Authors: Daniel Swain and S.O. Bade Shrestha
Landfill gas (LFG) is produced in an anaerobic environment and composed primarily of methane and carbon dioxide with small amount of nitrogen and other non-methane gases that can be collected and used to produce power either by extracting the methane or using the landfill gas directly in an internal combustion engine in what amounts to a net-negative greenhouse gas emission process. The carbon dioxide component of LFG diluted the fuel and absorbs some of the heat of combustion, causing reduced flame temperature that decreases NOx emissions and also suppresses knock.
A model is developed and validated with the experimental data available in literature, using the computation fluid dynamic code, KIVA-4, to model engine performance at various operating conditions and evaluate the benefits of methane purification and direct use of LFG as a fuel. It was found that landfill gas used directly at higher compression ratios than can be used for pure methane fuel produces higher fuel efficiency than can be achieved using pure methane fuel only.
Keywords: Landfill gas, SI engine simulation, Emissions, alternative fuel.