Forgot your password?
Power Technology

World's First Molten-Salt Solar Plant Opens 316

Posted by timothy
from the entire-mountain-is-covered-with-snow dept.
An anonymous reader writes "Sicily has just announced the opening of the world's first concentrated solar power (CSP) facility that uses molten salt as a heat collection medium. Since molten salt is able to reach very high temperatures (over 1000 degrees Fahrenheit) and can hold more heat than the synthetic oil used in other CSP plants, the plant is able to continue to produce electricity long after the sun has gone down. The Archimede plant has a capacity of 5 megawatts with a field of 30,000 square meters of mirrors and more than 3 miles of heat collecting piping for the molten salt. The cost for this initial plant was around 60 million Euros."
This discussion has been archived. No new comments can be posted.

World's First Molten-Salt Solar Plant Opens

Comments Filter:
  • by Anonymous Coward on Friday July 23, 2010 @02:02AM (#33000054)

    Ok, so it can produce after the sun has gone down, but wouldn't the inverse be true, too, i.e. it'll take longer for it to reach a heat at which it can start producing in the morning? Anyone who didn't fail physics want to help an ignorant AC out?

    • by jamesh (87723) on Friday July 23, 2010 @02:22AM (#33000134)

      I don't think you'd have to heat up all of your thermal mass to start producing energy. If you only need a certain fraction of the thermal mass to produce the amount of energy you need then the rest can be a 'battery' that you charge up during the day when there is extra solar radiation going into your system.

      • by Deflatamouse! (132424) on Friday July 23, 2010 @03:38AM (#33000426) Homepage Journal

        In other words, there's value in the ability to produce energy at a constant rate, rather than in bursts. Because when it's produced in bursts, you will have to find a way to store it, which means a loss in efficiency.

        • by Joce640k (829181)

          Yep. The way I read this article is that the plant is designed to produce 5 megawatts, 24/7, in pretty much any weather. Peak output at noon on a sunny day will be much higher than that (I hope - 30 square km of mirrors is a lot of mirrors!)

        • by TapeCutter (624760) * on Friday July 23, 2010 @06:56AM (#33001258) Journal
          "when it's produced in bursts, you will have to find a way to store it, which means a loss in efficiency."

          Yes, however you're only looking at energy loss in one particular circumstance rather than looking at the overall efficientcy of the system in dollar terms.

          Currently coal plants produce too much at night and not enough during the day. This means they waste fuel at nightly lows and have to be supplemented by "busrts" from gas turbines during daily peaks. Therefore (if it was possible**) there's much more value in producing energy that matches the peaks and troughs of consumption rather than trying to produce it at a constant rate capable of handling the peaks, especially if you have to pay for fuel.

          The fact is that producing electricity at a constant rate capable of handling the peaks is not how electricity is generated on a commercial scale. All methods of generating electricity are intermittent. The idea that we currently have an efficient steady stream of "base load" power provided by constantly running coal plants is largely a myth created by the coal industry.

          Coal plants are shut down for regular maintenance for ~45 days/year. Meaning one redundant coal plant needs to be built for (roughly) every seven coal plants in use. Plus to handle peaks you still need to build gas turbines that will sit idle for 20 or more hrs/day (or "inefficiently" pump water uphill). The advantage with wind, solar, etc, over fossil fuels is that; when it comes to handling the unavoidable peaks you can pump water uphill, (melt salt, whatever), during "bursts" and it will cost you some percentage of nothing in fuel costs.

          Sure, windfarms also require maintenance but you can do it one windmill at a time, the whole farm very rarely needs to be shut down all at once.

          ** = Regardless of how you produce the electricity the most economically efficient answer to the inherent problems of peaks, troughs, bursts and breakdowns is a large well managed grid with built in generation/transmission redundancy and plenty of pump storage capacity.
    • by arivanov (12034) on Friday July 23, 2010 @02:41AM (#33000214) Homepage

      The network peak is in the first hours in the evening. Morning (while it warms up) is relatively low consumption. So if it can work through to what in the UK is referred to as the "Eastenders hour" it is well worth it. Pity they built it in Cicily though, I would really like to see those built in quantity in the Sahara. More sun, hotter sun and less cloud. The distance across the mediteranean is well within the limits of modern tech for a high voltage line on the sea bed. High voltage is also considerably safer compared to gas or oil in an earthquake zone (which is pretty much all of the Med).

  • Ooooooh. (Score:4, Funny)

    by (245670) on Friday July 23, 2010 @02:03AM (#33000062)

    I thought the headline said morton-salt.

  • by RudyHartmann (1032120) on Friday July 23, 2010 @02:05AM (#33000064)
    LFTR's will render these things irrelevant. []
    • by LordLucless (582312) on Friday July 23, 2010 @02:24AM (#33000144)

      Ahhh! Nuclear! Ahhh! It'll explode and kill us all and poison the planet for a bejillion years!

      • Re: (Score:2, Insightful)

        That's not funny, that's insightful. Because you would have to fight exactly that attitude when trying to build a new nuclear reactor of any kind. And I can't see a lot of countries in europe where you could possibly win that fight (and I don't know enough about the popular opinion about nuclear energy in the US, but I'd guess it would be at least a pretty tough fight).
        • And just forget about trying it in New Zealand. The US aren't even allowed to bring nuclear powered vessels into NZ waters.
    • Solar's energy density is terrible, it doesn't store readily, and doesn't work when the sun goes down. Yeah, yeah, yeah, that's what the molten salt is for, but tell me this: how long can you afford to be without actual sun (number of consecutive cloudy or mostly cloudy days) before this is neutered? Thorium fission is the most likely way out of the current energy conundrum. If its proponents aren't lying to us or themselves about its economic viability.
    • by phantomfive (622387) on Friday July 23, 2010 @03:54AM (#33000512) Journal
      Yeah, and fusion will one day render liquid fluoride thorium reactors irrelevant, but they've built something now, and it's environmentally friendly, and as long as the cost is reasonable, who cares? They still have something good now.
    • by interkin3tic (1469267) on Friday July 23, 2010 @04:05AM (#33000554)

      LFTR's will render these things irrelevant.

      I try not to anticipate future technology that seems right around the corner, because otherwise I'll just get depressed thinking about where I am now: in an apartment, most appliances in which are not connected to the internet to manage themselves as I fly to Hawaii in my flying car, playing Duke Nukem Forever on my VR headset.

      And no that wouldn't be unsafe because cars today are supposed to be driving themselves, I'm assuming that would work for flying cars too.

      Anyway, if molten salt solar plats really do become obsolete because of whatever not-here-yet power source you're talking about, we'll have a good mass-popcorn maker.

    • Exactly as with this plant, there will be several proofs of concept along the way to regulatory approval and workable production plants. How long will it take? In the early days of reactors there was little regulatory oversight and a gung-ho approach. Not so now. It's reasonable to assume that this design is unlikely to be in volume production much before 2040 - by which time solar plants will be bigger, cheaper and well established.

      On one version of your argument, the Neandertals went extinct because one a

    • by dbIII (701233) on Friday July 23, 2010 @05:21AM (#33000872)
      Here we go again.
      There is no "one true energy" because that is instead called putting all of your eggs in one basket. Anyone that tells you otherwise is either selling something or is gullible enough to have been conned by somebody that is. Thus even if there was an actual physical LFTR in existence it would not render all other forms of electricity production irrelevant.
      Also we've got a hell of a long way to go before the practical details of working with molten radioactive materials are sorted out. I can't wait to see the "safe, clean" spin get put on liquid fluoride instead of treating it with the respect it deserves.
    • Re: (Score:3, Informative)

      by WindBourne (631190)
      America R&D nearly all of the nuclear power plant types, and nearly all of the current AE being sought out. In fact, this molten salt approach was pushed by Boeing in the 90's, but W's admin shot it down. Check out my Journal. And yet, we said that Coal plants made all of them irrelevant.

      The problem that America (and the west) has, is that far too many ppl wants us to depend on EXACTLY ONE THING. Well, that is the attitude that gets us in trouble. Instead, our leaders need to push a MATRIX of energy
  • by Antony T Curtis (89990) on Friday July 23, 2010 @02:09AM (#33000074) Homepage Journal

    This is big news!

    The larger the temperature difference, the more efficiently we can turn the heat into electricity. Superheated steam is just too difficult to manage over distances so this would make a great first step of collecting the solar energy and transporting it to a single location to make superheated steam.

    The best part is that NaCl is non-toxic and doesn't need to be kept under pressure. If you have a natural gas Bunsen burner and good test tubes handy, it is just about possible to melt salt and prove to yourself how stable it is. Just be careful about spilling it because it is hot enough to get things like wood and paper to auto-ignite on contact. The hottest temperature you can expect to achieve with natural gas is around 700 degrees Celsius, if I remember correctly.

    (as a side note, this is why low pressure nuclear power plants have such poor efficiency - because the water is only at 100 degrees Celsius after being heated by the nuclear fuel).

    • "Salt" != "NaCl" (Score:5, Informative)

      by billstewart (78916) on Friday July 23, 2010 @02:19AM (#33000112) Journal

      The article isn't specific about *what* salts they're using, but says "molten salts solidify at around 425 degrees F" - NaCl's melting point is about 800 C.
      One of the articles they reference refers to another project that uses a mixture of sodium and potassium nitrates.

      • Re:"Salt" != "NaCl" (Score:5, Informative)

        by c0lo (1497653) on Friday July 23, 2010 @02:48AM (#33000246)

        The article isn't specific about *what* salts they're using,

        This one [] does: the same as Solar One/Two - a mix of sodium/potassium nitrate.

      • Re: (Score:3, Interesting)

        by marcosdumay (620877)

        Well, you really don't want to run molten NaCl (or any other Cl, I of F salt) inside metal pipes. They can't be using carbonates, since you can't heat them that much. Sulfates are also too agresive, so they probably are using nitrates (altough I'd put a just a bit of a weak hidroxide in the mix).

    • Re: (Score:3, Interesting)

      by QuantumPion (805098)

      (as a side note, this is why low pressure nuclear power plants have such poor efficiency - because the water is only at 100 degrees Celsius after being heated by the nuclear fuel).

      The reason why nuclear power plants are not as efficient as coal or combined cycle plants is because as part of their design, they can not create super-heated steam, which limits the efficiency of the turbine. The steam created by the reactor or steam generators is typically at saturation temperature at 1000 PSI (~540 degrees F)

  • Wasn't another good reason to use salt, that molten salt has excellent thermal conduction properties??

    As, you barely have to pump it around, for the heat to reach the reservoir.

  • by not5150 (732114) on Friday July 23, 2010 @02:20AM (#33000120)
    The article is incorrect... Barstow had a molten salt plant in 1995 I believe. Excerpt from the Wiki - "1995 Solar One was converted into Solar Two, by adding a second ring of 108 larger 95 m (1,000 ft) heliostats around the existing Solar One, totaling 1926 heliostats with a total area of 82,750 m (891,000 ft). This gave Solar Two the ability to produce 10 megawatts. Solar Two used molten salt, a combination of 60% sodium nitrate and 40% potassium nitrate," - []
    • Re: (Score:3, Informative)

      by Anonymous Coward


      France had one of these, inaugurated in 1983, called "Thémis".
      (danger! websites in French).

      It used a circuit of molten salt, just like the OP's "world's first molten-salt solar plant"

      Both this and the Barstow plant were subsequently adapted for gamma-ray astronomy (on which I work, and spent much time there).

      The plant was experimental, and I believe only produced a surplus of energy on

      • by PybusJ (30549) on Friday July 23, 2010 @10:33AM (#33002846)

        Both the French and Californian plants were solar tower type where the mirrors all concentrate the sun on to one point (from where heat energy can be extracted with molten salt).

        The article is about a parabolic trough system where rows of mirrors with parabolic X-section concentrate the sun onto a pipe running along the focus point. This is easier to construct and scale than the towers you point to and is already deployed more widely. Previous trough systems have heated oil in the pipes then transferred the heat to salts for storage (then again to water to run a turbine).

        The advance here is to avoid this oil to salt transfer, while the slashdot headline is inaccurate (shock horror), this something new and a genuine step forward.

  • Desalinization? (Score:3, Interesting)

    by atomicstrawberry (955148) on Friday July 23, 2010 @02:24AM (#33000140)

    Could this technology be combined with desalinization, i.e. take salt water, pull the salt out to produce potable water, and use the salt to improve the plant's efficiency? Desalinization is a very energy-intensive process but I wonder if a lot of that could be offset using solar and redirecting the waste salt into the energy plant that powers the process in the first place.

    • Re: (Score:2, Offtopic)

      by TooMuchToDo (882796)
      Yes. You could use any waste heat after the generation process to convert salt water to steam, extract the salt and sell it, and condense the steam back to water and have fresh water. Using the salt from the process might be possible, but more importantly you're desalinating water using the sun instead of diesel generators or natural gas turbines.
    • Re:Desalinization? (Score:5, Insightful)

      by DerekLyons (302214) <fairwater&gmail,com> on Friday July 23, 2010 @03:33AM (#33000388) Homepage

      Could this technology be combined with desalinization, i.e. take salt water, pull the salt out to produce potable water, and use the salt to improve the plant's efficiency?

      No, once the plant is charged with working fluid, you don't need to add any more.

  • by QuantumG (50515) * <> on Friday July 23, 2010 @02:29AM (#33000170) Homepage Journal

    5MW for $60M (euro).. really?

    At 10c/kWh it can earn $500/hr. So it'll only take ~13.7 years to pay it off.. oh it's solar, right, well, with the seasons and everything I guess it's more like double that. Let's say ~27 years. How much is maintenance? Oh yeah, and the time value of money.

    Another way of looking at it: it's $12B/GW + operations. Nuclear power plants take 5-10 years and cost $4-10 billion to build, and $4-6 billion for fuel and operation over their lifetime, so $8B/GW to $16B/GW. So the cheapest nuclear reactor beats this by at least 35% and the most expensive nuclear reactor probably beats it also.

    But that fact that they've even made it into the right ballpark is impressive and perhaps once they scale it up to somewhere that is actually useful we'll have some idea how competitive it can be.

    • Can you spell the words; Prototype, Low-Maintances and Zero Emissions?
    • by BitZtream (692029)

      Yep, gotta start somewhere, it'll grow I'm sure as it already has. The key is that it (well, all combined renewable energy sources) needs to grow faster than our consumption does.

      I'm sure eventually that will happen as we'll run out of non-renewable fuels at which point our consumption and renewable fuel supplies will match perfectly!

    • Re: (Score:2, Redundant)

      by thegarbz (1787294)
      It's far worse than you think. 30,000 sq m of mirrors? 3 miles of pipe? Cost aside for 5MW that is an insane amount of real estate for such little area. Our 10MW natural gas turbine at work is about 4m wide, 8m long and 7m high. Add a Heat Recovery Steam Generator to the other side of it and for a little more space you get another 7MW, and all of that still fits into a typical restaurant car park. So if you had huge amounts of disposable cash this plant would still be useless anywhere near a city, or a tow
      • by Darkman, Walkin Dude (707389) on Friday July 23, 2010 @04:09AM (#33000574) Homepage

        Our 10MW natural gas turbine at work is about 4m wide, 8m long and 7m high.

        If your natural gas turbine doesn't generate the natural gas, you aren't giving the full story here though. You also need hundreds of miles of carefully sealed pipelines and/or freight infrastructure, you also need the refining and mining infrastructure, and you need to factor in the cost for exploration and developing the mine in the first place, with all the dead ends that implies. Natural gas might be cheap but its often subsidised at source, but hey so what you say, I don't pay it. If you live in Europe and the Russians want to extract a trade agreement or something from you, the cost of that natural gas might suddenly start to fluctuate wildly however.

        And thats the full story.

        • by QuantumG (50515) *

          Yep, and to make mirrors you need........

          • Re: (Score:3, Insightful)

            To keep them operational? Nothing at all. I guess sunlight if you wanted to be pedantic.
          • by Laser Dan (707106)

            Yep, and to make mirrors you need........

            ... manufacturing facilites only during the construction.
            After that, you're done.

            With gas pipelines you need the pipelines to stay there, without holes, and with someone pumping gas in the other end.

    • by Anonymous Coward on Friday July 23, 2010 @03:30AM (#33000366)

      5MW for $60M (euro).. really?

      That's normal. First, it's a prototype. Second, it's Italy. Third, it's Sicily.

      The project started something like 20 years ago by the Nobel Prize laureate (physics) Carlo Rubbia. Seven different governments (both right-wing and center-left-wing) made every effort to cripple the project with bad management and bureaucratic issues. At the same time they poured heaps of money to dubious Sicilian consulting organisations. After a while (actually, after being dismissed from the environmental cabinet) Carlo Rubbia got tired of all these problems and flew to Spain where he built in 3 years six or seven similar plants for a tenth of their Italian price.

    • by Rogerborg (306625)

      Your figures are ludicrously off.

      It's not 60M Euros for 5MW. It's 60M Euros plus the cost of the 5MW of coal, gas, oil or nuclear capacity that you'll need on cloudy days.

      If we're going to beat up on solar, let's do it properly.

    • by dbIII (701233)

      Nuclear power plants take 5-10 years

      Name the full scale plant that was built so quickly in recent years.

      and cost $4-10 billion to build

      Once again - name the plant.
      You've been misled by salesfolk that spin the nuclear debate off into never-never land with rubbery figures sprinkled with utter bullshit and shaped into what focus groups think would be about right for a price.
      If you are going to put numbers up on such a debate that is full of outright lies on both sides you are going to have to tie it to reality

    • by RichiH (749257)

      You forgot that

      a) nuclear power plants are the only industrial plants in the world which do not need to be insured to the full extent of possible damages they might cause. The insurance industry made politics cap the max at a mere 5 billion Dollar which may sound like a lot, but it's not. The population at large would shoulder those costs.

      b) the countries in which the plants operate are charged with long-term storage. So the population at large shells out for that.

      A prime example of privatizing earnings and

      • Re: (Score:3, Informative)

        by Myrv (305480)

        And the oil industry has a cap of $75 million on the possible economic impact of their mistakes so I fail to see your point. If the gulf has taught us anything it should be that fossil fuel usage can cause disasters just as bad, if not worst, than nuclear energy.

        As for nuclear storage, as others have pointed out, spent fuel can be recycled. The same can't be said for the waste products of fossil fuels. At the end of the day society pays a price for all our energy usage.

  • by T Murphy (1054674) on Friday July 23, 2010 @02:58AM (#33000268) Journal
    So in other words, they are seeing if this design is worth it's salt?
  • The costs for this plant are very high of course because its a new thing.

    This simple power point PDF reallyshows the numbers of the solar thermal salt plant in spain that is run as a research plant. []

    They actually concluded that Salt is Not the only option. The problem with salt is rust, and so you have to use carbon coating on all the steel parts, which makes it expensive.


  • Come on.. (Score:5, Insightful)

    by sisko (114628) on Friday July 23, 2010 @03:37AM (#33000412)

    What's this Fahrenheit rubbish?

  • []

    Solar Two used molten salt, a combination of 60% sodium nitrate and 40% potassium nitrate, as an energy storage medium

  • technically, it's far from being the first. It may be the first commercially operating one though
    the first is : []

  • by Ancient_Hacker (751168) on Friday July 23, 2010 @05:51AM (#33001034)

    Try estimating what the basic maintenance costs are for 3 miles of piping that can handle molten salt.

    Molten salt is rely, really *corrosive*. Either they're spending tons of money up front on miles of stainless steel, or even more every year replacing the pipes as they corrode away.

    Either way it's hard to even break even-- 5MW of electricity is only about $2 million a year wholesale, far less than the interest cost on a $60M plant, and likely less than the cost to maintain 3 mmiles of molten salt piping and collectors.

    • "Really corrosive" (Score:5, Informative)

      by Kupfernigk (1190345) on Friday July 23, 2010 @06:20AM (#33001144)
      Very few things are generally corrosive. It depends on the chemistry involved. For instance, dilute sodium hydroxide can be kept perfectly safely for years in mild steel tanks exposed to the air, whereas water or concentrated hydroxide would rapidly corrode them. It's a mistake to assume that even A4 (316), the industry standard, is suitable for everything; there are plenty of things that corrode it.

      Having said that, it's been known for a long time that certain austenitic high-chrome alloys resist molten alkali nitrates very well. I would imagine that the designers of this plant have optimised the piping for the salt mixture in use, using the usual lifetime/costs tradeoffs in corrosion engineering. (The same tradeoffs that make it much cheaper, for instance, to make a boat out of steel with sacrificial anodes than out of stainless steel or aluminum)

  • Aren't the posts subjected to revision before being published? Please be consistent with your units! Who can read this mess of standard and non-standard units? Fahrenheits and then square metres and then miles. What the fuck?
  • Thermal storage? No. (Score:3, Interesting)

    by goodmanj (234846) on Friday July 23, 2010 @09:22AM (#33002074)

    TLDR: Molten salt has zero benefit as a nighttime storage system. Ordinary boiling water is a better choice by a factor of >500.

    I can't find good data on the heat capacity of the particular salt used in this system, but heat capacities for salts in general are around 1 J/kg-K. []. If you're dealing with a temperature change of 700 K, that means each kg of salt can store around 700 J of heat. To store enough heat to power a typical American household overnight (1 kw x 12 hours), you'd need 61 tonnes of salt.

    Now, most power plants use water as the working fluid. The latent heat of vaporization of water means that steam stores *at least* 330,000 J per kg of water in the phase change alone, plus additional specific heat if the steam is stored above the boiling point, which I'm too lazy to calculate.

    That means that plain old ordinary water, already used in every thermodynamic power plant ever made, is at least 500 times better at storing heat than salt is.

    • Re: (Score:3, Informative)

      by goodmanj (234846)

      Oh god dammit. Units failure, I'm off by a factor of 1000, and boiling water and high-temperature salt are actually about equal in terms of heat storage.

      Mod parent down.

Man is the best computer we can put aboard a spacecraft ... and the only one that can be mass produced with unskilled labor. -- Wernher von Braun