Whenever a body engages in physical activity, muscles break down nutrients like fats and glucose for energy. This process generates energy but also releases heat as a byproduct. Generally speaking, this heat is a waste product of our metabolism.
Most of the heat is untapped and simply escapes into the atmosphere. Researchers are eyeing this heat to generate electric energy.
Experiments by researchers at the University of Limerick and the University of Valencia have revealed a sustainable method that converts body heat into electricity. This approach uses Lignin from the wood and salt solution to harness the energy.
The thermoelectric effect is a common phenomenon that converts waste heat into electricity. As electrons flow from a hot to a cool side, they produce electric potential to generate usable electrical energy.
However, thermoelectric materials are mostly made from cadmium, lead, or mercury. These elements come with environmental as well as health risks.
The study published in Advanced Functional Materials uses a substance from wood to create thermoelectric materials. Lignin is a complex organic polymer found in most plants in the bark.
During the research, the team found that lignin-based membranes, when soaked in salt solution, convert low-temperature waste heat (below 200°C) into electricity. The temperature gradient between the lignin and salt solution causes charged atoms to move.
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As negative ions shift toward the warmer side and positive ions toward the cooler side, this electric potential difference can be tapped as electrical energy. As 66% of industrial waste heat falls within this temperature range, this new technology has wide potential applications.
For heavy industries, these lignin-derived membranes may offer a solution to utilize their leftover heat. Given its eco-friendly nature, it could be a reliable mechanism for sustainable energy generation.
However, effectively storing the captured energy is a new set of trouble. While Supercapacitors are effective energy storage devices, their reliance on fossil-fuel-based materials asks for an eco-friendly alternative.
Muhammad and his colleagues have discovered that lignin-based porous carbon can serve as an electrode in supercapacitors. This enabled the lignin membrane to capture and convert waste heat into electrical energy.
“We have shown that abundantly available lignin polymer can be successfully used for low-grade thermal energy harvesting, especially in situations where sustainability and cost-effectiveness are crucial,” says the lead author Muhammad Muddasar.
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Journal Reference
- Muddasar, M., Nasiri, M. A., Cantarero, A., Gómez, C., Culebras, M., & Collins, M. N. (2024). Lignin-Derived Ionic Conducting Membranes for Low-Grade Thermal Energy Harvesting. Advanced Functional Materials, 34(12), 2306427. 10.1002/adfm.202306427