Abstract
This chapter evaluates the life-cycle assessment (LCA) studies of biomethane produced from lignocellulosic biomass as a biofuel and it is released into the environment in comparison with other bioenergy systems. A case study of grass biomethane that is produced by anaerobic digestion (AD) of grass silage and used as a transport fuel is described. The production of biomethane from AD is a well-known technological procedure that fulfills the requirements imposed by the environment, agronomy, and legislation in developing rural economies and sustainable biofuel production. All across Europe, the biomethane yield from various lignocellulosic biomass ranges from 10 to 1,150 m(3) h(-1). The LCA studies have been gaining importance over the past few years to analyze biofuel sources from cradle to grave in determining optimal biofuel strategies. Included in these, LCA studies is the indirect input of biofuel production processes, related emissions and waste as well as the fate of downstream products. Eighty-nine percent of greenhouse gas (GHG) emission savings are achieved by AD of grass silage to produce biomethane as a transport fuel.