Converting Temperatures Into Usable Energy As A New Source Of Sustainable Energy
With the continuous increase of world population, human development have always been the biggest contributor of new advancements and it is of great importance to understand that great civilizations happen along with energy being the key to sustainable growth. Our environment has quite a number of abundant sources of energy such as mechanical energy, solar energy, thermal energy, chemical energy etc. , which can be collected and utilized. As a result, there has been various developments of dependable and sufficient power systems made by researchers and professionals by consecutively looking for other forms of energy from our surroundings. However, there is still a wide gap of standards between the energy being produced today to the requirement of high-efficient and viable source of energy. Hence, it is a necessity to develop new harvesters that has a great sustainable capability and will generate sufficient amount of energy. In line with this, converting mechanical energy to electricity was made possible by the triboelectric principle.
Seizing the opportunity, researchers at Georgia Institute of Technology was determined to increase the power produced by piezoelectric nanogenerators by creating triboelectric generators. Researchers discovered that when two different kinds of plastics came in contact with each other, they will produce electric charge. This mechanism is called triboelectric effect. Zhong Li Wang and his team at Georgia Institute of Technology accidentally discovered this power generating effect while testing on piezoelectric generators. During the experiment, the piezoelectric generator surprisingly produced a huge amount of energy that was higher than expected. Inspections were made, revealing that the apparatus was incorrectly assembled that eventually resulted in the contact of two polymer sheets accidentally rubbing each other, which is mainly the reason why there was an excessive amount of current produced by piezoelectric generator. These rubbing sheets manifested a triboelectric effect that triggered the production of electrical current. Triboelectric generators are composed of two rubbing sheets of polyester and polydimethylsiloxane that acts together as electrodes. Polydimethylsiloxane sheet accepts the electrons produced while polyester sheet donates. These sheets are instantly separated after being in contact with each other, resulting to an interval between the materials that divides the electrons on polydimethylsiloxane, generating positive and negative charges. However, rubbing surfaces of same substance will not create a charge. Hence, two electrodes should be of different material in order to generate electric current.
As for the thermal energy, it is more of accompanied by human activities in the most natural state. The amount of energy lost in the atmosphere is beyond measurable, emerging several researchers to work on the retrieval of waste heat to energy. Unlike other resources, wasted heat does not involve any loss of economic profit. In addition, reusing wasted heat in converting a new source of energy can both lessen the effect of energy crisis and heat of the surroundings. Thus, recovering waste heat and turning it into electricity is beneficial.
The device used in converting temperatures into usable energy is called Thermoelectric generators (TEG). TEGs are perfect for recovering waste heat into energy, as this device does not require moving components when turning thermal energy to electricity. This generator is made from thermoelectric modules that applies the three thermoelectric effects known as the Seebeck, Peltier, and Thomson effects. Seebeck effect is when two junctions are preserved at different temperatures; there will be a production of electromotive force (EMF) in thermo-couple which is proportional to the temperature difference. Peltier effect, on the other hand, is the reverse phenomenon of seebeck effect. As stated by this principle, when an electric current is flowing through the thermo-couple, heat is absorbed at one junction and evolved at the other end. Thomson effect involves the absorption and evolution of heat when a current is passed through a conductor that is placed in a fluctuating temperature along its length. TEGs needs heat as a primary source of energy and it can produce energy as long as there is a heat source present.
The electricity being produced today is dominated and condensed by a tremendous and powerful supply of fossil fuels that accounts for about 80% of carbon emissions which is the main cause of the greenhouse effect. Because of this, harvesting heat from friction as a source of energy is an advantageous move as the vast majority of heat in our surroundings are being wasted.
