Methane from biomass digestion

Chynoweth DP et al (2001) Renewable methane from anaerobic digestion of biomass. Renew Energy 22 1—8... 

Methanation. The formation of methane and CO2 from biomass is a classical example of chemical disproportionation of the zero-valence carbon in biomass. The reaction is mildly exothermic and is the natural decomposition reaction of wet biomass in the absence of oxygen (anaerobic digestion of biomass). The reaction also proceeds at elevated temperatures (up to 400 °C) in supercritical water as a reaction medium [29]. Alternatively the reaction can be carried out in a two-stage process ofgasification ofbiomass to synthesis gas, followed by catalytic methanation at T < 400°C (BioUaz). 

Advanced Digestion Process Development for Methane Production from Biomass-Waste Blends... 

Methane is produced from organic waste (biomass) when it decays in the absence of air. This can be exploited as a source of energy. In the rural areas of countries such as India and China, biomass digesters are important sources of fuel for the villages (Figure 10.61). The methane is useful for heating and cooking, and the solid residue is used as a fertilizer. 

Ana.eroblc Digestion. Methane can be produced from water slurries of biomass by anaerobic digestion in the presence of mixed populations of anaerobes. This process has been used for many years to stabilize municipal sewage sludges for purposes of disposal. Presuming the biomass is all cellulose, the chemistry can be represented in simplified form as follows ... 

Schbnwiese (1995) calculates the CH share in the greenhouse effect of about 2.5% and agriculture is believed to account for roughly two-thirds of the total human-generated CH (Watson ef al. 1996). While paddy rice fields, cattle feedlots and the burning of biomass contribute to methane emissions, about 75% of methane on farms is emitted directly from ruminant animals, from digestive processes and excretion (Stolze ef al. 2000, Alfbldi ef al. 2002, Shepherd ef al. 2003). 

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