Author(s): Rong Dai, Chang Chun, Zhibin Xu
In the biogas production from agriculture manure by anaerobic digestion, it is necessary to keep the bioreactor optimum and steady temperature. The optimum condition usually can not be achieved automatically in winter in North China. The solar water heating system using evacuated tubes with auxiliary electrical heater was adopted to charge the thermal energy to the bioreactor, which made the bioreactor work regularly. It was experimentally investigated that the required solar collector area, the production amount of the biogas and the auxiliary electrical power at the temperature of 15°C, 20 °C and 25 °C of the bioreactor. The biogas production system has been running steadily for two years. As a result, when the daily average solar flux was 13.2 MJ/m2 and the temperature of a bioreactor of 6m3 was optimized to be at (20±1) °C in the coldest month in Beijing, 3.85m2 of solar collector area was required, and 0.2-0.25m3/m3d of biogas can be obtained.