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  (Source: Treehugger)

  (Source: Adhikara Ishtiyaq)
Solar power, available 24-7? It sounds too good to be true, but some believe it can be done efficiently

As a new way to store and release solar energy, U.S. state Nevada and Sicily, Italy will both use molten salt to operate solar thermal plants. 

The use of molten salt in solar thermal plants has been done before – Alcazar de San Juan, Spain obtained a molten salt plant in November 2009. Also, in May of this year, the U.S. Department of Energy gave 13 companies $62 million for the development of thermal solar technology, and a few of them are considering the use of molten salt.

SolarReserve, a Los Angeles-based solar thermal company, developed the technology to make this system possible. Large heliostats will be used in the two separate plants in order to reflect sunlight onto pipes that carry a molten salt liquid, which has potassium and sodium nitrates in it. The liquid salt then absorbs the heat from the sunlight in order to make high-pressure steam, which powers the turbine and produces electricity. 

What makes this technology useful above and beyond other solar thermal plants is that the molten salt holds the heat it absorbs up to 24 sunless hours, which means the plant can use it's heat for an extended amount of time increasing operation hours. Once the molten salt has cooled, it recycled back into the system where it will be reheated and used once again to create steam, restarting the process all over again. 

Nevada's plant, the Crescent Dunes Solar Energy Project, will be a 100-megawatt plant and is expected to generate 480,000 megawatt hours of electricity annually. The U.S. state received approval for this project by the Public Utilities Commission of Nevada on Thursday. In addition, SolarReserve's subsidiary, Tonopah Solar Energy, signed a power of purchase agreement with Nevada Energy that will last 25 years and will provide energy from the plant.  

"We are extremely pleased that NV Energy received approval from the Public Utilities Commission of Nevada to move forward on this important energy project," said Kevin Smith, CEO of SolarReserve. "Solar energy, and particularly solar energy with thermal storage, can help meet Nevada's renewable energy objectives while at the same time stimulate the economy by creating solid jobs in the state."

The plant is expected to create 450 construction jobs, 45 permanent jobs for plant operation and 4,000 indirect jobs for local service providers and suppliers.  

On the other hand, Sicily's solar thermal plant, named Archimedes, has already opened two weeks ago by the European energy company Enel. It was placed in the town of Priolo Gargallo in Syracuse, Sicily and will be a 5-megawatt plant.

While both solar thermal plants will use molten salt to power them, Sicily's plant will not work on molten salt alone. The liquid salt will work in "conjunction" with a gas-powered electricity plant that was already in use prior to the molten salt technology. The molten salt will produce the steam exactly the way it will in Nevada, but the difference is that the steam will power turbines in the gas plant and "continue to use gas as a supplement." 

Sicily's "Archimedes" has already been running on molten salt for two weeks, and no reports have yet provided an expected completion date for Nevada's solar thermal plant. 

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By InternetGeek on 8/1/2010 7:26:24 PM , Rating: 2
A similar technology is in use in Spain sucessfully. As usual power is not cheaper than other sources (nuclear, oil/gas, etc); however this is still a first generation technology.

I like the fact that it provides baseline. And in the case of a source distruption (as in galactic cataclysm that destroys the sun) I think we'd be pretty much done for.

It also doesn't use some strange material and has lots of room for improvement (better panels, etc).

I would like to see how it performs during cloudy days though. Solar panels do not perform well, but this is based on reflection. Even with little sun light many mirrors should still be able to melt the salt.

RE: Spain
By heffeque on 8/1/2010 8:55:46 PM , Rating: 2
Actually some times they actually have to set some mirrors to reflect outside the objective because it can get "too hot" in some sunny summer days.

RE: Spain
By bhieb on 8/2/2010 10:23:56 AM , Rating: 2
Although I do like the tech, as you said the same can be had for cheaper using traditional sources. Since Spain is pretty broke right now, I'd bet they wish they had some of the money back.

Don't get me wrong I'm not saying that this caused the bad economy (it was a housing bubble much like ours), rather that in hindsight it was not money well spent. Oh well glad the R&D was done on someone else dime so we can benefit from the technology now.

Grammar Alert...
By DougF on 8/2/2010 11:19:07 AM , Rating: 2
On the other hand, Sicily's solar thermal plant, named Archimedes, has already opened two weeks ago by the European energy company Enel. It was placed in the town of Priolo Gargallo in Syracuse, Sicily and will be a 5-megawatt plant.

Really? You couldn't just say:

On the other hand, Sicily's solar thermal plant, operated by the European energy company Enel, opened two weeks ago. The 5-megawatt plant is located near the town of Priolo Gargallo, in Syracuse.

I'm pretty sure 5min of research would tell you Enel didn't put the plant in Priolo Gargallo, but just south of the town (comune? is that another way to say "town/community" in Italian, or is it really a commune? I'm not very good with Italain and Google doesn't translate their home page very well) in conjunction with a gas-fired power plant.

Sorry folks, I couldn't resist...

RE: Grammar Alert...
By DougF on 8/2/2010 11:21:47 AM , Rating: 2
O.K., bad on me, I didn't read further and see where Tiffany wrote about it being in conjunction with another plant. "Self-slap"

RE: Grammar Alert...
By karielash on 8/4/2010 11:02:43 AM , Rating: 2
Priolo Gargallo is a Municipality (Comune), and the Power Plant is in that Municipality. Therefore the power plant is in Priolo Gargallo.

Solar power, available 24-7?
By Wy White Wolf on 8/2/2010 11:34:53 AM , Rating: 2
Not even close.

100 megawatt plant times 24 hours a day times 365 days a year would be 876,000MWH annually. The 480,000 MWH annually claimed in the article works out to ~55% availability. Far cry from 24/7, but better than solar PV.

By FITCamaro on 8/2/2010 3:59:49 PM , Rating: 2
That's still a best case as well. I also notice the cost of this 100MW plant is strangely absent.

More advantages
By Shadowmaster625 on 8/2/2010 1:49:33 PM , Rating: 2
As you know, any generator is most efficient when it is running at a constant load for which the generator is specifically designed to run at. Unfortunately, many generators run at a load that is above the point where they are most efficient. (Sort of like most cars drive down the highway faster than their most efficient 55mph.)

By using molten salt we are able to run a generator much closer to its most efficient load for 24/7, rather than peaking during the day and running very inefficiently, and then not running at all at night. The efficiency gains to be had here are very significant. (Yes, I am a major proponent of molten salt.) Also, given modern weather forecasting technology, we would be able to adjust the loading based on the expected weather for the following days. In other words, if its going to be cloudy tomorrow, we run the generators more slowly today, where they are more efficient. As a result, we generate even more overall kilowatts than we otherwise would. $$ And not to mention it creates a whole new engineering field and new business opportunities. Temporal Meteorological Power Optimization!

Another great thing about molten salt is that it can easily be integrated into a coal fired process. So a solar power plant could burn coal to keep those generators running at max efficiency both at night and on cloudy days. This gives you the greatest return on capital, so I expect this sort of coal/solar integration to become commonplace.

RE: More advantages
By FITCamaro on 8/2/2010 4:01:48 PM , Rating: 2
Not all cars are most efficient at 55 MPH. It depends on gearing.

By KillerNoodle on 8/1/2010 8:39:48 PM , Rating: 2
Nothing new to see here....keep moving....

Many places have used salt to balance heat over the daily, cyclical changes.

Don't remember where but there was a house in New England which had a glass shell around it with a moat of salt between the glass and house. During the day the salt would absorb heat and at night it would release it.

Recycling is good though.

By mattclary on 8/2/2010 12:59:41 PM , Rating: 2
As a new way to store and release solar energy, U.S. state Nevada and Sicily, Italy will both use molten salt to operate solar thermal plants.

Solar 2 was using molten salt in 1995.

And also
By YashBudini on 8/3/2010 9:34:56 PM , Rating: 2
A good place for the mafia to get rid of dead bodies?

By Murloc on 8/2/2010 7:56:54 AM , Rating: 1
which means the plant can use it's heat for an extended amount

how the hell did you get a writing job if you still do these basic errors.

By Akdor 1154 on 8/2/10, Rating: -1
RE: grrr
By FaaR on 8/2/2010 8:21:08 AM , Rating: 2
Don't get all bent out of shape over a typo, mmkay?

I suppose your own spelling and grammar must be absolutely flawless to warrant such an outburst... ;)

RE: grrr
By bhieb on 8/2/2010 11:09:39 AM , Rating: 2
True but is he getting paid to write? As a professional writer, DT should be held to higher standards. What is odd is that on AT if there is a typo pointed out in comments, the author usually thanks the commenter and fixes it. Here, at DT the author's just don't seem to give a crap, and instead of thanking the user for doing what is their job (aka proofreading), they either just fix it quietly or downplay it much like you have.

As users we all have typo's, it is after all an informal comment section. As a professional the author should try to avoid them, and if they are found have the courtesy to thank the individual that found your error. It would help diffuse some of the hostility at DT when a typo is found.

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