World's First Molten-Salt Solar Plant Opens 316
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."
Liquid Fluoride Thorium Reactors (Score:3, Interesting)
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.
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:What is the rating? (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 could be diluted to 3 MWth.
Why are they citing all of the different numbers in CO2 equivalent, oil equivalent, and equivalent kw-hrs instead of actually saying what the actual electrical output is going to be on average?
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:Already done? (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)
Re:You forgot something... (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.
Finally, while this technology is not old, industry-scale application of it is. So there are one-time and pioneer costs involved.
So yah, this plant may not have been cheap; but the cost is certainly inflated due to various circumstances.
Re:You forgot something... (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 risk their health to avoid the scary "nuclear" word. When scaremongering has been so extremely abused, the government does have an important role to play for such critical infrastructure (power, not medical). To be against this means you should also be against FDIC insurance, FEMA, and even the US military; including the Coast Guard and National Guard.
This is actually one of the areas where the government should shoulder part of the burden; especially the US government. The US military is the largest single consumer of oil in the world. As such, they force the price higher for all of us. Its not unreasonable for them to shoulder some of the potential financial burden such that it then allows for the price of electricity to be not only significantly lower and safer, but also extremely reliable.
As an interesting side note, Obama could have actually stimulated the economy with massive military energy modernization projects. Some estimates suggestions as much as 50% can be saved. Which for the US is EXTREMELY huge amounts of oil and money, especially when we have active, deployed forces. You need to keep in mind, much of the US military is still running on turbines and diesel engines designed and built during the late 50s to the 70s. HUGE strides in efficiency and power have been created since then. Best of all, such programs would stimulate almost all levels of the economy (white to blue collar) while making HUGE strides to decrease our dependence on foreign oil and lower the general public's price at the pump. Good thing we got more of the same, with one exception, they called it, "change."
Re:I truly hope you're right (Score:3, Interesting)
Isn't the idea to spread dependence away from one source ?
Re:Other reasons to use salt i.s.o. oil (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
Re:Should improve efficency! (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)
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:Already done? (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 everything. The average insolation in Florida is the same as the average insolation in the southern half of Oregon, maybe lower).
So, if they found a particularly sunny bit of Sicily, which I think is rarely cloudy as it is, an average insolation of 220 is probably believable. That puts it at 70% efficiency. That's kind of high, considering that they are doing solar energy to heat salt to heat water to turn steam turbine. But, it's not impossible. Plus, if their 5 megawatt figure is only the average when it's active, and it's inactive between midnight and dawn, that puts it more like 50% efficient, which is totally believable.
Re:"Salt" != "NaCl" (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).