Demand rising for fuel alternatives
Corn and soybeans - the dominant feedstocks for ethanol and biodiesel
production in the United States�grow well in the central regions of the
country. But are these the only available sources? What options exist
for US growers in other regions? How can corn and soybean feedstocks be
Scientists at the Eastern Regional Research Center (ERRC) in Wyndmoor,
Pennsylvania, are answering these and other questions about renewable
fuels production. Their research focuses on four major areas: biodiesel,
ethanol, thermochemical processes, and cost analysis.
"For years, ERRC has been a committed participant in alternative fuels
research," says center director John Cherry. "This is a particularly
exciting time, because so much of our research work is being adopted and
used by industry."
Microbiologist Rick Ashby (left) and molecular biologist Dan Solaiman
monitor bacterial growth and production of a biopolymer for use in
plastics and other products. The bacteria are growing in a nutrient
broth containing glycerol, a coproduct of biodiesel production.
Biodiesel: From Grease to Glycerol
What do animal fats, rendered materials, and restaurant grease have in
common? Besides ready availability and limited marketability, they're
all subjects of ERRC biodiesel research headed by research leader Bill
Marmer. Scientists in his group have demonstrated that products of the
rendering industry can be used as low-cost feedstocks for biodiesel
Biochemist Mike Haas and biologist Karen Scott are working with the
Philadelphia Fry-o-Diesel company to demonstrate that trap grease�waste
grease that restaurants and food companies collect from their drains�can
be converted into a clean-burning, renewable fuel source.
Haas and Scott helped characterize trap-grease samples, advised the
company on operation design, and analyzed the products of trial runs.
They have successfully produced fatty acid methyl esters, the chemical
compounds that make up biodiesel, from the grease. The esters are being
tested to determine whether they meet accepted biodiesel standards.
These researchers are also developing a method to produce biodiesel
directly from oil-bearing materials, including soybean flakes and
rendered products. The oils or fats in the feedstock are treated with 18
percent methanol, forming biodiesel as the extractant. This would
eliminate the need to isolate the oil before converting it to fuel,
thereby reducing production costs, and would expand the amount of
available fuel feedstocks.
Biologist Karen Scott prepares a sample of trap grease for conversion to
biodiesel. In the foreground are samples of distilled (left) and crude
(center) biodiesel from trap grease.
Another objective of biodiesel research is to find uses for glycerol, a
coproduct of biodiesel production.
"For every 100 pounds of biodiesel produced, you get 10 pounds of
glycerol," says chemist Tom Foglia. "Current markets are saturated."
Concerned that increased biodiesel production could result in a
hyperglutted glycerol market, ERRC researchers are investigating
alternative uses for the compound. Molecular biologist Dan Solaiman and
microbiologist Rick Ashby have found that crude glycerol can be used to
support microbial cell growth and production of polyester biopolymers,
which can be used as plastics or adhesives, and biosurfactants, which
are used in detergents or as antimicrobial agents. This is particularly
important because crude glycerol is less marketable than pure glycerol.
In related studies, chemist Victor Wyatt demonstrated that glycerol
could be used to produce a new class of prepolymers for making such
products as coatings, resins, foams, and agents for remediation of
These alternative uses for glycerol have proved successful on a trial
scale. Now the scientists are testing them at an industrial level
through a cooperative research and development agreement with an
international consumer products company.
Engineers Neil Goldberg (left) and Akwasi Boateng operate a
fluidized-bed thermochemical reactor they designed and built for
converting crop residues into renewable bio-oils and hydrogen fuels.
Ethanol: Beyond the Corn Belt
Affordable, available, and easy to work with, corn is the main feedstock
for ethanol in the United States. As ethanol production increases�USDA
chief economist Keith Collins estimates that our country could produce
12-13 billion gallons in 2009�so does the demand for suitable feedstocks.
To avoid overburdening the corn market, ethanol producers have two
options: increase conversion efficiency or use an alternative crop.
Several ERRC research projects have demonstrated how these can be done.
Food technologist David Johnston is investigating new processes using
protease enzymes from microbial and fungal sources to produce ethanol
more efficiently. In trials, Johnston found that adding enzymes during
fermentation sped up the process and increased ethanol yields.
"The enzymes make more nutrients available for the yeast. They expedite
the fermentation process and can also make it easier to separate liquid
from solids after the ethanol has been removed," Johnston says. "This is
important because the more efficiently you separate the free liquid from
the solids, the more energy efficient the process can be."
Engineers Andrew McAloon (left) and Winnie Yee (right) explain the
economic advantages of a new fuel ethanol process to ERRC director John
Corn isn't the only available feedstock for ethanol. Research leader
Kevin Hicks is collaborating with biotechnology company Genencor
International; Virginia Tech, in Blacksburg, Virginia; and members of
the barley industry to explore barley's potential as a feedstock in
regions of the United States where corn is not the principal crop.
Hicks estimates that barley grown in North America could supply about 1
billion gallons of ethanol per year. The crop is well suited to the
Mid-Atlantic, where it could be grown as a winter crop in rotation with
soybeans and corn in 2-year cycles.
Currently, barley yields less ethanol than corn does, and the ethanol
from barley is more expensive. Barley's physical properties�an abrasive
hull and low starch content�impede production efficiency. But Hicks and
his colleagues are overcoming these hurdles with research.
With Genencor, the researchers are developing new enzyme technology that
could improve the speed, efficiency, and cost of barley-based ethanol
They also collaborated with Virginia Tech researchers to develop barley
varieties with higher starch content and a loose hull that generally
falls off during harvest or grain cleaning. Initial studies suggest that
such varieties have promise as a feedstock. In one study, for example, a
hull-less barley produced 2.27 gallons of ethanol per bushel, whereas
hulled barley produced 1.64 gallons per bushel.
The scientists are now studying which conditions will promote the most
cost-effective production of barley-based ethanol.
Breaking Down the Biomass
There are two main processes, or "platforms," for making fuels from
biomass: sugar and thermochemical conversion. The sugar platform
involves breaking down complex carbohydrates in the biomass�materials
such as sawmill waste, straw, and cornstalks (stover). Then, yeasts
metabolize, or consume, the simple sugars to make alcohol.
Breaking down those complex carbohydrates requires a lot of energy,
Hicks says, and special microorganisms are required to convert some
sugars into ethanol. And, ironically, the process creates a lot of
carbon dioxide�the greenhouse gas that's helping to spur the biofuels
The thermochemical platform involves heating the biomass in a reactor
and converting it into liquid (bio-oil) and synthetic gas (gaseous fuels
comprising carbon monoxide, hydrogen, and low-molecular-weight
hydrocarbon gases such as methane and ethane). Chemical engineer Akwasi
Boateng has led much of the ERRC research on this process.
In a study with research leader Gary Banowetz and colleagues in
Corvallis, Oregon, Boateng converted grass seed straw into synthetic gas
using small-scale gasification reactors. Built to serve a farm or small
community, these reactors could provide an environmentally friendly and
economic use for the 7 million tons of straw produced by the grass seed
industry every year in the Pacific Northwest.
Neither the sugar platform nor the thermochemical platform has been
perfected yet, Hicks cautions.
"Each one has technical and economic hurdles that must be solved through
research," he says. "We're trying to compare the processes and determine
which, if perfected, would give the most useful energy from a given
amount of biomass. We're working with international experts to make
intelligent decisions on where to focus our efforts."
A Model Approach: Cost Analysis
Price is one of the major factors inhibiting the spread of biofuels.
Reducing production costs would make them more competitive with
petroleum-based fuels�but where can scientists cut costs?
Engineers Winnie Yee and Andy McAloon create technical models to guide
research efforts toward economically feasible processes. With the
models, they analyze every aspect of a biofuel production process and
determine where cost-cutting would be most effective. This allows
researchers to pinpoint the exact steps in the process that need to be
"It's important to know that our research makes economic sense, that
these processes will be competitive enough for industry to accept them,"
Haas used one of McAloon's models to analyze his efforts to create
biodiesel from soy flakes. The model estimated that by first drying out
the moist flakes, Haas could reduce the amount of methanol required
later, thereby reducing the cost per gallon from $2.83 to $2.66. Haas
and his colleagues are currently working to reduce that cost even
further to a point of commercial competitiveness.