NOVELTY - The system has preheaters (240) comprising charge air coolers (255) in communication with a first organic rankine cycle system (110) and a second organic rankine cycle system (120). The first organic rankine cycle system comprises an exhaust heat exchanger (130), a high temperature expander (150), a cascade heat exchanger (160) and a high temperature pump (170). The second rankine cycle system comprises the cascade heat exchanger, a low temperature expander (200), a condenser (210) and a low temperature pump (220).    USE - System for recovering waste heat from charge air cooling of an engine e.g. turbo-charged engine and internal combustion engine, in a cascaded organic rankine cycle system for generation of electricity. Can also be used for gas turbines, geothermal, solar, industrial and residential heat sources.    ADVANTAGE - The system effectively recovers waste heat over wide temperature range from low grade heat sources at different operating conditions. The system can efficiently use waste heat for increasing net power output. The system uses the waste heat from the charge air cooling for preheating working fluids so as to raise flow rate and net power output. The system uses the heat sources, while decreasing temperature differences between the source and the working fluids so as to increase efficiency and power output. The heat of low and high temperature coolers can be integrated in different ways into a low temperature loop for preheating and evaporation, while the heat of the high temperature charge air coolers and can be recovered in the high temperature loop for preheating the working fluid.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for operating a cascaded organic rankine cycle system.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a waste heat recovery system with two integrated organic rankine cycle systems using waste heat generated from charge air coolers.    Organic rankine cycle systems (110, 120)    Exhaust heat exchanger (130)    High temperature expander (150)    Cascade heat exchanger (160)    High temperature pump (170)    Low temperature expander (200)    Condenser (210)    Low temperature pump (220)    Preheaters (240)    Charge air coolers (255)