A load balance model is used to quantify the economic and environmental effects of integrating wind power into three typical generation mixtures. System operating costs over a specified period are minimized by controlling the operating schedule of the existing power generating facilities for a range of wind penetrations. Unlike other studies, variable generator efficiencies, and thus variable fuel costs, are taken into account, as are the ramping constraints on thermal generators. Results indicate that the system operating cost will increase by 83%-280% (pending generation mixture) at a wind penetration of 100% of peak demand. System emissions also decrease by 13%-32% (depending on the generation mixture) at a wind penetration of 100%. This leads to emission abatement costs in the range of $1300/tonne-CO(2)e for hydro dominated mixtures, $240/tonne-CO(2)e for coal dominated mixtures, and $215/tonne-CO(2)e for natural gas dominated mixtures. (C) 2008 Elsevier Ltd. All rights reserved.