Life Cycle Assessment of Beer Brewery Factory Based on Cumulative CO₂ Emission Unit

Abstract

We conducted a life cycle assessment (LCA) inventory analysis for input of raw materials, output of products, input of utilities such as electricity, gas, oil and water and various emissions concerning solid wastes in a beer brewery process and wastewater and evaluated environmental impact on global warming based on the cumulative CO₂ emission unit. Namely, the effect of energy recovery due to electric generation by a fuel cell using biogas from methane fermentation of wastewater on the cumulative CO₂ emission unit for the product was evaluated. Also, the effects of methods of treating beer lees on the cumulative CO₂ emission unit i.e., combustion, drying, methane fermentation, converting into livestock's feed or composting, were also estimated. In a beer brewery factory, the amount as much as 48.3% of the cumulative CO₂ emission unit charged on the product beer is found to be due to utilities such as water, electricity, gas and kerosene. These results show that important thing is how to reduce the energy input from the outside via recovering of energy from organic wastewater and solid wastes. It. is found that in the beer brewery factory, the electric energy recovered by the methane fermentation-fuel cell system saves 9.74% of the total electric consumption and it reduces about 2.31 % of the total cumulative CO₂ emission for the product beer. It is also found that the combustion of beer refuse, utilization of beer refuse as livestock's feed without drying or composting of beer refuse does not increase the cumulative CO₂ emission unit for the product beer. Also, it may be pointed out that if the organic carbon of the beer lees could be effectively converted into biogas by methane fermentation as well as that in the wastewater and the biogas could be converted to electricity via a fuel cell, about a 59.8% of total electric energy in the utilities would be saved.