Rice Straw Dry Fermentation Biogas Life Cycle Assessment

China’s industrial development and population pressures increase on the needs of the current economic system, China’s energy consumption and requests is also increasing. The current mainstream energy is still non-renewable fossil energy-based oil, coal and natural gas.These fossil resources are less and less, and led directly to the energy crisis. At the same time, from the exploitation of fossil energy to the stage, the whole process will be an impact on the ecological environment and even serious damage. These effects and the final destruction direct or indirect will be role in humans. Biogas fermentation is a new way to solve the energy crisis and environmental problem. In this paper, the rice straw dry fermentation biogas production experiment was carried out. On this basis, the dry fermentation installation of simulating solar heating was manufactured. And the installation was used for rice straw dry fermentation experiment. The life cycle assessment method was used to make an objective evaluation for the energy consumption and the associated economic, social and natural resources in the straw gas process. The results of the study are as follows:1) The results of rice straw biogas fermentation experiments show that biogas yield increased with the increase of the concentration increased under the same temperature. In terms of total biogas yield, when the concentration of material is6%,10%and15%, the total biogas yield is2935mL,7865mL and18685mLat25℃, respectively, the total biogas yield is2050mL,6245mL13205mL at30℃respectively, and the total biogas yield is6060mL,15015mL and26535mL at35℃respectively. The biogas yield increased with the increase of the temperature increased under the same concentration, and the order of biogas yield is35℃>25℃>30℃. The total biogas yield at30℃lower than25℃, its reason may be caused by the inoculum’s differences due to the segments experiment. At the same time, the potential of biogas production of6%is the best because the material is not compete fermentation at other concentration. About30days at begin the start of the fermentation is the peak of biogas production. With the increase in the concentration of fermentation, the maximum biogas production time remove toward in the future. Viewed from the overall situation, the biogas production efficiency will be improved with the increase of concentration of the fermentation and the temperature of fermentation. The thermal decomposition of materials about drying biogas fermentation of rice straw shows that the thermal decomposition reaction of straw, inoculums and fermentation material is arried out in stages. The first stage is main the dehydration treatment of the material. The second stage is the thermal decomposition conducted at250℃to460℃. Decomposition of hemicellulose, cellulose and lignin is taken place in this stage. The third stage is at460℃to520℃, the residual lignin is decomposed and the residual substances is decomposed slowly and become carbonization and ash.At the same time, thermal decomposition in the stage of250℃to380℃, the maximum rate of weight loss of the sample is largest. Both concentrations of10%and20%of the straw fermentation material was heated to250℃, the TG curve of sample has significant differences of before and after fermentation. This illustrates that is hemicellulose, cellulose and lignin consumed mainly in the process of fermentation of the straw.3) The dry fermentation installation of simulating solar heating shows that the dry fermentation of constant temperature, continuation and efficiency is realized through organic bond of solar hot water circulation system with biogas fermentation system.4) Hunan province as an example, the life cycle assessment of straw biogas dry fermentation production shows that, the biogas dry fermentation can bring good energy, economic and social benefits, which include as follows:①In terms of energy, the total energy input of HuNan Province in rice planting to harvesting stage is approximately2,088,700tons of standard coal,712,000cubic meters of water resources, That is inputted14,600tons of standard coal and500m3of water per hectare on average. High concentrations of fermentation processing can produce1.188million tons of standard coal in energy than the general use case, that is0.83million tons of standard coal more than common processing mode per hectare.2.0351million tons of biogas manures and pesticides are produced if the rice straw of whole province is used to produce biogas. So2.6334million tons of standard coal are saved, and that is18,500tons of standard coal are saved per hectare.②In terms of Ecological environment, biogas fermentation process will not damage the ecological environment impact. The main product of straw biogas fermentation converted into standard coal in the HuNan Province, its value is1.188million more than the average handling, to think that错误!未找到引用源。standard coal use less. At the same time, the fermentation reaction product can be converted into340million tons of biogas,2.0351million tons biogas pesticides and nearly20million tons of feed. In accordance with the energy stage pesticides can save2,633,400tons of standard coal, it is calculated in accordance with the2.66to2.72tons of carbon dioxide per ton of standard coal. About1000to1200tons of carbon dioxide emissions are reduced;7-8.4Ten thousand tons of carbon dioxide is reduced tons per hectare on average. Biogas mature and biogas pesticides can replace conventional chemical fertilizers and pesticides in the cultivation stage, its importance is not just a simple reduction in the cost of purchase, but the use of biogas, biogas pesticides will not damage the environment, and the soil is also improved.③In terms of the economic, the economic income of106.22billion yuan is won by the biogas dry fermentation approach in HuNan, which is5.6times of the general approach. If the addition value of dry fermentation biogas production is considered, the difference of economic value will be more increased. Through the use of straw biogas fermentation can effectively reduce environmental pollution, thereby reducing the cost of environmental governance and they are able to further reduce health care costs caused by environmental pollution.