Selected solar-hybrid power plants for operation in base-load as well as midload were analyzed regatding supply security (dispatchable power due to hybridization with fossil fuel) and tow CO2 emissions (due to integration of thermal energy storage). The power plants were modeled with different sizes of solar fields and different storage capacities and analyzed on an annual basis. The results were compared to each other and to a conventional fossil-fired combined cycle in terms of technical, economical, and ecological figures. The results of this study show that in comparison to a conventional fossil-fired combined cycle, the potential to reduce the CO2 emi.isions is high for solar-thermal power plants operated in base-load, especially with large .solar fields and high storage capacities. However, for dispatchable power generation and supply security it is obvious that in any case a certain amount of additional fossil fuel is required. No analyzed solarhybrid power plant shows at the same time advantages in terms of low CO2 emissions and low levelized electricity cost (LEC). While power plants with solar-hybrid combined cycle (SHCCf, Particle-Tower) show interesting LEC, the power plants with steam turbine (Salt-Tower, Parabolic Trough, CO2-Tower) have low CO2 emi.isions.