Turning food waste into smart energy materials: Engineered biochar boosts thermal storage performance

Researchers have developed a new way to transform food waste into high-performance materials that can store and regulate heat, offering a promising solution for energy-efficient buildings and sustainable thermal management.

“By engineering biochar from food waste and integrating it into phase change materials, we were able to significantly enhance thermal performance while maintaining sustainability,” said the study’s corresponding author. “This approach opens a new pathway for circular economy solutions in energy storage.”

Phase change materials, or PCMs, are widely studied for their ability to absorb and release heat during phase transitions, such as melting and solidifying. These materials can store large amounts of thermal energy at nearly constant temperatures, making them attractive for applications ranging from building insulation to wearable temperature regulation. However, conventional PCMs suffer from low thermal conductivity and limited stability, which restrict their practical use.

In the new study, researchers addressed these limitations by introducing a small amount of engineered biochar derived from food waste into microencapsulated bio-based PCMs. The biochar was produced through controlled pyrolysis and chemical activation, creating a porous structure with enhanced surface properties.

Despite adding less than 1 percent biochar by weight, the team observed substantial improvements in thermal performance. The composite materials showed more than a 30 percent increase in thermal diffusivity, meaning heat could move through the material more efficiently. At the same time, the materials maintained strong energy storage capacity, reaching up to 61.6 kilojoules per kilogram, which is comparable to or even slightly higher than the original PCM.

The study also found that the engineered composites exhibited improved thermal stability. Decomposition temperatures increased by more than 20 degrees Celsius compared to the unmodified material, indicating better resistance to heat-induced degradation. According to thermal analysis results presented in the paper, this enhancement is critical for long-term applications in real-world environments.

Microscopic imaging revealed that the biochar formed a network within and around the PCM microcapsules, creating pathways that facilitate heat transfer. Meanwhile, chemical analysis confirmed that the biochar and PCM remained compatible, with no undesirable reactions occurring during fabrication.

Beyond laboratory measurements, the researchers evaluated the practical impact of the material using building energy simulations. When incorporated into interior building materials, the biochar-enhanced PCM reduced annual cooling energy demand by approximately 13.3 percent compared to a standard building model. This finding highlights the potential of the material to contribute to energy savings and lower greenhouse gas emissions.

Importantly, the use of food waste as a feedstock adds an environmental advantage. Converting discarded biomass into functional materials not only reduces waste but also supports the development of low-cost, scalable technologies for clean energy applications.

The researchers emphasize that optimizing the structure of biochar, particularly its pore size distribution and activation conditions, is key to maximizing performance. Among the tested samples, biochar activated at 600 degrees Celsius with a balanced chemical ratio delivered the best overall results.

“This work demonstrates that sustainable materials can compete with or even outperform conventional additives,” the authors noted. “It provides a practical strategy for advancing green energy storage technologies.”

The study suggests that biochar-based PCM composites could play a significant role in future energy systems, especially in buildings where heating and cooling account for a large share of energy consumption. By combining waste valorization with advanced material design, the approach offers a scalable and environmentally friendly pathway toward improved thermal management.

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Journal Reference: Atinafu, D.G., Choi, J.Y., Nam, J. et al. Sustainable thermal buffering of microencapsulated bio-phase change materials through an engineered biochar dopant. Biochar 7, 27 (2025).   

https://doi.org/10.1007/s42773-025-00425-7   

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About Biochar

Biochar (e-ISSN: 2524-7867) is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field. 

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