Energy storage in quicklime (CaO) by a sunparabol?

Hello.

I am at my university working on an idea if it would be possible to store heat energy in quicklime CaO.
We are to use a solar parabol to concentrate the sunlight and get a temperature in focus around 1000 C degres.

In that temperature it is possible to burn limestone to quicklime and then save it in a airtight storage.
1000 kg have about 320 kWh and can be bought in my country for around 45 $/1000 kg.
Does anyone know if we are wrong about this becouse it seems to easy to save energy this way.
To save energy to heat a house I need to burn around 15000 kg to be able to heat a house over the winter and I try to calculate how big solarparabol we need to build to be able to burn 15000 kg limestone to quicklime in a summer.

After the winter the reaction with water have turned CaO to Ca(OH)2 and it can be burned again to store energy for the next winter.

Do you think it is possible?
Have anyone heard if someone does something like this?
Nobody have tried it in my country so I hope someone out there know something.

I found a PDF-document that NASA did about it, so it seem possible.

http://purl.access.gpo.gov/GPO/LPS58424

Regards Magi

 

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Designs for solar cookers for villages in undeveloped countries are out there, they involve a mirror maybe a metre across. Try looking for them, then scaling the idea up.
However, 15 tonnes of quicklime is rather a lot, storage would be a problem.

 

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Yes, it's not only possible but also really works.

However to deal with much more managable and easier to manage/achieve temperatures, I would suggest you turn your attention to phase-change salts. There are several that have a high heat of crystallization. You would not endanger life, limb and property nearly as much.

 

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wow, that is an interesting idea. I would love to see some numbers on how big/how many you need to heat a home in, say Michigan, for a winter with only 1 summer worth of cooking (cooking was the only word I could think of, I guess it works)

 

just had an idea. for your calculations: you can add to your quicklime stockpile during the winter as well. you may only get a fraction of the quicklime as you would in the summer, but it would probably be enough to include in your estimate of your yearly energy production.

 

And here's another thought for you. Do you have any idea how difficult it is to develop a temperature of 1000 C?

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I have heard it is possible to reach 3000 degrees in solarparabols so 1000 degrees wouldnt be that impossible.
It may be hard but if I can make it work I dont have to pay for heating my house again.

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if insulated, couldn't you get a solarparabola hotter too? that is untill you start melting things you don't want melted..

 

well, you would have to figure it out, if you can't get those temps in the winter, just use Light's suggestion of materials that undergo similar processes at lower temps.

 

Even though I didn't mention it specifically, that was one of the problems I had in mind when I mentioned the difficulty in getting and maintaining 1000 degrees C. You have to contain the calcium hydroxide in something and you have to be able to get it in and out. The chemicals are very crossive so the materials used will have to be both of high refractory grade and nearly chemically inert.

Those were the very things I was thinking about in my initial response to the poster. Very high temperatures, corrosive chemicals, and the danger involved. And that's why I suggested a way that wasn't such a danger to "life, limb, and property."

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something lined with a gold or platinum alloy might work, with a light absorbant outer shell encasing it. then again I'm not sure if alloys of noncorrosive metals are noncorrosive, and if you had them pure they'd melt under the heat we're talking I'd think.

calling all metalurgists...

 

Almost everything can be corroded in the right conditions. Not many metal alloys are much good above 1,000 , at least not any ones you can afford. On the other hand I dont see why calcium oxide would be that bad to contain, though the pressure might be bad, then theres gas control etc.

 

I have had discussions with companies that make cement and concreate and they told me that when I have burnt the lime stone I can put it in oil barrels and just plug them.
They are air tight.
You just have to be carefull when dealing with Ca(OH)2 becouse it is like acid in powder but they deal with it in tons when making cement so it cant be that hazardus.
They didnt say it was that dangerous.
You are not do get it on your skin.
It is not agressive to metalls.
Solar ovens of high concentration focus can get temperatures up to 5500 degrees.
Light's suggestion of materials "phase-change salts" are much more expensive and to store the energy you have to keep them hot.
There are systems like "ClimateWell" where you dont have to keep the salts hot but they are very expensive.

This is wrong.
" The chemicals are very crossive so the materials used will have to be both of high refractory grade and nearly chemically inert."
Ive been told by companies that handle tons of it every day and they told me that both CaO and Ca(OH)2 can bee stored in oil barrels if I just close them air tight.

I have talked to chemists and Universities and companies and the problems you write about just have not been a big problem in my discussions.

Strange.

Regards Magi