Potential of In-duct Hydropower Generation in Makueni County, Kenya

Literature shows that only 56 percent of Kenyan households had access to electricity, with rural areas having the lowest access rate at percent. The high cost of extending the power grid to remote areas and power losses on distribution are significant challenges facing rural electrification. In addressing power accessibility problems especially in the rural areas, there is a need for tapping hydropower generation through invention and implementation of in-duct turbines to maximize the utilization of already existing pressurised water ducts that supply water in various parts of Kenya for hydropower generation. This work focuses on identifying and mapping possible Micro Hydropower (MHP) sites for hydropower generation in Makueni County located in Eastern Kenya. The County is supplied by four gravity fed water ducts with slope lengths ranging from 40m to 800m. The study focussed mainly on duct sections with heads ranging from 14m to 183m located in Kweleli and Manooni water supply schemes in Nzaui Sub-County, and Ikokani and Mulima water supply schemes in Mbooni West Sub-County with pipe diameters ranging from 50mm to 200mm which offer a significant potential for construction of pico/micro hydropower generation systems. Potential micro hydropower sites were identified, evaluated, and mapped using the Open Data Kit (ODK) approach and GPS mapping. The heads/heights of possible locations along the gravity ducts were determined by recording the heights above sea level (asl) of the pipeline slope start and slope end along the pipelines using GPS and collecting hydraulic head data along the county's the four selected water supply ducts. The maps were generated using a quantum geographical information system (QGIS) where the prospective MHP locations varied in several ways, including particular power estimates ranging from 0.59 to 23.63 kilowatts. According to the analysis, there are 33 viable sites along the four water projects in which thirteen possible MHP locations were sited along Manooni, nine along Mulima, eight along Ikokani, and three along the Kweleli water supply pipelines. Applying an efficiency value of 0.7, out of the 33 identified potential MHP sites, six (6) had power ranges of 15 to 25KW, two (2) had power ranges of 10 to 15KW, five (5) had power ranges of 5 to 10KW, nineteen (19) had power ranges of 1 to 5KW, while one (1) site had a power range of 1 to 5KW. Based on these findings, it is concluded that excess energy (pressure energy) from the flowing water inside ducts can be extracted to meet electric power demand for rural communities in Makueni County, Kenya. It is clear from this research findings, that significant power/energy can be harvested from the ducts in different operating conditions and applications and provide a real promising alternative technology for power generation especially in rural areas of Kenya and other countries.