Energy Efficiency Analysis on a Farm Biogas CHP Plant

Based on the mode of off-grid and supplying power for a 10,000 Chicken Farm, there is a experimental study and energy efficiency analysis on a biogas CHP. The results indicate that, the biogas CHP system can satisfy the demand on heating of biogas digester and electricity of farm’s. Reusing the gas-fired remaining heating powered in the internal engine to heat the digester, it can guarantee the temperature in the biogas digester between 32°C and 34°C, even if the climate is very cold. The power load vary obviously in 24 hours, power efficiency and energy efficiency of the biogas CHP plant increase with increasing of the power load of the farm. In low power load operation, the power generation efficiency and energy efficiency of entire system is very low, respectively 4.3%–19%, with the increasing of the load, the measured power efficiency is up to 19.2% when energy efficiency up to 47%, which is lower than that of the fossil CHP. By analyzing the main reason, it is found that the off-grid mode restricts the power load to vary with that of the farm passively, the heat efficiency exchanging is low between the cylinder water and the flue gas heat exchanger of the system, need to be reconstructed and installed gear change iso-frequency mechanism for decreasing the in-gas-fired quantity.