Saving wind power for later (compressed air storage)

CNet News ^ | 3/27/2007 | Martin LaMonica

[Uncledave]

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.

The 'Saudi Arabia of wind' Compressed-air energy storage is promising, but Magee said General Compression itself faces a number of challenges.

The company has a substantial engineering task ahead of it, and it has to prove that the resulting equipment will be financially interesting to wind farm investors, he said.

Also, finding appropriate sites for General Compression's turbines would be even more complex than typical wind farms because some sort of geological formation, such as depleted gas fields or mines, would be required for storage in many cases.

Executives at General Compression, however, see a number of applications where on-site storage makes sense.

Its planned customers are utilities or energy-intensive industries, such as aluminum or fertilizer makers. The compressed air also can be used for carbon dioxide sequestration or to make hydrocarbon fuels like methane or methanol, Marcus said. U.S. government agencies have expressed interest in wind-powered military bases that would not be dependent on the electric grid.

In the case where there isn't a geologic formation available, underground pipelines--now used for natural gas--could store between 6 and 12 hours of a wind farm's power generation.

Marcus and his brother David, who is company CEO, have been working in the wind industry for about four five years. In trips to the Dakotas, Marcus said he feels he's standing in the "Saudi Arabia of wind power," although no one has yet to put a drill in the ground.

He predicts that if deployed widely, wind could make up over half of the U.S. power generation--a far cry from today. The total amount of power generated by wind turbines is growing rapidly worldwide, but it represents a tiny fraction of total electricity generation in the U.S., according to the Department of Energy.

"You're never going to change the fact that wind is intermittent, but there's so much energy there to be grabbed," Marcus said. "The equipment doesn't need to get better. The price for the energy needs to change."

[Uncledave]

This diagram illustrates how the Iowa Stored Energy Park plans to use compressed air to store power generated by wind turbines. Electricity from the wind turbines will power motors that compress air to many times atmospheric pressure. The air is injected under ground into an aquifer, a dome-shaped structure made of porous sandstone. When demand--and price--for electricity is highest during the middle of the day, the compressed air is released and used to power a generator, and electricity is sold to the grid.

General Compression, a start-up that recently gained seed funding, intends to use compressed-air energy storage but is taking a somewhat different approach. It intends to integrate the compressor directly onto a wind turbine. Storage can be in geologic formations like aquifers, or pipelines.

Credit: Iowa Stored Energy Park

[Uncledave]

Renewable Energy Ping

Please Freep Mail me if you'd like on/off

[pnh102]

This is excellent news. I hope we make further progress in being able to harvest this power.

[edpc]

This idea blows.

[camle]

uh... using a wind turbine to generate wind?

sounds an awful lot like a perpetual motion machine to me. Kinda like getting more energy than you use to generate it?

[DungeonMaster]

There are never enough numbers for me on this topic. How many mwhr can be stored for how long and how much is the additional equipment and what does that make the cost of the electricity?

[DB]

You would think there would be a lot of losses in all the steps the energy goes through...

For example when you compress air the air gets hot. When that heat dissipates it is all lost energy.

[P-40]

they can now make wind-generated power available when the demand--and price--is highest

Not to mention that they can also promise to deliver and deliver in a consistent fashion to the grid they are selling to.

[BuffaloJack]

Exactly.
Stupidest Liberal Ideas of the Decade.

[DB]

Compressing air has to have large losses.

[JB in Whitefish]

"Saving wind power for later (compressed air storage)"


I believe the Mexicans thought of this YEARS ago....

[camle]

the words "crack" and "pot" come to mind.

[Tarpon]

Couldn't they just use Mrs Bill Clinton?

I have heard of a new fangled device, it's called a battery. I wonder if it would be useful in this application?

[DungeonMaster]

Compressing air has to have large losses.

Yes, that's another concern. Meanwhile windpower only amounts to about 0.8 percent of all the power on the grid. We don't need to store it, just use it.

[The_Reader_David]

Interesting idea. I wonder how the cost and efficiency of energy storage/recovery as compressed air compares with other possible schemes?

e.g batteries--I'm fairly sure compressed air and an air-driven turbine beat event best batteries on both counts. But also composite material flywheels with a reversible generator/motor at the center and very low friction bearing (or better still floating magnetically over a superconduct in an evacuated chamber--no friction!) , on this one I guess, the flywheel scheme wins on efficiency, but not cost.

[edpc]

It may or may not work, but I meant it in the literal sense.

[The_Reader_David]

Um, no. I remember the ideal gas law, but your analysis would imply that the cans of compressed air used to clean electronic equipment have no stored energy. Obviously that's wrong, because when you push the button on the aerosol can, the energy stored as pressure becomes kinetic energy which blows the dust off your keyboard. The scheme uses that same kinetic energy from pressure on a massive scale to drive a turbine.

[KarlInOhio]

How long before Al Gore "finds" that taking energy from the wind promotes global warming.

"When your baby Earth has a fever, you don't slow down nature's fan."

[vietvet67]

Likes this system better. www.vrbpower.com And yes, I own shares.. :-)

[Red Badger]

Massaschusetts?..........Lots of hot air there.........Kennedy, Kerry, Frank, etc........