Research update: New way to store sun’s heat

[OKIsItJustMe]

http://web.mit.edu/newsoffice/2011/update-energy-storage-0713.html

Research update: New way to store sun’s heat

Modified carbon nanotubes can store solar energy indefinitely, then be recharged by exposure to the sun.

David L. Chandler, MIT News Office

July 13, 2011

A novel application of carbon nanotubes, developed by MIT researchers, shows promise as an innovative approach to storing solar energy for use whenever it’s needed.

Storing the sun’s heat in chemical form — rather than converting it to electricity or storing the heat itself in a heavily insulated container — has significant advantages, since in principle the chemical material can be stored for long periods of time without losing any of its stored energy. The problem with that approach has been that until now the chemicals needed to perform this conversion and storage either degraded within a few cycles, or included the element ruthenium, which is rare and expensive.

Last year, MIT associate professor Jeffrey Grossman and four co-authors figured out exactly how fulvalene diruthenium — known to scientists as the best chemical for reversibly storing solar energy, since it did not degrade — was able to accomplish this feat. Grossman said at the time that better understanding this process could make it easier to search for other compounds, made of abundant and inexpensive materials, which could be used in the same way.

Now, he and postdoc Alexie Kolpak have succeeded in doing just that. A paper describing their new findings has just http://pubs.acs.org/doi/abs/10.1021/nl201357n">been published online in the journal Nano Letters, and will appear in print in a forthcoming issue.

…

[tridim]

1. Off to read the paper, because this sounds too good to be true.

[CaliforniaHiker]

2. This could be revolutionary

If they can really get this to work on a large scale, this could truly revolutionize renewable energy.

[Bill USA]

3. recommended!

[kristopher]

4. Interesting but the fact that it delivers energy as heat limits applicability somewhat.

I look forward to seeing what applications are devised for it.

[OKIsItJustMe]

5. Hmmm…

Currently most electrical generation is done using heat (e.g. burning coal, “burning” uranium.) Some alternative sources of electrical generation (e.g. geothermal, concentrating solar thermal) produce electricity using heat.

The majority use of energy in US homes is heating (either heating the home itself or water for use in the home.)
http://www.eia.gov/consumption/residential/reports/electronics.cfm

Imagine (if you will) panels of the stuff sitting on a roof, with a heat exchanger and some sort of circulating fluid to bring heat into the home.

This is a way of producing round the clock heat from the Sun. It seems pretty applicable to me.


You’ve promoted energy storage methods (e.g. “http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x200954">Rock Batteries”) which are nothing more than thermal storage.

This is another form of thermal storage, but one which is virtually 100% efficient.

[kristopher]

6. Rock batteries deliver electricity not heat.

I'm having trouble imagining an application where this product is going to make a significant improvement over existing solar heat systems. With an energy density limited to the range of lithium batteries it can't compete in the arena with high energy density storage mediums like rock batteries (for electric) or salts for thermal. The losses associated with the short term storage is a trade off for density.

It overs one advantage that I see - the ability to put heat on the shelf in a cabinet for long periods of time until it is needed with no loss. We simply can't do that now therefore efforts to explore the potential of this new opportunity have not yet been explored. I'm sure some interesting uses will be found and look forward to seeing them brought to market.

What happens when it is saturated with energy? I wonder if it could be a thermal insulator?

[OKIsItJustMe]

7. Now, let me get this straight

You say, “Rock batteries deliver electricity not heat.”

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=200954&mesg_id=200954

…

Isentropic’s “battery” works like this. An electrical current feeds a heat pump, a bigger version of the device that keeps your fridge cold. The fridge in your kitchen uses electricity to drive a tiny heat pump to create a temperature split, chilling the inside of the fridge and warming the back.

Isentropic’s system uses Howes’s pump to heat argon gas to 500C on one side while cooling it to -150C on the other. The hot and cold gas is then passed through two giant gravel tanks, heating one and cooling the other. The power is stored in the gravel as a temperature difference. When power is needed, the process can be instantly reversed and the heat pump now works like an engine — the extreme temperatures are brought together and turn the engine, which powers a generator to create electricity.

…

OK… let’s see, so they take electricity, and use it to generate… “a temperature split.”

Perhaps I’m understanding, but that appears to be thermal storage.


Later, they use that “temperature split” to generate electricity.

Once again, perhaps I’m misunderstanding, but they appear to be using stored heat to generate electricity.


Now, this trick of changing a “temperature split” into electricity would not work with another method of thermal storage because…

[kristopher]

8. Seriously don't you have anything better to do than play silly games?

You are mischaracterizing, not misunderstanding. You know perfectly well how many elements are present in one and missing in the other.

[Nihil]

10. Pot, kettle, etc. (n/t)

:eyes:

[OKIsItJustMe]

11. I resent being called a kettle!

I am a teapot!

[phantom power]

9. It would be interesting if they could increase the energy density even higher

say, to that of gasoline