摘要
The present paper assessed a feasibility study to build a small-size anaerobic digester, where a forage legume, （Alfalfa, IVledicago sativa L.）, together with other crops, such as sorghum, could be used. Alfalfa is a highly sustainable crop, since it can fix nitrogen, with the benefit of avoiding underground water pollution by nitrates, its residual products are rich with nitrogen, thus improving soil structure and fertility more than popular graminaceous crops such as corn, and it needs little irrigation. All these characteristics make it one of the vegetable species with the lowest energy and water needs for growing. The aims of this feasibility study are： （1） optimization of feedstock in the bio-digester; （2） typology of bio-digester; （3） size of bio-digester in relation with land availability for growing the energy crops; （4） the utilization of bio-gas produced by bio-digester as fuel in combined heat and power systems; （5） disposal of waste-water according to regional and national laws. The final aim of this study is to verify the possibility to develop an alternative economical use of marginal soils in relatively dry areas of central Italy that could be applied in other areas with similar climatic conditions.
