The Wien Automatic System Planning Package (WASP) is an effective tool for power planning in developing countries. It helps to determine ‘optimal’ expansion plans for power generation within constraints identified by local analysts, which may include limited fuel availability, emission restrictions and system reliability requirements, among others. WASP explores all possible sequences of capacity additions that are capable of satisfying demand while also meeting system reliability requirements. It accounts for all costs associated with existing and new generation facilities, reserve capacity and un-served electricity.