In a recent study published in the journal Biochar, researchers Dimberu G. Atinafu, Jihee Nam, and Sumin Kim introduced a breakthrough in thermal energy management. The team developed an engineered biomineral hybrid designed to address the common limitations of phase-change materials, which are substances that store and release energy during the process of melting and freezing. While these materials are essential for sustainable energy infrastructure, they often suffer from low efficiency and poor structural stability. By integrating lignocellulose-based biochar derived from spruce trees with an organically modified nanoclay mineral, the researchers created a composite that significantly boosts energy storage density and thermal reliability.

The primary achievement of this research lies in the dramatic enhancement of the material’s internal structure. By using a structural engineering approach that involves doping cationic nanoclay into the biochar, the team achieved a surface area increase of 516.4 percent compared to bulk minerals. This expanded surface area allows the hybrid scaffold to absorb and hold a much higher volume of hexadecane, the organic phase-change material used in the study. Specifically, the engineered hybrid demonstrated a 223.3 percent enhancement in latent heat capacity, rising from 15.7 to 121.3 joules per gram. This means the material can capture and release significantly more thermal energy during temperature fluctuations than previous iterations.

Durability and reliability are critical for materials intended for long-term use in construction and energy systems. The study found that the new composite retained over 95.9 percent of its energy storage capacity even after undergoing 1,000 continuous cycles of heating and cooling. This level of stability is attributed to the strong confinement effect of the biochar and nanoclay network, which prevents the liquid phase-change material from leaking out during the melting process. In testing, the leakage rate was found to be less than 2.2 percent. The physical structure of the biomineral hybrid effectively acts as a 3D lattice backbone, maintaining its shape and performance under repeated thermal stress.

Thermal conductivity is another area where the biomineral composite showed significant improvement. The researchers reported a 78 percent enhancement in thermal conductivity compared to pristine paraffin. This improvement ensures that the material can charge and discharge heat more rapidly, making it more responsive to real-time temperature changes. To demonstrate the practical benefits of these properties, the team performed computer simulations using the composite as an interior building material in a historic structure. The results were impressive, showing a 54 percent reduction in annual cooling energy consumption compared to using standard heat-storing materials and a 24.3 percent reduction from buildings without any such materials.

This fabrication technique offers a rational and environmentally friendly approach to creating advanced thermal regulation systems. By using naturally sourced feedstocks like wood waste and minerals, the researchers are promoting a circular economy while advancing green energy storage. The study concludes that this biomineral-based material provides a promising path for the next generation of renewable energy materials. While the current process involves some challenges regarding surfactant costs and wastewater management, the team suggests that future transitions to bio-based surfactants and closed-loop recycling systems could make this high-performance technology even more sustainable for large-scale production in the building industry.

Source: Atinafu, D. G., Nam, J., & Kim, S. (2026). Engineered mineral-doped biochar-infused paraffin for synergistic enthalpy storage and enhanced thermal management. Biochar, 8(6).