The smell isn't all that's powerful about pig manure
By Miriah Meyer
By Miriah Meyer
URBANA, Ill. — Yuanhui Zhang has smelled the future of oil, and it stinks.
The pungent, earthy scent emanates from swine pens that professor Zhang's graduate students visit regularly at the University of Illinois. Holding spades in gloved hands, they collect buckets of moist pig poop and carefully drive it to a lab on the edge of campus.
Inside a white metal building nestled among fields of corn and soybeans, the students pressure-cook the messy muck until it becomes thick, black, energy-dense crude oil remarkably similar to the stuff pumped from deep within the earth.
As oil and gas prices continue their steep climb, the dedicated crew of engineering researchers at the University of Illinois are refining an economical process to transform smelly hog droppings into piggy petroleum that can be refined into industrial fuel.
Although experts say the oily end product is not likely to make a big dent in the U.S. energy shortage, the process may help relieve the odor and pollution problems that plague high-density animal farming by providing a use for porcine poop produced in vast quantities.
It's a promising technology, if sloppy and unpleasant at times.
"I have no choice," said graduate student Rong Dong of his waste-shoveling duties. "It's a part of my job; it's a part of my thesis."
Zhang had the idea 10 years ago of combating the mounting manure problems of dense hog farms with a technique called thermochemical conversion.
The process is a test-tube version of Mother Nature's recipe for crude oil, substituting pig manure for the prehistoric plant and animal substances that are the raw ingredients of petroleum, and a small metal reactor for nature's pressure-cooker of the planet's deep layers.
During the past decade, Zhang and his group perfected the process, finding they could break down the organic material into shorter petroleum molecules in less than an hour — a feat that naturally takes millions of years.
Although the technology can be modified to break down any type of organic material, the researchers focused on refining their method for the specific composition of swine manure.
"We wanted to take care of the waste material and take care of some of the environmental problems, and we found we can create some useful energy," Zhang said.
His work is just one of a growing number of experiments in renewable sources of power. Experts say President Bush's statement on America's "addiction to oil," along with the price hike of oil to more than $70 a barrel, has dramatically increased interest by investors in technologies that convert everything from corn to human waste into fuel.
At the University of Illinois, the accelerated version of the Earth's oil production pipeline begins with a machine that looks like a giant malt mixer, which blends the chunky raw swine manure into a thick brown slurry. The appliance sits on a table surrounded by rolls of toilet paper used to clean up any unfortunate messes, the remnants of which are splattered on the wall behind.
"We have to make sure there are no big chunks," said Dong, wearing a white lab coat smeared with dark brown stains.
The smooth slurry is carefully poured into an 8 gallon cylindrical tank and then creeps through metal pipes at a pace of just two tablespoons a minute. The mixture is pressurized to 100 times the normal atmospheric pressure before slowly draining into a reactor where it is heated to a broiling 575 degrees Fahrenheit.
The researchers were able to determine the precise balance between a temperature hot enough to break down the manure's molecular bonds and a pressure high enough to keep the super-hot poop from turning into a gas.
These conditions allow the pig excrement to emerge less than an hour later as thick, black, sludgy oil.
Along the way, the product is stripped of its telltale scent — it smells like wet coffee grounds — and is only slightly less pure than the natural stuff, Zhang said. The only byproducts are a small puff of carbon dioxide, a few dribbles of water and a tiny bit of dirt.
"What's fascinating is that it's a relatively simple process," said Ted Funk, a researcher in Zhang's group. "Even though the process has complex chemistry, it's relatively short, requires almost no extra materials, and you get a nice energy output."
In fact, the researchers have found the sludge contains three times the energy used to produce it.
This energy ratio, combined with a technical breakthrough earlier this year that allows continuous feeding of the system with fecal matter, has gained entrepreneurs' attention.
Zhang is "the only researcher that's been able to use animal waste and get oil in an economic way," said Otis Jessee, co-owner of Worldwide BioEnergy, a company based in Jefferson City, Mo., that has licensed the technology from the university.
"When oil was at $25 and $30 a barrel, this was an economically feasible thing to do," he said. "Now with oil more than $70 a barrel, it's even more so."
Jessee's company has sublicensed the technology to two engineering firms that are developing pilot plants. According to Jessee, both firms plan to be churning out barrels of crude oil within two months — one using swine manure processed in a mobile plant, the other using sewage in a Houston suburb.