Anaerobic biogas is a highly valuable new energy source, with a calorific value of 5500-6600 kcal/cubic meter. Biogas can be purified and sold as natural gas, and can also be used for power generation. While generating electricity, it also generates some waste heat that can be utilized. Of course, biogas can also replace coal and be directly used for boiler combustion. Taking biogas production of 10000m3/d as an example:

Option 1: Direct sale of biogas, expected to cost 0.35 yuan per cubic meter of biogas, with a daily yield of 10000 m3/d and an annual revenue of RMB 116000. No need for investment.

Option 2: Biogas power generation, with a minimum capacity of 2KWH per cubic meter of biogas (calculated at 0.7 yuan/KWH), generating 20000KWH of electricity per day, generating 20T of waste heat steam, and generating an annual revenue of RMB 4.6 million. The biogas power generation project requires investment: ① biogas desulfurization system; ② generator (domestic, assembled, imported); ③ Waste heat boiler

Option 3: After biogas purification, it can be sold for 7000m3 of biogas equivalent to natural gas quality per day. Local natural gas prices can be consulted for each cubic meter of pure biogas. We will start with a net profit of 2.5 yuan/m3 and an annual profit of RMB 5.7 million. (Biogas purification requires investment in biogas desulfurization equipment, biogas CO2 removal equipment, biogas compression equipment, and biogas transportation equipment.)

Option 4: Biogas is burned in a boiler, and each cubic meter of biogas is equivalent to 1KG of coal (coal is priced at 800 yuan/T), with an annual revenue of RMB 260000. But there is a considerable amount of H2S in biogas, H2S is burned in the boiler and converted into SO2, so a chemical desulfurization method for boiler flue gas is needed to solve the problem. Therefore, the annual revenue may be RMB 2 million. Direct use of biogas for boiler combustion requires investment in equipment: ① Booster fans for biogas transportation; ② Pipeline for biogas transportation; ③ Biogas desulfurization device (desulfurization operation cost is much lower than boiler flue gas desulfurization operation cost).