In just one week on NBC, the detectives on "Law and Order" investigated a cash-for-clunkers scam, a nurse on "Mercy" organized a group bike ride, Al Gore made a guest appearance on "30 Rock," and "The Office" turned Dwight Schrute into a cape-wearing superhero obsessed with recycling.

Coincidence? Hardly. NBC Universal planted these eco-friendly elements into scripted television shows to influence viewers and help sell ads.

The...