Approximately 9/10th pound of manure yields one watt of power for a day -therefore, one human yields about 3 watts/day. Further, the current US human population could theoretically produce 835 MW and the world population could produce 18.0 gigawatts per year.
It would take the waste of about 340 people to power the average American household.
Did you know that pigs "void" 0.7 lbs of "volatile solids" per day? A chicken puts out 0.044 lbs. Now this interests me: Dairy cows void 9.5 lb/day, but beef cows only void 5 lb. Yet the "gas yeild" of a beef cow is about twice as much (15 cu ft) as a dairy cow. So...dairy cows poop more, but beef cows fart a lot? Huh?
Have fun amusing your friends with that over lunch.