Thermoelectric Energy Harvesting Research Articles

A Series Compensated Buck-Boost Converter-Based Thermoelectric Energy Harvesting System with Sliding Mode Controller

A thermoelectric generator (TEG) is a semiconductor-based device that can exhibit a flow of electric current through the external circuit if the sides of the TEG are subjected to a temperature difference caused by a heat source. The terminal voltage and the TEG’s internal resistance are altered depending on the temperature difference. Therefore, a suitable power electronic converter with a maximum power point tracking (MPPT) feature is required to harvest maximum power from the TEG and store the harvested energy in a battery-based energy storage system. This paper investigates a novel energy harvesting methodology from TEG using a series compensated buck-boost converter (SCBBC). MPPT has also been implemented using a sliding mode controller (SMC). A mathematical model of a TEG source has been developed in MATLAB-Simulink and tested with generic boost converter (GBC) and SCBBC for their dynamic performances during battery charging. The efficiency of conversion is found to be higher for SCBBC, at 97.87%. An experimental prototype has been developed with SCBBC and tested for two configurations, viz high voltage and low current configuration. The former configuration exhibits an efficiency of 86.3%, while the latter has an efficiency of 83%. The results indicate that SCBBC, along with SMC, opens up new efficient prospects for harvesting waste heat energy using TEGs.

Correction to “Lattice Architectures for Thermoelectric Energy Harvesting”

Correction to “Lattice Architectures for Thermoelectric Energy Harvesting”

Advancing energy solutions: Carbon-based cementitious composites in energy storage and harvesting

The rapid progress of smart and sustainable cities has led to an increased demand for construction materials that possess functional capabilities in energy storage and harvesting. In light of this, a comprehensive literature review is conducted in this study to investigate the multifunctional properties exhibited by carbon-based cementitious materials. Specifically, the piezoelectric, thermoelectric, tensile, compressive, and flexural behaviors of carbon fiber (CF), graphene, graphite powder (GP), and carbon nanotubes (CNTs) are thoroughly examined through multi-scale research approaches. The electrical conductivity and mechanical properties of these carbon-based additives are analyzed in relation to their molecular structures. Evaluation results reveal that CNTs-based cementitious composites demonstrate 160 %–269 % superior multifunctional performance compared to their CF-based counterparts. Furthermore, the feasibility of potential applications of carbon-based cementitious composites in concrete construction is extensively discussed, encompassing diverse areas such as thermoelectric energy harvesting, intelligent structural adjustment, cathodic protection systems, snow and ice melting, electromagnetic shielding, and structural health monitoring. The research outcomes presented in this study offer a systematic evaluation of a wide range of carbon-based cementitious materials, providing valuable guidelines and recommendations for engineers.

An electrical analogy model for performance evaluation of natural air-cooled TEG modules considering nonlinear effect of heat convection

With the outstanding merits of the simple principle and low computational cost, the electrical analogy model of thermoelectric generator (TEG) modules plays an important role in evaluating the performance of thermoelectric energy harvesting systems. However, owing to the simplification of the heat dissipation structure and difficulty in determining the heat dissipation parameters, it is difficult to accurately describe the nonlinear influence of thermal convection on the heat dissipation performance of the TEG module under natural air-cooled conditions, thereby reducing the estimation accuracy of the module temperature and output. A new nonlinear electrical analogy model to evaluate the performance of natural air-cooled TEG modules was proposed in this study. The proposed model more accurately describes the nonlinear influence of thermal convection on the thermal dynamic characteristics of the TEG module by introducing a heat transfer branch between the cold and hot side surfaces of the TEG module and the environment. A parameter extraction method based on multi-objective optimization and the non-dominated sorting genetic algorithm II (NSGA-II) was proposed to overcome the problem of the heat dissipation parameters of natural air-cooled TEG modules. The experimental results show that under natural convection conditions, the maximum estimation errors of the temperature and output voltage evaluated by the proposed model and parameter identification method are less than 6.18 % and 9.14 %, respectively. Under forced convection, the maximum estimation errors of the temperature and output voltage were less than 7.36 % and 8.71 %, respectively. The above estimation errors are significantly lower than the traditional model.

Enhanced thermoelectric performance of W18O49/ZnO composite for waste heat recovery with induced high weighted mobility

Zinc Oxide (ZnO) exhibits a significant Seebeck coefficient, making it a promising candidate for thermoelectric energy harvesting. This study explores composite materials comprising xW18O49/(1-x)ZnO fabricated through conventional sintering at 1150°C, with x varying from 0 to 0.3. Incorporating a highly conductive secondary phase into the ZnO matrix enhances conductivity by 28 times, reaching 111.4 Scm−1 at 800°C, while maintaining 83 % of the pristine sample's Seebeck coefficient. Notably, the power factor improves to 3.8 mWK−2m−1 for the x = 0.1 sample, representing a 19 times heightening over unmodified ZnO ceramic. Additionally, these composites exhibit high weight mobility, indicating rapid electronic responses. As a result, the ZT value increases by 500 %, reaching 0.15 at 800°C for the x = 1 sample. This study presents a novel approach to fabricating high-power-factor thermoelectric materials by integrating highly conductive oxides into matrices with large Seebeck coefficients.

A Thermoelectric Energy Harvesting System Assisted by a Piezoelectric Transducer Achieving 10-mV Cold-Startup and 82.7% Peak Efficiency

A Thermoelectric Energy Harvesting System Assisted by a Piezoelectric Transducer Achieving 10-mV Cold-Startup and 82.7% Peak Efficiency

Lattice Architectures for Thermoelectric Energy Harvesting

Lattice Architectures for Thermoelectric Energy Harvesting

How efficient are thermoelectric materials? – An assessment of state-of-the-art individual and segmented thermoelectric materials

To efficiently convert heat into electricity using thermoelectric energy harvesting, it is essential to employ new material strategies. One effective approach is segmentation, where compatible materials optimized for different operating temperatures are combined to improve thermoelectric efficiency. Despite reports of severe efficiency reductions when segmenting incompatible materials, an updated assessment of the compatibility across state-of-the-art thermoelectric materials is missing. Here, we employ a numerical model to assess how efficiently non-segmented and segmented high-performing thermoelectric materials can convert heat into electricity. For the non-segmented materials, efficiency reaches up 17.9% at ΔT = 615 K without heat losses and contact resistances. Losses due to self-incompatibility were generally found to be small for most materials (<0.6% points) with few exceptions. In contrast, segmented thermoelectric legs were very sensitive to compatibility effects. Segmentation is found to only boost the efficiency significantly for ΔT > 300 K. Here, we find efficiencies of up to 24% for p-type AgSb0.94Cd0.06Te2/Pb0.98Te0.02-8%SrTe and 19% for n-type Bi1.8Sb0.2Te2.7Se0.3/Pb0.93Sb0.05S0.5Se0.5. We further map out the maximum tolerable contact resistances before segmentation becomes detrimental. By providing an overview of the achievable energy conversion efficiencies, this study highlights the present state of thermoelectric energy conversion and critically assesses the prospects of segmentation.

Thermoelectric Energy Harvesting from the Roof and Attics of a Building

Globally people are faced with difficulties in environmental pollution, increasing power costs, and global warming. As such researchers are focusing on enhancing energy-harvesting using thermoelectric generators for power generation to lessen the difficulties. Through the Seebeck effect, thermoelectric generators (TEGs) have proven their ability to convert thermal energy into electric power. Given the unique benefits they present, thermoelectric generators have arisen in the recent decade as a possible alternative to other green power generation technologies. A thermoelectric generator (TEG) is a solid-state device that converts thermal energy into electrical energy. TEG consists of elements of p and n-type semiconductors, connected thermally in parallel and electrically in series. In this paper, one hundred and ninety-two thermoelectric generators connected in series and parallel were used to investigate the thermal energy potential at the roof and attic area for domestic application for 20 days from the falling solar radiation on a residential prototype in Bashar, Wase Local government area of Plateau State. A theoretical analysis was used in determining the average output power (P) due to the delta T across the thermoelectric generator module junction. The load resistance value of the thermoelectric generator configuration was evaluated. The results show that the TEG generated power output ranging from 217 mW to 1.99 W throughout the day, 5.97 mW to 13.8 mW in the morning, and 6.8 mW to 36.9 mW in the evening. Furthermore, The finding also reveals that the attic side has the capacity to store thermal energy, which can be harnessed owing to the fast heat transfer to the surroundings during the convection process. In conclusion, solar irradiance has a major impact on the system.

Planar-type SiGe thermoelectric generator with double cavity structure

Thermoelectric power generation is a promising technology that can directly convert thermal energy into electrical energy and is expected to be applied as power supplies for low-power electronic devices, such as sensors. In particular, planar-type devices fabricated based on lithography processes not only enable significant device miniaturization and lower cost but also take advantage of materials with smaller dimensions, such as thin films and nanowires, which have attracted much attention in recent years. Silicon germanium (SiGe) is a promising thermoelectric material due to its relatively high power factor, low thermal conductivity, and compatibility with standard top-down fabrication process. We design and fabricate a planar-type thermoelectric generator with a double cavity structure using a 240 nm thick Si0.8Ge0.2 thin film and report its performance improvement. When the temperature difference is applied to the device, the measured power density of 100 μWcm−2 was achieved at ΔT = 15 K, namely, the performance normalized by the applied temperature was 0.43 μWcm−2K−2. Finally, the dependence of the device performance on the SiGe film thickness is discussed. The results from our simulation show that a maximum performance of 1.75 μWcm−2K−2 can be achieved by the current device structure, indicating the potential for future applications as thermoelectric energy harvesters.

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.

Kaolin Clay-Based Geopolymer for Ionic Thermoelectric Energy Harvesting.

Geopolymers, a class of sustainable inorganic materials derived from natural and recycled resources, hold promise for various applications, including thermoelectric power generation. This study delves into the thermoelectric properties of Ikere white (IKW)-geopolymer, derived from kaolin clay, by employing rigorous measurements of thermal conductivity, electrical conductivity, and Seebeck coefficient. The investigation elucidates the pivotal role of temperature and ions in shaping the thermoelectric performance of IKW-geopolymer. Electrical conductivity analysis pinpoints ions within the geopolymer's channels as primary contributors. Beyond a critical temperature, the evaporation of bulk water triggers a transition of charge carriers from one- to three-dimensional motion, resulting in reduced conductivity. The Seebeck coefficient exhibits a range from -182 to 42 μV/K, with its time-dependent profile suggesting that ions potentially drive thermoelectricity in cementitious materials. Notably, a unique transition from n-type to p-type behavior was observed in the geopolymer, opening new avenues for ionic thermoelectric capacitors. These insights advance our understanding of thermoelectric behavior in geopolymers and have the potential to propel the development of novel building materials for energy conversion applications.

Experimental Study on Thermoelectric Energy Harvesting From Indoor High-Voltage Disconnector

Experimental Study on Thermoelectric Energy Harvesting From Indoor High-Voltage Disconnector

A novel solution-based approach for PANI growth on PEDOT:PSS film to fabricate PEDOT:PSS/PANI-H2SO4 bilayer and its application in thermoelectric energy harvesting

The construction of bilayer or multilayer structures has been recognized as one of the most promising strategies for exploring high-performance organic thermoelectric materials. In this study, a novel poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate)/polyaniline (PEDOT:PSS/PANI) bilayer film was successfully fabricated through a facile solution method, wherein PANI was initially dissolved in concentrated sulfuric acid (H2SO4) to form a homogenous solution which was then applied to the PEDOT:PSS film. Benefiting from the introduction of PANI, the Seebeck coefficient of the PEDOT:PSS film was improved from 16.34 to 23.17 μV K−1, while the electrical conductivity experienced a remarkable enhancement, reaching 723.34 S cm−1. Accordingly, the resulting PEDOT:PSS/PANI-H2SO4 bilayer film demonstrated a high power factor (PF) of 38.83 μW m−1 K−2, which further increased to 44.38 μW m−1 K−2 at 380 K. Hence, this technique offers a facile method to fabricate large-scale PEDOT:PSS/PANI-H2SO4 bilayer films, expanding application fields of PANI via solution-based preparation.

A Novel and Green Method for Preparing Highly Conductive PEDOT:PSS Films for Thermoelectric Energy Harvesting.

As a π-conjugated conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is recognized as a promising environmentally friendly thermoelectric material. However, its low conductivity has limited applications in the thermoelectric field. Although thermoelectric efficiency can be significantly enhanced through post-treatment doping, these processes often involve environmentally harmful organic solvents or reagents. In this study, a novel and environmentally benign method using purified water (including room temperature water and subsequent warm water) to treat PEDOT:PSS film has been developed, resulting in improved thermoelectric performance. The morphology data, chemical composition, molecular structure, and thermoelectric performance of the films before and after treatment were characterized and analyzed using a scanning electron microscope (SEM), Raman spectrum, XRD pattern, X-ray photoelectron spectroscopy (XPS), and a thin film thermoelectric measurement system. The results demonstrate that the water treatment effectively removes nonconductive PSS from PEDOT:PSS composites, significantly enhancing their conductivity. Treated films exhibit improved thermoelectric properties, particularly those treated only 15 times with room temperature water, achieving a high electrical conductivity of 62.91 S/cm, a Seebeck coefficient of 14.53 μV K-1, and an optimal power factor of 1.3282 µW·m-1·K-2. In addition, the subsequent warm water treatment can further enhance the thermoelectric properties of the film sample. The underlying mechanism of these improvements is also discussed.

Recent Progress in Self-Powered Sensors for Structural and Human Monitoring Systems Using Thermoelectric Energy Harvesters

With the evolution of Internet of Things (IoT), it has become essential to build systems that enable real-time monitoring of structures, the environment, and the human body. Among them, various studies have identified self-powering of real-time monitoring systems as one of the most important technologies . Thermoelectric generators are reported to be one of the most suitable power sources for real-time monitoring systems because they have the advantage of converting thermal energy into electrical energy through temperature gradients without using additional power sources. In this review, we will discuss structural/environmental and human health monitoring systems utilizing thermoelectric generators (TEGs). First, we will introduce the type of thermoelectric generators. Then, we will provide an overview of the thermoelectric generators utilized in structural/environmental monitoring and biomonitoring systems. The latest applications of thermoelectric generator-based systems will also be introduced to showcase their potential in industrial applications.

A Compact Dickson Hybrid Boost Converter With 5-mV Input 90.5% Peak Efficiency and On-Chip Cold-Start for Thermoelectric Energy Harvesting

A Compact Dickson Hybrid Boost Converter With 5-mV Input 90.5% Peak Efficiency and On-Chip Cold-Start for Thermoelectric Energy Harvesting

Sub-60-mV Charge Pump and its Driver Circuit for Extremely Low-Voltage Thermoelectric Energy Harvesting

Sub-60-mV Charge Pump and its Driver Circuit for Extremely Low-Voltage Thermoelectric Energy Harvesting

A phase change material based annular thermoelectric energy harvester from ambient temperature fluctuations: Transient modeling and critical characteristics

Annular thermoelectric power generator has been increasingly considered in application of ambient energy harvesting owing to the advantages of simple structure and no pollution. To improve thermal stability and energy harvesting performance of this system, the latent heat of phase change materials to improve thermal management and the high thermal conductivity of the heat sink to enhance heat transfer with the ambient are harness to annular thermoelectric power generator. Motivated by this, a phase change material based annular thermoelectric energy harvester (PCM-ATEH) with fins is developed for ambient energy harvesting and its three-dimensional transient model is also built up through jointly with thermo-electric and phase change processes. This paper considers the influence of key parameters such as temperature fluctuation amplitude, temperature fluctuation period, height ratio of PCM and thermoelectric generator (TEG) and melting temperature on liquid fraction, temperature difference, voltage and power density. Moreover, the comparison of PCM-ATEH and PCM based thermoelectric energy harvester (PCM-TEH) with/without fins is further conducted in this study to explore thermal management and energy harvesting performance. The energy harvesting characteristics of PCM-ATEH with fins is developed concerning the combination of power generation of TEG and melting process of PCM. Based on the results, it is found that the temperature difference and power density of PCM-ATEH with fins vary periodically with the sinusoidal temperature boundary, and results show that increasing temperature fluctuation period is not always feasible. Additionally, the comparative results indicate that the peak power density and energy efficiency of PCM-ATEH with fins are increased by 0.126 W/m2 and 0.02 % compared with PCM-TEH with fins, and increased by 0.195 W/m2 and 0.041 % compared with PCM-ATEH without fins. The results of energy harvesting characteristics show that a maximum of 0.77$ per watt can be reached to power generation cost of PCM-ATEH with fins. This paper can provide theoretical guidance for thermal management and energy conversion of energy harvesting system.

Design and analysis of thermoelectric energy harvester with 85.6% peak end-to-end efficiency and 38 mV self-startup using 4.13 mΩ/°C indirect temperature dependent MPPT

We present an efficient power management system (PMS) to harvest energy from thermoelectric energy generators (TEGs) via indirect temperature tracking. The PMS includes a power converter with an indirect temperature-dependent (ITD) maximum power point tracking (MPPT) controller and two complementary self-startups. The ITD-MPPT controller consists of an ITD input sampling circuit (ITD-ISC) and an ITD impedance matching circuit (ITD-IMC). The ITD-ISC detects and samples the TEG voltage (VTEG) under dynamically varying temperature gradients. The ITD-ISC removes unnecessary detachments of the converter from multi-mode reconfigurable TEGs to recover the otherwise wasted power using an adaptive input sampling (AIS) technique. The ITD-IMC adjusts the on-time of the power switch to control the input impedance (RIN) of the converter with a relatively high resolution of 4.13 mΩ/°C. This approach provides an ultrawide range source tracking from 2 Ω to 200 Ω. We also present a precision zero current switching (ZCS) controller to manage the on-time of the two power switches simultaneously. Two complementary self-startup components are realized using transformer-based (TSC) and charge-pump-based startup circuits (CSC). Integrated circuits for the PMS are fabricated using 180 nm and 28 nm CMOS processes for high efficiency and low voltage, respectively. The measurements indicate that the proposed PMS achieves an end-to-end efficiency (ηEE) above 80% over a wide source VTEG range (100 mV – 450 mV). The peak ηEE of 85.6% is achieved for VTEG = 200 mV, demonstrating the high-performance MPPT using indirect temperature tracking. TSC and CSC demonstrate successful self-startups at input voltages of 38 mV and 200 mV, respectively, thus providing reliable startup methods for various renewable energy sources.