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| Energy method-based evaluation of the sustainability of the “Five-in-One” ecological orchard system |
| Received:August 15, 2017 Revised:November 22, 2017 |
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| KeyWord:energy analysis;the "Five-in-One" model;biogas-linked circular agriculture;sustainability;ecosystem assessment |
| Author Name | Affiliation | E-mail | | ZHANG Cong-guang | College of Mechanical and Electronic Engineering, Northwest A & F University, Yangling 712100, China
Western Scientific Observation and Experiment Station of Development and Utilization of Rural Renewable Energy, Ministry of Agriculture, Yangling 712100, China | | | HAN Jian-cong | College of Mechanical and Electronic Engineering, Northwest A & F University, Yangling 712100, China | | | QIU Ling | College of Mechanical and Electronic Engineering, Northwest A & F University, Yangling 712100, China
Western Scientific Observation and Experiment Station of Development and Utilization of Rural Renewable Energy, Ministry of Agriculture, Yangling 712100, China | xbgzzh@163.com | | ZHU Ming-qiang | College of Mechanical and Electronic Engineering, Northwest A & F University, Yangling 712100, China
Western Scientific Observation and Experiment Station of Development and Utilization of Rural Renewable Energy, Ministry of Agriculture, Yangling 712100, China | | | CHENG Jia | College of Mechanical and Electronic Engineering, Northwest A & F University, Yangling 712100, China
Western Scientific Observation and Experiment Station of Development and Utilization of Rural Renewable Energy, Ministry of Agriculture, Yangling 712100, China | |
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| Abstract: |
| The "Five-in-One" orchard is a typical biogas-linked agro-ecosystem and circular agricultural model that has social, ecological, and economic benefits. To investigate the model's inherent energy characteristics and system performances, the present study evaluated the sustainability of the system's development and productivity using a pig-biogas-grain(PBG) system, biogas ecological village(BEV) system, and single apple planting(SAP) system. The project was located in Chengcheng County, Shaanxi, which is located on the Guanzhong Plain. The system was generally analogous to other biogas-linked circular agriculture models with higher self-renewal ability, smaller environment load, higher production efficiency, and stronger sustainability. The environmental load ratio of the studied "Five-in-One" orchard system was 0.16, which was significantly lower than that of the SAP system(2.77) and similar to that of the PBG system. In addition, the energy yield ratios of the "Five-in-One" orchard system and the PBG system were 11.10 and 11.89, respectively, which were both higher than that of the SAP system(2.69). This indicates that the construction of the "Five-in-One" orchard systems would be less harmful to the environment than traditional apple production systems and would provide favorable economic and ecological benefits. However, the "Five-in-One" system had a higher energy waste ratio(1.26%) than either the PBF or BEV systems and a lower energy investment ratio(4.76). This is likely because the development and utilization of local natural resources were low and the energy feedback of the system was weak. The ESI value of the system was 69.10, which indicated better environmental sustainability than the BEC and SAP systems and fully reflected the strong vitality and development potential of the "Five-in-One" orchard system. Based on overall accounting, the reduction in greenhouse gas(GHG) emission was favorable, with a total reduction potential of as high as 1 251.99 kg CO2-eq per year. The GHG reductions generated by biogas utilization and bio-slurry fertilization were 975.42 kg and 1 290.79 kg CO2-eq, respectively, and the results suggested that anaerobic processes were the greatest contributor of the system to GHG reduction. Meanwhile the GHG emission of the other projects increased. |
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