Engine exhaust recovery
Turbochargers and turbo-compounding use exhaust energy in engines.
Recovery and reuse · Heat to power and cogeneration · No. 127
- Recovery and reuse
- Heat grade: Medium
Nearly every truck and ship engine reuses its own exhaust to spin a turbine at tens of thousands of rpm.
Chart: Illustration: Engine exhaust recovery
Where it comes from
A turbocharger uses fast, hot exhaust to pack more air into the engine; turbo-compounding adds a second turbine geared to the crankshaft, spinning above 40,000 rpm.
Accelleron, which calls itself the leader in high-power turbocharging, earned USD 1,263.1 million in 2025, up 23.5%, and built over 22,000 turbochargers that year.
Three things to know
- Exhaust is the only engine heat hot enough for turbines; jacket water and oil heat stay below about 150 C.
- Detroit dropped turbo-compounding from its DD15 truck engine in 2014 but kept it on the larger DD16.
- A turbocharger upgrade trial on a COFCO ship averaged 3.5% fuel saving, avoiding 1,030 t of CO2 over 13 voyages.
The journey
- 1 Hot exhaustLeaves cylinders at about 370-540 C
- 2 TurbochargerExhaust turbine drives an air compressor
- 3 Denser airMore air packed into each cylinder
- 4 Power turbineTurbo-compounding returns energy to the crankshaft
- 5 Less fuelSame power from a smaller engine