Full size aircraft use a RAT (Ram Air Turbine). This is a small windmill that sticks out into the airflow (not the jet pipe/exhaust gases). On full size aircraft this can provide electrical and hydraulic power. Personally, I would prefer this to having anything in the exhaust section.
The RAT is only used when everything else has failed. Each engine has an alternator , driven by a complex and heavy CSU (constant speed unit) and a hydraulic pump. In the event of engine failure the APU (auxiliary power unit) can be used to supply electrical, and therefore hydraulic, power. When all that fails the ram air turbine is exteneded, very rarely happens !
Regards,
David Gladwin.