March 27, 2007 4:00 AM PDT

Saving wind power for later

A start-up says it's devised a system to produce electricity from wind turbines even when there is no wind, taking on the major challenge of storing wind-generated power.

General Compression, based in Attleboro, Mass., last week said it received a $5 million round of seed funding to commercialize a wind-power storage system that uses compressed air.

Wind turbines typically have an onboard power generator that sends electricity down the tower and onto the grid. General Compression plans to break with that basic design and place an air compressor in the nacelle, the housing on a turbine where the generator usually sits.

Its plan calls for sending highly compressed air down the tower and into underground storage, such as caves or depleted gas wells, or through pipelines. The pressurized air can be released when needed to power an electricity generator, even if wind is not spinning the turbine's blades.

General Compression is one of a wave of companies trying to meet a growing demand for clean sources of power. Like others, the company is trying to commercialize concepts that have been around for decades but not fully pursued because they were considered too expensive or technically difficult. Now, with higher prices of energy forecast, these ideas are being applied to the clean-energy market.

Company executives argue that a compressed-air energy storage system will allow wind farm operators to charge more for their product.

Rather than get paid for electricity only when the wind is blowing, they can now make wind-generated power available when the demand--and price--is highest, say company executives.

"The problem with wind is intermittency," said company president Michael Marcus. "It does not garner high prices from power purchasers because it is not schedulable...(but) you can get a higher price if it's available on demand."

For example, if the wind is blowing hardest at 11 at night, a wind farm operator could store the energy generated from the wind and release it at 10 o'clock the next morning when demand for power starts spiking up.

The compressor was designed by Mechanology, a compressor research and development firm which spun off General Compressor in 2005 and remains a shareholder.

The company now has a prototype device and plans to build a large-scale version of put it through testing later this year. The plan is to test the "compressor array" in a turbine in the field next year, Marcus said.

Iowa's stored-energy park
Although General Compression's design is a radical change from existing turbines, the compressed-air energy storage (CAES) idea has already been implemented.

There are two existing compressed-air storage facilities in operation, one in Germany and one in Alabama. But neither is fueled by wind turbines.

A more recent development is the Iowa Stored Energy Park, which recently chose a site for a CAES operation with wind power in mind.

Projected to cost $200 million and funded primarily by municipalities, the Iowa Stored Energy Park will store compressed air in an underground aquifer in central Iowa, said Kent Holst, the project's development director.

In large part, the gear required for the operation is already available because they intend to modify equipment used to store natural gas underground, he said. "The most difficult part was finding a usable geologic structure. Several are already being used for natural gas storage," Holst said.

Compressed-air energy storage

In the Iowa project, set to be online in 2011, the wind turbines will not be on site, but the motors to power the compressor are expected to be generated from wind electricity.

The economic reasoning behind the operation is to store wind power when the resource is available and sell it on the market at peak demand times, Holst said.

Wind power--an industry that is seeing a boom in turbine construction--already operates in a cost-effective manner even though utilities can't rely on wind turbines at all times, said Josh Magee, senior wind analyst at Emerging Energy Research.

But if utilities were able to count on wind power to boost the capacity they need to meet their highest demand, such as the middle of a hot summer day, it would make wind power far more attractive, he said.

"If you could figure out a way to do it cost effectively and show (utilities) you can be very profitable at it...then you would have the ability to rapidly scale wind power," he said. "If all of the sudden you had capacity, you can make a bigger dent in climate change, energy security and make a significant contribution to peak demand."

For years, government research efforts have explored the idea of "firming up" wind power--that is, make it available during peak times--by storing electricity in fuel cells or batteries, but there have been few significant attempts, Magee said.

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Great News!!!
If this can be done efficiently, then this is huge. This could make most people happy, except for the people that think that wind farms are a blight on the land.
Posted by suyts (824 comments )
Reply Link Flag
If Only Wind wasn't Green Stalinism
I couldn't have said it better myself:

To quote Orwell Today
<a class="jive-link-external" href="" target="_newWindow"></a>

"The German wind power industry has already received tax breaks worth an estimated 1.1 billion euros just to erect its turbines. On top of that, the "windustry" is guaranteed a price of 8.8 cents per kilowatt hour, compared with the average market price of 3.5 cents. Yet the German grid is now plagued by the unpredictability of wind power generation. In one region, the wind was strong enough to utilise more than half the available capacity on only 36 days of the year - less than one day in 10. Not only are all these costs now being passed on to ordinary Germans in the form of rising electricity and tax bills, but an even bigger price is also being paid by home owners next to wind farm sites, where property values have collapsed. The only beneficiaries have been the super-rich Germans who have invested in wind farms because of the huge tax breaks - not to mention the politicians in the industry's pocket."
Posted by zeeboid (92 comments )
Reply Link Flag
Isn't that what they said about the automobile?
The first cars were so inefficient that they couldn't carry as much
or go as fast as a horse drawn carriage! The first planes couldn't
go much faster than the cars of their day. The first computers
spent most of their time down because of burned fuses, and
even when functioning they had far less capability than most of
today's calculators.

Any new technology needs to be developed before it can be
profitable. Unfortunately, that means that government
intervention is often required, since for-profit businesses often
lack the vision to see beyond the next fiscal quarter.
Posted by Macsaresafer (802 comments )
Link Flag
Sounds just like nuclear
Huge government subsidies, expensive electricity. Of course nuclear produces power much more dependably, but then wind power does not create highly toxic waste dangerous for hundreds of thousands of years.
Posted by expatincebu (156 comments )
Link Flag
My wife and I have traveled on cruise ships in the Baltic and in the Mediterranean, and as US citizens we have driven all over California, Arizona, and New York. We have seem thousands of wind turbines. Based on our random observation we would estimate that only 20-30% of time did we see them running. Our country is also providing the money to build and buy the artifically high priced electricty produce. We don't count it as part of our power capacity.
As in your country only the wealth and connected can invest in the companies that build them because only the connected companies receive tax grants.
Our president is finally considering a green source of energy that is proven. It's called Nuclear Power. We have one about 35 miles from our home that has operated for about 30 years without ever having an accident and every fuel rod used to power it has never left the site.
Posted by blue1939 (1 comment )
Link Flag
Seems Lossy
Wonder why not just store the electricity in a battery bank, for release during peak useage times? Wish the author had researched/asked this question.

Seems like Mechanical / Mechanical / Mechanical / Electrical converstion would lose far more energy than Mechanical/Electrical with some loss for storage. Probably take less space, and use existing engineered solutions....

Just seems very lossy... not sure though.
Posted by ThatScienceGuy (132 comments )
Reply Link Flag
It is lossy, but that is OK
All power generation is lossy, and this may be even more so, but that is OK. Remember, the fuel (wind) is without cost, you pay only for the equipment. A loss means having to build more capacity, but that may be cost effective if the power can be effectively utilized to reduce load and sizing of traditional power plants.
Posted by amadensor (248 comments )
Link Flag
Batteries have been tried.
Batteries are expensive, and over time, they lose their ability to
hold a charge. Compressed air will remain compressed until it is

Batteries also take up more space. Since this system takes
advantage of caves, all of the energy is stored underground. No
building is needed to store hazardous batteries.Because there is
no hazardous waste, with only hoses, compressors, and
electrical generators to be replaced, compressed air has the
potential to be much cheaper to operate.
Posted by Macsaresafer (802 comments )
Link Flag
Storage medium more durable
Batteries are lossy too. I don't know how the losses compare, but
one thing seems different and that is that the air, which is the
storage medium, probably won't wear out like the batteries will.
The compressors will, and maybe the piping, what there is of it. So
would that cost more than replacing batteries periodically?
Anybody know?
Posted by billmosby (536 comments )
Link Flag
I agree, seems very lossy
I also seems like it would have limited energy storage ability. It would be nice to see what the energy storage capability would be in terms of MWh for an installation, and the cost/MWh would be. When it comes to large energy storage, nothing beats a large reservoir...
Posted by fcekuahd (244 comments )
Link Flag
Electrical storage is expensive
Yes, storing compressed gas can be less efficient but the cost for the storage capacity is low and there are no toxic chemicals.
Posted by Seaspray0 (9714 comments )
Link Flag
Needs lots of natural gas
The biggest problem of this technology, other than the high cost added on to the already high cost of wind turbines, is that the compressed air needs to be heated up when directed against the generator turbines and uses HALF as much natural gas as a regular gas power plant would use!!! This is not good, folks. Chuck crappy wind power an dstart getting serious with reliable green technologies like geothermal hot rock, geothermal heat pump (twice as effective as wind in higher latitudes), SeaDog 24/7 wave power systems, Enviiromission 24/7 solar towers, nuclear energy, which cots about one third of wind and is reliable. Wind sucks and even with this new "technology," still sucks. It's far and away the stupidest method of making electricity.
Posted by theBike45 (90 comments )
Reply Link Flag
If you're right, it cuts natural gas consumption by 50%!!!! How is
that not a good thing?
Posted by Macsaresafer (802 comments )
Link Flag
Reading Carefully Pays
If you'd read more carefully, the company states that heat is doubles output power in the expansion phase, not that it is required. This is because of thermodynamics: the whole system functions like a refrigerator, generating heat in the compressor and absorbing heat in the expander. Also, they point out that the heat can come from any heat source. Once possibility is to use the chilling as a product for commercial refrigeration, or even air conditioning. What has to change is the idea that a power plant's waste energy (chilling actually is a source of energy if you need chilling for something else) is somehow a problem. You could even *pair* a wind farm with a conventional power plant or industrial plant and do away with the cooling towers or hot water discharges the conventional plant needs. Sounds like what's "stupidest" is your analysis.
Posted by enovikoff (170 comments )
Link Flag
It probably out of price range of the average consumer. But still
Posted by paulsecic (298 comments )
Link Flag
wind power
Posted by STOREYFORPAWS2 (1 comment )
Reply Link Flag
Mature life?
55 years of mature life - how many imature years in between?

Just joking :)
Posted by shoffmueller (236 comments )
Link Flag
Why Store Wind Power....
With solar I understand that storing energy becomes an issue, because the sun only comes out during the day. Why then do we need to store wind energy, when the wind blows all day...

The only application I could think is individuals or houses off the grid, that wish to store electricity, but a system like that seems expensive.

It actually seems that this may be better for solar than wind... you use your wind power throughout the day that get's boosted from solar when needed via compressed air, instead of batteries...

I still think hydrogen storage/fuelcells will win out though...
Posted by SiXiam (69 comments )
Reply Link Flag
Because power isn't used at the same rates all the time.
Wind power isn't produced at the same rates all the time either.
That means that power from peak production times must be stored
for use at peak demand times.
Posted by Macsaresafer (802 comments )
Link Flag
Solar is actually more predicatble than wind
But right now Solar costs 20x the open market power price, while wind is at about 5x. Neither of these 'solutions' will work. We need a Carbon tax so that the real winners can float to the top (likely nuclear, carbon sequesterd coal, and efficiency). Wind and Solar are like spitting on a forest fire.
Posted by knobsturner (46 comments )
Link Flag
Better Storage System
Believe <a class="jive-link-external" href="" target="_newWindow"></a> has a system developed and ready for commercial use.
Posted by goldeagle2222 (1 comment )
Reply Link Flag
Wind still too expensive and disgusting
The ability of windmills to destroy the value of hiundreds of thousands of acres of perfectly good real estate, both for development or recreation,plus its exorbitant costs makes it a
really dumb choice to make electricity. Also it
should be noted that simply storing a day or two's worth of wind energy doesn't mean that a windfarm can qualfy as a guaranteed producer. The
wind often doesn't blow, or blow enough , for days or even weeks on end. Sorry folks. And that build cost of 15 to 30 times that of nuclear makes me wonder why anybody not mentally challenged would ever opt for wind. It's a totally insane choice, just on the basis of economics without refgard to the enormous tracts of land that are ruined for the next two decades
by the errection of these 200 ton monstrosities,
at $2.5 to $3.5 million apiece, that can't generate more than a paltry 500 kilowatts. $1 miillion worth of nuclear can pump out 1 megawatt, all year long, every hour for three times the lifespan of that windmill.
Posted by theBike45 (90 comments )
Reply Link Flag
sounds like you work for an oil company
If you haven't noticed real estate is crap now and there aren't exactly humongous populations in the whole of the dakotas. I rather have wind power over nuclear power because of the toxic waste which nuclear power creates over it's lifetime which take thousands of years to nuetralize. Someone has to deal with that at some point because right now we're so mentally challenged we haven't figured out a way to resolve that issue. Obviously wind power is not the only solution nor is the right solution for certain geographical areas and should be used in conjunction with other technologies. The same fields where these wind power generators are located could also be used for biodiesel production. This would also generate a bunch of jobs for people in the middle of nowhere... I think you're missing the bigger picture.
Posted by rnieves1977 (105 comments )
Link Flag
Perhaps some of your have been living in a cave somewhere. In Texas, which is the now the largest producer of wind power, wind is the cheapest form of power available. The sites in West Texas where the power is produced is generally farm or scrub lands. Numerous articles in the Dallas Morning News refer to the "problem" of wind power "driving down prices". Funny, I thought that was to whole idea behind constructing the farms in the first place. The cost of producing wind power in Texas has been estimated at .05 per kw. Retail electric prices in Dallas are .16 to .24 kw. I say build more wind farms.
Posted by royce49 (1 comment )
Reply Link Flag
Merritt Lp of Danbury Connecticut has developed a wind power storage process that does not use compressed air or batteries. It is in the patent process at the persent time and will be announced later this year.
Posted by MerrittLP (1 comment )
Reply Link Flag
I would like to learn more about your process and how it works. Thank You.
Posted by propsmith (1 comment )
Link Flag
Wave Water Pumps - WWP
Utilize the wave energy to pump a small quantity of water to a high head, which is collected in a piping network and fed to a hydro-turbo generator to generate electric power at competitive cost.
A set of pumps up to ten and a mile wide may be installed in line with the incoming wave to extract most of the wave energy.
Wave Air Pumps - WAP
Utilize the kinetic energy of the wave to compresses a small quantity of air to a high pressure, which is collected in a piping network and fed into the air inlet of a turbo generator.
Fuel is injected as needed to maintain turbo generator output irrespective of availability of waves.
Compressed air technology and fogging (adding water vapor to turbine air inlet) are known and proven technologies.
Compressed Air ma;y be taken from a Wind Turbine, Collected and fed to the air inlet of a turbo-generator
The system generates energy at normal fuel rate in the absence of waves, and at reduced fuel consumption inversely proportional to wave heights.
Dependability of producing energy irrespective of availability of wave energy is achieved by controlling injected fuel
Ideal for off-shore wind turbine farms, as it utilizes the off-shore wind turbine supporting structure as a Wave Air Pump at negligible cost.
The WAP is ideal for sea water aeration. The WAP may be used to inject compressed air into the sea to enhance the oxidation process of organic materials.
? Simple construction, low capital and maintenance costs, efficient energy extraction.
? Auto-adjust to varying wave heights and sea levels, and provide dependable power output.
? Resist storms, and are safe to navigation.
? Zero emissions;
? Do not disturb marine life or shoreline scenic view, and provide a Free Floating Break Water Structure.
Details at
Posted by shamil11 (3 comments )
Reply Link Flag
Can you tell me has there been any update on this start up project, we operate wind turbines and are looking in to how to store the energy for use at peak times


Posted by 090733 (1 comment )
Reply Link Flag
Regarding Geothermal heating and compressed-air energy storage: wouldn't it be like cooling a cake from the inside except when the cake is cooled; we eat, but when the earth is cooled; it crumbles and you die? Just a thought....someone help me understand plz.
Posted by nuknght (1 comment )
Reply Link Flag

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