II-VI Marlow Blog

Pressuring Climate Change

With climate change posing an increasing threat to our environment, scientists believe pressure in thermoelectric generators and thermionic emissions could be the solution.

These alternative energy sources have provided renewable power by recycling “wasted” heat. Examples of this technology are found in gas pipelines and spacecraft. While this has contributed a sizable reduction in the nation’s energy budget, it still hasn’t reached its full potential. The flaw in current thermoelectric compounds is that it only truly succeeds at high heat. Better performance at room temperature is actually the most critical form of renewable energy, but that hasn’t seen improvement in 60 years.

Until now…

Scientist Liu-Cheng Chen hypothesized that combining pressure and charged chromium particles with lead selenide would produce this greater form of thermoelectric energy. He proved his theory by placing the lead selenide under 30x greater the normal atmospheric pressure. This caused certain changes at the atomic level and produced the most efficient level of room temp thermoelectric generation to date.

Another example of this groundbreaking discovery is thermionic emission of graphene. Thermionic emission happens when a metal is heated and electrons are shot out of the surface. Historically, these emissions have been used to power vacuums and has been experimented with heavily. Emissions from graphene are especially unique because the material is a nanomaterial that’s atomically thin, making it an unusual candidate for this type of energy generation.

Researchers at Singapore University of Technology and Design have created a new general framework to capture thermionic emissions in graphene. Undergrad student, Yueyi Chin, stated that traditional methods of recording this energy can be up to 50% inaccurate! This new theoretical framework helps decrease that inaccuracy by accounting for graphene’s reaction at higher energy states. The electronic properties of graphene are no longer the mystery it used to be. With this new thermionic emission model, we can better see the potential of graphene materials and devices.

Graphene thermionic emissions and pressurized materials will enable scientists to further experiment ways to create renewable energy and reduce our carbon footprint.

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Energy Harvesting in the Dark

energy harvesting

We’re all familiar with solar panels. How they absorb light that can power just about anything. But what if we told you energy can now be harvested in the dark.

UCLA scientist, Dr. Aaswath Raman, explored this idea of turning darkness to light after traveling through a village in Sierra Leone with no access to power at night. He hypothesized that coupling cool, dark air from space and natural heat flowing under a platform could generate enough energy to power a light bulb.

This theory is supported by the radiative cooling principle - objects radiate heat absorbed during the day into space at night. Radiative cooling also explains why you may see morning frost on the ground. The temperature difference between the exposed surface and the air beneath creates electricity.

Raman collaborated with scientists from Stanford University to test his theory using this principle. Together they created a thermoelectric generator comprised of styrofoam wrapped in aluminum, a metal disc painted black, a voltage convertor, and an LED light bulb. They placed the homemade model on a roof and monitored its electrical output for 6 hours. Not only did it power the light bulb, it generated 25 mW/m2.

While this experiment was minimal impact, it demonstrated three important things:

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This entry was posted in Energy Harvesting , Thermoelectrics , renewable energy and industries on January 06, 2020 by II-VI Marlow Industries

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