We have installed a removable bio-digester system at our office with the capacity 1m3. After the first charge, the system needs between 1 and 3 weeks to set up. During these week, it is not needed to feed the system in order to allow the bacteria digesting the waste anaerobically in the bag. During the operation, the feedstock should be fed into the system regularly to avoid the deficit of biogas yield. Currently, biogas is produced every 3-4 days and last up until 20 minutes. The results showed various duration of biogas usage, from 8 minutes up until 25 minutes of cooking. We have tried doing little experiments to cook based on biogas production: boiling water, cooking egg and roasting coffee. These food ingredients were well cooked but still unable to do continuous cook because the biogas system will require more time to produce gas.
Recently, when we were roasting some coffee beans, biogas pressure was manually controlled by pushing removable biodigester so that biogas can reach the stove. As a result, sometimes the flame was too high or low and this condition will impact the condition of coffee roasting. Thus, further analysis and improvement are still required to finally have a good quality of roasted coffee.