Research Article
Emergy Analysis of Biogas Systems Based on Different Raw Materials
Table 2
Energy accounting for BPF system.
| No. | Itema | Units | Raw date | Transformity | References | Solar emergy | Em | (sej/unit) | (sej/yr) | ($) |
| Local renewable resources | 1 | Sunlight | J | | | Odum, 1996 [16] | | 0 | 2 | Solid manure | J | | | Odum, 1996 [16] | | 0 | 3 | Feces | J | | | Odum, 1996 [16] | | 0 |
| Total (RR) | | | | | | 0 |
| Renewable purchased inputs | 4 | Human labor | J | | | Xi and Qin, 2006 [17] | | 4353 |
| | Total (RP) | | | | | | 4353 |
| Nonrenewable purchased inputs | 5 | Civil work costb | US $ | | | Xi and Qin, 2006 [17] | | 2963 | 6 | Equipments, PE pipesb | US $ | | | Xi and Qin, 2006 [17] | | 5200 | 7 | Appurtenant workb | US $ | | | Xi and Qin, 2006 [17] | | 713 | 8 | Maintenance cost | US $ | | | Xi and Qin, 2006 [17] | | 605 | 9 | Coal | J | | | Odum, 1996 [16] | | 738 | 10 | Electricity | J | | | Xi and Qin, 2006 [17] | | 1173 |
| Total (NP) | | | | | | 11391 |
| Total input | | | | | | 15744 |
| System feedback | 11 | Biogas (heated) | J | | | Bastianoni and Marchettini, 2000 [15] | | 13881 |
| Total (F) | | | | | | 13881 |
| Yield | 12 | Biogas (output) | J | | | Bastianoni and Marchettini, 2000 [15] | | 28561 | 13 | Nitrogen fertilizer | g | | | Zhang et al., 2005 [19] | | 1838 | 14 | Phosphate fertilizer | g | | | Zhang et al., 2005 [19] | | 6844 | 15 | Potash fertilizer | g | | | Zhang et al., 2005 [19] | | 6796 |
| Total yield (Y) | | | | | | 44039 |
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aLocal nonrenewable resources can be neglected.
bItems have been divided by a lifetime of 20 years.
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