Back EMF scavenging for BEAM photovore bot (Solar engine)?

First, a little explanation, so we all know what I'm talking about more precisely.

A BEAM "photovore" is typically a solar powered little robot, with cellphone vibrator motors, or something equally tiny, used to drive it around. Its called a Photovore ("eats light"), because the nature of its engine, and photo diodes, means that the motors will alternate which one pulses, depending on which direction the source of light is strongest.

Here is an example, of a very active, but not solar powered photovore behavior:

http://www.youtube.com/watch?v=4Ji0wx4b9SM&feature...

A solar engine is a way to get a small solar cell to actually drive a motor in a pulsed fashion- as the cell does not provide enough current by itself to drive a power hungry motor coil. It uses a large Capacitor (4700uf) that gradually builds up a charge, with a 1381 Voltage trigger watching the rising voltage level. once the triggers' voltage setting is reached, it energizes the base of an NPN transistor, which completes the circuit between the big cap and the motor. Motor runs, Cap discharges, trigger turns off, Cap recharges... repeat. see http://www.google.com/imgres?hl=en&sa=X&tbo=d&biw=...

Photodiodes cross connected (left eye goes to right wheel) mean that the trigger signal takes path of least resistance (the diode with more light hitting it) to determine which motor gets the capacitors worth of energy.

There, we should be all caught up by now for you engineering types to help me.

The nature of the Solar engine dictates that the motor (and the coil within) has to start and stop repeatedly in little bursts. Recent reading up on Back EMF spike phenomenon leads me to believe that I can "scavenge" the back EMF of even these tiny low voltage (3v) motors, as a way to eek even more energy out of the design.

So in addition to the Solar Engine; that gets its power from Light, this will be an ancillary "Scavenged Engine" that gets ITs power from back EMF/motor kickback from the pulsed motors!

Maybe a reverse (shottky) diode pair tapping off of the motor leads, leading to another cap and solar engine? As I understand the EMF, the main engine will pulse (and I believe would run the motor with less back inductance::better) once per second ad nauseum, while the scavenged engine would fire maybe every 100 main engine firing or so. Even if it did it this slowly, its STILL "free energy" that was always there to begin with, now being put to use. With a smaller Cap, the Scavenged Engine would weigh only grams (literally 2 transistor bodies and a cap)

Failing the Scavenged engine, maybe a "Kickback power giveback" circuit of some sort, that dumps that spike energy (that is now reversed polarity momentarily) back into the large Cap for while it lasts... recovering some ot the CAP charge, to speed up engine cycles...?

So what do you think? will it even work? is it practical? Is it "GENIUS!!!" ? is it old hat? Has it not been done before because it will simply fail? Or is back EMF spikes still to this day a little understood phenominon that is only treated as "merely noise"?

A more specific motor kickback question: with a typical Solar engine, when the trigger kills the ground to the motor, and its suddenly off, the motor would "coast" to a stop for a bit... would the draw of this scavenged engine act like a BRAKE to that motor, resulting in even LESS performance (actual movement)?