Mexico's prickly pear cactus: energy source of the future?

The prickly pear cactus is such a powerful symbol in Mexico that they put it smack in the middle of the national flag.Now scientists have come up with a new use for the bright green plant: producing renewable energy.Instantly recognizable with its jumble of spiny discs -- its bright red fruit protruding like fat fingers from each one -- the prickly pear cactus is farmed on a massive scale in Mexico.