Paper Title
Garden Waste Gasification for Electricity Supply

Abstract
Small scale electricity generation using biomass gasification is an attractive way to provide electrical power using available renewable fuels. In this context, downdraft gasification has the advantage of higher conversion efficiencies with a low rate of tar and particulate matter generation. Combustion gases of the biomass gasification process (syngas) can be directly used in the internal combustion engines such as diesel engine and modified gasoline engine. In this study, 5kW Downdraft Gasification system was successfully developed. Garden wastes such as fallen dry leaves and tree branches from surrounding this gasification system were used as biomass sources. Typical characterisation of these garden wastes were determined using calorific value determination, proximate analysis (%moisture, %volatile matter, %fixed carbon, %ash) and ultimate analysis (%carbon, %hydrogen, %nitrogen, %sulphur). It was found that the calorific values and carbon contents of the garden wastes were increased when higher moisture contents were removed from them. While, the ash contents were decreased when higher moisture contents of the garden wastes were removed. These findings showed that the surface moisture removal is important to increase biomass quality. The operating conditions of the gasifier were optimized in this study. The most important operating parameters for the gasification process are equivalence ratio (ER) and gasifier temperature. Different ratios of leaves:wood chips were used such as 20:80 and 40:60. The optimum operating condition was found at ER of 0.43 and gasifier temperature at 800oC while using leaves:wood chips (40:60). At this optimum condition the LHV of syngas (LHVg) was 18.23 MJ/Nm3 and output power was 5.5 kWe. High LHVg was most probably due to high tendency of tar cracking process in downdraft gasifier. Syngas was used to fuel syngas engine to generate 5.0kWe output power. 5.0kWe were utilized to power electrical devices. Therefore, with the success of this study, it is highly recommended to develop larger scale biomass gasification plant using garden waste and other biomass resources to produce larger electricity supply. Keywords - Electricity, Gasification, Syngas, Waste