Laboratory findings on the reactions of ash from solid municipal waste from aluminium-containing packages of typical food products indicate that the thermodynamic conditions in landfills and the metabolism of various bacterial strains lead to the formation of biomethane. In addition, laboratory measurements have shown that one kilogram of the waste ashes monitored generates 182 l of methane on average, which considering its relative radiation power corresponds to 9.0 kg of burnt brown coal. This implies the substantial influence of the resulting biomethane on the greenhouse effect when these waste ashes are landfilled.