Despite many biomass power plants, some of them are still running at the low efficiency using conventional burning to produce a steam for power generation. Hence, thermo-mechanical conversion process like gasification technology can help solve the problem. Rice husk is another attractive feedstock for biomass power plant due to its plentiful availability from the rice mills, its small size and low moisture. Recently, Ministry of Energy has funded a project to demonstrate the feasibility of constructing the community biomass gasification system (using rice husk) to Kasetsart University and Great Agro Co., Ltd. This project was initiated to foster Sufficiency Economy philosophy by His Majesty the Kind of Thailand. The system produces not only 80kW electricity but also heat and biomass ash for fertilizer, as shown in Fig. 8.4.3. The system design uses three-stage fluidized bed pyrolysis and gasification, comprising of 5 main units: drying, pyrolysis, gasification, cooling system and engine/generator set, as shown in Fig. 8.4.4.

As shown in Fig. 8.4.5 and 8.4.6, the system was installed at Lamlukka Cooperative Rice Mill & Paddy Center Market Co., Ltd for demonstration and test run for more than 360 hours. With gas flow rate of 240 m3/hr (heating value at 4.5 MJ/m3) and rice husk consumption of 85 kg/hr, the overall gasification system efficiency is 92%. In other words, 1.25 kg/hr consumption of rice husk generates 1 kW of electricity. Furthermore, the residue tar volume from the system is approximately 22 mg/m3. On the economic analysis, this 80kW system requires a capital investment of ~3.9M Baht with the operating cost of ~1.79 Baht/unit. Assume that the system produces the electricity at 460,800 unit/year, which substitutes the electricity cost of 3 Baht/unit, the net profit is estimated to be 0.56M Baht/year with the
payback period of 7 year. The next step would be the collaboration between MTEC and Great Agro Co., Ltd to scale up the system to 1MW capacity.

Further information

S. Nivitchanyong, Alternative Energy Cluster, National Metal and Materials Technology Center: MTEC (siriluck@mtec. or. th)