IN A WORLD of rapidly diminishing resources, there's one we tend to overlook. It's easy to produce and extremely abundant. But instead of viewing it as an embarrassment of riches, we're more likely to see it as just an embarrassment.
This neglected treasure is human waste. Urine is rich in nitrogen, potassium, and phosphorus, the three main ingredients in artificial fertilizer. Feces contains these nutrients, too, in smaller doses, and the methane it produces can be harnessed as biogas, a green energy source.