From Waste to Watt: Dr. Yan Li's Thermoelectric Breakthrough

In 2024, Yan Li, Assistant Professor of Engineering, received an Irving Institute Faculty Seed Grant to advance her research in thermoelectric engineering in partnership with Oak Ridge National Laboratory. Building on this work, she, her PhD student Ya Tang, and her ORNL collaborator Xianhui Zhao, recently published a paper titled A Novel Thermoelectric System for Enhancing Power Generation from Waste Heat in Energy Conversion and Management. 

Their innovative system maximizes power output by as much as 130% through modeling realistic temperature variations, unlike previous static approaches. This breakthrough has significant implications for energy conservation. By optimizing heat recovery and improving energy conversion efficiency, this technology could substantially reduce energy demand and carbon emissions. To learn more, I've interviewed Dr. Li about the research.

Question: What inspired you to focus on thermoelectric generators (TEGs) for waste heat recovery, and what potential do you see for this technology in addressing global energy challenges? 

Dr. Li: "Thank you for raising this important question. My interest in this research stems from the fact that many engineering systems, particularly in industrial processes and transportation, release a substantial amount of heat as a byproduct. Recovering this otherwise wasted thermal energy and converting it into electricity offers tremendous potential for advancing a more sustainable and energy-efficient future.

Traditional energy recovery systems, such as steam turbines, are heavy, bulky, and rely on multiple moving parts. Their size, complexity, and high maintenance requirements make them unsuitable for compact or distributed applications. In contrast, TEGs are compact solid-state devices without moving parts. Therefore, the maintenance cost is much lower. Another promising aspect of TEGs is that they are scalable both up and down. For example, they can be miniaturized to power wearable electronics or scaled up for deployment in geothermal wells. Because of these advantages, I do believe TEG technology holds tremendous potential for advancing global energy sustainability."

Question: How might this technology be most effectively applied in real-world scenarios?

Dr. Li: "I think the TEG technology can be most effectively applied in real-world scenarios where waste heat is abundant, space is limited, and maintenance needs to be minimal. These are their biggest advantages compared to traditional energy recovery approaches. For example, in next-generation transportation vehicles, such as electric vertical take-off and landing (eVTOL) aircraft, TEGs can be integrated to harvest heat to supplement power from batteries without adding significant weight or requiring complex maintenance. TEGs can also reduce or eliminate the need for frequent charging in wearable devices used in military or medical applications. These are all exciting real applications where TEGs can really make a difference."

Question: For students looking to get involved in this field, what skills or knowledge would be most valuable, and what specific research areas offer the most potential for innovation?

Dr. Li: "I believe thermoelectric materials research is inherently interdisciplinary and offers many exciting opportunities. From a materials science perspective, pushing the current temperature limits through the synthesis of novel material systems remains a highly promising area. Additionally, additive manufacturing of thermoelectric materials is still in its early stages, with significant challenges to overcome in establishing a robust design-to-manufacturing workflow. Moreover, the integration of AI for materials discovery, manufacturing optimization, and inverse design holds great potential to accelerate innovation and enable customized, high-performance thermoelectric devices.

For students interested in this area, a solid foundation in materials sciences, mechanics, thermal and chemical engineering is important. Specific skills, such as computational modeling, material characterization, and 3D printing are highly valuable. Dartmouth offers programs and research opportunities to help students develop these skills."

Question: How does the cost-effectiveness of your proposed system compare to existing waste heat recovery technologies, and what steps are needed to make it economically viable for widespread adoption?

Dr. Li: "Compared to existing waste heat recovery technologies, our proposed system does not require lubrication or mechanical upkeep. It can also harvest low-to-medium grade heat that is typically unusable by conventional systems. I think these are the primary cost advantages of our system and TEG systems in general. Currently the cost-effectiveness of TEGs is still constrained by the high cost of thermoelectric materials and relatively low energy conversion efficiency. At this point, the upfront cost may not be low, but they can be more cost-effective over the system's lifetime in applications."

Question: What are the next steps in your research? What specific aspects of the TEG system are you planning to further investigate or optimize?

Dr. Li: "In the next phase of my research, we are focusing on two main thrusts. The first involves 3D printing thermoelectric materials with geometries that can conform to diverse application environments, such as the complex structures found in geothermal wells. The second explores thermoelectrocatalysis (TECatal), a hybrid approach that leverages the unique properties of thermoelectric materials to enhance both energy conversion and catalytic reaction efficiency. We are very excited about expanding the scope of our previous work into these emerging areas and finding new pathways for multifunctional energy systems and advanced materials integration."