The pervasive reliance on charcoal and firewood for domestic cooking in Tanzania has intensified deforestation and environmental degradation, creating an urgent need for sustainable fuel alternatives. With over two-thirds of Tanzanians relying on 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 fuels, and urban households alone consuming more than two million tonnes of charcoal annually, a cleaner solution is vital. This study, conducted by researchers at the Tanzania Industrial Research and Development Organization (TIRDO) and REPOA, systematically investigated the optimization of biomass briquettes derived from locally available agricultural residues to replace traditional charcoal.

The research focused on carbonized agricultural residues—specifically coconut shell, palm kernel shell, and rice husk—and forest wastes (charcoal dust), combining them with different binders: starch, molasses, and clay. The goal was to meet the new Tanzania National Standard (TZS 3545:2024), which requires a gross calorific value (GCV) of ≥4300 kcal kg−1 and fixed carbon ≥44%.

The results showed that the type of feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More strongly dictates briquette performance. Coconut shell, palm kernel shell, and charcoal dust biochar excelled, demonstrating high fixed carbon content (exceeding 65%) and low ash content (below 10%). These materials yielded superior GCVs ranging from 6,299 to 6,737 kcal/kg. In stark contrast, briquettes made solely from rice husk were suboptimal, exhibiting very high ash content (38–52%) and a low GCV (2,441–3,859 kcal/kg) due to the husk’s high silica composition.

The binding material was found to have a significant impact on structural stability and combustion efficiency. Starch consistently produced the best results across all tests. Briquettes made with starch binder showed high shatter resistance (above 93%) and rapid ignition times (2–4 minutes), reflecting superior mechanical strength and usability. The optimal starch loading was determined to be 20% for single-feedstock briquettes and 25% for blended systems. Molasses produced moderately strong briquettes with acceptable energy output but slightly higher ash content, while clay increased ash content and prolonged ignition time due to its non-combustible nature.

A key innovation of the study involved optimizing blends to make use of abundant, low-grade residues like rice husk. Blending rice husk with high-energy biochar (coconut shell, palm kernel shell, or charcoal dust) at a 60:40 ratio successfully enhanced the briquette quality. This optimal blend ratio increased the calorific value to 4,741–5,552 kcal/kg and reduced the ash content to below 20%, bringing them within national and ISO standards. Blended briquettes at this ratio also exhibited robust mechanical properties, with shatter resistance above 92% and good water stability. A 50:50 blend, however, showed moderate performance with lower energy density and higher ash levels.

This research offers a practical, scalable model for sustainable energy transition in Tanzania and comparable African contexts. By replacing traditional charcoal, the optimized briquettes help mitigate deforestation, which has been rampant, with an estimated annual loss of 470,000 hectares of woodland between 2012 and 2021. Furthermore, carbonization and briquetting significantly reduce greenhouse gas and pollutant emissions, with studies showing a >70% reduction in greenhouse gas emissions and a 49–74% decrease in pollutants like carbon monoxide and particulate matter when compared to conventional burning methods. This aligns with Tanzania’s National Clean Cooking Strategy (2024–2034) and contributes to the country’s climate change goals under the Paris Agreement. The approach transforms waste into energy, fostering a circular economy and creating local employment opportunities.

Source: Lichinga, K. N., Sikazwe, K., Elibariki, R., Masse, A. A., Kayumba, H. I., & Shija, H. (2025). Cleaner cooking solutions: Optimizing biomass briquettes to replace charcoal and mitigate climate change in Tanzania. Scientific African, 30, e03056.