Energy parameters and feedstock management in farm-scale biogas plants: Survey in the North-East of Italy

Biogas production from agricultural energy crops is considered as a promising alternative to reduce the current dependence on non-renewable energy sources. Among these, Anaerobic Digestion (AD) of different feedstock has proved to be an interesting energy source in rural areas, especially when the AD plants are fed with local available feedstock and the energy generated is used near the plant. Nowadays, more than 1100 agricultural biogas plants are operating in Italy, particularly in the northern regions. In Italy biogas plants are mainly concentrated in Po Valley regions, (Lombardia, Piemonte, Emilia-Romagna and Veneto); although the biogas policy scheme concerns all the country, these regions have a highly productive agricultural system and densely populated urban areas. In this paper, real operative data (gas yield and feedstock management) of 28 farm-scale biogas plants localized in the Po Valley (North-Eastern Italy) are summarized and analyzed to investigate the increasing factors of biogas production and identify the important parameters for further positive developments. The survey results suggest a positive outlook for other crops and agricultural waste integration into the AD supply chain. More than half of the biogas plants present a nominal power higher than 2.2 MW and electric power values that in 60.7 % of the cases amount to 0.999 MWe, in order to remain into the dimensional limits and to benefit from the maximum energetic incentive.