Recovery and Use of Landfill Gas in Adelaide, South Australia

• Waste management practices for landfill gas extraction and control;• Applications for methane as an economically viable energy source;• Waste management alternatives for the future.RationaleThe emission of landfill gas from waste provides an opportunity to convert a potentialliability into an economic asset whilst reducing environmental degradation. Thesolutions are technically feasible, requiring incentives enforced by a regulatoryframework to provide the impetus for further exploitation of this resource.DiscussionSource and analysis of landfill GasThe main components of landfill gas are by-products of the decomposition of organicmaterial, usually in the form of domestic waste, by the action of naturally occurringbacteria under anaerobic conditions. A typical landfill gas analysis is shown in Table1.Methane and carbon dioxide production typically rises to peak within 6 to 12 monthsof the site closure, then gradually declines over a 30 to 50 year period. The rate of gasproduction is influenced by the interaction of several environmental factors. Thesefactors determine the decomposition rate which, in turn, affects the volatility andproductive life of a site. Figure 1 illustrates the interaction of the factors that influencethe gas production process.Table 1: Typical analysis of raw landfill gas.ComponentContentMethane (CH 4 ) 40-60%Carbon Dioxide (CO 2 ) 20-40%Nitrogen N 2 ) 2-20%Oxygen (0 2 )