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B.E.E.F: A Sustainable Process Concerning Negative CO₂ Emission and Profit Increase of Anaerobic Digestion

He, Qingyao, Shi, Mingfei, Liang, Feihong, Ji, Long, Cheng, Xin, Yan, Shuiping
ACS sustainable chemistry & engineering 2018 v.7 no.2 pp. 2276-2284
ammonia, anaerobic digestion, animal manures, biogas, carbon, carbon dioxide, carbon sinks, climate, electricity, energy, fertilizers, greenhouse gas emissions, greenhouses, nutrients, slurries
In organic wastes utilization, negative CO₂ emission and increase of profit can be achieved simultaneously based on anaerobic digestion (AD) through a novel Bio-Energy, Electricity, and NH₄HCO₃ Fertilizer (BEEF) system. In the BEEF concept, organic wastes are anaerobically digested to produce biogas, and then renewable ammonia recovered from biogas slurry is used to upgrade biogas. Negative CO₂ emission can be acquired by transferring the separated CO₂ into greenhouse plants or other carbon sinks. Compared with the baseline scenario that all the biogas from AD plant is combusted in a CHP unit, this study found that the average negative CO₂ emission with ∼277 N m³/h and net profit with ∼RMB¥ 365/h were acquired simultaneously by adopting BEEF system where animal manures were digested in a 1000 N m³-biogas/h AD plant. Meanwhile, BEEF system output the useful energy about 100% higher than the baseline scenario. Reducing the energy consumption of ammonia recovery could increase both the negative CO₂ emission and the net profit. Overall, this system provides a pathway to the sustainable nutrients and carbon management to deal with the climate and environmental problems.