NOVELTY - The system has an internal combustion engine (1) whose power output is regulated by variation of rotational speed and including a throttling element (35) in an intake section (22) of the engine. A controllable exhaust gas recycling system (38) is provided with an exhaust gas regulating valve (39) placed on the engine. Speed of the engine is adapted to electrical power demand or heating demand when the recycling system interacts with the throttling element. A controller ensures that the engine is operated at an essentially constant average pressure ranging from 5 bars to 8 bars.    USE - Force-heat coupling system for use in isolated and network operations for maintenance of network parameters and adjusting output power to requirements of a consumer or a network.    ADVANTAGE - The controllable exhaust gas recycling system is provided with the exhaust gas regulating valve on the engine, so that the speed of the engine is adapted to electrical power demand or the heating demand when the recycling system interacts with the throttling element, and the controller ensures that the engine is operated at the essentially constant average pressure ranging from 5 bar to 8 bar, thus allowing the engine to run with high efficiency in the region of medium pressure while reducing mechanical power of the engine by the controllable recycling system. The throttling element supports adjustment of the engine speed relative to the desired power output, so that the power adjustment can be done in a quick manner, thus avoiding inappropriate matching of range of the power of the engine relative to the desired power demand or heating demand, and hence optimizing adaptation of performance to the power demand in an effective manner.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for operating a force-heat coupling system.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic circuit diagram of a force-heat coupling system.    Internal combustion engine (1)    Intake section (22)    Throttling element (35)    Controllable exhaust gas recycling system (38)    Exhaust gas regulating valve (39)