Harnessing clean energy from the sun and deep space: A breakthrough in thermoelectric generators

As the world races to transition to renewable energy, researchers are exploring innovative ways to harness untapped natural resources. Among these, thermoelectric generators (TEGs) have emerged as a promising technology—converting temperature differences directly into electricity without moving parts or emissions. Now, a groundbreaking review from The Hong Kong Polytechnic University reveals how TEGs can leverage both solar heat and the cold depths of space to deliver clean, continuous power. 

Published in Energy Engineering, 2024, the study provides a comprehensive analysis to date of solar- and radiative cooling-driven TEG systems. "Most renewable technologies only work intermittently—solar panels don't function at night, for instance," explains Ir Prof. Lin Lu, the study's corresponding author. "Our work shows how TEGs can bridge this gap by harvesting energy from both the sun's heat and the extreme cold of outer space, offering truly 24/7 clean power generation."

The research highlights remarkable efficiencies, with concentrated solar TEGs reaching up to 9.6% conversion rates—comparable to early commercial solar panels. Meanwhile, radiative cooling TEGs can generate electricity even after sunset, with one experimental setup producing enough power (25 mW/m²) to light an LED at night.

"TEGs are a game-changer for sustainable energy," says Dr. Lin Lu. "By combining solar absorption and radiative cooling, we can achieve continuous power generation without relying on traditional energy sources." This novel approach offers a sustainable and efficient method for round-the-clock power generation, paving the way for eco-friendly energy solutions.

With global energy demands rising and the urgent need to decarbonize, this research provides a roadmap for making TEGs a practical component of our renewable energy future. "Imagine buildings that power themselves by simply harnessing temperature differences," Dr. Lu adds. "That's the transformative potential we're working toward."

The team's innovative approach involves utilizing specific coatings to optimize solar energy absorption and radiative cooling efficiency. This method not only enhances energy conversion but also provides a cost-effective and environmentally friendly energy solution for various applications.

"These systems could revolutionize how we think about renewable energy," adds Dr. Lu. "They’re silent, scalable, and perfect for areas with limited infrastructure." The study also highlights challenges, such as improving thermal management and scaling up production. However, the potential applications—from powering LED lights to integrating with buildings, with one prototype showing potential to generate 2.1 kWh/m² annually—enough to charge a smartphone daily—are vast.