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Published on August 31st, 2009 | by Susan Kraemer

43

For Base-Load Wind Cheaper than Fossil Fuels: CAES

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August 31st, 2009 by
 
As PG&E ramps up renewable power in response to the California RPS requirement that it get 33% of its electricity from renewables by 2020; it has been exploring ways to add that much renewable power to the grid while smoothing out the ups and downs of wind energy, which often peaks at night.

The utility needs a way to turn sometimes-too-much wind into anytime-always-there electricity.

The solution? Simple tech. Underground compressed air.

With compressed air energy storage; air is compressed and then pumped in natural underground reservoirs. The air is released later and converted into electricity. With enough storage, even fickle wind could actually supply base-load power.

So PG&E has applied for DOE smart grid stimulus funding under The Recovery Act; to build a compressed air energy storage project with output capacity of 300 megawatts. They are applying for $25 million.

By comparison, building a plant to burn fossil fuels would cost around $850 million for the same 300 megawatts of fossil energy.

PG&E estimates their $350 million project will take five years to design, permit and build. Wind turbines would compress the air during off-peak times and then draw from the reservoir during peak times. Shifting the energy from off-peak to peak times, such as the middle of the day, makes it more valuable as utilities pay far more for peak energy.

If granted, the utility would use the smart-grid stimulus funds available in The Recovery Act in order to build enough storage to hold and release as much electricity as a medium sized base-load power plant for about 10 hours each time.

PG&E would pump compressed air into an underground reservoir, using mostly wind energy to power the generators, and some natural gas – about a third as much as a gas-fired plant of that capacity.

Another proposal for reheating the air withdrawn from storage, is to use biomass-derived fuels produced locally from energy crops in remote, wind-rich areas.

Compressed air energy storage or CAES has orders of magnitude more capacity than typical utility batteries and appears to be the most cost-effective form of energy storage according to technical experts at the Electric Power Research Institute and a massive study of CAES at Princeton University which concluded:

“CAES appears to have many of the characteristics necessary to transform wind into a mainstay of global electricity generation. The storage of energy through air compression may enable wind to meet a large fraction of the world’s electricity needs competitively in a carbon constrained world.”

The concept has been proven. The Alabama Electric Cooperative in Alabama now has 20 years of experience with a 100 megawatt CAES system. A major new project is being backed by the DOE in Iowa, which gets 15% of its electricity from wind.

So just through time-shifting energy delivery; storage can make it possible for wind to essentially supply base-load power for far less money than building more fossil fueled power stations.  What this amounts to is adding 300 megawatts of new power to the grid.

Hmm… $25 million for 300 megawatts of carbon-free future-friendly time-shifted wind power or $850 million for 300 dirty megawatts of a dwindling resource?

I’m betting that that very smart Steven Chu of the DOE is going to grant this $25 million to PG&E…

Via GreenTech and PG&E

Image from PG&E and Flikr user The Eleven

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About the Author

writes at CleanTechnica, CSP-Today, PV-Insider , SmartGridUpdate, and GreenProphet. She has also been published at Ecoseed, NRDC OnEarth, MatterNetwork, Celsius, EnergyNow, and Scientific American. As a former serial entrepreneur in product design, Susan brings an innovator's perspective on inventing a carbon-constrained civilization: If necessity is the mother of invention, solving climate change is the mother of all necessities! As a lover of history and sci-fi, she enjoys chronicling the strange future we are creating in these interesting times.    Follow Susan on Twitter @dotcommodity.



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  • Uncle B

    Battery cars, now seemingly an inevitable part of a monumental paradigm shift from the “American Dream” as defined in the 1990′s, and being sold as we speak, in America, can ballast Wind and Solar vagrities too, but the question is: Enough? T Boone Pickens suggested compressed natural gas cars, and a Wind Turbine Corridor, both Avon guard, and viable ideas. Can our lifestyles be shifted by modern Science and the insulation technologies of say NASA? Saving energy is just as productive as producing it in a world of shortages, and the proposal is, we can live very comfortably and in sustainable fashion, outside the insane caterwallings of the advertising propagandists, by applying good common sense, and sound technologies to survival situations – No more SUV’s, lesson learned, No more McMansions, churned commissions and rapid foreclosures, lesson learned, No more extravagant “Fast Food” diets, with ill health, fat asses, and bad hearts to follow, Lesson learned! So, now what? How about massive Solar power development coupled with “Manhattan Project” scaled Wind development, to supplant nuclear power, a lesson we cannot afford to learn, with its disastrous waste products! How about mandating the processing of all bio-gasables to fuel and top-soil builders, for our depleted farmlands? How about Wind and Solar powered electric bullet trains, inter-city and computer controlled, for efficiency? How about extensive research on Wind Turbine desi9gns? How about geo thermal exploitation? America at a cross-roads, dollar falling, jobs escaping to Asia, and poverty encroaching on the fringes of and unsustainable current life-style, outdated by modern technologies, and held back by patent laws, civil codes, and corporate ROI fanaticism, insistent on the maintenance of an impossible “Status Quo” as oil gains and the dollar falls on world markets, faces paradigm shifts unprecedented for mankind! And the answer: is Blowin’ in the Wind!

  • Uncle B

    Battery cars, now seemingly an inevitable part of a monumental paradigm shift from the “American Dream” as defined in the 1990′s, and being sold as we speak, in America, can ballast Wind and Solar vagrities too, but the question is: Enough? T Boone Pickens suggested compressed natural gas cars, and a Wind Turbine Corridor, both Avon guard, and viable ideas. Can our lifestyles be shifted by modern Science and the insulation technologies of say NASA? Saving energy is just as productive as producing it in a world of shortages, and the proposal is, we can live very comfortably and in sustainable fashion, outside the insane caterwallings of the advertising propagandists, by applying good common sense, and sound technologies to survival situations – No more SUV’s, lesson learned, No more McMansions, churned commissions and rapid foreclosures, lesson learned, No more extravagant “Fast Food” diets, with ill health, fat asses, and bad hearts to follow, Lesson learned! So, now what? How about massive Solar power development coupled with “Manhattan Project” scaled Wind development, to supplant nuclear power, a lesson we cannot afford to learn, with its disastrous waste products! How about mandating the processing of all bio-gasables to fuel and top-soil builders, for our depleted farmlands? How about Wind and Solar powered electric bullet trains, inter-city and computer controlled, for efficiency? How about extensive research on Wind Turbine desi9gns? How about geo thermal exploitation? America at a cross-roads, dollar falling, jobs escaping to Asia, and poverty encroaching on the fringes of and unsustainable current life-style, outdated by modern technologies, and held back by patent laws, civil codes, and corporate ROI fanaticism, insistent on the maintenance of an impossible “Status Quo” as oil gains and the dollar falls on world markets, faces paradigm shifts unprecedented for mankind! And the answer: is Blowin’ in the Wind!

  • Reese Palley

    Does anyone have any information concerning the potential of stored compressed air to pick up pollutants such as CO2 or arsenic etc from the walls of the underground storage sites?

    Please respond by email to:

    reesepalley@aol.com

  • Reese Palley

    Does anyone have any information concerning the potential of stored compressed air to pick up pollutants such as CO2 or arsenic etc from the walls of the underground storage sites?

    Please respond by email to:

    reesepalley@aol.com

  • http://www.visionofearth.org Kyle Laskowski

    It seems unfair to compare the cost of the storage system with an output of 300MW to the cost of a fossil plant, as the storage can only keep up this output level for an amount of time not mentioned in the article, based on the maximum amount of stored energy the system is capable of. A fossil plant can keep generating 300MW while fuel is provided, this system will stop after the stored energy is gone, possibly minutes.

    And also, from what I’ve read CAES does require natural gas to release the energy, and a variable amount of the energy used to compress the air is lost depending on the speed it is stored and the laws of thermodynamics (the heat produced by compressing a gas will dissipate with time into the surrounding rock and not be recoverable to do useful work).

  • http://www.visionofearth.org Kyle Laskowski

    It seems unfair to compare the cost of the storage system with an output of 300MW to the cost of a fossil plant, as the storage can only keep up this output level for an amount of time not mentioned in the article, based on the maximum amount of stored energy the system is capable of. A fossil plant can keep generating 300MW while fuel is provided, this system will stop after the stored energy is gone, possibly minutes.

    And also, from what I’ve read CAES does require natural gas to release the energy, and a variable amount of the energy used to compress the air is lost depending on the speed it is stored and the laws of thermodynamics (the heat produced by compressing a gas will dissipate with time into the surrounding rock and not be recoverable to do useful work).

  • Cyril R.

    You cannot build 300 MWe CAES for 25 million US dollars. That is just the grant, not the total project cost.

    CAES is not very efficient which is a big problem. Use lots of natural gas.

    The way forward is to separately store the heat generated during compression and use that to replace natural gas in heating during expansion. This is called AACAES. Such a system must be efficient and cheap, this appears possible but more money for developing full scale systems would not be a luxury.

  • Cyril R.

    You cannot build 300 MWe CAES for 25 million US dollars. That is just the grant, not the total project cost.

    CAES is not very efficient which is a big problem. Use lots of natural gas.

    The way forward is to separately store the heat generated during compression and use that to replace natural gas in heating during expansion. This is called AACAES. Such a system must be efficient and cheap, this appears possible but more money for developing full scale systems would not be a luxury.

  • russ

    A NG fired combined cycle plant should no way cost more than 0.5 million USD per mW – reasonably current numbers are even in the .25 million USD per mW range.

  • russ

    A NG fired combined cycle plant should no way cost more than 0.5 million USD per mW – reasonably current numbers are even in the .25 million USD per mW range.

  • Susan Kraemer

    Solar Brook – recommend reading Samir’s study itself – looks like 80%

    http://www.princeton.edu/~cmi/research/Capture/Papers/SuccarWilliams_PEI_CAES_2008April8.pdf

  • Susan Kraemer

    Solar Brook – recommend reading Samir’s study itself – looks like 80%

    http://www.princeton.edu/~cmi/research/Capture/Papers/SuccarWilliams_PEI_CAES_2008April8.pdf

  • http://www.SolarElectricityHandbook.com Solar Book

    This is exciting technology. The only problem is that compressing air requires a lot of energy to start with. Would you really get much more than 25%-30% efficiency with this model?

  • http://www.SolarElectricityHandbook.com Solar Book

    This is exciting technology. The only problem is that compressing air requires a lot of energy to start with. Would you really get much more than 25%-30% efficiency with this model?

  • http://switchboard.nrdc.org/blogs/ssuccar/ Samir Succar

    Conventional “diabatic” CAES does require a fuel input (this is typically natural gas, although it could also be distillate, biomass-derived syngas [1], or any number of other options.) It is possible to capture the heat from the compressed gas in thermal energy storage and use that instead of a fuel source to heat the expanded gas withdrawn from storage. This adds to the cost of an already very capital intensive system so it would typically take very high fuel costs to make this an economic option. There’s a brief discussion of these “adiabatic” CAES systems toward the end of the report.

    Cheers,

    Samir

    [1] P. Denholm, “Improving the technical, environmental and social performance of wind energy systems using biomass-based energy storage,” Renewable Energy, vol. 31, pp. 1355-70, 2006.

  • http://switchboard.nrdc.org/blogs/ssuccar/ Samir Succar

    Conventional “diabatic” CAES does require a fuel input (this is typically natural gas, although it could also be distillate, biomass-derived syngas [1], or any number of other options.) It is possible to capture the heat from the compressed gas in thermal energy storage and use that instead of a fuel source to heat the expanded gas withdrawn from storage. This adds to the cost of an already very capital intensive system so it would typically take very high fuel costs to make this an economic option. There’s a brief discussion of these “adiabatic” CAES systems toward the end of the report.

    Cheers,

    Samir

    [1] P. Denholm, “Improving the technical, environmental and social performance of wind energy systems using biomass-based energy storage,” Renewable Energy, vol. 31, pp. 1355-70, 2006.

  • Susan Kraemer

    What sandra said

  • Susan Kraemer

    What sandra said

  • Susan Kraemer

    You’re welcome, Samir, one thing I am unclear about from the rather generic announcement from PG&E:

    Does CAES require the use of some natural gas to run the generator? Can this all be done using wind power electricity? Your long pdf raised the question but didn’t clarify it for me.

  • Susan Kraemer

    You’re welcome, Samir, one thing I am unclear about from the rather generic announcement from PG&E:

    Does CAES require the use of some natural gas to run the generator? Can this all be done using wind power electricity? Your long pdf raised the question but didn’t clarify it for me.

  • http://www.Utility-Savings.com Charles R. Toca

    Sandra, a couple of thoughts on your story.

    First, the $25 million requested is only for “initial analysis and design”. The anticipated cost for the project will be $368 million. And that’s before we see the cost over runs, delays and unexpected problems a huge project like this will invariably incur.

    Also, you make an interesting comparison by writing, “By comparison, building a plant to burn fossil fuels would cost around $850 million for the same 300 megawatts of fossil energy.” Since the compressed air is provided by wind energy, you should also factor in the cost of the wind farm.

    Regarding your question to Samir, yes, the end result of the project is to burn natural gas more efficiently in natural gas generators – making wind energy “dirty”.

    We’ve been discussing this a bit at my blog – for more information go to: http://energy-storage.blogspot.com/2009/08/pg-compressed-air-project-quick.html

  • http://www.Utility-Savings.com Charles R. Toca

    Sandra, a couple of thoughts on your story.

    First, the $25 million requested is only for “initial analysis and design”. The anticipated cost for the project will be $368 million. And that’s before we see the cost over runs, delays and unexpected problems a huge project like this will invariably incur.

    Also, you make an interesting comparison by writing, “By comparison, building a plant to burn fossil fuels would cost around $850 million for the same 300 megawatts of fossil energy.” Since the compressed air is provided by wind energy, you should also factor in the cost of the wind farm.

    Regarding your question to Samir, yes, the end result of the project is to burn natural gas more efficiently in natural gas generators – making wind energy “dirty”.

    We’ve been discussing this a bit at my blog – for more information go to: http://energy-storage.blogspot.com/2009/08/pg-compressed-air-project-quick.html

  • http://www.conseils-acheter-malin.fr/ sandra

    why not to invest massively in such cheap technologies

  • http://www.conseils-acheter-malin.fr/ sandra

    why not to invest massively in such cheap technologies

  • http://switchboard.nrdc.org/blogs/ssuccar/ Samir Succar

    Thanks for linking my “massive report”! More on my blog for those interested http://switchboard.nrdc.org/blogs/ssuccar/ -Samir

  • http://switchboard.nrdc.org/blogs/ssuccar/ Samir Succar

    Thanks for linking my “massive report”! More on my blog for those interested http://switchboard.nrdc.org/blogs/ssuccar/ -Samir

  • Martin

    One thing: Right now only diabatic CAES systems exist, AFAIK one in the US and one in Germany. In a diabatic system, the heat resulting from compressing air is lost and later replaced by burning natural gas. Neither as efficient as it could be nor renewable. Only an adiabatic CAES (i.e. one that stores the heat as well) can truly operate without fossil fuels.

    Lots of work to be done still.

  • Martin

    One thing: Right now only diabatic CAES systems exist, AFAIK one in the US and one in Germany. In a diabatic system, the heat resulting from compressing air is lost and later replaced by burning natural gas. Neither as efficient as it could be nor renewable. Only an adiabatic CAES (i.e. one that stores the heat as well) can truly operate without fossil fuels.

    Lots of work to be done still.

  • baselineshift

    $850 million is a generously low estimate – per that link = that coal plant has now gone over a $1 billion!

  • baselineshift

    $850 million is a generously low estimate – per that link = that coal plant has now gone over a $1 billion!

  • Tom Lakosh

    CAES can also improve the efficiency of gas turbines by reducing compressor loads. It’s a perfect match for thousands of declining gas fields where exhausted gas pockets can accommodate CAES and augment onsite peak power production. These fields are already drilled for air injection and often have onsite power turbines, just add compressors and wind power.

  • Tom Lakosh

    CAES can also improve the efficiency of gas turbines by reducing compressor loads. It’s a perfect match for thousands of declining gas fields where exhausted gas pockets can accommodate CAES and augment onsite peak power production. These fields are already drilled for air injection and often have onsite power turbines, just add compressors and wind power.

  • http://jean.posterous.com Jean

    According to the study from Princeton University, pg 11, the capital cost for a CAES is $580 per KW () or $174 Million. That’s a lot more (x7) than $25 Million.

  • http://jean.posterous.com Jean

    According to the study from Princeton University, pg 11, the capital cost for a CAES is $580 per KW () or $174 Million. That’s a lot more (x7) than $25 Million.

  • http://jean.posterous.com Jean

    I don’t understand why they need a grant if this is so cheap. What are they waiting for?

    I also question the cost of building a thermal power plant which is usually around $1 per watt or $300 Million for 300 Megawatts or about 1/3 the cost displayed in this article.

    I believe these companies plans are more about subsidies than renewable energy. First they want us to believe that renewable energy costs more so that they can request subsidies. Then they want us to believe that they can store energy for a lot cheaper than they made us believe in the fist place.

    Remember that energy storage is the most crucial and costly component of most renewable energy solutions and suddenly this cost would become marginal (3% the cost of a thermal power plant).

    There is a discrepancy here that needs to be explained.

  • http://jean.posterous.com Jean

    I don’t understand why they need a grant if this is so cheap. What are they waiting for?

    I also question the cost of building a thermal power plant which is usually around $1 per watt or $300 Million for 300 Megawatts or about 1/3 the cost displayed in this article.

    I believe these companies plans are more about subsidies than renewable energy. First they want us to believe that renewable energy costs more so that they can request subsidies. Then they want us to believe that they can store energy for a lot cheaper than they made us believe in the fist place.

    Remember that energy storage is the most crucial and costly component of most renewable energy solutions and suddenly this cost would become marginal (3% the cost of a thermal power plant).

    There is a discrepancy here that needs to be explained.

  • Ben

    Great article! Also there isn’t that much loss (around 15%) to compress the air then bring it back.

    One question, how many underground cavern sites are there around the USA? Do you have a map of these sites you can share?

  • Ben

    Great article! Also there isn’t that much loss (around 15%) to compress the air then bring it back.

    One question, how many underground cavern sites are there around the USA? Do you have a map of these sites you can share?

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