in the wind: Compressing air for renewable energy storage

[OKIsItJustMe]

http://www.pnnl.gov/news/release.aspx?id=985

[font face=Serif][font size=5]Not just blowing in the wind: Compressing air for renewable energy storage[/font]

May 20, 2013

Joel Scruggs, BPA, [phone]
Frances White, PNNL, [phone]

[font size=4]Study IDs two compressed air energy storage methods, sites for the Northwest[/font]

[font size=3]RICHLAND, Wash. – Enough Northwest wind energy to power about 85,000 homes each month could be stored in porous rocks deep underground for later use, according to a new, comprehensive study. Researchers at the Department of Energy's Pacific Northwest National Laboratory and Bonneville Power Administration identified two unique methods for this energy storage approach and two eastern Washington locations to put them into practice.

Compressed air energy storage plants could help save the region's abundant wind power — which is often produced at night when winds are strong and energy demand is low — for later, when demand is high and power supplies are more strained. These plants can also switch between energy storage and power generation within minutes, providing flexibility to balance the region's highly variable wind energy generation throughout the day.

…

But the research team determined the two sites are suitable for two very different kinds of compressed air energy storage facilities. The Columbia Hills Site could access a nearby natural gas pipeline, making it a good fit for a conventional compressed air energy facility. Such a conventional facility would burn a small amount of natural gas to heat compressed air that's released from underground storage. The heated air would then generate more than twice the power than a typical natural gas power plant.

The Yakima Minerals Site, however, doesn't have easy access to natural gas. So the research team devised a different kind of compressed air energy storage facility: one that uses geothermal energy. This hybrid facility would extract geothermal heat from deep underground to power a chiller that would cool the facility's air compressors, making them more efficient. Geothermal energy would also re-heat the air as it returns to the surface.

…[/font][/font]

[Gregorian]

1. There are so many things about this that are bad.

It is not the way forward. It may have some niche, but I seriously doubt it.

To get an adiabatic storage, it needs insulation. I don't see how they could avoid thermal losses in doing this storage.
Friction losses.
Other potential losses.

It seems that we have battery storage that easily rivals this scheme. But I don't know. I'm just blabbing.

[OKIsItJustMe]

3. Naturally there are losses… the question is whether they are acceptable or not

However:

http://www.pnnl.gov/news/release.aspx?id=985

…

The world's two existing compressed air energy storage plants — one in Alabama, the other in Germany — use man-made salt caverns to store excess electricity. The PNNL-BPA study examined a different approach: using natural, porous rock reservoirs that are deep underground to store renewable energy.

…

http://www.powersouth.com/mcintosh_power_plant/compressed_air_energy

[font face=Serif][font size=5]CAES[/font]

[font size=4] Located in McIntosh, Ala., the 110-megawatt Compressed Air Energy Storage (CAES) facility is PowerSouth’s most unique generating source.[/font]

[font size=3]The PowerSouth CAES unit was declared commercial in 1991. It is the only one of its kind in the U.S. and one of only two in the world. The other CAES unit is located in Huntorf, Germany.

The unit captures off-peak energy at night, when utility system demand and costs are lowest. Compressors force air into an underground storage reservoir at high pressure. PowerSouth uses the stored energy during intermediate and peak energy demand periods to generate electricity.

At full capacity, the CAES facility produces enough electricity to power approximately 110,000 homes.

The CAES plant burns roughly one-third of the natural gas per kilowatt hour of output compared to a conventional combustion turbine, thus producing only about one-third the pollutants.[/font][/font]

(Video available at the site.)

[Gregorian]

5. It's like hydro but with huge thermal losses. It might be good for special situations.

Compressors. High pressure. Bad stuff.

But then again, if the construction costs are really low compared to maybe even generators and batteries, then it would work. Also, I see from their website that they can provide full power within 14 minutes of startup. It would be great for some situations. There are only two of these in the world. You can take a guess why there aren't many more.

[OKIsItJustMe]

6. CAES figured prominently in Scientific American’s “Solar Grand Plan” in 2008

http://www.scientificamerican.com/article.cfm?id=a-solar-grand-plan

[Gregorian]

8. No prob if it's solar. That's a whole different ballgame. I assumed worst case- fossil.

If it's renewable, everything works. Losses are no longer killing the planet.

What a life we've lived. What a nightmare. But it was interesting. I should explain, I was raised to be aware of where our energy comes from by the time I was about 6. I don't think many people ever really know. I've always said that if people live in a modern society, they should be required to know how it works. It has been a source of rage for me to witness the stupidity of Americans just frittering away our environment. Hell, I have a friend who is an environmental engiineer, and just last weekend he was saying I should do a bike race that would require me to drive 200 miles! Are people really that unaware of what 400 ppm means?

So I'm sorry I just denied the value of the air battery system. As long as we're still burning campfires to convert energy, I have to be suspicious.

[OKIsItJustMe]

12. I was taught that everything was solar energy (at one time)

i.e. fossil fuels are simply stored solar energy

CAES is a less-than-ideal way to address the variability of some renewable energy sources (e.g. wind & solar.)

[BlueStreak]

2. Hmmmm ...

I doubt that there is any geology where you can just pump air into the ground and not have it leak through fractures (or create new fractures, as if we need any more earthquakes). As far as containers to store energy through compression, that might have a chance. I believe there was a French car that we being prototyped to run only on compressed air. They were hoping to get 200 miles in a minicar at city speeds. But it isn't clear that would be any better than battery power.

This video is almost laughable when it talks about perpetual motion. Your average 5th-grader should see the huge flaws in that reasoning without working up a sweat. That video was 5 years ago, and as far as I know, the vehicle never happened. If you could really pump it up for 3 minutes and then drive for 200 miles, this would be a huge deal, regardless of the cost of pumping it up.

And for storage at the power grid scale of things, there are reservoirs where water is pumped uphill already for storage. There are several big experiments with flywheels, and there is also a lot of interest in "flow batteries" which can scale up far more than the more common lithium-ion batteries. But if compressed air can work better than those alternatives, then great.

[kristopher]

10. Your assessment of the availability of suitable locations isn't accurate

Salt domes, aquifers and hard rock mines are all good potential sites for hosting CAES. There are a LOT of them. The chart below shows why CAES is in the running...

[BlueStreak]

11. And can they hold 100 PSI of pressure, for example?

That was the proposition, as I understand it, that we could pump air into the ground to store excess energy as PRESSURIZED AIR.

I don't believe any of these natural formations could hold much pressure without leaking a lot.

Your chart doesn't prove anything. I believe it is referring to MANUFACTURED VESSELS to hold compressed air, which might have some potential. But I can't see manufacturing a vessel the size of Lake Meade.

And the chart completely misrepresents the state of the art in flywheel storage.

[kristopher]

13. Well, if you don't believe it then all those academics and researchers must be wrong.

And you "believe" the chart is referring to MANUFACTURED VESSELS even though you haven't got a shred of evidence to support your belief.

Perhaps you should read a few studies and stop making such a fool of yourself.

[BlueStreak]

14. We'll see how this works out.

Academics with fundamentally flawed ideas, trying to attract some research money, are a dime a dozen. That's how most universities operate these days. And yes, I do know better than most of them because I don't have a vested interest.

Once in awhile one of these ideas actually works out, and I will certainly keep an open mind for that rare possibility.

[OKIsItJustMe]

15. And by “working out” you mean…

After all, there is a US facility which has been in commercial operation for 2 decades now. I think at this point, the concept is pretty well proven.

[BlueStreak]

17. That's interesting. Do you care to explain why

a) there are so few of these if it is all working out so well; and

b) there continues to be so much research in other technologies (such as flow batteries) if this is such a well-proven concept?

What they never want to talk about is the efficiency. It seems to be decent -- maybe 40% or a little better -- if you are talking about a 24-hour cycle. It isn't clear to me that any of these operations sees this as a technology that is suitable for working well beyond the 24-hour cycle. You know, not every day has exactly the same AC demand on the grid. And not every night has the same amount of wind available for generation. Clearly pumped water provides storage that has minimal degradation over weeks or even months. And flow batteries potentially could scale to provide something similar.

Again, I am not against the concept, but an not convinced it is "all that". I make my living investing and see all sorts of hype in the news as schools pitch ideas for research bucks and entrepreneurs try to get seed money from the equity markets. So I hope you will understand why I am skeptical of all this current hype surrounding compressed air. The fact that it has been around so long and never really established much of a foothold is a pretty good reason to be skeptical, I think.

[OKIsItJustMe]

18. By all means! Be skeptical!

Remind me… how long has solar power been around?

OK, I’ll make it easier. How long have photovoltaic panels been around?

[BlueStreak]

19. There are more than two photovotaic installations in operation in the world

That's it for compressed air. Just two: the one you cited and one in Germany, and another in Ohio that had to be abandoned. At least that is what this recent article reports:

http://www.zephyrenv.com/currents_archive/2Q13_currents.pdf

If it is a commercially viable solution, it will succeed. If not, then we'll continue to see the occasional demonstration project. So we really have no choice but to wait and see, unless you would like to put some money into it. Personally I am not taking any positions in these high-hype energy projects -- I actually bailed out of my last hype-driven position just this afternoon. That was a company that has been mostly a vaporware maker of CNG engines. They were exceptionally good at raising money, and eventually got themselves to the point that even if they ever were to make a profit (which I believe is unlikely), they have issued so many shares there will never be enough per-share profit to justify even 1/10th the current trading price.

But plenty of people are still buying that stock. Fortunately not everybody thinks the same way I do or else I would have taken a real haircut on that one. The founder of that company has done well for himself. PT Barnum would be proud of him.

[kristopher]

20. "The fact that it has been around so long and never really established ..."

There's no mystery, we don't need storage when we have a centralized system like we do now. When you don't need the product, then it doesn't make money. When it doesn't make money, no one builds them.

That doesn't mean it isn't valuable in a different system - like renewables. And it also doesn't mean the technology will not work as designed.

I'd suggest you refrain from investing in any of these techs (or advising others) until you actually understand how all the pieces fit together. For example, if you think 60-80% efficiency is the same as 40% you are going to lose your shirt.

[BlueStreak]

21. Thanks for your financial advice

If I wanted to be a dick, I'd put your little cartoon right back at you.

And just for the record, the 60% efficiency numbers I have seen have all been associated with theoretical projects. Of course they would have to be because there are only 2 plants actually operating, if I understand the facts correctly.

I do take your point about the economic incentive not being as strong before the era of wind and solar power, and that might make a change in the economic argument at some point if we reach 30-50% wind/solar generation.

But an equally robust economic argument is that globally interconnected power grids might have a much higher ROI. After all, when the US is at peak consumption, Australia is at their lowest consumption. It all comes down to efficiency in both cases.

[kristopher]

22. "f I understand the facts correctly"

From what you've shown here you haven't got a fricking clue about any of this technology.

That isn't a sin or a crime, but pretending to knowledge that you obviously lack puts you squarely in the category you just labeled me with.

Like I said, it isn't a sin or a crime to lack knowledge. But a little humility goes a long way when you are in the realm of those who have worked long and hard to acquire that knowledge and understanding.

[BlueStreak]

24. I am in the presence of greatness. Sorry that it wasn't as obvious to me as it should have been.

[kristopher]

25. You're the one out of line.

Review the thread.

[kristopher]

16. You don't know what you're talking about.

And you don't have the integrity to admit it.

They have all the data on their side and you have...

Bupkis (in all its original glory).

[silverweb]

4. Worth trying.

[font color="navy" face="Verdana"]If it turns out to be not practical for any reason, then move on to the next hopeful idea.

At this point, whatever gets us closer to clean, renewable, safe energy is worth trying. There's no single fix, and it will take a mixture of methods and innovations to get us where we need to go.

[wtmusic]

7. Theoretical this, theoretical that...

the best utility-scale compressed air storage facility returns 27% of the energy you put into it.

"The McIntosh, Alabama CAES plant requires 2.5 MJ of electricity and 1.2 MJ lower heating value (LHV) of gas for each megajoule of energy output, corresponding to an energy recovery efficiency of about 27%."

http://en.wikipedia.org/wiki/Compressed_air_storage

A waste of money and time.

[kristopher]

9. Poor little nuclear loving wtmusic...

You would rather live in an alternate reality than admit that all the pieces are in place for a carbon free/nuclear free world, wouldn't you?

2.4.3.2. Round Trip Efficiency
A CAES unit powered by wind energy will be compared to other electrical storage options that might be considered for wind back up such as electrochemical or pumped hydroelectric storage. Such alternative storage systems are typically characterized by a roundtrip electrical storage efficiency ?RT defined as
?RT = (electricity output)/(electricity input).

To facilitate comparisons of CAES to other electrical storage devices, a round trip efficiency can be introduced that employs an “effective” electricity input ? EM + ?NG*EF. The second term is the amount of electricity that could be have been made from the natural gas input EF, had that fuel been used to make electricity in a stand-alone power plant at efficiency ?NG instead of to fire a CAES unit. ...

For typical natural gas power systems, (heat rates in the range 6700-9400 kJ/kWh) CAES roundtrip efficiencies are in the range of 77-89% assuming a 1.5 ratio of output to input electricity and a heat rate of 4220 kJ LHV per kWh. An exergy analysis of conventional CAES systems indicates that 47.6% of the fuel energy input is converted into electrical work [71]. For this measure of the thermal efficiency, the roundtrip efficiency is 81.7%.

An alternative formulation ?RT,2 of an electrical roundtrip storage efficiency introduces an output correction term EF*?NG. Instead of expressing the fuel input as an effective electrical input, the electrical output is adjusted by subtracting the assumed contribution to the output attributable to the fuel. Correspondingly the output attributable to the electrical input is ET - EF*?NG [72].
Using the same assumptions as for ?RT,1 with the Zaugg efficiency for fuel conversion, ?NG = 47.6%, the round trip efficiency is 66%.

Thus, depending on the index chosen for its measure, the roundtrip efficiency for CAES is typically in the range 66-82%. This is in the same range as the roundtrip efficiencies cited for other bulk energy storage technologies such as pumped hydroelectric storage (74%) and Vanadium flow batteries (75%)

Compressed Air Energy Storage, Succar and Williams April 2008
http://www.princeton.edu/pei/energy/publications/texts/SuccarWilliams_PEI_CAES_2008April8.pdf

[NNadir]

23. Denholm was writing "studies" about this years ago. Lovins was handing out this bull in the 1970's

Denholm's paper - one of my favorites because it admits that the cost of this expensive garbage approach will rely. as all wind schemes do, on natural gas and will thus have a carbon impact 5 times greater than cleaner and more sustainable nuclear - is found here:

Environ. Sci. Technol., 2005, 39 (6), pp 1903–1911

http://pubs.acs.org/doi/pdf/10.1021/es049946p

What happened along these lines in the last 8 years?

A little over eight years ago, when this paper, one of thousands upon thousands of "renewables will save us" "studies" was published, the concentration of the dangerous fossil fuel waste carbon dioxide in the atmosphere was 378.47 ppm. It's 400 ppm today.

Zero huge "compressed air" facilities have been built on this planet since this Denholm study was published. It was wishful thinking then, and it's wishful thinking now, except now the emergency has accelerated beyond all reason, as 2012 was the second worst year ever observed for dangerous fossil fuel waste accumulations, and 2013 is well on track to be the worst.

All of these "miracle" "could" statements in the world have not prevented climate change, nor will they. All they will do is encourage more people to burn oil, coal and gas in order to tell us how great "renewable energy" is, even though it has a 50 year history of not doing shit.

Have a nice evening.

[kristopher]

26. Poor Nnads...

Still have your panties in a wad because no sane person wants nuclear, eh? I hate to break it to you but you aren't going to get a nuclear based system to work without either 1) inefficiencies on a scale we've never before encountered in the electric sector (building nukes for peaking plants), or 2) substantial storage or 3) peaking plants that have the same characteristics that a renewable grid could use.

Of course, with a renewable grid, you'd actually need less storage than you would with a nuclear based grid.

BTW, the same process works not only with natural gas but also with biofuels for Zero Carbon.

Poor Nnads.

[NNadir]

27. What a surprise...

...

You know, whenever I see this kind of rote recitation the same bull that went on for 50 years, leading all humanity into the abyss, I'm inclined to wonder what the person doing the recitation is smoking.

Then I think to myself, you know, whatever it is, it must be very dangerous - maybe not as dangerous as the mercury laced coal waste these people like to spread around via denial - and certainly very, very, very, very, very, very, very, very bad for brain cells.

At this point, at 400 ppm, with the rate of decline of the planetary atmosphere reaching unprecedented levels, especially after the uneducated anti-nukes got so much mileage out of claiming that everyone in Japan, China, Indonesia, Western Peru, California, died from Fukushima, it's a moot point, since there is nothing that can be done.

I certainly doubt that there will be history, since fear and ignorance may have foreclosed a future in which history can be contemplated, but if there is one, history will judge the stupid, the paranoid, and the ignorant for the role they played.

As a correspondent wrote on another website before I gave up and let the likes of the mindless anti-nukes bring on what they deserve - even if they dragged all of humanity, and all species with them:

The shit for brains community has won the day.

Congratulations.

You must be very, very, very, veryl, very, very, very, very proud.

[kristopher]

28. The larger problem has been dipshits pretending that a few nuclear plants will do anything...

...other than more firmly entrench the economics of fossil fuels.

If you want to blame someone for the situation we are in, look in the mirror.