Tokyo Gas Co., Ltd. announced on December 12, 2007, that it has launched a pilot project to recover bioethanol and biogas from food waste generated by schools in Koto Ward, Tokyo. It has been selected by the Ministry of the Environment as a next-generation waste management technology development project, and is being conducted jointly with Koto Ward and Tokyo Environmental Public Service Corporation. Both bioethanol and biogas recovery processes will take place at the same plant; construction of the project's pilot plant started on December 17 on the premises of the Waste Collection Office in Koto Ward, and tests began on February 25, 2008.
In Koto Ward, about 200 kilograms of food waste from school lunches is generated daily by elementary and junior high schools. Once delivered to the plant, this food waste will be broken into pieces and enzymes added to saccharify carbohydrates. The saccharified waste is then squeezed to separate liquids and solids. Bioehanol is extracted from the liquid through fermentation, and biogas is recovered from a mixture of the solid portion and the liquid left over after ethanol is distilled. The targeted recovery amounts are five liters of bioethanol with more than 90 percent purity and 20 cubic meters of methane gas per day.
The aims of this pilot project are to verify a technology for producing bioethanol and biogas together, and to establish a more efficient and higher value-adding system of recycling energy as compared to conventional methane fermentation biogas recovery systems.
Tokyo Gas will contribute to environmental education with this project, for example raising local residents' awareness through plant tours. Since the pilot plant is small in scale, the company intends to use the recovered energy as a local resource; extracted ethanol will be used at schools and biogas will be used for a 9.9 kW generator and a boiler used to operate equipment and distill ethanol at the plant.