Any new process designs must be competitive in the larger electric grid markets. The objective is to develop optimization models to identify the necessary characteristics in new generation systems and transmission infrastructures required to meet the projected demand for electricity over the next few decades. The modeling framework, which is based on MILP, takes the viewpoint of a central planning entity whose goal is to identify the type, location, and capacity of future power generation technologies (e.g., coal, gas, nuclear, wind, solar, hydropower) and transmission infrastructure that can meet the projected electricity demand while minimizing the amortized capital investment of all new generating units and transmission lines, the operating and maintenance costs of both new and existing units, and suitable environmental costs (e.g., carbon cost, and penalty for not meeting the minimum renewable energy source quota). To be able to capture the variability of generation by renewable source units and assure that the load demand is met at any time, detailed operational constraints are also included. This multi-scale formulation involves long-term investment plans while considering unit commitment decisions at multiple levels. To make the model tractable and able to be solved in a reasonable amount of time, timescale and clustering approaches are used, and complemented with special multi-scale decomposition techniques to address the temporal and spatial scales of the problem.