Laura A. Shepard for Popular Science:  Picture a giant toilet bowl looming larger than life outside the UN headquarters in New York. It sounds like an absurd scene, but the stunt from three years ago was not a childish prank. It was a serious statement to mark the first World Toilet Day and raise awareness of the fact that one third of the worlds population lacks access to toilets.
Addressing the global sanitation crisis is a top priority among the UNs Sustainable Development Goals, and it now has an exciting solution.
In fact, science may soon make your toilet bowl a viable alternative energy source. Your flushes can produce two or three gallons of biofuel per year when the wastewater is treated using a process, developed scientists and engineers at the Department of Energys Pacific Northwest National Laboratory, called hydro-thermal liquefaction (HTL).

HTL emulates the way crude oil forms naturally, when biomass decays under high pressure and heat for millions of years — but it only takes 45 minutes.  Cont'd...