Thermoelectric Generation Technology Research Articles

Design and Application of Low-Temperature Geothermal Thermoelectric Power Generation (Lotemg–TPG) in Sari Ater Hot Spring, Ciater, Subang, West Java, Indonesia

The use of surface geothermal manifestations in Indonesia is still very limited as a tourist attraction. Solid-state thermoelectric generator technology is an alternative to converting electrical energy directly from a heat source in the form of low-temperature geothermal manifestation. Low-temperature geothermal thermoelectric power generation (Lotemg–TPG) was designed, manufactured, and tested to take advantage of this opportunity. It was also applied to the Sari Ater Hot Spring, Ciater. The Lotemg–TPG unit comprises seven M8T modules in two frame blocks equipped with hot- and cold-water circulation channels. The M8T module is the main part of the Lotemg–TPG, which consists of eight TEG elements of type TEG1-241-1.4-1.2, flanked by a hot-side radiator and a cold-side radiator. The measurement results showed that at the temperature difference between the hot-side Th and the cold-side Tc of ∆T 17.38 °C, one module can produce 1.30 W of power, so the total power of the Lotemg–TPG unit is around 9.10 W. This result is quite good considering that the heat source is obtained for free, and the device can operate to produce stable electrical power.

Numerical energy evaluation of an optimized hybrid energy harvesting system (CPV-TEG) considering the effects of solar tracking

Currently, the energy demand at a global level is accelerated, and the use of non-renewable energies increases the problems related to global warming. Solar technologies, mainly photovoltaics, have been used as an alternative, but conversion efficiency is still low. Hybrid generation systems, which integrate photovoltaic and thermoelectric technologies, seek to provide a solution to efficiency and high costs per area unit. These systems need high tracking precision to concentrate solar energy, which requires robotic tracking systems, which generate energy waste due to the tracking action. The studies and developments do not contemplate in their analysis the losses due to tracking or the precision required by the optical concentration element. The present research develops a novel methodology for the design of optimized hybrid energy harvesting systems, integrating the concentrated photovoltaic and thermoelectric generator technologies and including the effects of solar tracking in the energy sense. In addition, a process for the numerical evaluation of hybrid systems is presented, considering thermal and tracking simulations to estimate the global energy balance. Consequently, the design methodology and numerical evaluation are implemented, comparing three concentration configurations. Additionally, a focus control device is designed for a high concentration index and evaluated. The mean total electrical efficiency of the hybrid system is 40.6763%, 38.84%, 13.3439%, and 35.0484%, respectively. With global gain estimates of 189.48 Wh, 201.83 Wh, 47.43 Wh, and 141.91 Wh. Finally, the results are compared with other developments, concluding that the hybrid system has high energy production. In conclusion, the proposal increases the overall performance of hybrid energy harvesting systems, allowing the development of future research regarding novel concentration devices, cooling methods, harvesting systems, and absorbing designs, among other innovations in more realistic energy evaluation terms.

A Novel Application of a Parabolic Trough Collector for Solar Cooking, Thermal Storage and Thermoelectric Energy Harvesting

The work here involves designing a solar solution for safe cooking and low-power generation intended for application in rural communities. A system was developed that combines Concentrated Solar Power (CSP) and Thermoelectric Generator (TEG) technologies. The CSP provides heat for clean cooking, and the excess heat is harvested by the TEG and converted into electrical power. A storage tank was integrated into the system, storing excess energy and serving as the medium for indirect cooking and supplying the heat required by the TEG. The Parabolic Trough Collector, having a resulting average thermal efficiency value of 21%, provided the useful energy to store over 4.25kWh of heat in the tank during the initial testing of the system. The TEG developed has four Peltier modules and attained 23W - over 80% of their rated power and a maximum conversion efficiency of 4.14% at a temperature difference of 220°C between the cold and hot surfaces of the generator. During the experiment, the TEG operation was limited to only four hours before subjecting a no-load test to assess the total energy storable from the system. The initial results from the test carried out here show the potential of the hybrid system in storing energy in the tank for an extended period and simultaneous operation of the TEG. Excess energy stored can be utilised further in providing the heat required for cooking or further electrical power generation.

A Review of Thermoelectric Generators in Automobile Waste Heat Recovery Systems for Improving Energy Utilization

With the progress of modern times, automobile technology has become integral to human society. At the same time, the need for energy has also grown. In parallel, the total amount of waste energy that is liberated from different parts of the automobile has also increased. In this ever-increasing energy demand pool, future energy shortages and environmental pollution are the primary concerns. A thermoelectric generator (TEG) is a promising technology that utilizes waste heat and converts it into useful electrical power, which can reduce fuel consumption to a significant extent. This paper comprehensively reviews automobile thermoelectric generators and their technological advancements. The review begins by classifying different waste heat technologies and discussing the superiority of TEGs over the other existing technologies. Then, we demonstrate the basic concept of and advancements in new high-performance TEG materials. Following that, improvements and associated challenges with various aspects, such as the heat exchanger design, including metal foam, extended body, intermediate fluid and heat pipe, leg geometry design, segmentation, and multi-staging, are discussed extensively. Finally, the present study highlights research guidelines for TEG design, research gaps, and future directions for innovative works in automobile TEG technologies.

Parametric analysis and potential evaluation of thermoelectric generator driven by solar energy and radiative sky cooling

Solar energy and radiative cooling (RC)-driven thermoelectric generator (TEG) technology, which harnesses the extraterrestrial heat and cold sources from the sun and deep universe, is attracting increasing attention. However, existing studies on solar TEG (STEG) and RC TEG (RCTEG) only focus on either solar spectrum or infrared spectrum. To investigate the TEG performance considering full spectrum’s influence, a thermal-electrical coupled model based on thermal resistance theory is developed. Results indicate the TEG with ideal selective absorber (ISA) provides the best power generation performance, with a power generation of around 2.06 W/m2 and a temperature difference of about 3.18 K. The maximum power generation is 2.89 and 2.87 W/m2 for the ISA and ideal broadband absorber (IBA) systems when the bottom cooling temperature is 275 K, respectively. For every 100 W/m2 increase in solar irradiance, there is a temperature difference increment of about 0.31 K. The IBA and ideal selective absorber and emitter (ISAE) systems are capable of generating electricity continuously, ensuring a 24-hour power supply. Moreover, the radiative cooling capacity provided by the ISAE system is greater than that of the RCTEG system. The proposed STEG system has promising application potential for power generation in view of its carbon footprint features.

Recent Progress in Colloidal Quantum Dot Thermoelectrics.

Semiconducting colloidal quantum dots (CQDs) represent an emerging class of thermoelectric materials for use in a wide range of future applications. CQDs combine solution processability at low temperatures with the potential for upscalable manufacturing via printing techniques. Moreover, due to their low dimensionality, CQDs exhibit quantum confinement and a high density of grain boundaries, which can be independently exploited to tune the Seebeck coefficient and thermal conductivity, respectively. This unique combination of attractive attributes makes CQDs very promising for application in emerging thermoelectric generator (TEG) technologies operating near room temperature. Herein, recent progress in CQDs for application in emerging thin-film thermoelectrics is reviewed. First,the fundamental concepts of thermoelectricity in nanostructured materials are outlined, followed by an overview of the popular synthetic methods used to produce CQDs with controllable sizes and shapes. Recent strides in CQD-based thermoelectrics are then discussed with emphasis on their application in thin-film TEGs. Finally, the current challenges and future perspectives for further enhancing the performance of CQD-based thermoelectric materials for future applications are discussed.

Renewable Energy Integration in Bangladesh: Opportunities and Challenges for Thermoelectric and Thermoionic Systems

This paper presents a comprehensive analysis of the potential of thermo electric and thermo ionic power generation technologies in Bangladesh, with a focus on utilizing the heat generated from industry, thermal power stations, and solar irradiance. The study assesses the current energy landscape in the country and highlights the need for alternative and sustainable sources of energy to meet the increasing demand. The paper reviews the relevant literature and discusses the principles and working mechanisms of thermo electric and thermo ionic power generation technologies. It also examines the feasibility of these technologies in the context of Bangladesh and provides recommendations for their implementation. The paper concludes that thermo electric and thermo ionic power generation have the potential to significantly contribute to the country's energy mix, reduce its dependence on non-renewable sources, and promote sustainable development. The recommendations offered in this study are expected to help policymakers, industry stakeholders, and researchers in making informed decisions towards a sustainable and resilient energy future in Bangladesh.

Exhaust heat harvesting of automotive engine using thermoelectric generation technology

Exhaust heat recovery from internal combustion engines is growing interest to reduce fuel consumption, increase the efficiency and consequently, reduce the environmental pollution and global warming. Thermoelectric generator (TEG) is a promising technology to harvest engine exhaust heat by directly converting it into electrical power via the Seebeck effect. In this work, commercial Bi2Te3 (SP1848-27145 SA) thermoelectric modules (TEMs) were used for recovering exhaust heat from gasoline engines and convert it directly into electricity. Two types of setups were constructed using copper and steel materials, where both setups consist of triangular channels. The first setup was constructed entirely from copper material to work as a heat exchanger from exhaust heat to the TEMs’ hot surface. The second setup was constructed with a portion of copper at the installation area of TEMs and the rest of the portion was constructed with steel material to investigate the best performance from these two TEG systems. Six TEG modules which are electrically series connected were installed on the outer surfaces of each copper made and steel made setup. The maximum power output from copper made TEG was found to be 2.96 W for an exhaust temperature of 297 °C and at 126 °C temperature difference between the hot and cold sides. Whereas steel made TEG provided the maximum power output of 2.0 W for an exhaust temperature of 305 °C and at a 107 °C temperature difference between hot and cold sides. Therefore, the copper made TEG setup provided 48% higher power output than the steel made TEG setup. The higher power output of copper made TEG lowers the expelled exhaust temperature to the environment, which results in the decrease of entropy loss. Furthermore, since there is no effect of engine operating pressure on enthalpy loss, therefore, the engine can operate at higher operating pressure which means the contribution of the reduction of fuel cost, fuel consumption and environmental pollution parallelly. Between exhaust gas temperature ranges 297 °C to 300 °C, the highest conversion efficiency was found 4.65 % and 4.63% for steel made TEG setup and copper made TEG setup, respectively.

Dual-boost thermoelectric power generation in a GeTe/Mg3Sb2-based module

Studies on thermoelectric materials have been primarily centred on conversion efficiency, as if to assert a high-efficiency thermoelectric module always generates a large electrical power. However, there is a trade-off between conversion efficiency and power density under thermal and electrical energy losses due to contact resistances at electrode junctions. Thus, simultaneously boosting the power density and conversion efficiency (‘dual-boost’) is essential. Here, to overcome the trade-off by minimizing energy losses, we focus on two approaches for p-type GeTe- and n-type Mg3Sb2-based thermoelectric materials. First approach is to reduce thermal conductivity of GeTe by inducing a strong phonon scattering and tuning the hole concentration. Second approach is to reduce electrical contact resistivities of GeTe and Mg3Sb2 by optimizing highly conductive electrode junctions. As a result, we achieve a record-high dual-boost performance (1.94 W/cm2 and 10.1%) in a practical-size module. The result will advance thermoelectric generator technology for widespread applications.

Design and Research of Thermoelectric Generator Simulation System for Boiler Flue Gas Waste Heat

One of the significant factors contributing to high energy consumption is the unutilized waste heat from flue gas in industrial boilers. Thermoelectric generator (TEG) technology can directly convert thermal energy into electrical energy, and has been gradually applied in the field of waste heat recovery due to its simple and reliable structure, environmental protection, and other advantages. In this paper, a thermoelectric generator simulation system of boiler flue gas waste heat is proposed. The experimental platform is designed by simulating the flue gas waste heat temperature condition of boiler, and the structure of cold end module and hot end module is optimized. During the experiment, the fixed temperature difference was set at 120 °C (hot end:150 °C~cold end: 30 °C). An analysis is conducted on the volt-ampere characteristics and output power of the TEG module. The output characteristics of the TEG system are analyzed under the conditions of variable load, constant load, different pump speed, different heat dissipation modes, and series and parallel connection method. The results show that the experimental platform can instantaneously and accurately test the output parameters of the TEG system, and ensure the intended design requirements. When the ratio of the load resistance to the internal resistance of the TEG module is approximately 1–1.15, the output power of the system reaches its maximum. In order to optimize the output power of the TEG system, a power prediction-based adaptive variable step size maximum power point tracking (MPPT) algorithm is introduced. Additionally, a corresponding mathematical model is formulated. Simulations demonstrate that the time of the improved algorithm to reach the stable maximum power point is 1.54 s faster than that of the traditional algorithm. The improved MPPT algorithm satisfies the criteria for speed and accuracy, diminishes superfluous energy waste, and enhances the overall system efficiency. The research results have certain guiding significance for the design and application of subsequent TEG system.

A Sustainable Method to Convert Waste Heat Energy to Electricity by Using Thermo-Electric Generators

This paper aims to generate clean electricity by utilizing waste heat available in the environment. To achieve this, a thermoelectric generator (TEG) is used in conjunction with a Peltier module, voltage regulator, and USB charging module. The Peltier modules are connected in series to maximize voltage and minimize loss. The proposed methodology is first numerically modeled and simulated using Ansys and COMSOL, after which the model is developed with an assembly of all the above-mentioned modules. The paper mainly focuses on the sustainable use of waste heat energy to produce clean energy in the form of electricity. The paper demonstrates the working principle of thermoelectric generators and their efficiency in generating electricity from waste heat energy. It also explores the various applications of thermoelectric generator technology. The results of all three simulations are compared, and the paper emphasizes the adoption of thermoelectric generators as a practical option to recover wasted heat and reduce the environmental impact of energy-intensive industries. Overall, this paper showcases a practical solution to mitigate environmental degradation caused by industrial waste heat, while simultaneously producing clean energy.

Photovoltaic, thermoelectric and electromagnetic generation technologies applied in power systems for mobile unmanned systems

Photovoltaic, thermoelectric and electromagnetic generation technologies applied in power systems for mobile unmanned systems

Hybrid nanoarchitectonics of carbon/titanium carbide integrated hydrogel/melamine foam for highly efficient solar steam and thermoelectric power generation

Solar driven interface water evaporation, a feasible approach to solve the global water crisis, requires a rational combination of high efficiency photothermal material and evaporation structure. In this paper, carbon/titanium carbide (C/TiC) nanohybrids from Ti-based metal-organic framework (Ti-MOF) were controllable synthesized and applied for highly efficient solar steam and thermoelectric power generation. Considering inherent defects of single-component materials, the synthesized unique porous C/TiC nanohybrids exhibit both lattice resonance and plasmonic absorption properties, achieving a high solar-steam conversion efficiency of 90 %. Further, a multi-structured hydrogel (TMH) was prepared by dipping porous melamine foam in gel containing porous C/TiC nanohybrids, and a high evaporation rate of 1.93 kg m−2 h−1 under one sun irradiation has been achieved for its excellent light absorption performance and thermal management ability. Long-term desalting experiments exhibit TMH presents desirable self-cleaning characteristic and can meet its performance requirements in 3.5–20 wt% brine. More importantly, as a proof-of-concept demonstration of synergistic solar steam and thermoelectric power generation, the synergistic system simultaneously realized a high evaporation rate of 0.93 kg m−2 h−1 and produced a stable voltage up to 150 mV under one sun irradiation. This solar-thermal evaporation and thermoelectric generation technology provides a promising avenue for practical desalination and thermoelectric power generation.

Water‐resistant organic thermoelectric generator with >10 μW output

AbstractFlexible p–n thermoelectric generator (TEG) technology has rapidly advanced with power enhancement and size reduction. To achieve a stable power supply and highly efficient energy conversion, absolute chemical stability of n‐type materials is essential to ensuring large temperature differences between device terminals and ambient stability. With the aim of improving the long‐term stability of the n‐type operation of carbon nanotubes (CNTs) in air and water, this study uses cationic surfactants, such as octylene‐1,8‐bis(dimethyldodecylammonium bromide) (12–8–12), a gemini surfactant, to stabilize the nanotubes in a coating, which retains the n‐doped state for more than 28 days after exposure to air and water in experiments. TEGs with 10 p–n units of 12–8–12/CNT (n‐type) and sodium dodecylbenzene sulfonate/CNT (p‐type) layers are manufactured, and their water stability is evaluated. The initial maximum output of 16.1 µW (75 K temperature difference) is retained after water immersion for 40 days without using a sealant to prevent TEG module degradation. The excellent stability of these CNT‐based TEGs makes them suitable for underwater applications, such as battery‐free health monitoring and information gathering systems, and facilitates the development of soft electronics.

Keynote Review of Latest Advances in Thermoelectric Generation Materials, Devices, and Technologies 2022

The last decade created tremendous advances in new and unique thermoelectric generation materials, devices, fabrication techniques, and technologies via various global research and development. This article seeks to elucidate and highlight some of these advances to lay foundations for future research work and advances. New advanced methods and demonstrations in TE device and material measurement, materials fabrication and composition advances, and device design and fabrication will be discussed. Other articles in this Special Issue present additional new research into materials fabrication and composition advances, including multi-dimensional additive manufacturing and advanced silicon germanium technologies. This article will discuss the most recent results and findings in thermoelectric system economics, including highlighting and quantifying the interrelationships between thermoelectric (TE) material costs, TE manufacturing costs and most importantly, often times dominating, the heat exchanger costs in overall TE system costs. We now have a methodology for quantifying the competing TE system cost-performance effects and impacts. Recent findings show that heat exchanger costs usually dominate overall TE system cost-performance tradeoffs, and it is extremely difficult to escape this condition in TE system design. In regard to material performance, novel or improved enhancement principles are being effectively implemented. Furthermore, in addition to further advancements in properties and module developments of relatively established champion materials such as skutterudites, several high performance ZT ≈≥ 2 new material systems such as GeTe, Mg3(Sb,Bi)2 have also been relatively recently unearthed and module applications also being considered. These recent advancements will also be covered in this review.

Thermoelectric generators as an alternative for reliable powering of wearable devices with wasted heat

Everyday life relies heavily on electricity, which is also the foundation of innumerable other uses. Therefore, a continual study is required to enhance current ways or discover new ones for boosting power generation. One well-known and widely used method of generating electricity is the thermoelectric generator (TEG), which employs the Seebeck effect to transform waste energy into electrical energy. A TEG can be used whenever there is a temperature differential since the Seebeck effect allows temperature change to be converted into electrical energy. The foundation of the TEG is presented in the current study, along with an analysis of the current state of the art on TEGs. The different TEG geometries and their associated issues are also presented in this study. The new TEG technologies and the difficulties they provide are also discussed in this paper.

Experimental Investigation on Waste Heat Recovery from a Cement Factory to Enhance Thermoelectric Generation

This work investigated the potential for waste heat recovery from a cement factory using thermoelectric generation (TEG) technology. Several TEGs were placed on a secondary coaxial shell separated from the kiln shell by an air gap. The performance of the system was tested and evaluated experimentally. Two cooling methods, active water and forced air, were considered. A forced closed-loop water cooling system with a heat exchanger was considered for the active-water cooling method. A heat exchanger was inserted before the water tank to improve cooling efficiency by reducing the inlet temperature of the cooling water tank, in contrast to forced-air cooling, in which a heatsink was used. The obtained results indicated that the closed-loop water-cooled system equipped with a radiator, i.e., active water, has the highest conversion efficiency. The maximum absorbed heat for the forced-air and active-water cooling systems were 265.03 and 262.95 W, respectively. The active-water cooling method improves the power of TEG by 4.4% in comparison with forced-air cooling, while the payback periods for the proposed active-water and forced-air cooling systems are approximately 16 and 9 months, respectively.

Influence of geometric parameter and contact resistances on the thermal-electric behavior of a segmented TEG

Thermoelectric (TE) generation technology plays an increasingly significant role in a global environment. A desirable approach to improve the efficiency of thermoelectric generator (TEG) is to segment the n- and/or p-leg into several parts with different materials for increasing the average thermoelectric figure of merit of the legs, and to operate with a relatively larger temperature gradient. In this study, a three-dimensional model is developed for the performance analysis of a segmented TEG, and the geometric design optimization of the TEG is examined numerically with the use of the temperature-dependent thermoelectric materials. Specifically, the temperature, heat flow, electric potential, electric current and Joule heating in the thermoelectric modules are investigated in detail. Also, the efficiency and effectiveness of the TEG is analyzed with the design variables such as the ratio of cross-sectional area of p-leg and n-leg, the length ratio of different materials in the segmented leg, and the geometry configurations of p- and n-legs. Furthermore, the effect of the contact resistance on the TEG performance is considered. The results show that a proper design of the geometric parameters can lead to an optimal design of thermoelectric generation systems with higher efficiency.

Integrated Heat Regenerator (IHR) Designs with Hydrogen Preheater and Thermoelectric Generator for Power Enhancement of a 2 kW Fuel Cell Vehicle

The power train efficiency of fuel cell vehicles (FCV) can be enhanced by improving the hydrogen energy utilization. Based on a mini FCV running on a 2 kW open-cathode Polymer Electrolyte Membrane (PEM) fuel cell, a waste heat recovery system design needs to be developed as an approach towards higher energy efficiency. The novelty of the system is on the integration of thermoelectric generator technology with hydrogen preheating process for a combined heat and power output. This manuscript presents the proposed integrated heat regenerator (IHR) designs, analysed using numerical computational modelling. Three IHR designs were proposed where the main design criteria are (i) a minimum of 10oC hydrogen preheating degree, and (ii) non-parasitic active cooling for the Thermoelectric generator (TEG) cells. Three design concepts were studied to identify its design and performance limitations. The numerical results were validated with theoretical modelling analysis for hydrogen exit temperatures and TEG surface temperatures. The analysis on predicted fuel cell power enhancement, TEG power generation and waste heat utilization were performed by relating the temperature profiles of the hydrogen reactant and TEG surfaces to fuel cell reaction models and TEG power relationships. A compact IHR design that produced 7.7 to 8 % total power enhancement and suitable in size for a mini FCV was identified for future development works

Influence of foamed metal core flow heat transfer enhancement on the performance of thermoelectric generators with different power generation characteristics

• Core flow heat transfer enhancement with foamed metal has been studied by experiment. • The effect of different PPI of the foamed metal has been analyzed. • The effect of different filling rate of the foamed metal has been analyzed. • PEC and OP are used to analyze the performance of enhancing heat transfer at core flow. With the development of science and technology, how to recycle the waste heat of high-temperature exhaust gas discharged from daily life and industry has become the focus of attention of the scientific community. Using thermoelectric generation technology to recover and utilize the waste heat of high-temperature gas of this part can effectively improve the efficiency of energy utilization. The thermoelectric generator (TEG) is modified by inserting the foamed metal copper (FMC) at the core flow field of the heat exchanger tube to enhance the heat transfer, and the heat exchange capacity of the heat exchanger can be effectively improved, so that the power generation efficiency of the TEG can also be effectively improved. At the same time, the core flow filling method can also reduce the increased amplitude of the back pressure of the TEG. Therefore, in this article, experiments have been conducted to investigate the effect of improved heat transfer of FMC at the core flow field on the performance of TEG with different power generation characteristics. We first evaluate the effect of different enhanced heat transfer conditions on the heat transfer capacity of TEG hot end heat exchanger with the Performance Evaluation Comprehensive (PEC) evaluation method. The results showed that the enhanced heat transfer by the FMC at the core flow field can significantly improve the heat transfer capacity of the heat exchanger. Then we use the Overall Performance (OP) evaluation method to evaluate the effect of TEG on its performance under different enhanced heat transfer conditions. The results showed that the power generation of the TEG filled with FMC at the core flow field is higher than that of the unfilled TEG, and the filling of FMC with a high filling rate and high pore density can significantly improve the power output and power generation efficiency of the TEG. However, by evaluating the TEG filled with FMC at the core flow field through the OP evaluation method, it was found that the use of FMC with a low filling rate and low pore density can better improve the overall performance of TEG.