Evaluation of Solar Energy for Processing Aloe Secundiflora Sap into Paste Using Parabolic Solar Concentrating Technology

ABSTRACT

This paper presents an alternative method of processing Aloe secundiflora sap into paste using solar concentrating technology. Local communities living in arid and semi-arid areas of Kenya and other African countries harvest A. secundiflora sap and process it into paste for export and local use by boiling using traditional 3-stone cooking stoves. Consequences of these activities have led to widespread deforestation and environmental degradation. The study focused on establishing the effectiveness of solar concentrating technology in processing A. secundiflora sap into paste and ascertaining the effect of environmental parameters on processing. Optimum processing temperature, processing time, cooker efficiency, yield and quality of the resultant paste were also investigated. Results showed that absorber and pot content temperatures and solar radiation significantly affected the heating time. It was established that optimum processing temperature ranged from 90-100°C, giving an average overall heat transfer coefficient of 17.40W/m2 K under clear sky conditions. Results demonstrated that solar concentrating technology had great potential in processing A. secundiflora sap into paste, which is a stable, portable and value added product. In the longer term, using solar energy to substitute fuelwood energy would contribute to reduced deforestation, environmental degradation, global warming and climate change. It would also improve biodiversity conservation and reduce the burden on women and children associated with collecting and transporting fuelwood. As a follow-up to this study, an elliptical parabolic solar concentrator was installed at Kinango in the semi-arid Kinango District, Coast Province of Kenya for pilot-scale processing of A. secundiflora sap by a local women group.