[eng] In a centralized wholesale power system market scenario, the transmission and distribution constraints limit dispatch and require additional generationto support an integrated area known as Security Generation. This one must be covered in each area, and its cost transferred to the final users. Thesecurity generation cost gets higher when operation implicates the use of thermal power plants whose price equation depends on international fuelscosts. This paper examines the consequences of a high reliance on thermal power plants. It focuses on scheduled reserves affecting electricity unit costsand the potential for constraints to lead to long-term consequences. The paper analyzes the security generation behavior based on reports and uses a realscenario to support simulations and decisions, evidencing monthly cost and an estimated CO2 emission. Results show the direct cost-saving potential ofinvesting in renewable projects and technology. The paper can allow to replicate the analysis in comparable areas and regions with similar challenges