Pig Manure Converted to Crude Oil

Stefan Lovgren
for National Geographic News
July 2, 2004

Crude oil and gasoline prices are near an all-time high. But don't despair. One scientist has found an alternative source of energy: pig manure.

Yuanhui Zhang, an agricultural engineering professor at the University of Illinois in Urbana-Champaign, has succeeded in turning small batches of hog waste into oil.

The process, called thermochemical conversion, uses heat and pressure to break down carbohydrate materials and turn waste into liquid. The project is still in its infancy.

For now, each half-gallon (two-liter) batch of manure converts to only about 9 ounces (0.26 liter) of oil.

But Zhang believes the conversion process could eventually solve the problem of pollution and odor at modern hog farms, where farmers pay big money to get rid of the waste. And, he says, pig oil could also offer an alternative to petroleum oil.

"If 50 percent of U.S. swine farms adopted this technology, we could see a [U.S.] 1.5-billion-dollar reduction in crude oil imports every year," Zhang said. "And swine producers could see a 10 percent increase in their income—about $10 to $15 per hog."

Oil Crisis

During the oil crisis in the 1970s, U.S. researchers attempted to turn wood sludge and coal into oil. But it proved too costly. When oil prices later fell, the whole idea of turning waste into fuel became less attractive.

"The science is not new, but it has failed because of economics," Zhang said. "If you can buy crude oil at [U.S.] $20 a barrel, why bother with pig oil? It's too expensive."

But with crude oil prices now hovering around U.S. $40 a barrel, pig oil once again seems like an attractive fuel alternative.

Zhang's research team developed a small-scale thermochemical conversion reactor that applies heat and pressure to swine manure. The process breaks the manure's long hydrocarbon chains down into shorter ones. Methane, carbon dioxide, water, and oil are produced as by-products.

Continued on Next Page >>


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