An assessment of thermal energy storage in phase change materials (PCMs) to generate electrical energy through thermoelectric generators (TEGs) for low power devices: a review

Due to technological advancements, the energy demand on electronic devices has been reduced from milliwatts (mW) to microwatts (µW), and this microwatt power will be manageable with the usage of thermoelectric generators (TEGs). The TEGs work on the Seebeck effect and generate electricity due to temperature differences. To ascertain the temperature difference required for the power generation, phase change materials (PCMs) are widely recommended to integrate with TEGs. It is desired to prefer the PCMs of low temperature and high temperature types for cold and hot sides of TEGs, and as a result, it could be indeed beneficial to achieve a larger temperature difference for the power generation. The power output from TEGs could be sufficient to feed low power devices such as sensors, IoTs, ships, locomotive industries, wearable devices and signal indicators. The latest research progresses on the materials used for fabricating TEGs, placement of TEGs in the waste heat areas so as to achieve a maximum conversion efficiency, and heat transfer enhancement of PCMs used in TEGs. Due to their environmental sustainability, reliability, minimal maintenance costs, and direct power generation, TEGs are widely employed in various industries. The Internet of Things periphery devices are classified into three categories: Smart Home, Smart Factory, and Energy Efficiency. The high thermal capacity of PCM protects TEG and prevents device failure. The expansion of PCM-TEG's cooling capacity enhances its efficacy. The results indicate that the operating duration is extended by higher thermal power levels and that PCM reduces output voltage fluctuations. Inadequate heat source power may lead to partial PCM melting, which could result in a reduction in electricity output during non-heating periods. This study illustrates the great potential of thermoelectric power generators to herald in a new era of Internet of Things sensing devices by extracting energy from the ambient temperatures. This work could portray the wide area from the development of the novel generators and materials for better performance (Figure of merit), less space, and economically feasible, and the mechanism of heat transfer, critical analysis, importance of IoT, applications, advantages to drawbacks of TEG-PCM module.