Pretty Soon, Your Car Might Run On Poop

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On farms livestock produces more than a billion tons of solid waste a year, or roughly 87,000 pounds of (execrement) a second. That's more than 130 times greater than the amount of human waste that goes into sewers. Farm waste—especially on large industrial feedlots—often ends up polluting nearby drinking water and contributes to a significant chunk of greenhouse gas emissions.

Researchers at the University of California are working on turning piles of poo into something useful—fuel that can run in ordinary cars instead of gas, and fertilizer that can replace the energy-intensive fertilizers that are usually used on farms.

"If you take a lot of cow manure, there's not an efficient way to handle it quickly for farmers, and the result of that is that a lot of it sits around and aerobically composts," says UCLA grad and Fulbright scholar David Wernick, who spent his time as a PhD student tweaking a process that can convert waste. As manure sits in giant piles on feedlots, it emits methane and nitrous oxide, both significantly more potent as greenhouse gases than carbon dioxide.

In the lab, the researchers genetically engineered a type of bacteria that can break down the protein in manure (or in human waste, or other waste, such as leftover yeast used in making wine or beer). Then the bacteria converts it into fuel and recycled fertilizer.

Biofuels like ethanol have other problems, such as the fact that it takes energy to grow crops and land that could otherwise be used to grow food. Manure and sewage already exist, in huge quantities, without requiring any extra steps for production.

When the poop-based fuel is burned in a car or truck, it creates carbon dioxide—but because that carbon dioxide originally existed in the form of plants fed to livestock, it's part of a closed carbon cycle. Fossil fuels, on the other hand, dug up from underground, add new carbon to the atmosphere.

Others are also working on turning poop into fuel, such as Bristol, England, which now runs a bus route on methane made from sewage sludge. But the new process the University of California is developing has some advantages—it consolidates manufacturing into fewer steps and automatically creates fertilizer in the process. 

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