Exploratory scenarios for the power sector in Nigeria are analysed in this paper using possible pathways within the Nigerian context and then compared against the Government's power expansion plan in the short to medium term. They include two fossil-fuel (FF and CCGT) and two sustainable-development-driven scenarios (SDI and SD2). The results from the FF scenarios indicate this is the preferred outcome if the aim is to expand electricity access at the lowest capital costs. However, the annual costs and environmental impacts increase significantly as a consequence. The SDI scenario, characterised by increased penetration of renewables, leads to a reduction of a wide range of environmental impacts while increasing the annual costs slightly. The SD2 scenario, also with an increased share of renewables, is preferred if the aim is to reduce GHG emissions; however, this comes at an increased annual cost. Both the SDI and SD2 scenarios also show significant increases in the capital investment compared to the Government's plans. These results can be used to help inform future policy in the Nigerian electricity sector by showing explicitly the range of possible trade-offs between environmental impacts and economic costs both in the short and long terms. (C) 2010 Elsevier Ltd. All rights reserved.