Economic performances of anaerobic digestion plants: effect of maize silage energy density at increasing transport distances.

Abstract In Italy, more than 1150 agricultural anaerobic digestion (AD) plants are currently running. Their concentration in specific areas resulted in an increase in the biomass price and transport distances. For the AD plants located on farms with small area, often the feedstock are purchased on the market. However, when transport distances increase, it can be less expensive to buy biomasses with high energy density. With this regard, maize experimental tests were carried out to evaluate the methane production by harvesting the whole plant, the plant cut at 0.75 m and only the ear. The aim of this paper is to evaluate the economic performances of biogas plants fed with different maize silages by considering increasing extra-farm transport distances. Two different scenarios were considered with regard to the subsidy framework and to the maize biomass yield. The results show that, for short distances (