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Largest US Power Storing Solar Array Goes Live
Lucas123 writes "A solar power array that covers three square miles with 3,200 mirrored parabolic collectors went live this week, creating enough energy to power 70,000 homes in Arizona. The Solana Solar Power Plant, located 70 miles southwest of Phoenix, was built at a cost of $2 billion, and financed in large part by a U.S. Department of Energy loan guarantee. The array is the world's largest parabolic trough plant, meaning it uses parabolic shaped mirrors mounted on moving structures that track the sun and concentrate its heat. A first: a thermal energy storage system at the plant can provide electricity for six hours without the concurrent use of the solar field. Because it can store electricity, the plant can continue to provide power during the night and inclement weather."
The plant doesn't really store electricity. It can however, store heated salts that can be used to generate electricity well after sunset.
So I'm not going to respond to the first post because it makes no sense. But I'll happily use the "first reply" spot, thank you very much, to actually say something. This $2 billion plant breaks down to close to $30,000 per home serviced. Seems a wee bit excessive, considering the average home electric bill in Arizona runs something like $200 (I researched the web for a few minutes to estimate this). Consider that installing a home solar system would run something like $10-$20k at most in a sunny place like Arizona (considerably less w various tax incentives). Looking like a bit of a boondoggle?
I did the calculations and it is around 1200 square feet per household that this project is powering. I'm not sure this type of land use could really scale.
Economics. You don't need nearly as much power between midnight and 6 (7? 8?), during which time the nukes and coal, which can't be throttled too much, will oblige. Designing heat storage capacity for around-the-clock is wasting money, at least in the current grid configuration and state of the tech.
Nighttime lasts longer than that.
Or more likely, they did some demand modeling and found some value that made the economic sense?
Electricity demand follows a predictable pattern, with the lowest demand between 10pm and 7am. If surplus power (to storage) were to transition from positive to negative in the early evening, then 6 hours of stored capacity might work out pretty well.
Yes, night is longer than the 6 hours mentioned in the story summary. But the story summary is a bit misleading.
That is six hours running at full capacity and also running entirely from the salt tanks. Neither of those conditions are likely to be true overnight.
Solar plants continue operating at reduced power during cloud cover and at night time. Even at times of reduced sunlight or at night there is still energy available. It does not need to run entirely from the salt tanks.
Secondly, nighttime is not peak usage hours.
The Solana salt tanks are about 740 cubic meters so they could probably store around 16TJ of energy. (For physics impaired, 1 joule per second == 1 watt.) That is a lot of power. Since it will mostly be relying on that stored energy at night and not running at full capacity, that stored energy could reasonably last through the night and on through a good portion of the following day.
//TODO: Think of witty sig statement
Technically nothing stores electricity except for super-cooled superconductors. Batteries "store electricity" in the form of chemical energy and even capacitors only "store electricity" as two charged plates. But I think we all know what they meant, that it was storing the potential for electricity.
Well after sunset?
Actually, when you read up on it, the storage capacity is exhausted shortly after sunset. 6 Hours max.
The efficiency falls off at low sun angles.
Sunset usually happens right at peak demand time, evening cooking, and late afternoon air conditioning.
Plus the site has high ground to the immediate west, sunset comes earlier for them.
Don't get me wrong, this is an impressive feat of engineering.
It was installed very fast, hacked out of prime farm land (or as prime as it gets in Arizona).
Google Maps Satellite view, with imagery dated 2013 http://goo.gl/maps/Qh7e5 shows nothing
but desert with truck roads laid out, and now they are up and running.
(Either that or Google is Playing Fast and Loose with image dates, because Google Earth shows the same
images but has a 2010 date on them)
Sig Battery depleted. Reverting to safe mode.
According to this it is a bit lower than that at about 94.2%. It is also a bit skewed by the fact that Seattle is close to mountain ranges with lots of valleys that can produce hydroelectric power. If you remove the hydroelectric, 89.8% the percentage drops to 4.4%.
Not everyone lives in an area that has plentiful hydroelectric generation. It is like Arizona touting how much solar based electricity they are generating and slagging Seattle for falling behind.
Meanwhile, I just shelled out $150 to buy one unit of the Seattle Aquarium solar panel array, which will reduce my annual already green electric bill by about $46 until around 2035.
That is only because you are getting credited for $1.15/KWh when electricity sells locally for $0,0672. You are being paid over 17 times the going rate. Making money due to tax incentives really skews the picture.
By the way according to Seattle Power the credits amount to "an estimated annual credit of almost $29 per solar unit"
I really don't think comparing a highly subsidizes small , 49 kW, project with al large commercial project is very valid at all.
Those education cuts really did hurt :(
The efficiency falls off at low sun angles.
It falls off faster for solar hotwater (like this plant) than for photo-voltaic.
You start drawing on your stored heat WELL BEFORE sunset, usually several
hours before sunset, because as I pointed out that is the peak demand period, and your
storage is exhausted in 6 hours, from the time you start drawing.
So maybe two or three hours after sunset your storage is exhausted.
Its a long time till sunrise.
Sig Battery depleted. Reverting to safe mode.
Not at large scales. PV does not scale well since if you double the size you only double the output. With thermal solutions of all types you can get a lot more heat out of stuff if you have a lot of hot stuff, so doubling the size gives you more than double the output due to an increase in the amount of energy you can get out. For example, if you don't have much steam you can only have a high pressure turbine but if you have a lot you can use the leftover steam that comes out of the first turbine and feed it into another with a different blade pattern to extract more energy and so on.
With thermal it has to be big so you have an enormous capital cost, but if it's big enough PV just will not match it. A 500MW PV array would cost a vast amount more than a 500MW thermal solution.
China 2007:
Tianwan Nuclear Power Plant
$3.3 Billion for 2,120 MW
$1.56 Million/MW
US 2013:
Solana Solar Power Plant
$2 Billion for 280 MW
$7.1 Million/MW
And we wonder why we keep having to borrow money from them?!
-- "Government is the great fiction through which everybody endeavors to live at the expense of everybody else."
Do you think they vent the steam to the atmosphere? Or do you think they might put it in a closed loop so they can reuse the water?
That was the turning point of my life--I went from negative zero to positive zero.
More storage capacity beyond peak hours probably isn't profitable. You want to sell electricity during peak because that's when you're getting the highest dollar value for your power. They probably designed the salt storage, so the total output of the plant was extended long enough to generate during those peak evening hours, and no longer, so baseload power takes over. The smaller your storage is, the less power you would put into storage and the more power you put into spinning your turbine.
Helps to read this in the voice of Sheldon.
Unfortunately, the link you posted doesn't mention the timescale for energy generation. I am under the impression that, like nearly all solar energy technology, that the primary cost is up-front installation, and maintenance costs are virtually zero thereafter. Using this assumption, we have
price / kWh = 2 (billion $) / (280 MW * t)
This gives t = (2 billion hours) / (280e3 * [100 * price in cents/kWh]) as the amount of time it would take to break even, or with some simplification, 81.485 years / P where P is the price in cents / kWh at which you wish to sell.
So if you were to sell at $.07 / kWh, it would ideally take 11.64 years to recoup investment (not taking into account additional costs and possible fluctuation in energy output). At double that price, it will take half the time. Either way, after that, I would say it's free energy. I don't see why there aren't more projects like this.
I have left slashdot and am now on Soylent News. FUCK YOU DICE.
Unless there are some nuclear reactions going on in there, I really don't think it is creating any energy at all, much less "creating enough energy to power 70,000 homes".
Solar energy converts energy from the nuclear reactions in the sun into electricity. Ok, conversion.
Hydroelectric - captures energy stored from gravitational potential energy and converts it using a turbine into electricity. Fine, conversion again.
Coal/Nat. Gas - takes stored energy in the form of deposits of oil, coal and natural gas and uses them to drive turbines... oh, you get the picture. Check, conversion of energy again.
Clearly nuclear energy reactions "create energy" - no wait, it's converting stored energy in the form of nuclear bonds into radiation, which can then be captured as a heat energy which can then drive a steam turbine turning into electricity.... uh... huh.
Conversion is all we can do apparently. We might want to thank/curse this lousy law [1] .... who's with me for repeal?!?
[1] http://en.wikipedia.org/wiki/First_law_of_thermodynamics
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No matter what the power plant... No matter how clean and low-impact it is, some moron ALWAYS has to find something stupid to bitch about.
Are you suggesting that a nuclear power plant would be a scenic tourist attraction, right at home inside Yellowstone? How about a coal power plant, along with the huge open-pit mine where the coal comes from? Or maybe some nice tar sands right outside your back yard?
If you don't like the fact that electricity generation is going to use some land, then cut the power lines coming into your house and live in the nice, scenic, non-blighted dark and cold.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
No, TFA clearly says that it can run for 6 hours after sunset, not six hours from some indeterminate point where the sun reaches a low angle before sunset.
Anyway, peak time is during the day, not the evening. It's when people need air-con and industry is active. In the evening it gets cooler and commercial buildings shut down.
You also make the classic mistake of judging the technology as if it were the only source of energy, which of course it isn't and was never intended to be.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC