a centrifugal fan exhaust duct 318 which is positioned to provide an airflow 320 aimed at generating unit 30 in the present arrangement the airflow 320 is directed vertically the airflow 320 exits from the centrifugal fan 310 at an outlet 324 in the present embodiment the outlet 324 is rectangular in a horizontal plane it is desirable to intercept as much of the airflow 320 as practicable therefore a turbine 340 is provided with blades 344 substantially subtending the entire radial extent of the casing 30 the blades 344 extend from a central hub 350 the central hub 350 may have a curved lower axial surface 352 in order to reduce wind resistance the central hub 350 is supported to a driveshaft 150 and with the turbine 340 rotates the driveshaft 150 the support 40 comprises a horizontal bar 360 supported on opposite horizontal sides by first and second a frame supports 362 and 364 the support is dimensioned to hold the generator system 30 at a desired vertical height the desired vertical height is defined by a distance from the centrifugal fan outlet 324 this distance is an optimization of maximum air velocity capture by the generator system 30 versus back pressure created on.