I guess the reference is to an intercooler after the turbo-charger?

For alternative-energy,   something more homebrew comes to mind.
Previous designers have used a big rotating wheel with a high thermal
mass: outgoing air warms one section, incoming air heats a following
section of the rotating wheel - or vice-versa.
This never seemed particularly elegant to me.

The first thing that comes to me is an aluminum irrigation tube inside
a bigger PVC sewage tube.   The air flows are arranged in
counter-flow: cold air in at one end of the irrigation pipe, hot air
into the coaxial sewage tube at the opposite end.
By the time the airflows have reached the far ends respectively,
the cold air has warmed a good fraction of the inlet temp of the hot
air.    And the hot air has cooled a good fraction of the way towards
the cold air inlet temp.  If you do it right, the cold air leaves at a
higher temperature than the exiting air from the hot inlet.

The devil is in the detail, as always. It would be good for you to
specify the mass flow rates and temperatures of the two air streams,
and how much space you can provide for the heat exchange.

Brian Whatcott    Altus OK