To provide a formation method and formation system of a biogas capable of degassing contained N2 and O2 at low cost, upon formation of the biogas obtained by methane fermentation from an organic waste.
The formation method of the biogas includes: an off-gas discharging step for introducing an off-gas discharged by a purification apparatus 65 into a lower part in a dilution tank 10 in a primary raw material M1 casted state and discharging the off-gas to a bottom surface 10a of the dilution tank 10; and a stagnation gas sucking step for floating N2 and O2 mixed in the primary raw material M1 in the dilution tank 10 after the off-gas discharging step onto an uppermost surface SL of the primary raw material M1 from the lower part of the dilution tank 10 by the off-gas and sucking the stagnation gas stagnating in an upper part of the dilution tank 10 by using a second suction pump P2.
MIZUNO SHIHO
MORIOKI MASAKATSU
NAGAI TSUNEKI
MATSUI TORU
OSAKA NORIKO
TOKYO GAS CO LTD
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