ABSTRACT
Agricultural resources represent a strong potential for biogas production, with an annual output of agricultural residues estimated at nearly 1000 Mt. This chapter explores the available resources for biogas production and provides global figures about their ability to be fermented into methane. It focuses on the current practices for biogas processes used for anaerobic digestion of agricultural resources. Wood wastes correspond to the portion of forest products that have no value to energy, furniture, and construction. For forestry residues and wood industry, destructuring the lignocellulosic complex is a major challenge for biogas recovery. Residual crops are relatively dry, rich in lignocellulose, and low in nitrogen. These properties make them difficult to use as such in a biogas plant, but they can be incorporated as co-substrates. The reaction time is a common design parameter. In continuous systems, the reaction time is defined as the hydraulic retention time (HRT), that is, the ratio between the reactor volume and the average input flow.
