Results in Table 2 also show that environmental impacts from FET, MET and ALO were marginal for co-digestion of mainly MSW and residues of agriculture and food industry (Base SS-2, Base LS, Base LS-2), compared to scenarios co-digesting energy crops (Base SS, Base SS-1 and Base LS-1). For example, Base SS-2 incurred only 3% of the ALO impact of Base SS (84.21 m2a). Furthermore, Base SS-2 reduced the FET impacts (0.03 kg 1.4-DB-eq), compared to Base SS (0.34 kg 1.4-DB-eq). The difference arises from the fact that agricultural and food industry residues incur up to 130 times lower FET impacts (e.g., 0.02 kg 1.4-DB-eq for food residues) and may even enhance FET impacts (e.g., 0.07 kg 1.4-DB-eq for straw) in single feedstock digestion, compared to energy crop feedstocks (e.g., 2.57 kg 1.4-DB-eq for wheat plant silage) (Table 1).