Blinky McSquinty wrote:
The heat from combustion produces an expanding medium, the exhaust gases. The exhaust gases, because they are hot and thus expanding, force themselves out the exhaust pipe once the exhaust valves open. That hot exhaust flow (kinetic energy) pushes against the impellers of the turbine, converting that hot gas energy into mechanical energy, the turning of the turbocharger shaft. That torque on the turbocharger shaft is transferred to the turbocharger compressor, or to the MGU-H. Going one step further, the MGU-H converts that torque into electrical energy.
If you really want to dig deeper, electrical energy going to the battery produces a chemical reaction. In the case of a lithium battery, when the battery charges, ions of lithium move through the electrolyte from the positive electrode to the negative electrode and attach to the carbon. During discharge, the lithium ions move back to the LiCoO2 from the carbon.
Energy can be converted. It starts with potential chemical energy in the gasoline, converted to heat energy>kinetic>mechanical>electrical>chemical.
But that is not the only way to convert heat energy into mechanical energy. One auto manufacturer is considering placing a small boiler to the exhaust system, it heats up, steam is produced, a small turbine converts that into electricity.
Or a Sterling engine.
When I was young, we used to wire foil wrapped meat onto the exhaust manifold of my Volks van when we went to the beach. They would be ready just about when we arrived. That is recovering heat energy