World's First Molten-Salt Solar Plant Opens 316
Posted
by
timothy
from the entire-mountain-is-covered-with-snow dept.
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."
Sounds cool, but... (Score:3, Insightful)
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?
Re:Sounds cool, but... (Score:5, Insightful)
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.
Re:Sounds cool, but... (Score:5, Insightful)
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.
Re: (Score:2)
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!)
Re: (Score:2)
Ok, it's not 30 square km. I spotted it myself after I hit 'send'...
Re: (Score:3, Informative)
173.2m by 173.2m.
square 0.1732 km
0.03 km - Doh!
Base load power is mostly bullshit (Score:5, Informative)
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.
Re:Sounds cool, but... (Score:5, Interesting)
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).
Re:Sounds cool, but... (Score:5, Insightful)
Re:Sounds cool, but... (Score:5, Funny)
I think it would be better for harvesting solar power. Producing solar power in the Sahara could be little more destructive than hoped.
Re:Sounds cool, but... (Score:4, Informative)
Re:Sounds cool, but... (Score:5, Informative)
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.
Re:Sounds cool, but... (Score:4, Funny)
At least until the Mafia figures out a way to block out the sun.
Ooooooh. (Score:4, Funny)
I thought the headline said morton-salt.
Re: (Score:2, Funny)
When it rains, it p.... OH GOD! It's melting through my skin!!!!!
Liquid Fluoride Thorium Reactors (Score:3, Interesting)
You're forgetting something (Score:5, Funny)
Ahhh! Nuclear! Ahhh! It'll explode and kill us all and poison the planet for a bejillion years!
Re: (Score:2, Insightful)
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I truly hope you're right (Score:2)
Re: (Score:3, Interesting)
Isn't the idea to spread dependence away from one source ?
Re:Liquid Fluoride Thorium Reactors (Score:5, Insightful)
Re: (Score:3, Insightful)
Which is why the externalities of pollution need to be accounted for via regulation
Re:Liquid Fluoride Thorium Reactors (Score:4, Informative)
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.
In how long? (Score:2)
On one version of your argument, the Neandertals went extinct because one a
Re:Liquid Fluoride Thorium Reactors (Score:5, Insightful)
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)
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
Re:Liquid Fluoride Thorium Reactors (Score:4, Insightful)
I wish it would hurry up and come true instead.
Should improve efficency! (Score:5, Informative)
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)
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)
The article isn't specific about *what* salts they're using,
This one [sicilyguide.com] does: the same as Solar One/Two - a mix of sodium/potassium nitrate.
Re: (Score:3, Interesting)
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)
(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)
Re:Should improve efficency! (Score:4, Informative)
30000 sq. m = 0.03 sq. km
Re: (Score:2)
Oh, duh! That's what I get for reading slashdot at 7am.
So we're talking a patch of ground, say, 300m by 100m. That's not so bad...
Re:Should improve efficency! (Score:5, Informative)
30 square kilometers of land for 5 megawatts output? To me that doesn't seem very viable...there's single wind turbines with more output than that.
30000 sqm does not make 30 sq km. Let's try some computations of achieved efficiency:
Minimal modelled efficiency: 27%. - I'd say definitely a decent efficiency.
Can they improve? Keeping into account the last step of energy transformation (thermal->electric) operates between say 825 K (molten salt) and 400 K (water at 120 C - moving the turbines) and assuming a perfect Carnot cycle, the maximum efficiency achievable would be lower than 52%.
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You have done toe conversion wrong.
Its not 30 square Kilometers, it is a thousandth of that size - 30,000 Square meters.
30 Square Kilometers means 30 * 1000 * 1000 meters, or 30,000,000 Square meters - not 30 square kilometers.
Re: (Score:3, Insightful)
Er, I ingested more than 400mg of NaCl on my lunch today.
True, my government's recommendation is to ingest less that 6000mg per day, but it's manufacturers of processed food not renewable energy who threaten that.
Not that these heat storage systems use Sodium Chloride, I think they actually use Nitrates (i.e. fertilizer).
Other reasons to use salt i.s.o. oil (Score:2)
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.
Re: (Score:3, Interesting)
I guess you could have (redundant) electric heaters for that
Or change the salt mixture, maybe something that goes "sludge" instead of becoming solid
Errr Barstow had a molten salt plant in the 90s (Score:5, Informative)
Re: (Score:3, Informative)
Errrrr....
France had one of these, inaugurated in 1983, called "Thémis".
http://www.outilssolaires.com/pv/prin-centraleB.htm
http://fr.wikipedia.org/wiki/Centrale_solaire_Th%C3%A9mis
(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
Re:Errr Barstow had a molten salt plant in the 90s (Score:5, Informative)
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)
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)
Re:Desalinization? (Score:5, Insightful)
No, once the plant is charged with working fluid, you don't need to add any more.
It's really not competitive yet (Score:5, Informative)
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.
Re: (Score:2)
Re:It's really not competitive yet (Score:5, Funny)
Can you spell the words; Prototype, Low-Maintances and Zero Emissions?
Well, I can, but...
Sorry, couldn't resist.
Re: (Score:2)
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!
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Re:It's really not competitive yet (Score:5, Insightful)
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.
Re: (Score:2)
Yep, and to make mirrors you need........
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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.
Re:It's really not competitive yet (Score:5, Insightful)
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.
Re: (Score:2)
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.
Re: (Score:2)
Name the full scale plant that was built so quickly in recent years.
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
You forgot something... (Score:3, Informative)
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)
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.
Re: (Score:3, Interesting)
While that is not hard data, this plant has been in the works for about 20 years under several different governments. Sicily means that a large, if not the largest, part of the money went to Mafia bribes and related costs.
Point in case, the southern half of the cross-italian highway costs _more_ than the northern half even though there are literally dozens and dozens of tunnels in the North.
The guy who started it all became fed up with waiting and built a few smaller-scale plants in Spain within a few years
Re: (Score:3, Interesting)
I saw a documentary not long ago. They talked about the fact that one of our nuclear subs hadn't needed to be refueled in twenty plus years.
Nuclear is extremely cost effective so long as scaremongering twits stay out of the political spot light. As such, the reason insurance caps exists is because anti-nukers were specifically attempting to create an environment where nuclear is uninsurable. Such scare mongering is literally why "NUCLEAR MRI" was simply renamed to "MRI". Otherwise people would literally ris
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The $4-6 includes waste disposal. Actually what I'm ignoring is the cost of decommissioning the plant and that's because I have no way of estimating how much this mirror farm will cost to decommission.
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If you reprocess the nuclear fuel and use breeder reactors you can power fission reactors for a few hundred years. At the end of it you end up with small amounts of hot material that remains dangerous for a couple hundred years. Not the couple eons of the current system of fueling reactors. And we're talking about hundreds of GW's of power for a couple hundred years with not a lot of waste.
We know what the costs are and as it stands, nuclear is really best form of energy for base load generation we have
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Most American nuclear engineers have a low opinion of nuclear because of the once-through policy. Everyone else in the world uses their nuclear material up a lot more and store just the waste, the US stores perfectly good fuel because it might be a "strategic asset" one day. As such, nuclear in the US is legally required to be inefficient by the highest law in the land. Which is amazing, when you consider how much it still kicks butt.
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What waste? If there is something coming out of the plant that is radioactive, then it's not waste and can be refined and used as fuel.
Ideally you'd have uranium coming in and lead going out. But stupid laws prevent that stateside.
Proof of concept? (Score:5, Funny)
its much cheaper in reality (Score:2, Informative)
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.
http://www.dlr.de/tt/Portaldata/41/Resources/dokumente/institut/thermischept/Solar_Thermal_Energy_Storage_Technologies_Hannover2008.pdf [www.dlr.de]
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.
Sim
Come on.. (Score:5, Insightful)
What's this Fahrenheit rubbish?
Re:Come on.. (Score:5, Funny)
It is a German temperature scale used between the years of 1724 and 1742, which is the current era for all US science :-)
First to use Molten Salt, Bull. (Score:2)
http://en.wikipedia.org/wiki/Solar_Two [wikipedia.org]
Solar Two used molten salt, a combination of 60% sodium nitrate and 40% potassium nitrate, as an energy storage medium
It's not the first (Score:2)
technically, it's far from being the first. It may be the first commercially operating one though
the first is :
http://en.wikipedia.org/wiki/Themis_(solar_power_plant) [wikipedia.org]
Oh yeah, 3 miles of molten salt piping! (Score:3, Informative)
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)
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)
Please get your units right! (Score:2)
Thermal storage? No. (Score:3, Interesting)
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. [engineeringtoolbox.com]. 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)
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.
Re:Already done? (Score:5, Informative)
Re: (Score:2, Interesting)
5MW? Its sad that one HV pump on a process plant will use all of this. Miners should really have to purchase some of their power from renewable energy. It will stop them(us) from blatantly wasting power because its cheap.
Re:Already done? (Score:4, Interesting)
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A 5MW windmill can be up and running for about 1.5M euros
Do you happen to have a source on that? I know that at the moment it's like $1.3 per , but last I heard wind turbines were running $2/watt and up.
So I might believe 5M, but not less than a third of that.
60M for 5MW is 12($15.60) per watt, which is kinda, sorta, acceptable for a test plant. But I'd say costs would have to come down nearly an order of magnitude for this to be truly economical.
I'd also want to know if that 30k m^2 can actually RUN that plant at 5MW all day and night, on average. What sort o
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Someone needs to explain me how you can create 5 megawatts with only 30.000 square meters. That would make the plant produce 160 Watts/sq. meter on average.
Theoretical maximum efficiency for any kind of solar plant (on the equator) is less than 200 Watts per square meter (to give you an idea, in southern florida it drops below 150, and this is north of florida). That would make this plant over 120% efficient (at least).
Unless, of course, you know, they're lying and it's like 5 megawatts peak capacity at 12h
Re:Already done? (Score:5, Informative)
Re:Already done? (Score:5, Informative)
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.
Re: (Score:3, Interesting)
Excellent point. Except, your numbers are wrong. The peak insolation in Sicily is over 1 kW/M^2 at high noon on the equinox. So, that would mean they are horribly inefficient if 5 MW was their peak. At any rate, 250 Watts is the average for the entire world, for the entire year. Sicily isn't that far north...I believe its average insolation (again averaged over an entire year, not just during daylight) is around 180-220 Watts. (Italy is farther north than Florida, you're right, but latitude isn't eve
Re:Already done? (Score:5, Informative)
"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"
Re:Conversions... (Score:4, Informative)
30,000 square meters = 0.03 square kilometers
Re: (Score:2, Funny)
Try again, smart guy.
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Except 30,000 square meters is about 0.03 square kilometers according to Google.
It comes out to be about 7.5 acres, or 0.0115830648 square miles.
18.5 square miles would be quite large and cover an area slightly larger than 4 miles by 4 miles. That would be quite large.
Re: (Score:2)
Whoa there, buddy! I know a meter is large, but not that large! 30,000 sq m is the area of a field that is 150 m by 200 m. Which is about 500 feet by 660 feet.
Back of the envelope power cost calculation (Score:5, Interesting)
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.
Re:Back of the envelope power cost calculation (Score:4, Insightful)
Euro 60M is about 50 years payback at that rate. Or 25 years if it's 20c/kWH.
As the plant buffers the energy to use it at night, I'd be inclined to use a 24 hours/day * 5 MW.
Assuming that all the other calculations are correct, this would mean approx 21 years for the payback at 10c/kWh, or 10.5 years at 20c/kWh.
Re:Back of the envelope power cost calculation (Score:4, Informative)
Re: (Score:3, Insightful)
60 years is ok, so long as the EROI is good. Power stations aren't something you're just going to get sick of in 60 years and want to get rid of. Also, for a prototype plant, I'd expect there to be a lot of waste of both manpower and horsepower in building the thing that would get trimmed over time if it was at all profitable to do.
Re:Back of the envelope power cost calculation (Score:5, Funny)
So if anything, the parents estimates are wildly optimistic
Yeah, you should definitely take those numbers with a grain of salt.
Re: (Score:3, Informative)
and not *way* out of line compared to other power sources like coal plants, but it's not aggressively cheap either.
First the whole idea of melting salt and storing it is to provide a steady energy capacity. The 5MW is steady output 24/7. Not the 10 hours you assumed. The article does not say so explicitly. But the peak solar output is slightly over 1 kW/m^2. The peak production capacity would be 30 MW for an hour or so at around noon. Accounting for the angle of incidence, cloud cover, nights, storage losses etc averages the output to 5 MW steady. So the revenue is $12000 a day at 0.1 $/kWh. or 4.4 m$ a year. works out
Re: (Score:3, Informative)
Tax might be cheap in Spain, but Sicily is in Italy.
Re: (Score:2, Interesting)
These numbers really don't add up. The article cites 2,100 tonnes of oil equivalent (which works out to about 3 MWth) and another cites 10 million kw-hrs of electricity per year (which works out to about 1.1 MWe). This would seem to imply the plant is about 3 MW thermal on average (and perhaps the extra 2 are only counted during the day). 30,000 square meters of reflectors perfectly aligned would generate about 30 MW thermal maximum at the best time of the year. Counting for night, seasons, etc., perhaps it