Turkey, as a recent signatory to the United Nations Framework Convention on Climate Change (UNFCCC) has to adopt policies to restrict greenhouse gas emissions at a time when energy demand is increasing rapidly. We report on an intertemporal, spatial network model representing the energy system that seeks to address the difficult trade-offs involved. We compute and optimal mix of fuels and technologies / considering efficiencies and investments in generation and transmission. The model allows analysis of emissions and investment decisions to attain set targets. Extensions allowing the study of dependency on fossil fuels and imports are also discussed.