In the present work, the design-environmental and economic (D2E) comparative study of seven different configurations of Linear Fresnel solar thermal power plants using two-generation modes (direct and indirect steam generation) with nine various working fluids, with and without integrated thermal energy storage or/and backup fuel system is presented, with minimum levelized cost of energy (LCOE) as objective.This study is based on a power plant of capacity of 50 MW. A sensitivity analysis is developed to optimize the solar multiple of the solar field, Fossil fuel fraction of backup system (BS), and TES hours capacity, using System Advisor Model software.The results show that the wrong choice of plant's components and inexact performance optimization lead to the increasing cost of electricity generated due to operating costs and additional investments. The BS was the most significant contributor to greenhouse gas emissions at all sites, contributing over 90% of total emissions, due to its relative contribution (95 kg/MWh). Finally, the combination of the storage and BSs in molten salt mode makes it more competitive under Algerian climates, which confirms that molten salt linear Fresnel solar plant with 25% of a BS and 6 hr of the storage system is the best and optimum solution. K E Y W O R D S levelized cost of electricity, assessment, linear Fresnel plant, system advisor model 1 | INTRODUCTION The 2015 United Nations Climate Conference in Paris marked a turning point for renewable energy (RE). It reinforced what advocates have long argued: That a rapid and global transition to RE technologies offers a realistic means to achieve sustainable development and avoid catastrophic climate change. 1 Moreover, RE technologies can help countries meet their policy goals for secure, reliable and affordable energy, electricity access for all, reduced price volatility, and the promotion of social and economic development. 2 In Algeria, With the development of economy and the rapidly increasing of electricity demand, environmental issues, and fossil energy shortage are becoming increasingly serious, which allows the government to use other sources as REs. Therefore, the challenge facing governments has shifted from identifying what needs to be done and how best to achieve it.Different questions can be given for the electricity system by variable renewable, but the principle is the same: A mix of technologies in a range of locations will be required to meet the demand that varies