A device, method, and system for generating electric power and desalinating seawater, combining concentrated solar energy with one-or-more cogeneration alternatives; utilizing seawater as a working fluid. An inclined Fresnel-mirror-system of east-west primary axis, and site-latitude justification, is utilized to reflect the sun's incidental irradiance to a central receiving tube, and raising temperature of working-fluid therein, producing dry saturated, or wet steam, whereby resultant energy turns a rotary-screw-expander engine, providing mechanical power, thence turning a generator; producing electric power. Heat recovered in the working-fluid is utilized in seawater desalination using a Multi-Effect-Distillation system, whereby, during non-solar-dependent productive hours, a molten-salts Single-Temperature-Thermal-Energy storage system is utilized as a battery. Waste heat from industry, renewable, and conventional power systems, is recycled to generate electrical power utilizing an organ fluid in a rotary-screw-expander engine arrangement, within an Organic Rankine-Cycle process, and desalinate seawater, accordingly.