Research Article
Emergy Analysis of Biogas Systems Based on Different Raw Materials
Table 4
The comparative table of energy index.
| Item | Evaluation index | BPC | BPF |
| Ecological-economy benefit | Purchased emergy ratio (PER) | 0.38 | 0.12 | Natural emergy/purchased emergy | 1.62 | 7.26 | Emergy investment rate (EIR) | 0.62 | 0.14 | Emergy yield ratio (EYR) | 8.86 | 13.95 | Emergy self-sufficiency ratio (ESR) | 0.62 | 0.88 |
| Environmental benefit | Waste processing ratio (%W) | 61.30 | 87.89 | Environmental load ratio (ELR) | 0.53 | 0.13 |
| Sustainable development | Feedback yield ratio (FYR) | 2.59 | 5.08 | Renewable ratio (%R) | 65.15 | 88.70 | Sustainability index (ESI) | 16.57 | 109.50 |
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