You've heard of Big Oil. How about Pig Oil? The process is far from perfected, but an agricultural engineer at the University of Illinois in Urbana-Champaign has reported success in turning hog manure into oil. "Scientifically, yes, we did convert manure to oil," said Dr. Yuanhui Zhang, a professor in the department of agricultural and biological engineering. "But to compete with Mobil and Amoco, we still have a long way to go." Dr. Zhang, who has been researching manure conversion for eight years, subjects a waste slurry to heat and pressure in a process called thermochemical conversion. Long hydrocarbon chains...