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| Srl | Item |
| 1 |
ID:
150926
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| Summary/Abstract |
Existing policies of household biogas projects focus mainly on supports on construction, but less consider management and maintenance, resulting in high scrap rate and waste of resources. Alternative policies must be explored to balance construction and operation. Taking the costs and benefits from a typical rural household biogas project, this paper assesses the economic performance at three different subsidy levels, i.e., no subsidy, existing standard and positive externality based standard. Furthermore three subsidy alternatives, one-time, annual and combined option are applied to the externality based standard. The results show that household biogas digesters have unsatisfactory economic performance without any subsidy and even in current subsidy policies. Environmental benefits of the digester were estimated as 2732 Chinese Yuan, significantly larger than existing subsidy standard. To keep continuous work during the 20-year lifespans of digesters, the income disparity of farmers among regions must be considered for policy application. With the increasing of labor costs, the ratio of initial subsidies must be reduced. These results provide policy implications to the future development of biogas projects in terms of both their construction and follow-up management, reuse of the abandoned digesters as well as the exploitation of other emerging renewable energy projects.
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| 2 |
ID:
137668
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| Summary/Abstract |
The belief that small hydropower (SHP) systems are sources of clean energy with few or no ecological problems has been driving the rapid expansion of SHP plants in China and elsewhere. This paper presents an evaluation of the ecological impacts of SHP based on an emergy analysis of a plant located in Guizhou Province in southwest China. The results suggest that periodic downstream drying-up of the river is the largest contributor to the induced ecological impacts in terms of emergy cost. In 2010, the ecosystem service losses caused by downstream ecosystem degradation totaled 2.35E+18 seJ, which accounts for 38% of the total emergy utilized in the annual operation of this plant. If such losses could be avoided, i.e., if the SHP operated as designed, SHP projects would produce relatively modest impacts on the environment. When the reaches downstream of the SHP plant are not affected, the environmental loading ratio (ELR) is 2.20 and the emergy sustainability index (ESI) is 0.93; however, the ELR increases to 3.82 and ESI decreases to 0.38 when river drying-up occurs. These results indicate that China should rigorously investigate potential ecological problems of SHP development and proceed with caution rather than readily believing unjustified assumptions.
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