A black box has been sitting on the roof of a Massachusetts Institute of Technology building for the last few months. Beside it sits a weather monitoring system and a bigger black box to monitor the performance of the first one. That first black box is the first device that can generate power from differences in the temperature of the air—the ultimate clean energy. But how feasible is this on a larger scale?
The team of researchers from MIT’s Chemical Engineering department is calling this device a thermal resonator: a device that draws heat from the air around it and turns this heat into electricity. It does not need to be in the sun, it could actually be put in the perpetual shade below a solar panel, and it would still generate power thanks to the always present temperature fluctuations.
Such a device might sound too good to be true; this is early days for the device, and the thermal resonator can only generate tiny amounts of power. But it is a promising gadget nevertheless as it has the hypothetical potential to make batteries obsolete—certainly an exciting idea.
As the lead researcher for the project, Professor Michael Strano, explains, the resonator works by one of its sides capturing heat from the air. This heat then slowly “oozes” into the other side of the device. The temperatures in the two sides are always different, and this difference is used to produce electricity through thermoelectric. Related: Should OPEC And U.S. Shale Collaborate For Survival?
The main challenge is the material. For the process to work, the researchers needed a material that has both high thermal conduction—the rate at which heat spreads through it—and thermal capacity, or the ability to store a certain amount of heat per certain volume.
Usually, these don’t come in high values together. When conduction is high, capacity tends to be low and vice versa. So the team used a combination of materials, including metal foam from copper or nickel, a coat of graphene, and an infusion of octadecane.
Graphene, which is superconductive, enhances the conductivity of the metal foam. Octadecane is a kind of wax that changes its state from liquid to solid within a specific temperature range that is chosen based on what the material will be used for. The octadecane stores the heat and the graphene accelerates the conduction.
When the material was tested during a 10-degree temperature change as day turned into night, it produced, according to MIT’s press release, 350 millivolts of potential and 1.3 milliwatts of power. Minuscule as this amount sounds, it would be enough to power environmental sensors or communications systems. Related: Oil Market Fears: War, Default And Nuclear Weapons
The potential applications of the material are vast, given that the resonator can work anywhere, capturing heat from anything that produces it. It could in the future be made to work with the temperature differences in the on-and-off cycle of a refrigerator, for example, or the cycle of an industrial machine, or even the heat that escapes from a solar panel, reducing heat waste and putting the heat to good use.
The device could also be used as part of a hybrid power generation system where parts are independent of each other; if one fails, others would keep going. Could it make batteries obsolete? It’s too early to say and even if it could, that would take a very long time for us who alive now to get excited.
By Irina Slav for Oilprice.com
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