Abstract: A rotary vane engine system for using exhaust heat energy of a fuel-based heat engine. The heat engine includes a crankshaft being driven by a combustion cycle, and the heat engine generates exhaust gases by combustion. The system comprises an independent air system, wherein the independent air system contains air separate to the exhaust gases. A heat exchanger system is provided for transferring exhaust heat energy from the exhaust gases to the air contained in the independent air system to generate pressurized air. A rotary vane engine is also provided having a housing, a rotor contained within the housing and coupled to the crankshaft of the heat engine, and a plurality of vanes extending radially from the rotor. The pressurized air is expanded within the rotary vane engine for rotation of the rotor thereby providing drive to the crankshaft of the heat engine.