The ever increasing demand for energy is pushing for the adoption of more clever energy management approaches.
One way to increase energy system efficiency is to recycle waste heat into clean electricity using what’s called thermoelectric generators or TEGs.
Because of their ability to recover lost thermal energy, these devices are the focus of green energy harvesting research.
A new study suggests using silicon-based nanoblades to increase the power generation capacity of TEGs even more.
Silicon Nanoblades’ Energy Generation Power
TEGs can be used to provide clean energy to a variety of devices off-grid and without batteries, like sensors in remote areas or IoT devices.
However, one obstacle that’s been hindering the wide adoption of TEGs in microelectronics is their incompatibility with the existing silicon integrated circuit technology. But it seems that a physicist from the University of Texas at Dallas (UT Dallas) has found a way to make it work.
Dr. Mark Lee is the head of the Department of Physics in the School of Natural Sciences and Mathematics at UT Dallas. He teamed up with Texas Instruments Inc., a semiconductor company, to show how to enhance silicon’s thermoelectric harvesting power.
“Thermoelectric generation has been expensive, both in terms of cost per device and cost per watt of energy generated,” Dr. Lee said. “The best materials are fairly exotic — they’re either rare or toxic — and they aren’t easily made compatible with basic semiconductor technology.”
The team used silicon nanoblades, or nanostructured silicon thermopiles, that allow making thermoelectric generators with high power generation capacity.
These nanoblades enable TEGs to be mass-produced, seamlessly integrated into large-scale silicon fabrication process line, at very low marginal cost.
“We optimized the configuration of our devices to place them among the most efficient thermoelectric generators in the world,” added Gangyi Hu, co-author of the study. “Because it’s silicon, it remains low-cost, easy to install, maintenance-free, long-lasting and potentially biodegradable.”
Since the 1950s and up to a few years ago, silicon was thought to be a poor thermoelectric material in its bulk form.
In 2008, new research showed that silicon could be an efficient thermoelectric material in the form of nanowires, filament-like shapes less than 100 nanometers thick, 1,000 times thinner than a sheet of paper.
As Dr. Lee notes, a decade of research experiments into silicon TEGs wasn’t successful because nanowires were too small to be compatible with circuit-manufacturing processes.
The solution Lee and his colleagues found was nanoblades, which are “only 80 nanometers thick but more than eight times that in width. While that is still much thinner than a sheet of paper, it’s compatible with chip-manufacturing rules.”
According to the team, nanoblades’ shape, compared to nanowires, loses some thermoelectric ability, but packing many silicon nanoblades at once can yield as much thermoelectric energy as the best exotic materials.
Full results of the study are published in Nature Electronics.
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