By: Johan Jeson
Thermoelectric generators are new sources of energy that can transform industries and societies across the globe.
Ever wondered what the world would be like without energy…blank, empty, vacuum. In short, the world needs energy.
Energy has been at the crux of various industries and commodities since it powers machines and systems to carry out different operations with efficiency and accuracy. However, the generation of energy has been a disturbing issue since non-renewable sources of energy are used. Renewable sources of energy like solar polar, wind, and hydropower tend to fall short of the supply threshold due to variable weather patterns and atmospheric conditions. This where thermoelectric generators come into play.
Thermoelectric generators (TEG) are electronic devices that consist of a solid-state semiconductor that converts differences in temperatures and heat flow into viable Direct Current (DC) power. The Seebeck effect is the foundation of TEGs since it creates current from variances in temperature absorbed by dissimilar metals. The semiconductor makes use of the Seebeck effect to generate a voltage. The voltage is then used to propel electric current and produce power. The thermocouple is at the heart of the TEG and envelopes the p-type and n-type semiconductors. These semiconductors are also called thermoelements. The p-type elements are doped with a positive charge while the n-type elements are doped with a negative charge and the Seebeck coefficient is negative [1]. The n-type element has electrons as their charge carriers while the p-type element has holes as their charge carriers. Diffusion takes place when the semiconductor is hot since the charge carriers move away from this hotter side. When there’s an accumulation of charge it leads to the formation of the voltage potential which corresponds to the temperature differences along the semiconductor.
Thermoelectric generators are created with cool materials like bismuth (Bi2Te3) telluride, lead telluride (PbTe) and Silicon germanium (SiGe). The design of the thermoelectric generator depends on the heat source, cold sink, and electrical conductivity. These generators are similar to heat engines but they don’t have any moving parts and they are not heavy [2].
A new device was developed to generate electricity by gleaning energy from the cold night sky. This novel invention that is anti-solar could extract energy from temperature differences between the Earth and outer space and produce electricity. The nucleus of this device is the thermoelectric generator. The generator is faced skyward and adjoined with an aluminum plate sealed beneath a transparent cover and enclosed with insulation to keep heat out.
Ambient air doesn’t influence the plate since it keeps cool by emitting heat that is received, as infrared radiation. Moreover, the rear of the generator is fastened to an open aluminum plate that’s constantly warmed by ambient air. During night time the top portion of the plate gets a few degrees colder than the bottom part of the generator. Stanford University Engineer Wei Li and her colleagues experimented with a 20-centimeter prototype of this device on a clear night sky in Stanford, California. It generated about 25 milliwatts of power per square meter of device. This could power a small LED bulb with sufficient energy. The team says that more enhancements can be made to the device such as better insulation around the cool top plate since it could bolster output up to at least 0.5 watts per square meter [3]. Even though this device generates half as much energy when compared to a solar panel, scientists say that this thermoelectric generator could be a vital emergency power backup in case of any power outages or energy-deficient problems. This device can also be expanded to power up houses, streets, and towns in remote and rural areas that live in colder regions of the world since they experience longer night hours and shorter daylight hours.
Thermoelectric generators can be the key to a brighter future built upon sustainability and ingenuity.
References
[1] How Do Thermoelectric Generators (TEGS) Work? (n.d.). Retrieved November 11, 2019, from https://www.marlow.com/how-do-thermoelectric-generators-tegs-work
[2] Beirnes, B., Alfred, Asaf, & J.p Malalwa-Arachie. (2019, July 20). How Thermoelectric Generators Work. Retrieved November 11, 2019, from https://thermoelectricsolutions.com/how-thermoelectric-generators-work/
[3] Temming, M. (2019, September 26). This device harnesses the cold night sky to generate electricity in the dark. Retrieved November 11, 2019, from https://www.sciencenews.org/article/device-harnesses-cold-night-sky-generate-electricity-dark?utm_source=Latest_Headlines&utm_medium=email&utm_campaign=Latest_Headlines