Clean Power

Published on November 3rd, 2009 | by Susan Kraemer

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Ex-United Technologies Rocket Scientists To Build 150 MW Solar Heliostat in Sonoran Desert

November 3rd, 2009 by  



SolarReserve; a California start-up spin-out from United Technologies’ Rocketdyne has filed an application with the CPUC to build a 150-megawatt heliostat solar farm with seven hours of after-sunset energy stored in molten salt. These are the rocket scientists responsible for our solar-powered space exploration.

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Theirs would be the first heliostat type of solar array to produce grid power in California. Abengoa has several in Spain, and plans one in Arizona. United Technologies has licensed the original technology to the new company SolarReserve and its wholly owned subsidiary Rice Solar Energy, LLC, (RSE).

The start-up has years of solid research behind it. The Rocketdyne scientists developed the solar salt technology they will use in the Rice Solar Energy Project, and they proved that it worked back in the 90’s in a 10 MW demo.

Here’s how their heliostat mirror solar works:

1. Nearly 18,000 billboard-sized sized mirrors will be arranged on 12-foot posts in a circle to aim concentrated beams of sunlight at a salt-filled receiver at the top of a 538 foot tower.

2. The molten salt gets hotter and hotter all day as the sun beats down (up to 1,050 degrees) and then when it’s needed, that heat can be released to generate electricity the old fashioned way, by flowing through a steam-generating system driving a turbine at the bottom of the tower.

3. As the mixture loses heat it is recirculated back up to the top to get fired up again by the suns heat reflected off the heliostat mirror sytem, and round and round it goes, all 4.4 million gallons of molten salt.

The salt is a mixture of simple sodium nitrate and potassium nitrate and will be mixed onsite as received directly from mines in solid crystallized form and used without additives. When melted it looks like water.

Any utility-scale solar plant needs to bypass NIMBY opposition, whether that is genuinely heartfelt or merely the fossil-funded kind of “environmentalist” opposition. Unfortunately the Heartland Institute (of “500 scientists who deny climate change” fame)  is preying on the uninformed with complete falsehoods about how much water solar power uses.

In reality, even wet-cooled solar thermal, utility-scale solar’s piggiest water hog, uses only 1/60th of the water that nuclear can use and one 1/50th as much as a coal plant can; according to the (pdf) Report to Congress on Concentrating Solar Power Commercial Application Study: Reducing Water Consumption of Concentrating Solar Power Electricity Generation.

But to bypass these real or trumped-up impediments to clean energy SolarReserve will build their heliostat solar array on private land and will air-cool it. Dry cooling uses only about 10% of the relatively miniscule amount of water that wet cooled solar thermal uses.

United Technologies will guarantee the output for investors. SolarReserve got $140 million in investment in September last year.

Image: Flikr user perljeff

Source: Todd Woody





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About the Author

writes at CleanTechnica, CSP-Today and Renewable Energy World.  She has also been published at Wind Energy Update, Solar Plaza, Earthtechling PV-Insider , and GreenProphet, 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.



  • Joel Saliman

    Do you know how much the plant will cost? Is it $140 million. I thought that any type of power plant cost $900 to $2000 per kilowatt?

  • Joel Saliman

    Do you know how much the plant will cost? Is it $140 million. I thought that any type of power plant cost $900 to $2000 per kilowatt?

  • Joel Saliman

    Why are they not using solar concentrators like the one developed by MIT that generate more heat there fore they would require less of them.

  • Joel Saliman

    Why are they not using solar concentrators like the one developed by MIT that generate more heat there fore they would require less of them.

  • Joel Saliman

    Do you know how much the plant will cost? Is it $140 million. I thought that any type of power plant cost $900 to $2000 per kilowatt?

  • Joel Saliman

    Why are they not using solar concentrators like the one developed by MIT that generate more heat there fore they would require less of them.

  • Bill Woods

    I get the feeling we’re talking past each other.

    No, this project doesn’t use water in the heat collection or storage. And the mirrors aren’t actively cooled at all.

    The power generation loop does use water, turning it into steam in one heat exchanger and condensing it back to liquid in the other.

    And the condenser uses water; a fair amount if it’s wet-cooled, much less if it’s dry-cooled.

  • Bill Woods

    I get the feeling we’re talking past each other.

    No, this project doesn’t use water in the heat collection or storage. And the mirrors aren’t actively cooled at all.

    The power generation loop does use water, turning it into steam in one heat exchanger and condensing it back to liquid in the other.

    And the condenser uses water; a fair amount if it’s wet-cooled, much less if it’s dry-cooled.

  • Bill Woods

    I get the feeling we’re talking past each other.

    No, this project doesn’t use water in the heat collection or storage. And the mirrors aren’t actively cooled at all.

    The power generation loop does use water, turning it into steam in one heat exchanger and condensing it back to liquid in the other.

    And the condenser uses water; a fair amount if it’s wet-cooled, much less if it’s dry-cooled.

  • Susan Kraemer

    Bill,

    the company’s application to the CPUC shows that there is NO water used. The heat storage is in molten salt. The mirrors are dry cooled.

    “Liquid salt (The salt is a mixture of sodium nitrate, a common ingredient in fertilizer, and potassium nitrate, a fertilizer and food additive. These mineral products will be mixed onsite as received directly from mines in solid crystallized form and used without additives or further processing other than mixing and heating.), which has viscosity and appearance similar to water when melted, is circulated through tubes in the receiver, collecting the energy gathered from the sun.

    The heated salt is then routed to an insulated storage tank where it can be stored with minimal energy losses.

    When electricity is to be generated, the hot salt is routed to heat exchangers (or steam generation system).

    The steam is then used to generate electricity in a conventional steam turbine cycle. After exiting the steam generation system, the salt is sent to the cold salt thermal storage tank and the cycle is repeated.

    The salt storage technology was demonstrated successfully at the U.S. Department of Energy-sponsored 10-MW Solar Two project near Barstow, California, in the 1990s.”

  • Susan Kraemer

    Bill,

    the company’s application to the CPUC shows that there is NO water used. The heat storage is in molten salt. The mirrors are dry cooled.

    “Liquid salt (The salt is a mixture of sodium nitrate, a common ingredient in fertilizer, and potassium nitrate, a fertilizer and food additive. These mineral products will be mixed onsite as received directly from mines in solid crystallized form and used without additives or further processing other than mixing and heating.), which has viscosity and appearance similar to water when melted, is circulated through tubes in the receiver, collecting the energy gathered from the sun.

    The heated salt is then routed to an insulated storage tank where it can be stored with minimal energy losses.

    When electricity is to be generated, the hot salt is routed to heat exchangers (or steam generation system).

    The steam is then used to generate electricity in a conventional steam turbine cycle. After exiting the steam generation system, the salt is sent to the cold salt thermal storage tank and the cycle is repeated.

    The salt storage technology was demonstrated successfully at the U.S. Department of Energy-sponsored 10-MW Solar Two project near Barstow, California, in the 1990s.”

  • Bill Woods

    You’re paraphrasing Table 2 on p.17? If you’re building a fossil-fuel or nuclear plant, you may have the option of siting it next to a large body of water. If so, you can dump your waste heat into the water, heating it up slightly.

    “Once-through water cooling returns all of the withdrawn water to the source. Although it does not consume any water in the cooling process, it does increase the temperature and hence the evaporation rate from the body of water. This cooling method is limited in application and is not typically available for a solar power plant.” (p.12)

    If you’re trying to dump your waste heat into the air, your wet-cooling (“Recirculating”) or dry-cooling system doesn’t *care* what the source of your heat is. It’ll take the same amount of water per unit of heat. The differences in water use come from the variation in efficiency of the different technologies, which come from the differing temperature of the steam they generate. Gas burns extremely hot, so it has the highest efficiency. Solar power tower and dish systems can reach much higher temperatures than parallel trough systems (See p.14.), hence the difference in water consumption.

    Again, don’t take my word for it:

    “Based on thermodynamic principles, a water-cooled linear Fresnel reflector plant which generates steam directly in the heat collection tube, is estimated to require somewhat more water than a trough plant owing to its lower operating temperature and reduced cycle efficiency (greater heat rejection per MWh of electricity). Conversely, a power tower with a conventional Rankine cycle would presumably use somewhat less water, approximately 600 gal/MWh similar to a coal plant, by virtue of its higher operating temperature and efficiency.” (p.11–12)

    “Consider water-use information from the 2006 report Energy Demands on Water Resources, Report to Congress on the Interdependency of Energy and Water prepared by the U.S. Department of Energy: a coal fired plant uses 110 to 300 gallons per megawatt hour; a nuclear plant uses between 500 and 1100 gallons/MWh; and a solar parabolic trough plant uses 760-920 gallons/MWh.”

    http://www.ag.arizona.edu/azwater/awr/septoct08/d3aa3f8e-7f00-0101-0097-9f6724822dfe.html

  • Bill Woods

    You’re paraphrasing Table 2 on p.17? If you’re building a fossil-fuel or nuclear plant, you may have the option of siting it next to a large body of water. If so, you can dump your waste heat into the water, heating it up slightly.

    “Once-through water cooling returns all of the withdrawn water to the source. Although it does not consume any water in the cooling process, it does increase the temperature and hence the evaporation rate from the body of water. This cooling method is limited in application and is not typically available for a solar power plant.” (p.12)

    If you’re trying to dump your waste heat into the air, your wet-cooling (“Recirculating”) or dry-cooling system doesn’t *care* what the source of your heat is. It’ll take the same amount of water per unit of heat. The differences in water use come from the variation in efficiency of the different technologies, which come from the differing temperature of the steam they generate. Gas burns extremely hot, so it has the highest efficiency. Solar power tower and dish systems can reach much higher temperatures than parallel trough systems (See p.14.), hence the difference in water consumption.

    Again, don’t take my word for it:

    “Based on thermodynamic principles, a water-cooled linear Fresnel reflector plant which generates steam directly in the heat collection tube, is estimated to require somewhat more water than a trough plant owing to its lower operating temperature and reduced cycle efficiency (greater heat rejection per MWh of electricity). Conversely, a power tower with a conventional Rankine cycle would presumably use somewhat less water, approximately 600 gal/MWh similar to a coal plant, by virtue of its higher operating temperature and efficiency.” (p.11–12)

    “Consider water-use information from the 2006 report Energy Demands on Water Resources, Report to Congress on the Interdependency of Energy and Water prepared by the U.S. Department of Energy: a coal fired plant uses 110 to 300 gallons per megawatt hour; a nuclear plant uses between 500 and 1100 gallons/MWh; and a solar parabolic trough plant uses 760-920 gallons/MWh.”

    http://www.ag.arizona.edu/azwater/awr/septoct08/d3aa3f8e-7f00-0101-0097-9f6724822dfe.html

  • MD

    KN03 aka Good ol salt peter – keeping the power on.. LOL

    Pretty cool…

  • MD

    KN03 aka Good ol salt peter – keeping the power on.. LOL

    Pretty cool…

  • Susan Kraemer

    No, I have not misread my source. The pdf “Report to Congress on Concentrating Solar Power…” lists coal as using UP TO 50,000 gals a megawatt hour, nuclear UP TO 60,000 gals per megawatt hour produced.

    That’s why nuclear plants got shut down in France in the heat wave drought and coal plants were shut down in Australia in 2007: drought.

    Most coal plants here are older, and closer to the high end. Because they got grandfathered in. Nuclear has not been updated since the 70’s. Maybe in theory they could use less water, but in fact both use on the high side.

    And to compare apples to apples I included the high side of solar thermal water use too: UP TO 1,000 gallons per megawatt hour.

    I know dry cooling is less efficient. But even wet cooled solar thermal is not comparable to fossil plants. The fossil-funded Heartland Institute is claiming that solar thermal uses MORE water than fossil plants.

  • Susan Kraemer

    No, I have not misread my source. The pdf “Report to Congress on Concentrating Solar Power…” lists coal as using UP TO 50,000 gals a megawatt hour, nuclear UP TO 60,000 gals per megawatt hour produced.

    That’s why nuclear plants got shut down in France in the heat wave drought and coal plants were shut down in Australia in 2007: drought.

    Most coal plants here are older, and closer to the high end. Because they got grandfathered in. Nuclear has not been updated since the 70’s. Maybe in theory they could use less water, but in fact both use on the high side.

    And to compare apples to apples I included the high side of solar thermal water use too: UP TO 1,000 gallons per megawatt hour.

    I know dry cooling is less efficient. But even wet cooled solar thermal is not comparable to fossil plants. The fossil-funded Heartland Institute is claiming that solar thermal uses MORE water than fossil plants.

  • Susan Kraemer

    No, I have not misread my source. The pdf “Report to Congress on Concentrating Solar Power…” lists coal as using UP TO 50,000 gals a megawatt hour, nuclear UP TO 60,000 gals per megawatt hour produced.

    That’s why nuclear plants got shut down in France in the heat wave drought and coal plants were shut down in Australia in 2007: drought.

    Most coal plants here are older, and closer to the high end. Because they got grandfathered in. Nuclear has not been updated since the 70’s. Maybe in theory they could use less water, but in fact both use on the high side.

    And to compare apples to apples I included the high side of solar thermal water use too: UP TO 1,000 gallons per megawatt hour.

    I know dry cooling is less efficient. But even wet cooled solar thermal is not comparable to fossil plants. The fossil-funded Heartland Institute is claiming that solar thermal uses MORE water than fossil plants.

  • Bill Woods

    “In reality, even wet-cooled solar thermal, utility-scale solar’s piggiest water hog, uses only 1/60th of the water that nuclear can use and one 1/50th as much as a coal plant can; according to …”

    You’ve misread your source, which says,

    “The majority of new fossil power plants use evaporative water cooling to reject the steam cycle heat. A typical coal plant or nuclear plant consumes 500 gallons of water per MWh (gal/MWh) of electricity generated.1, 3 This is similar to the water consumption by a power tower. A combined-cycle natural gas plant consumes about 200 gal/MWh.4 A water-cooled parabolic trough plant consumes about 800 gal/MWh.”

    *Any* thermal plant can use dry cooling — if it’s willing to take the performance hit. The amount of water needed to get rid of a given amount of waste heat doesn’t depend on the source of the heat. But ordinarily, fossil-fuel and nuclear plants aren’t built in the middle of a desert, so they don’t have to.

  • Bill Woods

    “In reality, even wet-cooled solar thermal, utility-scale solar’s piggiest water hog, uses only 1/60th of the water that nuclear can use and one 1/50th as much as a coal plant can; according to …”

    You’ve misread your source, which says,

    “The majority of new fossil power plants use evaporative water cooling to reject the steam cycle heat. A typical coal plant or nuclear plant consumes 500 gallons of water per MWh (gal/MWh) of electricity generated.1, 3 This is similar to the water consumption by a power tower. A combined-cycle natural gas plant consumes about 200 gal/MWh.4 A water-cooled parabolic trough plant consumes about 800 gal/MWh.”

    *Any* thermal plant can use dry cooling — if it’s willing to take the performance hit. The amount of water needed to get rid of a given amount of waste heat doesn’t depend on the source of the heat. But ordinarily, fossil-fuel and nuclear plants aren’t built in the middle of a desert, so they don’t have to.

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