Performance and emissions of a small scale generator powered by a spark ignition engine with adaptive fuel injection control

Distributed generation of electricity is more and more viewed as a solution for reducing transmission losses and provide better catering for the needs of end users. Small-scale generation is therefore likely to increase its share in the energy sector, as it ensures high degree of flexibility, quick start-up and good performance in combination with intermittent power sources such as solar or wind. One drawback of small scale generators driven by internal combustion engines is, however, low fuel conversion efficiency and high specific emissions compared to medium or high scale power units. A new control strategy for fuel injection and emissions reduction is proposed to mitigate both aspects, while ensuring flexibility in the choice of fuels for a spark ignition engine powered generator. Performance and emissions are compared for carburetor and fuel injection combined with the use of a three way catalytic converter, with the latter solution proving to be more efficient and environmentally friendly. Significant improvements in fuel conversion efficiency and reductions of carbon monoxide and unburned hydrocarbons emissions were obtained by employing the proposed setup and control strategy. Flexibility in the use of different fuel types was evaluated by performing measurements with gasoline, iso-butanol and combined use of alcohol and natural gas. Financial aspects are also covered through a brief analysis of initial capital costs and payback time in order to offer a more detailed view of both fuel systems.