This is the thermo-chemical approach, in which solar energy is captured in the configuration of certain molecules, which can then release the energy on demand to produce usable heat. And unlike conventional solar-thermal systems, which require very effective insulation and even then gradually let the heat leak away, the heat-storing chemicals can remain stable for years.
Researchers explored this type of solar thermal fuel in the 1970s, but there were big challenges: nobody could find a chemical that could reliably and reversibly switch between two states, absorbing sunlight to go into one state and then releasing heat when it reverted to the first state. Such a compound was discovered in 1996, but it included ruthenium, a rare and expensive element, so it was impractical for widespread energy storage. Moreover, no one understood how the compound worked, which hindered efforts to find a cheaper variant.
Now researchers at the Massachusetts Institute of Technology (MIT) have overcome that obstacle, with a combination of theoretical and experimental work that has revealed exactly how the molecule, called fulvalene diruthenium, accomplishes its energy storage and release. And this understanding, they said, should make it possible to find similar chemicals based on more abundant, less expensive materials than ruthenium.
MIT Professor Jeffrey Grossman explains how this material can be used to store and release energy in the form of heat.
Source: Popular Mechanics
Green technology is surging ahead, probably mostly due to necessity- we cannot continue to use polluting, environmentally damaging energy sources if we are to save our planet from irreversible destruction.
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