Fig. 7 shows that for net environmental benefit, the maximum transportation distance for cattle manure, corn silage and MSW feedstock should be less than 64, 53 and 229 km, respectively. The comparatively lower value for corn silage reflects the compounded inputs of chemical fertilizers and pesticides, and land use factors accounted in the cultivation process (Ecoinvent v2.1 database), in
contrast to cattle manure where only transportation was required. In the related study (Pöschl et al., 2010), energy balances were assessed to be negative for cattle manure, corn silage and MSW
transportation distances in excess of 22, 345 and 425 km, respectively. The results suggest that MSW is most ideal where feedstock procurement involves long transportation distance.