The Energy Matrix

One of the obstacles to the widespread adoption of solar energy is the issue of storage. Photovoltaic cells, which are currently used to convert solar energy into electricity and are commonly made from crystalline silicon, cannot store energy indefinitelyinstead, heat is lost over time. With thermo-chemical technology, solar energy is stored in the form of heat within the molecules of chemicals.Scientists actually first attempted chemically storing solar energy in the 1970s, but couldn’t come up with a chemical that would satisfy all requirements. It turns out that the key ingredient is ruthenium, a rare transition metal discovered by Russian scientist Karl Klaus. Certain ruthenium complexes, especially fulvalene diruthenium, are capable of absorbing light from across the visual spectrum.MIT researchers are currently testing this chemical’s possibilities. It seems that after trapping solar energy, fulvalene diruthenium can remain in a stable, high-energy state until some sort of catalyst is given. At that point, heat is released. MIT Associate Professor of Power Engineering says the fuel “can get as hot as 200 degrees C, plenty hot enough to heat your home, or even to run an engine to produce electricity.”However, ruthenium’s rarity still makes cost a prohibitive factor in moving this technology forward150 grams costs approximately 650. Grossman and the other researchers on the team are hoping to discover an easily-synthesized chemical with the same properties. The researchers believe that now that they understand the “fundamental mechanism of how the fulvalene diruthenium molecule works,” it will be easier to come up with a replacement. The team is also hoping to find an effective catalyst that will easily draw out the stored energy.Even with these obstacles ahead, this is an exciting step forward for thermo-chemical technology. Imagine devices of the future being powered by rechargeable solar batteries. If these researchers are successful, that future could be closer than we think.