Urine, though distained by modern society, was once surprisingly useful stuff. Street-facing laundries in ancient Rome had pissoirs attached to them, to encourage passers-by in need of relief to provide, free of charge, a raw material which was then fermented into a degreasing agent. Urine also found employment as a mordant, to assist in the dying of cloth—Scottish tweed was once notorious for smelling of the stuff when it got wet. And urine was, too, a source of potassium nitrate, one of the ingredients of gunpowder.
Now, Chen Wei-Shan of Wageningen University, in the Netherlands, thinks he has found yet another use for urine...
The Economist: Using urine to heat homes