Abstract
A simulation model was created based on measurement data gathered from joint-use-type biogas plants in operation. The effects of biogas utilization methods on energy balance during plant operation were compared quantitatively for cases in which a gas boiler, a combined heat and power supply (CHP) or a refining/compressing/filling device is used, to determine the most efficient biogas utilization method. The greenhouse gas emissions were also measured from the amounts of fossil energy input and methane in the off-gas discharged during refinement, to clarify the environmental burden.
The results revealed that the energy production efficiency was the highest for biogas plants treating waste from 1 000 dairy cows using a CHP. The greenhouse gas emission was the smallest in the case using a CHP and the largest in the case using a refining/compressing/filling device. The greenhouse gas emission per GJ of output energy in the case of using a refining/compressing/filling device was more than ten times that of the case using a CHP.
