Energy recovery from landfill gas emissions using a stepped piston segregated scavenge engine

Atmospheric landfill gas emissions present serious problems when trying to counter the effects of global warming. The main constituent of landfill gas is methane, a more damaging greenhouse gas than CO2. European Union directives require the control and collection of landfill gases and promote energy recovery via combustion of the gas. A key challenge for combustion of landfill gas is the highly corrosive nature of the gas constituents which causes heightened maintenance and failure of applied engine systems. Conventional engines suffer from the effects of corrosion; however, stepped piston engine technology has yet to be considered for operational use at landfill sites. The engine has inherent advantages for such an application when compared with current conventional engines. The engine allows improved lubricating oil health compared to conventional engines and hence reduced oil use. This study discusses the challenges along with modelling of stepped piston and equivalent four-stroke engine solutions.