Okay, say “Ewww,” but read this anyway.
According to an article by Luba Ostashevsky in the July/August issue of Popular Science, we have a continual fuel source source in our sewers that is a valuable commodity—brown grease.
A residue that congeals in sewer pipes and traps at waste water treatment plants, brown grease is a combination of human excrement and vegetable oils and animal fats from food scraps and washed dishes. Lawrence Pratt, a chemistry professor at Medgar Evers College in New York City, want to use pyrolysis to transform brown grease into a commodity—fuel.
Pyrolysis is a process to break compounds into smaller molecules by heating them without oxygen (to avoid burning) which turns brown grease into fuel. Backed by the National Science Foundation, Pratt’s plans for pyrolysis will melt the grease and distill its vapors into a molecular combination that is similar to gasoline. This is where it can become a commodity—fuel for internal combustion engines or a home-heating unit.
A single, medium-sized wastewater plant can collect 15,000 tons of grease per year. That will convert t0 2.5 million gallons of fuel. That is enough to heat 7,000 homes. If the current 16,000 such facilities in the United States added pyrolysis to their regime, we could make quite a dent in our energy needs.
Let’s put our money into recovering and using fuel sources that will not run out.