www.newscientist.com/article/mg22229654-100-giant-solar-farm-uses-molten-salt-to-keep-power-coming/?ignored=irrelevant
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A 900 gigawatt hr per year
solar farm in Arizona is not photo electric, but heats oil to 400C to super heat steam to run a conventional turbine generator. The thing that makes it so useful is the ability of molten salts to store large amounts of heat and deliver back to the system when needed.Select to expand quote
Thick pipes run away beneath me like arteries, pumping oil out to the mirror field. There, it is channelled into thinner piping that runs right through the focal points of the mirror troughs, absorbing the heat of the Arizona sun until the oil reaches nearly 400 ?C. It then returns to the plant, where the oil superheats water vapour that spins two 140-megawatt turbines.
Six enormous white tanks surround the platform. Filled with molten salt, they can store enough heat to keep those turbines spinning at full capacity for 6 hours. The oil from the mirror field unloads its heat into the salt when the generators are at capacity. These tanks are what make Solana truly useful, not just producing carbon-free energy for
Arizona, but storing it for use whenever the grid operator needs it.
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A concentrated solar power (CSP) plant like Solana can play the baseload role because, unlike solar cells, it produces energy in the form of heat. Heat can be stored far more efficiently than electricity, as it does not need to be converted to other forms.
"The attractive thing about thermal storage, particularly with CSP, is that the round-trip efficiency is very high," says Charles Barnhart, a physicist at the Global Climate and Energy Project at Stanford University in California.
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More plants like Solana are due to come online in the next year or so. In California's Mojave desert, Abengoa, the company which built and runs Solana, is constructing an even larger plant. Globally, CSP capacity is set to roughly double over the next three years as more plants come on stream, and a further 10 gigawatts of CSP has been announced worldwide.
For now, Solana is one of the few of its kind. Albert says its flexibility has already proved invaluable. "In the wintertime when it's cold, we have a morning peak in demand at 6 to 7 am, an hour or two before the sun comes up. We'll ask Solana to store energy overnight and start up a couple of hours before sunrise. How cool is that?"
It sounds like you could even use it to smooth out conventional solar cells, and use the combination of the two.
Hopefully its economical and makes it here.
Select to expand quoteFormulaNova said..
It sounds like you could even use it to smooth out conventional solar cells, and use the combination of the two.
Hopefully its economical and makes it here.
It is economical, but has a low ROI
There was a group trying to get a pilot station installed in SA. It was completely planned and costed and ready to begin construcion.
Instead a gas powered facility that had a larger ROI was given preference
As they get the melting point of the salt lower this will be a great way for base load
You do realise that 900GWh /year means that the plant is ~10MW average output? How many deserts would you have to cover with mirrors to get a large chunk of baseload from solar thermal?
Are you sure, they say it's enough energy for 70,000 homes.
There's only 8,760 hrs in a year.
So isn't that .1GWh /hr meaning an average output of .1GW
I think that's 100MW output, assuming a thousand MW in a GW
Sorry, I'm out by an order of magnitude. That happens when you run on biofuels.
But, to maintain my sceptcal stance, isn't the current Renewables Energy Target something over 41,000 GW?
Obviously not an instant fix, but as somebody said we do have an awful lot of desert.
My point really I guess is that the common answer to renewables, is that they can't be stored, so it's not worth sinking any money into RD, we'll put all that money into geosequestration instead.
And have they even produced 1GW of clean coal power yet?
The sun is always shining somewhere on the planet, do we have to burn every drop of oil?
Unfortunately these things incinerate birds, the disintegrate in a puff of flames when they pass thru and... they are even attracted to them, it is thought the mirrors look like water
Select to expand quoteBeaglebuddy said..
Unfortunately these things incinerate birds, the disintegrate in a puff of flames when they pass thru and... they are even attracted to them, it is thought the mirrors look like water
Evolution will take care of that after a few years.
I think the areas these things are ideal for shouldn't have too many birds anyway.
Select to expand quoteBeaglebuddy said..
Unfortunately these things incinerate birds, the disintegrate in a puff of flames when they pass thru and... they are even attracted to them, it is thought the mirrors look like water
Perfect breeding habitat for the Phoenix
Select to expand quoteBeaglebuddy said..
Unfortunately these things incinerate birds, the disintegrate in a puff of flames when they pass thru and... they are even attracted to them, it is thought the mirrors look like water
Extensive research needs to be done how molten salt solar plant effect our fruit bats population. They ( fruit bats) will use to hang on horizontal pipes at the night and all will be incinerated when day come in.
But seriously that is at least one of the designed power plants that we could produce in Australia without the needs of expensive Photo voltaic solar cells that need to be imported.
All we need are pipes, sheet metal mirrors, construction steel, pumps, storage tanks.
Seems to be very doable by our own industry.
Beyond Zero Admissions did a study and they concluded that investing 47 billion a year for 10 years would see Australia at 100% renewables.
So thats 10 NBN's
I actually wrote to a few organisations suggesting that if 10% of all new superannuation contributions and 10% of all earnings from our super were invested we would achieve this target or close to.
So in ten years time our collective superannuation would own Australia's power supply.
If Tony wants a direct action plan there you have one.
The ones who would not like this is Big Coal and Big Gas
Select to expand quoteBeaglebuddy said..
Unfortunately these things incinerate birds, the disintegrate in a puff of flames when they pass thru and... they are even attracted to them, it is thought the mirrors look like water
So free energy and KFC? I'm sold
Select to expand quoteTheWolf said..
It is economical, but has a low ROI
There was a group trying to get a pilot station installed in SA. It was completely planned and costed and ready to begin construcion.
Instead a gas powered facility that had a larger ROI was given preference
Can you give a link to a reference for the economics?
About 400 of these would be enough to supply all of AUS. I wonder what they cost to build and operate?
Select to expand quoteHarrow said..TheWolf said..
It is economical, but has a low ROI
There was a group trying to get a pilot station installed in SA. It was completely planned and costed and ready to begin construcion.
Instead a gas powered facility that had a larger ROI was given preference
Can you give a link to a reference for the economics?
About 400 of these would be enough to supply all of AUS. I wonder what they cost to build and operate?
The cost of the replacement of Playford with two solar
thermal plants would be equivalent to 0.7c/kWh power price
increase if the cost were levelled across South Australian
electricity consumers. The cost of the replacement of
Northern with four solar thermal plants and ninety five
wind turbines would be 0.15c/kWh levelled across national
electricity consumers. This is a fraction of the 36% price rise
predicted by the AEMC to occur out to 2013
media.bze.org.au/Repowering_PortAugusta.pdf
dailycaller.com/2014/04/10/its-a-mega-trap-obama-backed-solar-facility-incinerates-birds/
Until this issue is solved it probably won't happen.
^^^ combined power station and KFC facility.
What's not to like?
EDIT: oops too slow
If these mirror arrays are producing enough heat to fry birds, they must be heating the air a lot as well. So a combined power station, KFC, and world class gliding destination is there
Select to expand quoteTheWolf said..FormulaNova said..
It sounds like you could even use it to smooth out conventional solar cells, and use the combination of the two.
Hopefully its economical and makes it here.
It is economical, but has a low ROI
There was a group trying to get a pilot station installed in SA. It was completely planned and costed and ready to begin construcion.
Instead a gas powered facility that had a larger ROI was given preference
And I bet that decision was taken before the Gladstone gas port was started on. Export facilities mean a doubling of East Coast gas price at wholesale level, so I guess that would have some impact on the cost of power from a gas plant
Select to expand quoteMr Milk said..
If these mirror arrays are producing enough heat to fry birds, they must be heating the air a lot as well. So a combined power station, KFC, and world class gliding destination is there
Wouldn't the infrared rays pass through the air until it hit an object. Either the block of salt, or some unfortunate bird. And I'm not sure I'd want to be circling the area in a glider!
Select to expand quoteHarrow said..Mr Milk said..
If these mirror arrays are producing enough heat to fry birds, they must be heating the air a lot as well. So a combined power station, KFC, and world class gliding destination is there
Wouldn't the infrared rays pass through the air until it hit an object. Either the block of salt, or some unfortunate bird. And I'm not sure I'd want to be circling the area in a glider!
For an electrical engineer, you seem to have forgotten a lot of basic physics. And ignored the physics driving climate change.
Let me remind you. Radiation is absorbed by any atoms or molecules with a sympathetic or harmonic frequency of the wave function of its electronic structure or bonds. H2O is an excellent absorber of radiation because it is non linear, so has many vibrational degrees of freedom. That is why it is a powerful greenhouse gas, as well as handy in your radiator.
If you looked at the absorption spectrum of air, you would find that it varies with wavelengths, but it will absorb at some wavelengths and that energy increases the kinetic energy of the molecule doing the absorbing. ie It heats it.
If you are in the glider, you would be wise to avoid the focii of the mirrors. But that would be the pipes that are carrying the heat transfer fluid, so you'd be instants away from a crash when your glider lit up
Select to expand quoteMr Milk said..
For an electrical engineer, you seem to have forgotten a lot of basic physics.
Over the short distance that the sun rays pass from the mirrors to the tower, the air would absorb a lot less heat than would otherwise have been absorbed if the sun rays were allowed to hit the ground. Without the solar tower, the sun rays would heat up the ground, which would then generate warm air and associated lift, but with the solar tower the sun rays are reflected to heat up the salt, and the heat would be stored, instead of released to the local atmosphere. The amount of heat generated by the rays travelling the short distance to the mirrors in the tower would be orders of magnitude less than the heat that would have been generated if the rays were left to hit the dirt. So the actual effect of the solar tower would be a considerable reduction in thermal lift in the area, with the energy being sent away as electricity.
We could of course number the mirrors surrounding the tower as such: 1, 2, 4, 5, 6, 7....997, 998, 999, 1000, and let the maintenance staff spend all their time looking for the missing mirror.
More importantly, when are you going to bring some more pies for sampling? Some warm tucker after a cool autumn southerly session would be just the ticket!
Select to expand quoteHarrow said..Mr Milk said..
For an electrical engineer, you seem to have forgotten a lot of basic physics.
Over the short distance that the sun rays pass from the mirrors to the tower, the air would absorb a lot less heat than would otherwise have been absorbed if the sun rays were allowed to hit the ground. Without the solar tower, the sun rays would heat up the ground, which would then generate warm air and associated lift, but with the solar tower the sun rays are reflected to heat up the salt, and the heat would be stored, instead of released to the local atmosphere. The amount of heat generated by the rays travelling the short distance to the mirrors in the tower would be orders of magnitude less than the heat that would have been generated if the rays were left to hit the dirt. So the actual effect of the solar tower would be a considerable reduction in thermal lift in the area, with the energy being sent away as electricity.
We could of course number the mirrors surrounding the tower as such: 1, 2, 4, 5, 6, 7....997, 998, 999, 1000, and let the maintenance staff spend all their time looking for the missing mirror.
More importantly, when are you going to bring some more pies for sampling? Some warm tucker after a cool autumn southerly session would be just the ticket!
"Thick pipes run away beneath me like arteries, pumping oil out to the mirror field. There, it is channelled into thinner piping that runs right through the focal points of the mirror troughs, absorbing the heat of the Arizona sun until the oil reaches nearly 400 ?C. It then returns to the plant, where the oil superheats water vapour that spins two 140-megawatt turbines."
What tower?
Last time I put my hand on a metal reflector that was sitting in the sun, I rapidly pulled it off. I think you will find that the steel or aluminium mirrors get a damn sight hotter than the ground does, thus generating a better contact heat source for the thermal.
Which leads me to another by product of the plant. Cooler soil and a sheltered microenvironment with lower evaporation under and between the reflectors. Good for a market garden.
So you have electricity, gliding, KFC and Sumo Salads in the mix
Yes harrow, this isn't a solar furnace with very long focus mirrors aimed at a tower, it's a lot of very short focus mirrors aimed at a pipe centimeters away. I don't see many birds getting fried.
All jokes and navel gazing aside, there seem to be quite a few of these being installed around the globe, including a few that are a worthwhile size. I wonder if they really are the answer?
I wonder how many rooftop sized units are made. Would be better for storing energy for night time use.
Having felt the heat reflected from solar panels, you'd think that you could combine the 2 principles using pv plated reflectors for dual production of energies(electricity/heat storage). Even if only for power and hot water you could run the heat collection pipes ont the back of PV panels, cooler panels would surely lower electrical resistance if only slightly and surely be a more efficient use of space on a roof.
Select to expand quoteTest pilot 1 said..
I wonder how many rooftop sized units are made. Would be better for storing energy for night time use.
Having felt the heat reflected from solar panels, you'd think that you could combine the 2 principles using pv plated reflectors for dual production of energies(electricity/heat storage). Even if only for power and hot water you could run the heat collection pipes ont the back of PV panels, cooler panels would surely lower electrical resistance if only slightly and surely be a more efficient use of space on a roof.
I think that you would find the problem with a small solar thermal system is that you can't heat up enough of your heat storage medium (ie salt solution or oil) to make it worthwhile. A big tank has less surface area per unit of volume, so it leaks less heat to the environment. And there is a problem in that solar PV works best when the collector is perpendicular to the sun's rays, while solar thermal uses rough parabolas to focus the rays onto a pipe.
As for cooling solar PV, I have read of it being done by Wollongong Uni Architecture students on a house that they refitted as a project to show that an old fibro house could be made energy efficient. They did it with fans under the panels drawing a little of the power that the panels generate. If you try to do it with water I think that there are a few problems to overcome. Weight of the system immediately increases. Then you have to get flow going through the pipes. Pumping water is harder than blowing a fan. Sharp temperature gradients in the materials near the cooling pipes could accelerate ageing. And, the big one.....water and electricity is a dangerous mix
