Waste heat recovery using a thermoelectric power generation system in a biomass gasifier

The aim of this study is to investigate the use of waste heat that is recovered from a biomass gasifier. In the gasification process, the low heating value of biomass can be transferred to a high heating value for combustible gaseous fuel, a form that is widely used in industry and power plants. Conventionally, some of cleaning processes need to be conducted under higher operating temperatures that the low temperatures typically used to burn biomass. Therefore, the catalytic reactor was designed before installation the scrubber in the downdraft gasifier system to make effective use of the waste heat. The experimental result shows that the temperature of the gasifier outlet is about 623–773 K; dolomite is used for tar removal in the catalytic reactor. To further improve the use of waste heat, a thermoelectric generator is added to provide for the recovery of waste heat. The thermoelectric generator system is manufactured using a Bi₂Te₃ based material and is composed of eight thermoelectric modules on the surface of catalytic reactor. The measured surface temperature of the catalytic reactor is 473–633 K that is the correct temperature for Bi₂Te₃ as thermoelectric generator. The result shows that the maximum power output of the thermoelectric generator system is 6.1 W and thermoelectric generator power density is approximately 193.1 W/m². - Highlights: • Set up the thermoelectric power generation system to recover waste heat from biomass gasifier. • Bi₂Te₃ based material is suitable for choosing as a thermoelectric generator in the waste heat recovery temperature range of 473–633 K form gasifier. • The maximum power density can reach 193.1 W/m² for waste heat recovery