For the purposes of this thesis, a model is created to optimize generation and transmis­sion line expansion planning simultaneously. This model is applied to an Alberta-like power system in an attempt to find a framework for the economic expansion of gener­ation and transmission lines for the next 20 years. The sensitivity of the results to a number of relevant parameters such as cost of building transmission lines, gas price, greenhouse gas offset costs, wind generation development, higher generation capital costs in Southern Alberta, higher rate of load growth in Southern Alberta, proposed generation additions and retirements in the province, and new federal requirements on coal is then analyzed to determine the important driving factors behind the value of transmission lines (in the context of congestion). The same sensitivity analyses also illustrate the value of coal versus gas-fired generation.