https://www.google.com/search?client=firefox-b-m&q=granit+preise+pro+tonne&oq=granit+preise+pro+tonne&aqs=heirloom-srp..0l3 (https://www.google.com/search?client=firefox-b-m&q=granit+preise+pro+tonne&oq=granit+preise+pro+tonne&aqs=heirloom-srp..0l3)
Earth rock = "granite" prices beginning with 80 Euros/90 USD per ton material
1 metric ton cement 130 USD
https://www.statista.com/statistics/219339/us-prices-of-cement/ (https://www.statista.com/statistics/219339/us-prices-of-cement/)
tin( not thin) foil
13 metric ton transformed material as thermal battery for 700-3500 KWh( 70 units as demonstration example) propagated heat capacity
10-50 KWh heat storage per "battery"-unit, capacity storage temperature dependent
http://circuminvent.com/low-cost-thermal-battery/ (http://circuminvent.com/low-cost-thermal-battery/)
With 3500 KWh heat storage capacity and by 13 metric ton material and by average industrial/gross-selling prices + transport-costs : pure material costs based = 1 USD per KWh heat storage capacity
transformation costs( manufacturing/production) and estimated end-price by Stefan Nystroem :
10000 USD for 700- 3500 KWh heat capacity ~ < 3 USD per KWh heat storage capacity
Low cost solar heat as possible heat source :
https://judbarovski.livejournal.com/133020.html (https://judbarovski.livejournal.com/133020.html)
Included heat to electricity option !
Later instead parafin :
Phase-change material : silicon 900° to 1600° Celsius = energy storage capacity improvement
https://www.forbes.com/sites/natalieparletta/2019/04/03/new-thermal-battery-could-be-a-game-changer-for-storing-renewable-energy/#1d3480ff4f95 (https://www.forbes.com/sites/natalieparletta/2019/04/03/new-thermal-battery-could-be-a-game-changer-for-storing-renewable-energy/#1d3480ff4f95)
Older up to 10 KWh/Kg -3000° Celsius molten carbon- high temperature battery
https://worldwide.espacenet.com/publicationDetails/biblio?CC=WO&NR=9907804A3&KC=A3&FT=D# (https://worldwide.espacenet.com/publicationDetails/biblio?CC=WO&NR=9907804A3&KC=A3&FT=D#)
I think the industry is just going with salt
comparatively just as cheap, and easier to work with
Molten salt holds its' heat longer
smokey, the industry has to deliver to the deepest possible price or their extincton is allowed. !
Cheaper than D. IY. -concepts or alternatively with higher quality ( if possible) !
What in the last 5 decades the universities and industry labs did as R&D and what they actually are in exploring
https://www.google.com/search?q=betonkugeln+als+waermespeicher&ie=utf-8&oe=utf-8&client=firefox-b-m (https://www.google.com/search?q=betonkugeln+als+waermespeicher&ie=utf-8&oe=utf-8&client=firefox-b-mis)
is in competition/ concurrence with D.I.Y.-concepts for the deepest possible price for the endconsumer,by needed safety standarts !
In the last decades there were many overestimated producte ,also with " inter-/national award"- granted, which commercial failed ! TOO expensive related energy low prices. !
latent heat salt storage( f.e Glauber" salts: US solar homes pioneers in the 50/60' ) ; sand boxes under buildings, zeolith storage, Michel-Trombe black Beton/ cement wall, beton/cement roof with ( scratch)- metall particle filling ,.......
10000 USD for 700-3500 KWh ~ 3-15 USD/KWh and several decades long functionality is a good comparison" benchmark/target" for the industrial competitors. !