http://www.biodieselmagazine.com/articles/84770/new-sustainable-biodiesel-process-uses-ethanol-from-glycerin
New, sustainable biodiesel process uses ethanol from glycerin
By Michigan State University | May 21, 2014
A new fuel-cell concept, developed by a Michigan State University
researcher, will allow biodiesel plants to eliminate the creation of
hazardous wastes while removing their dependence on fossil fuel from
their production process.
The platform, which uses microbes to glean ethanol from glycerol and has
the added benefit of cleaning up the wastewater, will allow producers to
reincorporate the ethanol and the water into the fuel-making process,
said Gemma Reguera, MSU microbiologist and one of the co-authors.
“With a saturated glycerol market, traditional approaches see producers
pay hefty fees to have toxic wastewater hauled off to treatment plants,”
she said. “By cleaning the water with microbes on-site, we’ve come up
with a way to allow producers to generate bioethanol, which replaces
petrochemical methanol. At the same time, they are taking care of their
hazardous waste problem.”
The results, which appear in the journal Environmental Science and
Technology, show that the key to Reguera’s platform is her patented
adaptive-engineered bacteria—Geobacter sulfurreducens.
Geobacter are naturally occurring microbes that have proved promising in
cleaning up nuclear waste as well as improving biofuel processes. Much
of Reguera’s research with these bacteria focuses on engineering their
conductive pili or nanowires. These hair-like appendages are the
managers of electrical activity during a cleanup and biofuel production.
First, Reguera, along with lead authors and MSU graduate students
Allison Speers and Jenna Young, evolved Geobacter to withstand
increasing amounts of toxic glycerol. The next step, the team searched
for partner bacteria that could ferment it into ethanol while generating
byproducts that ‘fed’ the Geobacter.
“It took some tweaking, but we eventually developed a robust bacterium
to pair with Geobacter,” Reguera said. “We matched them up like dance
partners, modifying each of them to work seamlessly together and
eliminate all of the waste.”
Together, the bacteria’s appetite for the toxic byproducts is inexhaustible.
“They feast like they’re at a Las Vegas buffet,” she added. “One
bacterium ferments the glycerol waste to produce bioethanol, which can
be reused to make biodiesel from oil feedstocks. Geobacter removes any
waste produced during glycerol fermentation to generate electricity. It
is a win-win situation.”
The hungry microbes are the featured component of Reguera’s microbial
electrolysis cells, or MECs. These fuel cells do not harvest electricity
as an output. Rather, they use a small electrical input platform to
generate hydrogen and increase the MEC’s efficiency even more.
The promising process already has caught the eye of economic developers,
who are helping scale up the effort. Through a Michigan Translational
Research and Commercialization grant, Reguera and her team are
developing prototypes that can handle larger volumes of waste.
Reguera also is in talks with MBI, the biobased technology “de-risking”
enterprise operated by the MSU Foundation, to develop industrial-sized
units that could handle the capacities of a full-scale biodiesel plant.
The next step will be field tests with a Michigan-based biodiesel
manufacturer.
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