Waste Thermal Energy Harvesting (I): Thermoelectric Effect

Abstract

Waste thermal energy (heat) is the second type of energy to be discussed. Usually, it is generated in a process by way of fuel combustion or chemical reaction, and then ''dumped'' into the environment even though it could still be reused for some useful and economic purpose. The essential quality of heat is not the amount but rather its ''value.'' The strategy of how to recover this heat depends in part on the temperature of the waste heat gases and the economics involved.Waste thermal energy is one of the largest sources of inexpensive, clean, and fuel-free energy available. The vast amount of heat that is discharged into the atmosphere everyday is one of the best sources of clean, fuel-free, and inexpensive energy. According to the US Department of Energy (DOE), up to 50 % of all fuels burned in the US goes unused into the atmosphere as waste heat is released to the atmosphere. Research indicates that the energy currently wasted by the industrial facilities in the U.S. could produce as much as 20 % of the total US electrical output with the associated 20 % reduction in greenhouse gas emissions. Various sources that can be classified as waste thermal energy (heat) with their properties are listed in Tables 4.1 , 4.2, 4.3, and 4.4 [1].Among the large quantities of waste heat that have been directly discharged into the Earth's environment, much of it is at temperatures which are too low to recover by using the conventional electrical power generators. Thermoelectric power generation, also known as thermoelectricity, has been demonstrated as a promising technology in the direct conversion of low-grade thermal energy, such as waste heat energy into electrical power. Probably, the earliest application is the utilization of waste heat from a kerosene lamp to provide thermoelectric energy to power a wireless device. Thermoelectric generators have also been used to provide small amounts electricity to remote regions, for instance, Northern Sweden, as an L. B. Kong et al., Waste Energy Harvesting, Lecture Notes in Energy 24,

Multifunctional composite nanofibers with shape memory and piezoelectric properties for energy harvesting

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Induced Piezoelectricity in Cotton-Based Composites for Energy-Harvesting Applications

“…The constant depletion of conventional energy resources and rising environmental pollution are the major challenges the world is facing and are the driving forces for the development of alternative sustainable energy sources. − Several approaches have been developed in the prospect of alternate energies like fuel cells, solar cells, and supercapacitors, which are continuously being modified to enhance their efficiency and greater energy production. Energy harvesting is one of the alternate sources, which capitalizes the waste or unused mechanical or vibrational energy sources and converts them into productive electrical energy .…”

Piezoelectric transducer comparison for vibrational motion energy harvesting

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“…The researchers use a piezoelectric cantilever in bending mode to harvest energy from motor vibration [5]. This collected energy can be used for various purposes [6].…”