Lv, Huang, & Zhou (2024) Performance investigation of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More/paraffin composite phase change materials in latent heat storage systems: Feasibility of biochar as a thermal conductivity enhancer. Journal of Energy Storage. https://doi.org/10.1016/j.est.2024.112106

With the global shift towards renewable energy, efficient thermal energy storage solutions have become increasingly vital. One promising technology in this field is Latent Heat Storage (LHS) systems, which utilize Phase Change Materials (PCMs) to store and release thermal energy. Recent research has focused on enhancing the thermal performance of PCMs by incorporating additives that improve heat transfer. A groundbreaking study published in the Journal of Energy Storage investigates the use of biochar as a thermal conductivity enhancer in paraffin-based PCMs, revealing significant practical implications for sustainable energy storage.

Researchers Laiquan Lv, Shengyao Huang, and Hao Zhou conducted a comprehensive experimental analysis to evaluate the performance of biochar/paraffin composite PCMs in comparison to pure paraffin and expanded graphite (EG)/paraffin composites. The study aimed to understand how the inclusion of biochar and EG affects the thermal conductivity, charging, and discharging times of the PCMs within an LHS system.

Key Findings

Thermal Conductivity Enhancement. The thermal conductivity of paraffin increased from 0.293 W/(m·K) to 0.366 W/(m·K) with the addition of 10 wt% biochar and to 0.56 W/(m·K) with 2 wt% EG.

Charging and Discharging Times. Incorporating biochar extended the charging time by 48.11%, whereas EG reduced it by 20.13%.During discharging, biochar and EG shortened the time by 8.54% and 51.77%, respectively.

Overall Cycle Time. The cycle time for charging and discharging with pure paraffin was 93.92 minutes. This extended to 107 minutes with biochar and shortened to 57.08 minutes with EG, representing a 13.93% increase and a 39.22% decrease, respectively.

Practical Implications

The findings of this study highlight the dual impact of biochar on the thermal performance of PCMs. While biochar extends the charging time, it significantly shortens the discharging time, which could be advantageous in certain applications. Here are some practical considerations for implementing biochar in LHS systems

Extended Cycle Time for Energy Storage. The longer charging time with biochar implies a slower absorption of heat, which can be beneficial in applications where gradual energy storage is needed, such as solar water heating systems during peak sunlight hours.

Improved Heat Release Efficiency. The faster discharging time suggests that biochar-enhanced PCMs can release stored heat more efficiently. This is particularly useful in scenarios where rapid heat availability is required, such as in nighttime heating applications.

Environmental and Economic Benefits. Biochar is derived from abundant and renewable biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More sources, making it a cost-effective and environmentally friendly additive for PCMs. Its use can contribute to reducing reliance on fossil fuels and enhance the sustainability of thermal storage solutions.

The study by Lv, Huang, and Zhou provides valuable insights into the potential of biochar as a thermal conductivity enhancer for PCMs in LHS systems. By improving the heat transfer properties and optimizing the charging and discharging cycles, biochar/paraffin composites present a promising avenue for advancing renewable energy technologies. As the global demand for sustainable energy storage solutions grows, the incorporation of biochar into PCMs offers a practical and eco-friendly approach to meeting these evolving needs.