Swine manure is being converted to
crude oil at the University of Illinois using a thermochemical
conversion process. But researchers have refined this existing
process to make it more efficient and faster. The economic impact of
such technology could be dramatic.
"If 50 percent of swine farms adopted
this technology, we could see a $1.5 billion reduction in crude oil
imports every year," said Yuanhui Zhang, U of I agricultural
engineer. "And swine producers could see a 10 percent increase in
their income -- about $10 to $15 per hog."
In addition, Zhang said, the
environmental benefits of this research are numerous. Minerals are
preserved in the after-treatment stream, odor is reduced and the
oxygen demand of manure is reduced by 70 percent.
Thermochemical conversion, or TCC, is a
chemical process that reforms organic compounds in a heated and
pressurized enclosure to produce oil and gas. The process that Zhang
has developed uses swine manure as the organic material and coverts
it to crude oil using a small-scale batch TCC reactor developed by
Zhang's research team.
According to Zhang, they conducted a
series of experiments on variables that affected the oil conversion
efficiency and oil quality. As result, they were able to define the
desirable temperature range for the process and reduce the retention
time to about 15 minutes. Retention time is the time required for
the manure to remain in the TCC processor to allow oil conversion.
"The process we have developed is quite
different from most conventional TCC processes," said Zhang. "There
is no need for the addition of a catalyst, and our process does not
require pre-drying of the manure. Swine manure containing 80 percent
water can be fed directly into the reactor."
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Zhang said that
although the presence of water requires more energy to heat up the
media, most of that energy can be recovered with a heat exchanger.
With the batch
reactor, researchers achieved an average of 70 percent conversion
from swine manure volatile solids to oil. At that conversion
efficiency, the manure excreted by one pig during the production
cycle could produce up to 21 gallons of crude oil. What's more, a
swine farm producing 10,000 market hogs per year could produce 5,000
barrels of crude oil per year.
"We further processed
the TCC crude oil in our lab and obtained refined oil that had a
heating value similar to that of diesel fuel," Zhang said.
The next step for
Zhang's research team is to develop the batch process into a
"In a continuous TCC
process, the heat generated from the process can be recycled more
efficiently, reducing the operating costs," said Zhang. "Reactor
volume can be reduced for the same capacity, which reduces the
investment costs, and automated controls can be adapted more
readily, which reduces the labor costs."
hopes to develop a TCC pilot plant, which will increase production
capacity and allow them to analyze the oil properties and seek
alternative applications of the TCC oil, such as making plastics or
continuous TCC reactor will advance this technology one step closer
to a TCC pilot plant," said Zhang.
Zhang's research proposal was approved
for funding under the Grainger Emerging Technology Program in the
College of Engineering and awarded $100,000.
of Illinois news release]