Recovery of Photovoltaic Module Heat Using Thermoelectric Effect

The growing demand for renewable energy sources, in particular for solar technologies, requires more detailed studies to increase power and efficiency. Among them, thermoelectric energy conversion is a well-known technology used for decades including solar thermal generators (STEG), radioisotope thermoelectric generators (RTG), automotive thermoelectric generators (ATG) and thermoelectric generators (TEG). This chapter aims to demonstrate that the thermoelectric effect (Seebeck effect) can be used to harness the thermal energy retained in photovoltaic panels to increase their overall efficiency with its direct conversion into electrical energy and vice versa. It is also observed that solar radiation can be converted directly into electric energy, as in photovoltaic modules, or yet can be converted directly into electricity, as in thermoelectric modules. It is emphasised that although the energy conversion by thermoelectric effect still has low electrical efficiency, this source is characterised by a high degree of reliability, low maintenance, appreciable durability and absence of moving parts, and it allows generating electric energy through recovery of the thermal energy from several industrial processes. At the end of this chapter is presented a case study related to the thermal energy absorbed by a polycrystalline photovoltaic module to illustrate their increased efficiency and power in thermoelectric-photovoltaic cogeneration

Characterization and Dynamic Analysis of Long-Cavity Multi-Section Gain-Levered Quantum-Dot Lasers

This research investigates the impact of different device architectures on the frequency response of long-cavity multi-section quantum-dot lasers. This work focused on a novel 8.3-mm multi-section quantum-dot device which possessed the flexibility to be configured either as a single- or multi-section device having gain-to-modulation section ratios of 14:2 and 15:1. The long-cavity device design facilitated the testing of increased gain-to-modulation section length ratios previously unexplored in the context of the gain-lever effect. The investigation of the gain-lever effect showed improvements to both the modulation efficiency and modulation bandwidth of the device under test. The modulation efficiency and modulation bandwidth were found to vary as the modulation section length was increased, leading to the conclusion of an ideal gain-to-modulation section ratio. In addition to providing a means to investigate the gain-lever effect, the long-cavity quantum-dot device exhibited passive mode locking both with and without a saturable absorber present. While the predictable gain-lever effects were observed, long-cavity and mode-locking effects were also present in the response; these effects presented unexpected characteristics that are not captured by current published models

Body powered thermoelectric systems

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (p. 107-111).Great interest exists for and progress has be made in the effective utilization of the human body as a possible power supply in hopes of powering such applications as sensors and continuously monitoring medical devices [1]. This report furthers into the area of thermal energy harvesting, which focuses on using the temperature differential generated between the human body and the ambient environment to generate power. More specifically, a body-powered, thermoelectric-based power supply and system will be introduced and examined, with hopes that this technology will be utilized alongside low-power, medical monitoring applications in order to achieve self-sufficiency. This report also analyzes the performance of existing thermoelectric-based body-powered energy harvesting applications and compares that with the new design introduced in this work. The new designs were able to output upwards of 25[mu]W/cm2 or, equivalently, 280µW for the entire heat sink system. Additionally, this report details the physics associated with thermoelectric modules, addresses the issues with modern thermoelectric heat-sinks, introduces two new types of wearable, conformal heat sinks, quantifies the performance of the body-powered thermoelectric supply, tests a flexible EKG processing board, and analyzes future paths for this project.by Krishna Tej Settaluri.M.Eng

Autonomous Sensing Nodes for IoT Applications

The present doctoral thesis fits into the energy harvesting framework, presenting the development of low-power nodes compliant with the energy autonomy requirement, and sharing common technologies and architectures, but based on different energy sources and sensing mechanisms. The adopted approach is aimed at evaluating multiple aspects of the system in its entirety (i.e., the energy harvesting mechanism, the choice of the harvester, the study of the sensing process, the selection of the electronic devices for processing, acquisition and measurement, the electronic design, the microcontroller unit (MCU) programming techniques), accounting for very challenging constraints as the low amounts of harvested power (i.e., [μW, mW] range), the careful management of the available energy, the coexistence of sensing and radio transmitting features with ultra-low power requirements. Commercial sensors are mainly used to meet the cost-effectiveness and the large-scale reproducibility requirements, however also customized sensors for a specific application (soil moisture measurement), together with appropriate characterization and reading circuits, are also presented. Two different strategies have been pursued which led to the development of two types of sensor nodes, which are referred to as 'sensor tags' and 'self-sufficient sensor nodes'. The first term refers to completely passive sensor nodes without an on-board battery as storage element and which operate only in the presence of the energy source, provisioning energy from it. In this thesis, an RFID (Radio Frequency Identification) sensor tag for soil moisture monitoring powered by the impinging electromagnetic field is presented. The second term identifies sensor nodes equipped with a battery rechargeable through energy scavenging and working as a secondary reserve in case of absence of the primary energy source. In this thesis, quasi-real-time multi-purpose monitoring LoRaWAN nodes harvesting energy from thermoelectricity, diffused solar light, indoor white light, and artificial colored light are presented

NASA SBIR abstracts of 1990 phase 1 projects

The research objectives of the 280 projects placed under contract in the National Aeronautics and Space Administration (NASA) 1990 Small Business Innovation Research (SBIR) Phase 1 program are described. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses in response to NASA's 1990 SBIR Phase 1 Program Solicitation. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 280, in order of its appearance in the body of the report. The document also includes Appendixes to provide additional information about the SBIR program and permit cross-reference in the 1990 Phase 1 projects by company name, location by state, principal investigator, NASA field center responsible for management of each project, and NASA contract number