Table 5 System II: ecological footprint (SPI [m2/ha]) of w-cc (for biogas or mulched) with maize as main crop and biogas production from maize on 20% of field; and from maize straw
From: Ecological evaluation of biogas from catch crops with Sustainable Process Index (SPI)
V0 without cc | V1 cc mulched | V2 cc biogas, ploughing | V3 cc biogas no ploughing | V4 cc biogas no ploughing, biomethane | V5 ZF cc biogas no ploughing, 100% self-sufficiency | Biogas maize on 20% field | Biogas from 75% maize straw (4.5 t DM/ha) | |
|---|---|---|---|---|---|---|---|---|
Maize (50 or 15 t DM/ha) | Silo-maize 100% used as fodder | Silo-maize 80% fodder, 20% biogas | 9 t DM CCM as fodder | |||||
Import/purchase fodder | – | – | – | – | – | – | 3 t DM maize silage | – |
ZF Biomassebildung (t TS/ha) | 0 | 2.5 | 4.5 | 4.5 | 4.5 | 4.5 | 0 | 0 |
Wheat, technique, fuel, maintenance resource | 387,000 | 365,000 | 346,000 | 335,000 | 312,000 | 312,000 | 464,000 | 387,000 |
Cc technique, fuel | 0 | 3,000 | 20,000 | 21,000 | 21,000 | 21,000 | 0 | 21,000 |
NO3, H2O, erosion, humus | 293,000 | 172,000 | 104,000 | 101,000 | 101,000 | 101,000 | 351,000 | 293,000 |
SPI sum maize/biomass production | 679,000 | 541,000 | 470,000 | 457,000 | 434,000 | 434,000 | 815,000 | 700,000 |
SPI change in relation to V0 (%) | 100 | 80 | 69 | 67 | 64 | 64 | 120 | 103 |
SPI change in relation to V1 (%) | 100 | 87 | 84 | 80 | 80 | 151 | 129 | |
Biomethane/natural gas (m3) | 1260 | 1260 | 1260 | 1260 | 1260 | 1260 | 1260 | 1260 |
Natural gas need/biogasfermentation, cleaning, compression | 675,000 | 675,000 | 280,000 | 280,000 | 280,000 | 118,000 | 280,000 | 323,000 |
SPI sum incl. natural gassubstitution | 1,354,000 | 1,216,000 | 750,000 | 737,000 | 714,000 | 552,000 | 1,095,000 | 1,023,000 |
SPI change in relation to V0 (%) | 100 | 90 | 55 | 54 | 53 | 41 | 81 | 76 |
SPI change in relation to V1 (%) | 100 | 62 | 61 | 59 | 45 | 90 | 84 | |