Development of Energy use Profiles, Reduction Concepts, and Implementation of Renewable Energies in the Central Ugandan Pineapple Processing Chains

Pineapples, like all fruits, are highly perishable and require either immediate consumption or preservation. To make them more stable and add value, four major processing methods are being employed in Uganda, i.e. drying, munaanansi (local drink), wine, and juice making. Energy is one of the main inputs required to achieve any of the processing methods. The aim of this research was to develop energy use profiles, gain insights into energy use reduction options, and to evaluate the applicability of renewable energies in Ugandan pineapple processing chains. Fifteen processing enterprises were selected from Kampala, Kayunga, and Wakiso (central Uganda) and investigated for a maximum of six days each. Measurements were conducted at three pineapple drying systems (S01 – processor one, S02 – processor two, and S03 – processor three) and five munaanansi makers (P01 –maker one, P02 – maker two, P03 – maker three, P04 – maker four, and P05 – maker five). Similarly, measurements at four winemakers (W01 – maker one, W02 – maker two, W03 – maker three, and W04 – maker four) and three juice makers (J01 – maker one, J02 – maker two, and J03 – maker three) were performed. Drying is the most developed and formalized processing method in Uganda. The selected drying processors employ forced convective hybrid and traditional direct solar dryers, and results showed that the average inlet and outlet temperatures were 69.50 0C and 47.11 0C at S01, 118.26 0C and 59.20 0C at S02, and 44.79 0C and 45.62 0C at S03 respectively. The specific energy consumption (SEC) at S01 was 28.28 kWh/kg and 13.91 kWh/kg in Jan and Apr respectively, 32.28 kWh/kg at S02, and 3.22 kWh/kg at S03. The drying ratio at S01 was 17:1 (Jan) and 16:1 (Apr) while 22:1 and 16:1 at S02 and S03 respectively. Additionally, for munaanansi, wine, and juice making; firewood and charcoal are the main fuels used, and the three stone firewood and traditional charcoal stoves (“sigiri) are the most applied among the investigated makers. The average SEC was 1.24 kWh/l for munaanansi, 0.80 kWh/l for wine, and 0.66 kWh/l for juice making. The study further indicates relatively low energy use profiles among pineapple processors, but there are opportunities for energy use improvement in terms of quantity, quality, conversion devices, and control. Moreover, energy use reduction options were identified and resource use assessment frameworks were developed and proposed for application. The use of renewable energies, especially photovoltaic and solar thermal energy for heating purposes is of particular importance, and there is also energy saving potential with regard to devices for better conversion of biomass into heat.