EcoRenovator - Solar Thermal Storage Research

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Solar Thermal Storage Research

Update on current research being done on thermal storage of solar arrays.

http://ecorenovator.org/forum/attach...1&d=1446830125

Quote:

The system hinges on the reversible decomposition of strontium carbonate into strontium oxide and carbon dioxide, which consumes thermal energy. During discharge, the recombination of strontium oxide and carbon dioxide releases the stored heat. These materials are nonflammable, readily available and environmentally safe.

In comparison to existing approaches, the new system could also allow a 10-fold increase in energy density – it’s physically much smaller and would be cheaper to build.

The proposed system would work at such high temperatures that it could first be used to directly heat air which would drive a turbine to produce electricity, and then residual heat could be used to make steam to drive yet another turbine.

In laboratory tests, one concern arose when the energy storage capacity of the process declined after 45 heating and cooling cycles, due to some changes in the underlying materials. Further research will be needed to identify ways to reprocess the materials or significantly extend the number of cycles that could be performed before any reprocessing was needed,

Thermal energy storage using phase change materials has been ongoing for the last 60 years, with reversibility problems being a persistent issue. What is new to me in this study is the very high temperature at which this phase-change is designed to occur, and the double use off the energy as the temperatures decline from one phase to another. Nice example of the exploitation of exergy concepts.

MORE_HERE...

-AC

tThe article mentions temperatures in the 600 to 1200 degC range. What kind of piping and vessels can stand up to these temperatures in a residence? What pressures are involved in the process? The research looks promising for industrial/powerplant processes.

[Wet blanket mode on] When I googled "strontium cost", the number $1.00 per gram comes up. That's only $454 per pound. [Wet blanket mode off]

Large scale solar energy storage is necessary if we want to get away from burning dead dinosaurs for power. A 10 kWh battery pack is one thing, 10 GWh is something else entirely.

Strontium carbonate is not strontium metal. It is used in fireworks and ceramic glazes. As with most chemicals, purity costs more. I believe technical or reagent grade is like 10 bucks a kilo, ultrapure maybe 20. In bulk, it is around $400 or so per ton for industrial grade. China has become a huge exporter of these "specialty chemicals" as well as rare earth metals. There is a long list of these chemicals that are no longer economical to produce in America due to government regulation of production.

EDIT: Hey! I just realized that I knew about this from somewhere... It's the next thing up the periodic table from calcium! Same basic problem set also. I don't know about the hydration states of strontium carbonate, but I bet they are a lot like calcium carbonate. Good phase change chemical. I do know that calcium carbonate decomposes the same way at high temperature, though, with similar somewhat predictable reversibility.