turbocompounding and AC

In an earlier thread of mine…
http://boards.straightdope.com/sdmb/showthread.php?t=125050&highlight=turbo

the technology exists to recapture exhaust energy and return it to the output shaft for use.

Suppose I want to make the alternating current a function of the compounder’s RPM (via a reduction gear due to the turboshaft speeds in excess of hundreds of thousands of revs.)

IIRC, household AC reverses polarity 70 times a second.
An engine would be cycling up and down the RPM range, thus creatong AC frequencies above and below 70 hertz.

How much more or less efficient would a home-engineered AC st-up be?

(bump)

This is not a very efficient way to increase output shaft power. The game is hardly worth the chase.

Alternating Current power is distributed throughout the US at 60 (sixty ) cps.
In Europe it is distributed at 50 (fifty) cps.

They perform OK on bigger recips. A Wright 3350 would recover about 600 horsepower using recovery turbines. Not too shabby.

That’s not a huge problem. Aircraft use a hydraulic constant speed drive unit on the generator to maintain a desired frequency despite variations in engine RPM.