Energy Production from Thermal Gasification of Selected Solid Wastes from Kiambu County, Kenya

Increased population growth resources competition and the diminishing of conventional energy sources calls for development of innovative technologies for power generation Thermal gasification is a promising technology for conversion of carbonaceous waste into energy resources such as synthesis/producer gas- (methane, carbon monoxide (CO), hydrogen (H) and carbon dioxide (CO2) and other gases). The study assessed the potential for conversion of rice husks, maize cobs and sawdust to energy resources by thermal gasification using a locally assembled gasifier. Rice husks, maize cobs and sawdust samples were collected and dried to a moisture content of 8 %. The process parameters that were controlled included temperature, pressure, process time and air injection. The resultant gas was upgraded by passing it through a series of wood shavings filters before collecting it for analysis. Portions of 1cm3syngas samples were sampled and injected into a gas chromatograph with thermal conductivity detector (GC-TCD) to determine the concentration of CO2, CO, CH4, H2, N2, and O2. Results show that 25Kg of rice husks, produced 5804.2 m3 of syngas, while sawdust and maize cobs produced 4802.8 m3 and 4203.1 m3respectively. Syngas derived from rice husk contained 9.810.99 % CH4, 28.550.99 % CO, 12.590.99 % CO2 7.440.99 % N2, 8.340.99 % O2 and 34.061 %H2 while that from sawdust contained 12.061.13 % CH4, 34.341.13 % CO, 8.241.1 % CO2 5.111.1 % N2, 5.961.13 % O2 and 34.41.1 % H2respectively. The calorific value of syngas derived from sawdust was approximately 16 MJ/m3. Rice husks and maize cobs produced 13 MJ/m3and 12 MJ/m3 respectively. The high content of CH4 and CO in sawdust contributes to its higher calorific value than rice husk. This gas is therefore sufficient to directly drive a 10-kWe AC synchronous generator at a speed of 1, 800 rpm producing 220 volt current, which can supply a total of 16 pieces of 50-watt bulbs, can be energized by the plant for 8 to 10 hours continuous operation. The results indicate that there is potential of energy production from carbonaceous wastes. Independent power producers can adopt this waste to energy (WtE) conversion technology.