Slashdot Mirror
World's First Molten-Salt Solar Plant Opens
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 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).
No sig. Move along - nothing to see here.
This one doesn't use salt, but we have had one very similar built here back in 2008. http://www.renewableenergyworld.com/rea/news/article/2010/07/areva-boosts-solar-supersteam-parameters-in-bakersfield
Life moves pretty fast; if you don't stop and look around once in a while, you could miss it. -FB
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.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
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," - http://en.wikipedia.org/wiki/The_Solar_Project
30,000 square meters = 0.03 square kilometers
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.
Ahhh! Nuclear! Ahhh! It'll explode and kill us all and poison the planet for a bejillion years!
Just because you're paranoid doesn't mean there isn't an invisible demon about to eat your face
Most articles talking about power generation are talking about electrical power, so I'd guess that.
Is this thing really cost-effective? If it's mostly a proof of concept it doesn't have to be, of course. I did a back-of-the-envelope calculation:
So it's shiny and renewable (assuming the plant lasts a long time and doesn't break down into rusty mirrors encrusted with stray salt leaks in a year or two), and not *way* out of line compared to other power sources like coal plants, but it's not aggressively cheap either.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
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.
How we know is more important than what we know.
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).
Baker's Law: Misery no longer loves company. Nowadays it insists on it
http://www.sigsegv.cx/
The Sahara may be a good place for mass production of solar power, but for a first-of-its-kind plant, keeping it close to home is a safer move (assuming the firsts involved don't put the neighbors at risk), in addition to needing to prove it is worth scaling up as opposed to other designs. This plant isn't wildly different, but given the cost of power plants and the demand for power, reliable and proven technology is a must before going beyond small-scale.
My webcomic
So in other words, they are seeing if this design is worth it's salt?
My webcomic
No, once the plant is charged with working fluid, you don't need to add any more.
What's this Fahrenheit rubbish?
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.
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.
Qxe4
The location of the plant in Priolo Gargallo is not that far from the Sahara. It's actually a little more south than the northernmost part of the Sahara in Tunesia, which is roughly 250 miles west of the plant. The solar radiation will be roughly equivalent, no need for undersea cables. Most importantly Sicily is a (slightly) more stable region that does not rely on income from oil like many of the North Sahara states.
the pun is mightier than the sword
Do you mean the one mentioned in the middle of this article
"Molten salts have been used in many industries as a high temperature heat transfer medium. The 'highest profile' use of molten salts in this regard is the Solar Power Tower near Dagget, California (excuse the pun). It uses a Sodium Nitrite/Nitrate mixture to absorb and store the sun's heat from the focus of many mirrors in the desert upon a central tower. The heat from the salt is then transfered via a heat exchanger to produce steam to drive a conventional steam turbine and generator to produce electricity from the sun for Southern California.3a"
"Last modified, 20 Nov 97"
--= Isn't it surprising how badly I spell ?
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.
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)
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
"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.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
I think it would be better for harvesting solar power. Producing solar power in the Sahara could be little more destructive than hoped.
Then you must know that solar plants are often stated to have a rating which is at peak output. And by peak I mean maximum you'll ever see on the ideal day in the ideal weather. For that matter, so is any other power plant -- the nameplate output is peak, not average.
BZZZT. The solar constant is 1360 W/m2 (minus atmospheric effects). With this, the efficiency is a reasonable 12%.
I suspect the number you have quoted there is the TMI of solar cells. This plant depends on thermal conversion, not liberating electrons across a silicon band-gap. I do respect your effort, and so will not request that you turn in your geek card.
"I guess the moral of the story is, don't paint your airship with rocket fuel." -- Addison Bain