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CA's First Molten Salt Energy Plant Approved 270

An anonymous reader writes "This year we've seen molten salt power plants start to pick up steam around the world, and now the technology is heating up stateside — California just approved its first molten salt energy plant. Designed by SolarReserve, the plant uses heliostats to focus thermal energy on a power tower filled with salt, which is able to reach very high temperatures (over 1000 degrees Fahrenheit) and can hold heat for an extraordinary length of time. Heat from this reserve of molten salt can then be pumped through a steam generator to provide on-demand energy long after the sun has set."
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CA's First Molten Salt Energy Plant Approved

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  • by Anonymous Freak ( 16973 ) <`' `ta' `revird.suirp'> on Thursday December 16, 2010 @03:41PM (#34578210) Journal

    We get it already, heat jokes. Knock it off!

  • Fahrenheit? (Score:2, Informative)

    by mrphoton ( 1349555 )
    810.777 Kelvin .... nuff said.
    • Re: (Score:3, Insightful)

      by noidentity ( 188756 )
      Eliminate that make-believe accuracy, as the original was probably rounded at least +/-50 F to the round 1000 figure. 800 Kelvin is plenty accurate here.
    • According to Wikipedia the melting point is 801 degrees Celsius (1074 Kelvin).

      The boiling point is 1686 K and the specific heat capacity is 864 Joules/Kilo/degree so you can do the numbers... :-)

  • by bhcompy ( 1877290 ) on Thursday December 16, 2010 @03:42PM (#34578236)
    Any way to work this out for home use? Without digging too deep, sounds suitable here in So Cal, but maybe the scale is too small to provide any real benefit
    • by Yvan256 ( 722131 )

      Home use? Sure, here's your order of molten french fries...

    • Re:home use? (Score:4, Insightful)

      by Nadaka ( 224565 ) on Thursday December 16, 2010 @04:11PM (#34578756)

      Realistically? No. The thermal mass required to keep a steam turbine running 24/7 is not something you want in your house. This is large scale industrialized energy production. The only personal scale applications are solar hot water heaters and greenhouses, and in those cases your goal is to take advantage of the stored heat directly instead of converting it to electricity.

    • by Raptoer ( 984438 )

      You would have to get it up to a high enough temperature to stay molten throughout the night, while still providing power. It's a lot more practical to use other solar technologies for home use and keep these ones in big arrays. It's a bit like why power plants will always have higher efficiency than home generation, it's a matter of scale.

      • by geekoid ( 135745 )

        Actually you could, but not with salt. there are other liquid that would work well enough for home use. You could also use troughs. BUT, you need a heat exchangers, storage device. If I had a free 1/2 acre I would give it a try. Even if it doesn't last through the night, if it got you just an extra 2 hours after sundown, it would still be a big help.

        • Heat capacity is proportional to the volume of the liquid while radiative heat loss is proportional to the surface area. volume grows to the third power while surface area grows to the second as you add more liquid (assuming a non pathological design) so a smaller facility is signifigantly less useful than a simple scaling of the power output of a larger one might imply.

    • Without digging too deep, sounds suitable here in So Cal, but maybe the scale is too small to provide any real benefit

      I don't think this would be viable on a small scale.

      National Geographic had a decent article sometime in the past couple years on different solar energy technologies. Part of that article was an excellent writeup (and photos) of this technology, which is currently in use in Spain.

      The basics are:

      A column with a salt reservoir at the top
      A field of mirrors that can focus the reflected solar

    • it depends on how big your lot is. You're going to need enough land to construct a pretty large mirror array, and then you'll need a power tower to collect all that heat. If you can't get away with building a tall structure, you could use a parabolic trough. The main reason you wouldn't want this on a small scale is you can't shut it off. If the salt cools into a solid, you'd never get it flowing again.

      For your safety, as well as the safety of your neighbors, I'd say it's best to leave that 800-degree (Cels

    • by skids ( 119237 )

      You're stuck waiting for flywheels or redox batteries to be packaged for consumer level installations, I'm afraid. This one here is a "big boy only" toy.

      However, if you are interested in space heating, look up Glauber's Salt.

      • Whoa, cool. I had no idea. Wikipedia missed one use -- if you want to get the most intense turquoise from procion dyes [] (tie-dye, often), you use Glauber's salt instead of salt when mixing the dye (note that the referenced site sells anhydrous sodium sulfate, not the deca-hydrated form you were thinking of).
    • by dbIII ( 701233 )
      Just using it for hot water saves a pile of electricity and removes the annoyance of a cold shower in a blackout. For those that think it's a bleeding heart liberal communist green hippy sort of idea I suggest you direct those insults at the government in Israel where solar hot water is inb the building regulations (it's just that good an idea when you have a lot of sun).
  • RTFA, looks like a giant penis...
  • Not the first... (Score:5, Informative)

    by Foo2rama ( 755806 ) on Thursday December 16, 2010 @03:45PM (#34578282) Homepage Journal []

    Only if you ignore Solar II that ran from 1996 to 1999....
  • by $RANDOMLUSER ( 804576 ) on Thursday December 16, 2010 @03:50PM (#34578398)
    Nothing from or controlled by Computer Associates should be trusted with warm water, much less molten salt.
  • by 140Mandak262Jamuna ( 970587 ) on Thursday December 16, 2010 @03:57PM (#34578530) Journal
    Any excess salt left over after building the plant will be given to Gawker to help them improve their salted password hashes.
  • Silicon Production (Score:4, Interesting)

    by UdoKeir ( 239957 ) on Thursday December 16, 2010 @03:57PM (#34578532)

    Slightly off-topic (or on-topic considering the bigger picture). Can this method of heat concentration be used in the refinement of silicon. My understanding is that silicon production is expensive because of the energy needed to generate heat for the process. []

    • Re: (Score:3, Insightful)

      Yes of course. It could even be used to create mirrors for more solar towers. The whole damn thing could be self-replicating.

  • Why is this thing a tower? What if the system controlling the mirrors fails and suddenly they melt the tower, causing the molten salt to crash down on everything below?

    Wouldn't it be safer to have that molten salt at ground level?

  • by Taibhsear ( 1286214 ) on Thursday December 16, 2010 @04:00PM (#34578584)

    Does anyone know exactly how long the reservoir tanks will keep the molten salt at a high enough temp to be useful? It says it can run for 24 hours but should an abnormally long string of cloudy days occur would this inhibit its usefulness? I realize it's California so it should be fairly sunny year round but I'm not familiar with the area it's being built at. Looked up the salt as well. (Had a hard time thinking it would be sodium chloride...) It's a mixture of sodium and potassium nitrate. I was a bit worried as nitrates tend to be violently reactive/explosive but this would only be with reducing agents. (so it should be relatively fairly safe if there was a leak.) However when potassium nitrate is heated above 560C (as it would in this plant) it turns to potassium nitrite and gives off oxygen. I'm curious if this would be an issue or if the sodium nitrate or something else in the mixture inhibits this. I imagine the oxygen would either stick in the solar collector part as a gas bubble or just be dissolved in the molten salt mixture. Anyone know? (My expertise is more in biochemistry than inorganic/industrial chemistry)

    • by Nadaka ( 224565 )

      It could, but I don't know how cloudy it would have to be or for how long. If the designers were wise, they might have a backup system using natural gas or hydrogen to keep the boilers hot in case of emergencies.

    • The duration of energy storage depends on how large the container is and how well it is insulated. Wikipedia claims []: "the thermal energy can be usefully stored for up to a week."
      • A lot of that wouldn't be so much to try to cover cloudy days, but to not waste good days. If you have to turn off the mirrors more than x percent of the time because you can't store more thermal load, you've probably under built for the conditions you're in.

    • I realize it's California so it should be fairly sunny year round but I'm not familiar with the area it's being built at.

      As a Californian, let me *facepalm* over such an asinine comment for the rest of my Golden Coast brothers and sisters.

    • by corbettw ( 214229 ) on Thursday December 16, 2010 @04:21PM (#34578948) Journal

      It's being built in the Mojave Desert. Anything capable of causing sufficiently cloudy days for long enough to prevent solar collection is going to be a bigger problem by itself that not being able to pump out heat from the now-cooled salt. An eruption of the Yellowstone Caldera, comet impact, nuclear attack, something on that order is what we're talking about.

    • by Biogenesis ( 670772 ) <overclocker,brent&optushome,com,au> on Thursday December 16, 2010 @04:28PM (#34579074) Homepage

      I've been doing some research into renewable energy in an Australian context at the University of Newcastle. The most commonly thrown around figure is 1C/day of loss at operating temperatures.

      In doing some simple simulations (using real world demand, wind farm output and direct solar irradiance data) I've found that 50GW of wind farms (peak, scaled by 50x from Australia's current ~1GW peak wind capacity) and ~42GW of concentrated solar thermal (roughly 53x53km square area, spread across Australia on 12 sites) with 24hrs of storage is able to supply all of Australia's current electricity demand. The thermal storage dropped to ~10% capacity at it's lowest point.

      The simulation tried to closely model the Beyond Zero Emissions Zero Carbon Australia 2020 [] plan. Their modeling uses a different demand profile, one scaled to a proposed 2020 level after compensating for growth, electrification of cars etc.

      • by shermo ( 1284310 )

        Electrical systems for heating ... can have significantly higher efficiency

        Huh? Burning gas to produce heat is pretty damn efficient. Whereas if you convert it to electricity you'll get 60% efficiency at best and then lose 5-7% in transmission. Perhaps the article has a different definition of efficiency.

        • I'm not familiar with the context of your quote, but I suspect the logic is something like this: gas "amount" is typically measured is joules, as in "the number of joules of heat energy you'll get from burning x "amount" of gas. So, burning 1J of gas results in roughly 1J of heat being deposited in a room. However, if you use a heat pump powered by electricity 1J of electricity produces ~2-3J of heat in the room, as a heat pump cools down outside in order to heat inside.

          The same logic is applied when comp

    • According to one report, Proposed 150 MW Solar Plant Would Store 7 Hours []

      This storage is similar to the Andasol 1 plant in Spain. It certainly would not be sufficient for 24/7 operation at nominal 150 MW output by a fair bit.

  • I though mythbusters proved that this was impossible.
    They even reported their findings to the president.

    • Re: (Score:3, Informative)

      by Raptoer ( 984438 )

      They didn't have the desert sun pouring onto a thousand large mirrors perfectly aligned on something for hours on end. Their test was more about the ability to align all of these mirrors without technology. These kind of things are dependent on energy going in vs energy going out. A thin sail surrounded by cool damp sea air only being shone upon from one side is going to have a lot less energy going in, and a lot more energy going out than a desert solar array.

    • by skids ( 119237 )

      This will use heliostats.

      Not twitchy third graders.

  • ...over 1000 degrees Fahrenheit

    Wake me up when it's over 9000.

  • And like so many other solar energy projects in California someone will sue to prevent it from being built because it's on "pristine desert habitat".

  • by WindBourne ( 631190 ) on Thursday December 16, 2010 @07:43PM (#34581824) Journal
    As I pointed out in my logs about 3 years ago, we should build molten salt generators, BUT use these for excess electricity storage. By building SMALL units (1-20 MW) these will take 1 acre or less to run. Then set up tax breaks to encourage small businesses of these. With that approach, it could buffer energy from AE, but also, it would allow grabbing the energy at night (cheaply) and then selling it during the day (for a profit).

"Everyone's head is a cheap movie show." -- Jeff G. Bone