http://www.greenoptions.com/2007/06/28/researchers_aim_to_solve_biodiesel_glycerol_problem
Researchers Aim to Solve Biodiesel Glycerol Problem
Clayton Bodie Cornell's picture
Filed on Jun 28, 2007 at 12:48 PM PST
By Clayton Bodie Cornell
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Researchers at Rice University claim they've discovered a way to make
ethanol from the waste glycerol (syn: glycerin) produced in biodiesel
manufacturing. If true, it could be the biggest breakthrough in
biodiesel production in years.
"We identified the metabolic processes and conditions that allow a known
strain of E. coli to convert glycerin into ethanol," said Ramon
Gonzalez, the William Akers Assistant Professor in Chemical and
Biomolecular Engineering. "It's also very efficient. We estimate the
operational costs to be about 40 percent less that those of producing
ethanol from corn."
Biodiesel is made by splitting fat molecules into smaller pieces and
draining off the thicker components, better known as glycerin. Anyone
familiar with homemade biodiesel knows what glycerin is: a sticky, nasty
mess that's also a disposal headache. Waste glycerin is no small problem
for the commercial biodiesel industry either, since 10 lbs. of biodiesel
produces 1 lb. of glycerin, and what was once a valuable commodity now
frequently entails a disposal cost. In the short span of two years,
glycerin commodity prices have decreased by a factor of 10, while
overall production has increased by 400%. Finding a solution to the
waste problem has been a top priority for some time now (check out the
Glycerol Challenge):
Researchers across the globe are racing to find ways to turn waste
glycerin into profit. While some are looking at traditional chemical
processing -- finding a way to catalyze reactions that break glycerin
into other chemicals -- others, including Gonzalez, are focuse on
biological conversion. In biological conversion, researchers engineer a
microorganism that can eat a specific chemical feedstock and excrete
something useful. Many drugs are made this way, and the chemical
processing industry is increasingly finding bioprocessing t be a
"greener," and sometimes cheaper, alternative to chemical processing."
Researchers have been 'racing' over this issue for some time, but until
now the best use of waste glycerin I'd heard of is dust suppression on
country roads. But biodiesel producers are keen on finding valuable
co-products that can pad their very slim profit margins ($0.079 per
gallon of biodiesel according to one source).
Skeptical? By now most of us in the renewable energy crowd have to see
it to believe it. Anyone familiar with the waste product produced from
even the cleanest-looking waste vegetable oil would be hard-pressed to
imagine it successfully converted to ethanol. If feasible, however, it
could be the next big thing for commercial biodiesel producers everywhere:
"We are confident that our findings will enable the use of E. coli
to anaerobically produce ethanol and other products from glycerin with
higher yields and lower cost than can be obtained using common
sugar-based feedstocks like glucose and xylose," Gonzalez said."
These statements released by Rice University stem from a scientific
review paper entitled Anaerobic fermentation of glycerol: a path to
economic viability for the biofuels industry. This scientific review
paper is not available without subscription, but here are a few excerpts:
"The implementation of biorefineries has been proposed as a means
to increase the economic viability of the biofuels industry [9]. In its
'conventional' form, a biorefinery would make use of a fraction of the
feedstock (e.g. a portion of sugars or oils) to co-produce a higher
value, small-market chemical along with the biofuel(s). The higher
revenue from the co-product, which benefits itself from the economies of
scale available in a large biofuels plant, would improve the economics
of biofuel production. A more economically viable model for a
biorefinery, however, should consider the use of byproducts or waste
streams generated during the production of the biofuel. Glycerol-rich
streams generated by the biofuels industry (Figure 1a) have the
potential to be used in this context. This review focuses on the
anaerobic conversion of crude glycerol into higher value products as a
means to improve the economic viability of the biofuels industry."
"For example, an analysis of the feedstock and processing costs in
the production of biodiesel from soybean oil yields a gross processing
margin of about $0.079 per gallon of biodiesel (including a glycerol
credit of $0.021, but excluding any interest expense, tax credits or
fixed costs) (04/11/2007: www.thejacobsen.com). Essentially, if 2004
glycerol prices (Figure 1b) were still valid, the glycerol revenues by
themselves would amount to about three times the current gross
processing margin (i.e. crude glycerol at $0.25/ lb 0.85 lb/gal would
result in a glycerin credit of $0.21). Clearly, the development of
processes to convert crude glycerol into higher value products is both
an urgent need and a 'target of opportunity' for the development of
biorefineries. Such technologies could be readily integrated into
existing biodiesel facilities, thus establishing true biorefineries and
revolutionizing the biodiesel industry by dramatically improving its
economics. Moreover, waste streams containing high levels of glycerol
are generated in almost every industry that uses animal fats or
vegetable oils as starting material (Figure 1a). For example, the
oleochemical industry generates waste streams containing 55–90% glycerol
[14]. Such glycerol surplus will not only result in a further reduction
in prices, but the disposal of these streams will become a major issue
[12]."
"At current prices (2.5 cents/lb), glycerol is very competitive
with sugars used in the production of chemicals and fuels via microbial
fermentation. Given the highly reduced nature of carbon atoms in
glycerol, additional advantages can be realized by using glycerol
instead of sugars. For example, conversion of glycerol into the
glycolytic intermediates
phosphoenolpyruvate (PEP) or pyruvate generates twice theamount of
reducing equivalents produced by the metabolism of glucose or xylose
(Figure 2). Fermentative metabolism would then enable higher yield of
fuels and reduced chemicals from glycerol compared with those obtained
from common sugars such as glucose or xylose."
Biotech breakthrough could end biodiesel's glycerin glut (June 19, 2007)
Syed Shams Yazdani and Ramon Gonzalez. Anaerobic fermentation of
glycerol: a path to economic viability for the biofuels industry.
Current Opinion in Biotechnology: Volume 18, Issue 3, June 2007, Pages
213-219
Photo Credit: Rice University
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Check for earlier Pacific Biofuel posts: http://pacbiofuel.blogspot.com/
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