building would not the present system utilizes a self regulation heating element 80 specifically a positive thermal coefficient ptc heater element connected with the rotor generator assembly resulting in an extremely compact and efficient system these devices are self regulating in that the electrical resistance they cause in the system is inversely proportional to the system 39 s ability to accept heat the more heat that is needed the lower the resistance and the faster the rotor generator unit turns to provide the needed power the less heat that is needed the higher the resistance and the slower the rooftop unit turns u2014 or it can stop almost completely fig9 provides a chart of the surface temperature vs resistance profile of a positive thermal coefficient heater element in some applications it may be advantageous to integrate the above described system with a building 39 s existing furnace based heating system in such cases the system adds a furnace intercept controller the furnace intercept controller receives a command for heat from the building 39 s thermostat and determines the most efficient manner to provide the required amount of heat based on this determination the furnace intercept controller can engage the fluid driven system the furnace or both units of course it is also possible to incorporate the rotor generator assembly described herein into an electrical generating system in such a system the additional components required would include a charge regulator 82 battery 84 and inverter 86 as described in connection with prior art systems other objects features and advantages of the present invention will be apparent to those skilled in the art while preferred embodiments of the present invention have been illustrated and described this.