Turkey relies heavily on natural gas in electricity generation and imports almost all of its natural gas needs. The country's natural gas import bill currently comprises a large proportion of the country's total energy bill, and the government of Turkey wants to reduce the weight of natural gas in the energy mix to reduce dependency in its energy policy. In this study, three different scenarios were considered to explore whether renewable energy sources or nuclear energy can be alternatives to natural gas to reduce energy dependency. The economic and technical analyses and comparisons of these scenarios have also been carried out. First, electricity generation expansion planning of Turkey for the 2015-2030 planning horizon was realized by using a genetic algorithm. In the first scenario, besides all conventional energy sources, renewable energy sources were included in the model as an input. In the second scenario, the first scenario was repeated without natural gas. In the third scenario, all conventional energy sources are included in the first scenario, except natural gas and renewable energy source. It was concluded from these calculations that nuclear energy is not likely to have a significant place in Turkey's future energy policy since it has a high investment cost and leads to dependence on foreign resources. Additionally, it is argued that renewable energy source cannot be an alternative to natural gas or other energy sources considering the low capacity factor and high investment costs.