Instead of turning the sun heat to electricity, it can be stored in chemical form and kept in a heavily insulated container and used when needed. Saving the chemical materials are of course capable to be stored for long periods without losing its stored energy. That is not a new approach but the elements that has been used were rare and expensive, or the storage needed a lot of cycles.
MIT researchers, have reached a new application for carbon nanotubes, as they found that they have the ability to store the sun energy to be used when needed.
Last year, MIT associate professor Jeffrey Grossman and four co-authors puzzled out exactly how fulvalene Di-ruthenium (known to scientists as the most effective chemical for reversibly storing solar energy, since it did not degrade) was able to execute this feat. Grossman said at the time that better understanding of this process could make it easier to search for other compounds, made of ample and inexpensive materials, which could be used in a similar way. Now, he and postdoc Alexie Kolpak have accomplished just that. Their new findings were published online in the journal Nano Letters, and will appear in print in a forthcoming issue.
Grossman explains that one of the greatest advantages of the new approach to harnessing solar energy, is that it simplifies the procedure by fusing energy harvesting and storage into a single step. “You’ve got a material that both converts and stores energy. It’s robust, it doesn’t degrade, and it’s cheap,”he says. One limitation, however, is that while this process is useful for heating applications, to produce electricity would require another conversion step, using thermoelectric devices or producing steam to power a generator.
The key to operating solar thermal storage is an energy barrier distinguishing the two stable states the molecule can assume; the elaborated understanding of that barrier was fundamental to Grossman’s previous research on fulvalene dirunthenium, accounting for its long-term stability. Too low a barrier, and the molecule would revert easily to its “uncharged” state, failing to store energy for long durations; if the barrier were too high, it would not be able to easily release its energy when needed. “The barrier has to be optimized,” says Grossman. Already, the team is “very actively looking at a range of new materials. While we have already identified the one very promising material described in this paper, I see this as the tip of the iceberg. We’re pretty jazzed up about it,” he says.