In Addis Ababa, Ethiopia, a new study shows that fruit waste can be turned into usable cooking fuel. Briquettes made from avocado pits and banana peels, supplemented with bagasse from the sugar industry, perform remarkably well in lab tests. They ignite easily, provide stable heat, and produce little smoke. This suggests opportunities for urban kitchens if the transition to production proves feasible.
The study was published on November 17, 2025, in Scientific Reports. The research was conducted by Addis Ababa University, Center for Environmental Science, in collaboration with the Bio and Emerging Technology Institute, Nanotechnology Directorate, under the leadership of Eldana Zeleke Gebremariyam, with co-authors Eyasu Derbew Demeke, Wondimagegn Mamo Mengistu, and Yedilfana Setarge Mekonnen.
Pilot project with local waste streams
The researchers collected avocado pits and banana peels from juice bars around Arat Kilo in Addis Ababa and bagasse and molasses from the Wonji sugar factory near Adama. The material was air-dried, then charred for thirty minutes at 500 degrees Celsius in a low-oxygen oven, finely ground, and pressed into oval briquettes with water and molasses as a binding agent. The briquettes dried in the sun for five days to approximately ten percent moisture. The molds have openings on both sides to improve airflow during burning.
In the test series, a blend of 40 percent avocado and 60 percent bagasse stood out with a lower value of 29,93 megajoules per kilogram. Ignition times ranged from 1,39 to 2 minutes, and the burn time ranged from 29,1 to 43,41 minutes. Measured carbon monoxide levels ranged from 1,8 to 14,5 ppm, indicating efficient combustion in the setup used. The reported density is 1,26 grams per cubic centimeter, contributing to a longer, more even heat release.
The energy value of the best briquettes is close to that of household charcoal. A net calorific value of around 30 megajoules per kilogram is often used for charcoal. This makes the measured 29,93 MJ per kilogram relevant for cooking and space heating, especially if production and distribution can be made affordable.
Ethiopia relies heavily on solid biomass for cooking, including in cities. Recent analyses show that the share of households with access to clean cooking solutions is still limited and that the transition to cleaner options is slow. In this context, briquettes made from local fruit waste and bagasse can contribute, provided they meet the price, convenience, and availability requirements necessary for large-scale use.
Preconditions for scaling up
The authors used locally available techniques, such as sun drying, a hand press, and molasses as a binder. Consistent quality requires attention to moisture content, pressing pressure, and the ratio of avocado, banana, and bagasse, as this combination determines the ash fraction, ignition, and burning time. The design and use of cooking appliances must ensure airflow around the oval briquettes, so that the low emissions from the lab are also reflected in a kitchen. The article emphasizes the need for standardization and organizational integration to move from experimental batches to a viable supply chain.
Source:
Scientific Reports, November 17, 2025, Briquette production from industrial and fruit wastes as a clean fuel for versatile applications, by Eldana Zeleke Gebremariyam and co-authors.
