This article presents a sustainable thermal energy harvesting system for generating electricity, integrating solar absorbers (SA), radiative coolers (RC), and thermoelectric generators (TEG). The system simultaneously harvests thermal energy from the sun and cold space, offering a promising solution for clean electricity generation. The sun provides a vast amount of thermal energy, while cold space offers an abundant and timeless resource for maintaining Earth's energy balance. SA converts solar radiation into heat, RC emits infrared radiation into cold space for cooling, and TEG converts the temperature difference into electricity. The integration of these components enables uninterrupted power generation throughout the day. The SA is designed to efficiently absorb sunlight, while the RC selectively emits infrared radiation into cold space. Advanced micro/nanoengineering strategies have been employed to enhance the performance of these components. The TEG, a solid-state heat engine, converts heat into electricity without moving parts, emissions, or noise. The efficiency of TEGs is evaluated using parameters such as figure of merit (zT) and efficiency (η). Recent advancements in materials and device design have improved the performance of TEGs, with experimental efficiencies reaching up to 15.2%. The integration of SA, RC, and TEG enables a self-powering system that can generate electricity continuously. The SA-TEG-RC system has shown promising results, with the SA absorbing solar energy during the day and the RC cooling the TEG at night. The system can generate electricity throughout the day, with theoretical efficiencies reaching up to 40.5%. The potential of this system is significant, with the ability to generate enough electricity to meet global demand. Despite these advancements, challenges remain, including ensuring spectral selectivity, optimizing the configuration of SA and RC, and implementing effective thermal management. Future opportunities include small-scale customization, regional and global applications, and deep space exploration. This technology offers a decentralized, sustainable solution for energy generation, with the potential to transform the global energy structure and contribute to environmental preservation and economic development.This article presents a sustainable thermal energy harvesting system for generating electricity, integrating solar absorbers (SA), radiative coolers (RC), and thermoelectric generators (TEG). The system simultaneously harvests thermal energy from the sun and cold space, offering a promising solution for clean electricity generation. The sun provides a vast amount of thermal energy, while cold space offers an abundant and timeless resource for maintaining Earth's energy balance. SA converts solar radiation into heat, RC emits infrared radiation into cold space for cooling, and TEG converts the temperature difference into electricity. The integration of these components enables uninterrupted power generation throughout the day. The SA is designed to efficiently absorb sunlight, while the RC selectively emits infrared radiation into cold space. Advanced micro/nanoengineering strategies have been employed to enhance the performance of these components. The TEG, a solid-state heat engine, converts heat into electricity without moving parts, emissions, or noise. The efficiency of TEGs is evaluated using parameters such as figure of merit (zT) and efficiency (η). Recent advancements in materials and device design have improved the performance of TEGs, with experimental efficiencies reaching up to 15.2%. The integration of SA, RC, and TEG enables a self-powering system that can generate electricity continuously. The SA-TEG-RC system has shown promising results, with the SA absorbing solar energy during the day and the RC cooling the TEG at night. The system can generate electricity throughout the day, with theoretical efficiencies reaching up to 40.5%. The potential of this system is significant, with the ability to generate enough electricity to meet global demand. Despite these advancements, challenges remain, including ensuring spectral selectivity, optimizing the configuration of SA and RC, and implementing effective thermal management. Future opportunities include small-scale customization, regional and global applications, and deep space exploration. This technology offers a decentralized, sustainable solution for energy generation, with the potential to transform the global energy structure and contribute to environmental preservation and economic development.