The power generation sector is increasingly affecting global warming due to its greenhouse gases (GHGs) emissions. Hence, improving the efficiency of thermal power plants is effective action in mitigating national and global GHG emissions. Accordingly, Long-range Energy Alternatives Planning has been used to the prediction of electricity consumption and supply, types of costs, and GHG emissions for a 20-year period (2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020)(2021)(2022)(2023)(2024)(2025)(2026)(2027)(2028)(2029)(2030) in Iran thermal power plants. In this paper, a business-asusual (BAU) scenario and seven different scenarios were designed to investigate the impact of simultaneous management of supply-side and demand-side power generation. The findings showed that all alternative scenarios allowing the country to fulfill its unconditional (Nationally Determined Contribution) NDC. Further, the EEP, EPI, and ATD scenarios will have respectively 25%, 22%, and 12% lower emission than the BAU scenario, which will enable Iran to fulfill its conditional NDC by 2030. The superior scenarios in terms of electricity generation costs were found to be EPI and EEP, which will result in approximately US$5 billion cost-saving compared to BAU. The hybrid scenario was known as the preferred scenario, which will generate approximately US$12 billion greater benefit than BAU in terms of net present value.