Uganda's energy needs are skewed toward biomass consumption, which accounts for more than 90% of the country's needs. Wood accounts for 70% of biomass consumption, charcoal for 16%, and agricultural waste for 4% [1–3]. Other energy sources include fossil fuels which make up 5% and hydroelectricity with only 5% from two large dams and small hydro projects. Such reliance on biomass fuels, along with Uganda's fast population increase, has put significant constrain on natural resources, particularly forests. With a total forest coverage of 9%, Uganda has lost 15% of its forest estates in the previous 25 years, standing for about 3.06 million of lost hectares, from 4.88 million ha in 1990 to 1.82 million ha in 2015 [4]. This has greatly contributed to the irregular and rampant soil erosion, as well as the non-uniform and erratic rainfall distribution [5] and to social impacts like poverty [6]. Uganda’s population has continued to grow rapidly to approximately 43 million people in 2022 [7]. In 2019, over 76 percent of Uganda's population did not have access to the national grid, making biomass production of wood fuels a key source of fuel [8]. Wood fuels are also being used in small-scale businesses such as brick and tile manufacture, agro-processing, and seafood processing [6].
Considering that agriculture is still the most widely practiced economic activity in Uganda [9], by-products and/or wastes can be utilized for energy generation [2, 10]. The produced energy is used for domestic culinary duties while also contributing to the agricultural waste reduction and disposal system in use. Leaving these agricultural wastes to degrade is typical practice, and they are occasionally used to enhance animal diets in subsistence farms [10–13]. Uganda’s banana fruit processing alone is estimated to generate more than 4.3 MT of banana waste annually [9]. Kayunga district, one of the leading pineapple producing districts in Uganda produce approximately 15,960 tons of pineapple in a single season [14], of which 80% is waste. The waste can sustainably be utilized through converting this organic material into briquettes [10, 15, 16]. Water hyacinth, a water weed causes interference to human activities, adversely affecting flora and fauna in lakes and rivers, and hence is considered as a noxious weed [17, 18]. One of the potential solutions is its utilization for energy generation. Water hyacinth has been evaluated for production of briquettes [19], therefore it can provide a co-substrate for briquettes with banana peels or pineapple peels. Briquettes are produced using both low- and high-pressure techniques, hence are affordable to the local people, and can be used to partially substitute the use of firewood and charcoal.
Briquettes are eco-friendly, energy-efficient low technology fuel, and also a cleaner energy source used for daily cooking compared to wood fuels which are often linked to indoor pollution and its related health problems [20]. A shift to a more sustainable alternative of prevailing Uganda’s energy system to primarily support domestic cooking applications is beneficial and crucial in activating and promoting long-term conscientious alleviation of environmental degradation and reducing impact on climate change [20, 21]. The study assessed the suitability of utilizing banana peels and pineapple peels blended with water hyacinth for briquette generation.