A second life for a tea leaf: Turning waste into clean energy

GUWAHATI: What if your morning cup of tea could one day power your car or light up your home? A groundbreaking study by researchers at the University of Science and Technology Meghalaya (USTM) has shown that discarded tea leaves can be transformed into a clean and renewable source of energy.

Published in Springer Nature’s journal Biomass Conversion and Biorefinery, the study by Dr Shruti Sarma and Dr Rajib Saha demonstrates how spent Camellia sinensis leaves—commonly known as used tea waste—can be converted into bioethanol, a sustainable fuel that offers a promising alternative to fossil fuels.

As the world grapples with rising greenhouse gas emissions and depleting energy reserves, the need for eco-friendly fuels has become more urgent than ever. Unlike conventional biofuel production, which often relies on food crops, the USTM research focuses on an abundant and underutilised waste resource—tea leaves. India, being one of the largest tea producers globally, generates vast amounts of such waste daily, much of which ends up in landfills.

“Our aim was to find value in what is otherwise discarded,” said Dr Sarma, lead author of the study. “Tea waste contains rich organic compounds, and by using advanced nanotechnology, we’ve been able to tap into its potential as a renewable energy source.”

The innovation hinges on an iron–zinc oxide (Fe–ZnO) nanocatalyst, which accelerates the conversion of tea leaf oil into bioethanol with high efficiency. These nanoparticles, measuring just 30–50 nanometres, enabled faster reactions with minimal energy loss. Combined with a microwave-assisted process, the method drastically reduced reaction times from hours to minutes and achieved an impressive 75% yield of bioethanol.

“This approach not only enhances efficiency but also makes the process more sustainable,” said Dr Saha. “It’s a small step toward reducing waste and building circular, low-carbon systems.”

Comprehensive analyses using GC-MS, NMR, and FTIR confirmed the quality and energy potential of the produced bioethanol. The findings suggest that even a small-scale conversion of tea waste could contribute significantly to India’s renewable energy goals.

Beyond the lab, this innovation highlights the power of simple ideas rooted in local realities. From a humble cup of tea to a source of clean fuel, the research symbolizes how sustainability can begin with everyday resources. As Dr Sarma puts it, “Every leaf has a second life—and in that second life, it might just power the world.”

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