Thursday, 13 August 2020



Author: Vansh Sachdeva 


The modern advancements and development of technologies in the field of Semiconducting materials have played a major role in transferring the world's views and thoughts towards developing sustainable and renewable energy sources and also towards the Global Energy Crisis. This data accumulated paper emphasizes on the conversion of Chemical/Thermal, Solar, Nuclear, and Biogas fueled energies to direct Electric Energy by solid-state semiconducting devices. The heat energy from the exhausts of industries world-wide does not do any potential work and thus this energy is regarded as Waste Heat Energy. These renewable, environment-friendly, sustainable, and machine-free Electricity Generators/Heat Engines are capable to be used and integrated with Industries Heat Engines, Mufflers, Exhaust Engines, and Recovery of the Waste Heat into useful Electricity. The main emphasis of the paper is on Thermo Electric Generators (TEG), its applications and characteristics and ways to improve its efficiency so that this can be used on a large-scale. Also, Hydrogen generated from renewable sources like Biogas can play a vital role in future energy development. Solar Energy cells have been used in many places but what if the Solar Energy is utilized in another manner with TEG's and its efficiency is compared and analyzed. Surely, it will eliminate the use of batteries to store energy which again requires charging. This paper also contains various applications of TEG which can be used as an alternative for conventional methods and also a brief description of a model of a TEG driven Chem-Car made by me and my class fellows which works on the principle of Seebeck Effect i.e. more the temperature gradient across the Thermo Modules more will the voltage that is connected to an external motor that drives the car.


Energy production and consumption are the major factors that determine the development of a country. More production and consumption of energy means more economic growth of the industries, means of transport and the quality of life we live in. However, most of the energy used and produced is Fossil Energy which contributes around 90% of the global energy demand. By 2040, the world energy consumption is expected to increase by 40%. 1/3rd of the world energy consumption belongs to the transportation sector and from that, 85% consumes by the road transportation sector, according to International Energy Outlook [1]. But more the consumption of the conventional sources of energy like the burning of fossil fuels, petroleum, diesel, etc. more will be the impact on the environment. Around 20075 TWh of energy was released to the atmosphere in the US in 2018 [2]

So, the present need of the generation is to shift the production of Energy from the conventional and non-renewable sources to sustainable and renewable resources of energy. Also, due to the waste heat energy losses to the environment without treatment and any successful plan from the exhaust engines of the industries we are losing a major portion of our global energy. So, there is a need to convert and renew this waste heat energy into useful electric energy. Kreith and West [3] showed that, in SI (spark ignition) engines, nearly 70% of the total energy is wasted as heat and in CI (compression ignition) engines; nearly 60% is wasted as heat. 

This can be achieved using Thermo Electric Generators (TEG). A TEG is a type of heat engine that works on the principle of Thermodynamics and directly converts heat energy into electricity without any machine through noise-free operations, is maintenance-free, environment-friendly, has long life-span and cost-effective as well. A TEG consists of Thermo-Electric Couples or Modules(TM) that are made up of tens and hundreds of Thermo-Electric Elements (TE) connected in a series that is made up of p-type and n-type of semi-conductors connected thermally in parallel and electrically in series. However, till the 21st Century researchers and scientists have tried their best to improve the performance, power output, and efficiency of TEG by altering some of the properties of the semiconductor but till now it is evident that a TEG provides only 2-3 % of efficiency which cannot meet the global energy needs. Therefore an integrated method of combining a TEG with the other engines is on primary focus and different researches are being carried which has shown positive results. 

A TEG can be integrated with the exhaust engine of an Inner Combustion Engine (ICE) of an industry because by doing so, the backward pressure drop would not increase which means the capability of the Engine to throw the heat energy and also the load on the engine would not get affected and both the ICE and TEG will work efficiently under normal conditions.

There is a need for Substantial implementation of a decentralized energy system and another important application of TEG is when it is integrated with Solar Energy(sun being the most abundant and widely spread energy source) System which works on Concentrated Photovoltaic Systems(CPV). However, previously we have been using solar energy in the form of Photovoltaic cells which captures and stores Solar Energy but in recent researches implementation of CPV along with TEG is under the spotlight. It’s justified by these researches that if a solar energy absorber which is called spectrally selective absorber is placed in integration with a TEG, the efficiency of the system increases by manifolds.[4] 

Another way in which TEG can work more efficiently in an integrated way is by utilizing the Heat Energy of gases produced while making Biogas. Various researches are administered to use biogas as an alternate fuel in IC engines. Studies by Surata et al. [5] have concluded that higher performance of the engine using biogas can be attained by completely removing the H2S impurity and H2O content from biogas. It has been found in an investigation that the performance of the engine in terms of thermal efficiency and power output improves by increasing the CH4 concentration in a biogas but the HC (Hydrocarbons) emissions from the exhaust engine also increase.[6]

So, if we can integrate such Biogas and TEG systems then we can develop sustainable Energy Systems in form of grids where the Hydrocarbons emitted from the exhaust can be used as a medium to provide heat energy to TEG. Hydrogen gas (H2) has been identified as the energy carrier of the future due to its inherent high energy content [7]. As we know that only small fractions of Hydrogen gas are present in the atmosphere so we have to make hydrogen commercially which can be achieved by electrolysis of water etc. But in recent years Hydrogen that is being produced by renewable resources like Biogas is taking attention because it can either be used in fuel cells to generate electricity directly or can be used in Internal Combustion Engines (ICE) of industries and as a fuel for vehicles. Time is not far when we will be using Hydrogen driven vehicles. So, if this produced Hydrogen, be used in increasing the temperature of Heat Exchangers and then be integrated with TEGs, the quest for global economic energy-demand can be fulfilled. Nuclear power generation provides 7% of the world's total energy supply and 14.7% of generated electricity. This indicates the many role atomic energy plays as compared to standard means. Now worldwide operate 436 nuclear power reactors generating 370 GW of electricity.[8] Contrary to oil and gas reserves which are considered depleting resources, nuclear fuel has extended lifetime. With appropriate nuclear fuel cycle technology, the lifetime of nuclear fuel may extend to several thousands of years. According to current estimates, the life-extension of crude oil is estimated at 130–150 years, of gas – at 210–250 years and of coal and lignite – at 350–450 years. Nuclear fuel is much more abundant, both for fission (uranium and thorium) and fusion (deuterium). Moreover, nuclear power is characterized by its good safety record accounting for only one accident with death casualties (Chernobyl) during more than 12,700 reactor-years of operation. [9]


REF [1] :
Waste heat recovery from thermo-electric generators (TEGs)
L.S. Hewawasam, A.S. Jayasena, M.M.M. Afnan, R.A.C.P. Ranasinghe∗,M.A. Wijewardane
Department of Mechanical Engineering, University of Moratuwa, Katubedda, 10400, Sri Lanka
Received 7 October 2019; accepted 22 November 2019
International Energy Outlook 2017 (2017), Online:, Date accessed: 01/09/2018.

REF[2] :
Prospects of waste-heat recovery from a real industry using thermoelectric
Generators: Economic and power output analysis
Miguel Araiza, b, ⁎, Álvaro Casia, Leyre Catalána, b, Álvaro Martíneza, b, David Astraina, b
a )Department of Engineering, Public University of Navarre, Campus Arrosadía, 31006 Pamplona (Navarre), Spain
b )Institute of Smart Cities, Public University of Navarre, Campus Arrosadía, 31006 Pamplona (Navarre), Spain

Lawrence Livermore National Laboratory, Data Based on DOE/IEA MER (2018),
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Waste heat recovery from thermo-electric generators (TEGs)
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M.A. Wijewardane
Department of Mechanical Engineering, University of Moratuwa, Katubedda, 10400, Sri Lanka
Received 7 October 2019; accepted 22 November 2019
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Performance evaluation of a thermally concentrated solar thermoelectric generator without optical concentration K.Y.Sudharshan 1, V.PraveenKumar, Harish C.Barshilia n Nanomaterials ResearchLaboratory,
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a) Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India
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[5] I.W. Surata, T.G.T. Nindhia, I.K.A. Atmika, D.N.K.P. Negara, I.W.E.P. Putra,
Simple conversion method from gasoline to biogas fuelled small engine to powered electric generator, Energy Procedia 52 (2014) 626e632.

[6] E. Porpatham, A. Ramesh, B. Nagalingam, Investigation on the effect of concentration
of methane in biogas when used as a fuel for a spark-ignition engine, Fuel 87 (8e9) (2008) 1651e1659.

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Electricity generation prospective of hydrogen derived from biogas using food waste in south-western Nigeria T.R. Ayodele,*, M.A. Alaob, A.S.O. Ogunjuyigbeb, J.L. Mundaa
a.) Department of Electrical Engineering, Tshwane University of Technology, Pretoria, South Africa
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H.J. Alves, C.B. Junior, R.R. Niklevicz, E.P. Frigo, M.S. Frigo, C.H. Coimbra-AraúJo,
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IAEA. Nuclear technology review 2008; 2009.

About the Author:

Vansh Sachdeva, studying at University School of Chemical Technology, GGSIP University, Delhi, India.