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."
TOO MANY PUNS!!! (Score:3, Funny)
We get it already, heat jokes. Knock it off!
Re:TOO MANY PUNS!!! (Score:5, Funny)
It took me 4 reads just to find the two puns that you appear to be so steamed over.
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Re:TOO MANY PUNS!!! (Score:4, Funny)
You RTFA? I’m sorry, but I’ll have to take that claim with a grain of salt.
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Re:TOO MANY PUNS!!! (Score:4, Funny)
Way to pour salt on his wound.
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Careful, you'll make him hot under the collar. ;-)
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Careful, you'll make him hot under the collar. ;-)
This kind of flamebait is an assault on our sensibilities.
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Let's all just simmer down now.
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You make a saline point.
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Well, my goal was to be crystal clear. All these puns, makes you want to shake your head.
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Stop peppering him with bad puns. It's thyme for serious discussion.
Re:TOO MANY PUNS!!! (Score:5, Funny)
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If you’d add a bit of butter you’d make the bitter battery better.
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I don't care about the heat puns, I just want to know if all of that sodium will cause high steam pressure.
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You sound a little hot under the collar. Maybe you should chill out.
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I'm going to have to rub salt in your wounds, which will probably just boil your blood more.
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I thought Jon went over this already...you're not punny!
http://www.thedailyshow.com/watch/mon-november-29-2010/you-re-not-punny [thedailyshow.com]
Fahrenheit? (Score:2, Informative)
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Going back to the original topic of how hot the salt is .. if you stuck one hand in molten salt that was 810.777 kelvin and the other hand in molten salt that was 800 kelvin could you tell the difference ?
To mere mortals 800 kelvin or 1000 Fahrenheit is perfectly acceptable :-)
Don't know where you got that from... (Score:2)
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... :-)
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According to my experience [google.com] and my digital thermometer salt melts at 800 Celsius.
Of course, my thermometer has a 0.5% +/-1 digit accuracy, so that's consistent with the 801 degree theory ;)
Re:Don't know where you got that from... (Score:5, Insightful)
I didn't see anywhere in the article where they say that Sodium Chloride (i.e. table salt) was going to be used. I thought power plants typically used a different kind of salt (Sodium Nitrate?) to store thermal energy?
Since the diagram in the article shows the "cold" tank being at 550 degF, then they must not be using sodium chloride or it would be a solid in that tank.
Re:Don't know where you got that from... (Score:4, Informative)
home use? (Score:3)
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Home use? Sure, here's your order of molten french fries...
Re:home use? (Score:4, Insightful)
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.
Re:home use? (Score:4, Informative)
1 horsepower isn't enough to run a house. And smaller heat engines are inherently less efficient than larger ones. And a smaller reservoir will loose heat faster than a larger one that has proportionally less surface area.
You still don't want the thermal mass in or near your house. A thousand degrees is enough to make paper and wood instantly catch fire. It is enough to melt aluminum and damage commercial bricks and concrete. It is enough to cause 3rd degree burns in seconds.
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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.
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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.
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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.
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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
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Fuel is free. Capital and maintenance costs are something that another power plant would have, in addition to fuel costs.
Re:home use? (Score:4, Insightful)
Efficiency is going to directly impact the size of the collector you need for a given application, and thus cost. So yes, efficiency is quite important in solar power, as it is in every other renewable energy source. It is less important than with other energy sources, yet still quite important. And it could easily mean that below a certain size of application, the technology is economically infeasible.
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Collector size has nothing to do with cost.
Of course it does. A bigger solar concentrator is more expensive than a smaller one, and a bigger sugar cane field is more expensive than a smaller one.
You can't directly compare the efficiencies and costs of wildly different technologies, but that's a vastly different statement than saying efficient does not matter! If you are converting sugar cane with an efficiency 1/10th of someone else, that is going to mean you're growing 10 times as much sugar cane for the
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Efficiency directly affects cost.
If you're trying to argue that modifying some technology to make it more efficient will necessarily make it cost less per unit of energy, then that is patently false. I can make any thermoelectric device more efficient by making it out of diamonds and gold, but that won't make it cheaper. Any technology with a different efficiency is a different technology, full stop. If all we care about is cost/energy, there are lots of factors more important than efficiency to consider.
smaller turbines are less efficient
With CHP systems, turbine efficie
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If you're trying to argue that modifying some technology to make it more efficient will necessarily make it cost less per unit of energy, then that is patently false.
Why even have a conversation with someone who only sees the possibilities that "efficiency doesn't matter" or "increased efficiency necessarily reduces cost regardless of mechanism" and argues against one idiotic half of this false dichotomy to prove the other?
Any technology with a different efficiency is a different technology, full stop.
Nonse
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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
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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.
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Figures... (Score:2)
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Not the first... (Score:5, Informative)
Only if you ignore Solar II that ran from 1996 to 1999....
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not forgetting Helios 1
Really really bad idea (Score:5, Funny)
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They are going lend some salt too. (Score:3, Funny)
Silicon Production (Score:4, Interesting)
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.
http://en.wikipedia.org/wiki/Silicon#Production [wikipedia.org]
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Yes of course. It could even be used to create mirrors for more solar towers. The whole damn thing could be self-replicating.
It's a tower? (Score:2)
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?
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Wouldn't it be safer to have that molten salt at ground level?
Not if you wanted to get within 100 feet of the central collector during the day.
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Did you look at the picture? How do the mirrors reflect the light onto something on the ground and still be able to have more than one row of the mirrors?
Re:It's a tower? (Score:5, Informative)
Besides that it is also a "trivial geometry" case. If you assume the collector constant the more obtuse the angle of reflection requires a bigger mirror. If the receiver is low, you end up with an obtuse angle out of necessity. The higher it is, the easier to obtain that magic 90 degrees that minimises the mirror size and from there cost and everything else.
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Because mirrors are easier than a ginormous magnifying lens.
http://inhabitat.com/wp-content/blogs.dir/1/files/2010/12/Rice-Solar-Project-CA-2.jpg [inhabitat.com]
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God, that thing looks like it's going to be used to power ARCHIMEDES II
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The salt isn't kept in the tower, that's just the thermal energy receiver.
Re:It's a tower? (Score:5, Funny)
It would drive the Fundies nuts, that they could then equate solar energy with Sodom and Gomorrah.
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Yes, lord knows the solar energy people don't want to literally make a pillar of salt.
It would drive the Fundies nuts, that they could then equate solar energy with Sodom and Gomorrah.
Not only that but I prefer my utility bill as it is: measured in kwh not in Lot's Wives.
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Heat retention for how long ? (Score:5, Interesting)
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)
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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.
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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.
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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.
Re:Heat retention for how long ? (Score:5, Interesting)
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.
Re:Heat retention for how long ? (Score:5, Interesting)
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 [beyondzeroemissions.org] plan. Their modeling uses a different demand profile, one scaled to a proposed 2020 level after compensating for growth, electrification of cars etc.
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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.
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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
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It doesn't have anything to do with the amount of heat loss. That just affects sizing. Heat pump efficiency depends on the temperature differential between outside and inside.
And I'm including the efficiency of electricity generation via fossil fuels in my statement. That should be obvious, since the thermodynamic efficiency of the heat pump alone can be upwards of 400%. Also, comparing the efficiency of renewable energy generation to fossil fuels is pointless.
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According to one report, Proposed 150 MW Solar Plant Would Store 7 Hours [treehugger.com]
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.
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I don't think that oxygen outgassing would be an issue, since the salt is going to be in a pressurized system.
Don't count on a pressurized system staying pressurized. I'm sure they've figured how to deal with the issue, but it is a risk.
jamie and adam said "busted" (Score:2)
I though mythbusters proved that this was impossible.
They even reported their findings to the president.
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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.
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This will use heliostats.
Not twitchy third graders.
Adam & Jamie have a bit of troll in them (Score:4, Insightful)
Over 1000 (Score:2)
Wake me up when it's over 9000.
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FTFY
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Meh, it's just a broken scouter, nothing to wake yourself over.
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Whoosh.
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Water holds a lot of calories per degree, relatively speaking.
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You’re converting heat to mechanical energy, so you want something that holds a lot of heat.
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Steam generation is used because utilities have staff and equipment to maintain steam generation facilities already.
There are proposed systems with rankine engines, sterling engines, and IIRC some ammonia based contraption, but the utilities like them some good ole steam.
Someone Will Sue (Score:2)
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".
Modify this (Score:3)
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Their mascot? The Molten Salt Girl
And if they do this in situ in a salt mine, then what could go wrong?
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Answer: (Score:5, Funny)
What happens when a bird flies too near to the tower?
A republican will pretend to care about the environment long enough to sound like a complete asshole.
Re:Answer: (Score:4, Insightful)
Well, the tower itself will be ridiculously hot, so I don't think many birds would voluntarily get near it. It's not like you cross a threshold and suddenly fry, it's more like walking toward a large fire. You'll feel uncomforatble long before it's actually dangerous, and if you keep approaching you're probably doing your species a favor.
The energy reflected from the mirrors isn't inherently dangerous. In any given beam, you'll get twice the solar energy that is expected; the normal part fromt he sun plus the reflected beam. This won't be fun to stand in on an already hot desert day, but it's not like you're walking through a high-powered microwave beam or something.
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A bird dies.
Now take the time to go look up how many birds die from hitting high rise buildings every year. I'll maybe accept that windmills have an issuebut only because they are, by their very nature, positioned along common soaring and migration routes for many species. This is in the middle of the desert, with no special wind currents around it, the avian population is going to be as near to zero as you could hope for.
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right... as if that sunlight wasn't already going to be making the desert hot. This just changes the distribution of heat a little.
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Next time the sun comes, up, the salt's all cooled down, right?
TFA says it’s capable of producing electricity 24 hours a day, so presumably it doesn’t cool all the way down overnight.
Re:Doesn't thermal inertia work both ways? (Score:4, Informative)
It takes several days and nights of little to no sunlight for the salt to cool down enough to no longer be molten and useful.