Bengaluru Researchers Achieve 12% Efficiency in Waste Heat Conversion

A team of researchers at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) in Bengaluru has made significant strides in thermoelectric energy conversion, achieving a remarkable maximum power conversion efficiency of nearly 12%. This figure surpasses the average efficiency of commercial thermoelectric energy converters, which typically range from 6% to 7%.

The research, led by Professor Kanishka Biswas, has focused on harnessing waste heat—a resource often overlooked in energy conversion processes. According to Biswas, “When you take the example of any energy conversion process, we only end up utilizing about 35% of it; 65% goes out in the form of waste heat.” This phenomenon is prevalent across various applications, from household light bulbs to the fuel conversion in automobiles and even energy conversion in power plants.

Transforming Waste Heat into Usable Energy

The new thermoelectric energy conversion method developed by the research team converts waste heat directly into electricity. This process not only enhances energy efficiency but also provides a path for sustainable energy solutions by minimizing consumption and emissions. Notably, thermoelectric systems produce clean electricity without the release of harmful gases such as Carbon Monoxide (CO) and Carbon Dioxide (CO2), and they require minimal maintenance due to the absence of moving parts.

For effective thermoelectric energy conversion, materials must exhibit high electrical conductivity while being poor heat conductors. The researchers successfully engineered a compound of Germanium Telluride (GeTe), achieving an extraordinary thermoelectric figure of merit, known as ‘zT,’ of approximately 2.7 at 628 K. “This approach induces polar local distortions that strongly scatter heat-carrying phonons, dramatically boosting thermoelectric performance,” said Biswas.

The findings from this research have been published in the esteemed journal Advanced Materials, marking a significant contribution to the field of materials science.

Wide-Ranging Applications and Future Implications

Professor Biswas highlighted the extensive applications of thermoelectric energy conversion technology. “Capturing and converting waste heat into usable electricity could transform sectors such as power generation, steel manufacturing, and even the automobile industry.” For instance, in hybrid vehicles, waste heat from fuel conversion can be harnessed to recharge electric batteries. In rural areas of India, heat generated from wood stoves could potentially be utilized to charge mobile phones.

The research team has also developed a new quaternary entropy-stabilized compound designed to enhance thermoelectric energy conversion efficiency. This innovative material benefits from an exceptional balance of properties, featuring ultralow thermal conductivity akin to glass and electrical conductivity similar to metals. This advancement was published in the Journal of the American Chemical Society.

The ongoing work at JNCASR not only exemplifies cutting-edge scientific research but also underscores the potential for practical applications that can lead to significant advancements in energy efficiency and sustainability across various industries.