Much attention is lavished on using novel technologies such as microturbines and fuel cells in distributed generation (DG) applications. While using internal-combustion engines (ICEs) for DG applications receives comparatively little press, ICEs’ technology maturity, proven performance in DG applications, rapid start-up and shutdown, relatively high efficiencies, and low costs make them competitive with newer technologies for many DG applications. ICEs are, in fact, the dominant prime-mover technology used in DG applications under 1000 kW generation capacity.