HomeBiogas, based in Israel, is currently in the pilot testing stage at several commercial kitchens with its HBG-100 on-site anaerobic digester designed to treat up to 1 ton/day of food waste. All types of food waste can be digested. An external grinder is used to feed the digester that is designed to conserve water; the slurry has a total solids content of 20%. The digester operates at mesophilic temperatures. Retention time is about 30 days on average. Digesting 1 ton/day of food waste generates about 120 m3/day of biogas that, according to an interview with the company, is equivalent to around 54 kg of LPG (propane) and 720 kW of energy. “This amount should be enough to meet daily gas demands of a restaurant,” notes Alon Civier, HomeBiogas’ special projects director. “Assuming the kitchen uses 6 kW burners, they can get up to 120 hours a day of cooking. Usually, we will prefer to use it for heating water as cooking might not be sufficient to handle all gas.”
The digestate goes through a post treatment pasteurization step if it is being used as fertilizer in the commercial establishments’ gardens. It can be discharged to the sewer if a garden isn’t available. HomeBiogas will be leasing the system and providing service. According to the company, the system saves on waste disposal fees and the biogas is used in place of other energy sources. “Customers pay monthly an amount equal to about 50% of their regular expenses on waste management and energy costs.” The system will be commercially available around the end of 2021.