■ The National Bioethanol Program
Today, fuel ethanol in the United States is made from
corn starch, a biopolymer of glucose that is readily
broken down to sugars. The goal of the National
Bioethanol Program is to develop technology which
can utilize non-food sources of sugars for ethanol
production. We call ethanol made from these non-
conventional forms of biomass “bioethanol.”
Biomass Feedstock Development
DOE researchers are developing new sources of bio-
mass for bioethanol production. These include the
residues left over after harvesting of existing food
crops and, further down the road, new energy crops
like switchgrass. Today, farmers leave millions of
tons of residue on the ground after harvesting corn.
The responsible collection and use of this residue—
known as corn stover—offers a huge opportunity for
expanding the supply of ethanol from its current
level of 1.5 billion gallons per year to more than 10
billion gallons per year. As demand expands beyond
this level, newly developed energy crops will come
into play.
Bioethanol Conversion Technology
Two key steps are at the heart of the DOE
Bioethanol Program’s research and development
activities for bioethanol conversion technology:
1. Hydrolysis. This is a chemical reaction that
releases sugars, which are normally linked together
in complex chains. In early biomass conversion
processes, acids were used to accomplish this.
Recent research has focused on enzyme catalysts
called “cellulases” that can attack these chains more
efficiently, leading to very high yields of fermentable
sugars.
BioethanolBioethanolMoving into the MarketplaceMoving into the Marketplace
T echnology for producing transportation fuel from biomass is moving out of the
laboratory and into the marketplace. In the past decade, advances in biotechnology
have allowed us to reduce the projected cost of bioethanol by nearly 25%. In the
1990s, the U.S. Department of Energy National Bioethanol Program:
■ Developed new, more versatile, micro-
organisms capable of squeezing more
ethanol from biomass■ Gained a greater understanding of how
the individual technology components
work together in an integrated process■ Supported the private sector’s initiatives
to commercialize bioethanol technology.
As we enter the 21st century, we are
seeing federal investment in research begin-
ning to pay dividends in the marketplace.
Meanwhile, the DOE Bioethanol Program is
building on these successes. Our research program targets process improvements that will
ultimately allow bioethanol to compete head to head with gasoline as a fuel supply for the U.S.
transportation sector. Our strategy is simple. We will ride the growing wave of biotechnology
advances to build efficient bioprocesses for ethanol production.
To develop cost-effective, environmentally friendly
technologies for production of alternative transporta-
tion fuels and fuel additives from plant biomass
The Biofuels Program is managed by the Office of
Fuels Development (OFD) at the U.S. Department of
Energy (DOE). Biofuels research and development
includes work on a range of renewable liquid fuels,
and covers the whole spectrum of technology devel-
opment from basic science to commercial deployment.
DOE’s Bioethanol Program is by far the largest of sev-
eral fuel development efforts managed by OFD under
the auspices of the Biofuels Program.
The Biofuels Program Mission:
What is biomass?
We define biomass simply
as any “nonfood” form
of plant matter. Because
plants recycle carbon
dioxide from the atmos-
phere, they represent a
renewable and sustainable
source of energy.
2. Fermentation. Microorganisms that ferment sugars
to ethanol include yeasts and bacteria. Research has
focused on expanding the range and efficiency of
the organisms used to convert sugar to ethanol.
■ Breakthroughs in FermentationTechnology in the Past Decade Leadto Commercialization of BiomassConversion Technology
Common sense suggests that we need to convert
every bit of biomass into fuels and coproducts. For
ethanol production, this means using all the avail-
able sugars. For most of this century, researchers
assumed that many of the sugars contained in bio-
mass were unfermentable. This meant that as much
as 25% of the sugars in biomass were out of bounds
as far as ethanol production was concerned. In the
1970s and 80s, microbiologists discovered microbes
that could ferment these sugars, albeit slowly and
inefficiently. The race was now “on” to understand
how these organisms handled these sugars, and to
create new organisms capable of efficient conversion
of all the sugars found in biomass. With the advent
of new tools in the emerging field of biotechnology,
researchers at DOE labs and at universities across
the country, have succeeded in producing several
new strains of yeast and bacteria that exhibit varying
degrees of ability in fermenting the full spectrum of
available sugars to ethanol. The advances made in
Zymomonas recognized
by scientific peers
1995—R&D 100 Award
1995—Science magazine
publication, “Metabolic
Engineering of a Pentose
Metabolism Pathway in
Ethanologenic Zymo-
monas mobilis.”
1996—U.S. Patent #5,514,583
“Recombinant Zymomonas
for pentose fermentation”
1998—U.S. Patent #5,712,133
“Pentose fermentation by
recombinant Zymomonas”
1998—U.S. Patent #5,726,053
“Recombinant Zymomonas
for pentose fermentation”
1998—U.S. Patent #5,843,760
“Single Zymomonas mobilis
strain for xylose and arabi-
nose fermentation”
the 1990s are now the starting point for entrepre-
neurs interested in realizing a new bioethanol indus-
try. Existing ethanol producers are also looking to
these new organisms as a pathway for improving
their own bottom line as well.
■ A Decade of GeneratingEngineering “Know-How”
Along the continuum of technology development
from basic science research to commercialization,
process engineering data bridges the gap between
scientific inventions in the lab and commercial pro-
duction facilities. The Bioethanol Program, over the
past ten years, has increased the engineering knowl-
edge base by collecting rigorous material and energy
balance data on integrated bioethanol processes.
Today, we have greater confidence about projected
process performance and cost, and a far more realis-
tic understanding of the engineering issues remain-
ing to be solved. This kind of information is critical
to entrepreneurs and financiers looking at multimil-
lion-dollar investments in bioethanol technology.
Hydrolysis Fermentation
Bioethanol recycles carbon dioxide
The race to create new microbes capable of ferment-ing the full range of sugars found in biomass has fol-lowed several successful pathways. Dr. Lonnie Ingramat the University of Florida started with an E. coli bac-terium capable of metabolizing multiple sugars andadded the ability to make ethanol—a feat for whichhe received U.S. Patent #5,000,000 in 1990. His workwas sponsored by the Biofuels Program and others.
Taking an approach that complements Dr. Ingram’sE. coli, other DOE researchers started with the bac-
terium Zymonomonas, a naturally efficient ethanol-producing bacterium, and added the capability forutilizing multiple sugars (see “Zymomonas recognizedby scientific peers,” above left).
DOE also helped support Purdue’s Dr. Nancy Ho,who started with the "industrial workhorse" forethanol production—the yeast Saccharomyces—andadded the capability for utilizing multiple sugars.
All three organisms are now being tested by indus-trial partners for use in bioethanol production.
Biotechnology—‘more than one way to skin a cat’
At the Bioethanol Program’s one-ton-per-day Process Devel-
opment Unit, bioethanol developers can test proposed
processes under industrial conditions without having to
build their own pilot plants.
Association are working with DOE researchers to
tailor new microbes that can ferment these specific
sugars. This is work that builds directly off the
Bioethanol Program’s successes of the past decade.
Customized organisms developed in this cooperative
project will be available to the member companies
of these two important industry trade groups.
Supporting industry pioneers for a new
bioethanol industry
Several companies are now pursuing niche opportu-
nities for introducing bioethanol technology in the
U.S. Each of these companies has identified one of
several variations of the process for converting bio-
mass into ethanol. Two of the processes involve the
use of sulfuric acid, in either concentrated or dilute
form, to hydrolyze the cellulose and hemicellulose,
while the third introduces the use of enzymes called
cellulases to hydrolyze the most challenging of the
biopolymers—cellulose.
■ Support for Today’s Industry andTomorrow’s Pioneers
The Department of Energy’s Bioethanol Program
supports a portfolio of activities that is balanced
across the spectrum of technology development. To
this end, we supplement our core R&D program
with activities focused on near-term deployment
opportunities. Our goal is to plant the seeds today
for the technology we are developing for tomorrow’s
renewable fuel industry.
Giving a boost to today’s fuel ethanol industry
Today’s ethanol producers are looking for ways to
push their yields as high as possible. They are turning
their attention to corn fiber—the shell of the kernel—
as a source of additional sugars for ethanol produc-
tion. But, corn fiber, like other forms of biomass,
contains sugars that are not fermentable by today’s
industrial fermentation organisms. The National
Corn Growers Association and the Corn Refiners
Concentrated Acid Technology
Arkenol. Arkenol is currently working with DOE to establish a commercial facility that will
convert rice straw to ethanol, taking advantage of opportunities for obtaining rice straw in
the face of new regulations that would restrict the current practice of open field burning of
rice straw in California. DOE researchers are working with Arkenol to tailor DOE’s recombi-
nant Zymomonas organism for their process conditions and feedstock.
Masada Resource Group. Masada is a waste management company that views bioethanol as one of sev-
eral tools in its aresenal for managing waste and recycling operations. They are planning on constructing
a bioethanol plant in New York State, where solid waste disposal costs are very high. The plant will con-
vert the biomass portion of municipal solid waste into fuel grade ethanol. DOE researchers have worked
with Masada to collect engineering data on one of the key process steps—the separation and recycling of
sulfuric acid from the sugar stream prior to fermentation.
Dilute Acid Technology
BC International. BCI is building a facility that will initially produce 20 million gallons per year of
ethanol from bagasse—the residue left over after sugarcane production. BCI will utilize an existing
ethanol plant located in Jennings, Louisiana. At the heart of BCI’s process is the recombinant E. coli
originally patented in 1990. DOE researchers have worked with BCI to collect critical process engi-
neering data.
Enzyme Technology
Iogen. Iogen is a Canadian enzyme producer who recently entered into a joint venture with PetroCanada to
demonstrate the use of cellulase enzymes in the production of bioethanol. The Bioethanol Program is support-
ing research at the University of Wisconsin and the University of Toronto to evaluate the use of a yeast strain
and DOE’s recombinant Zymomonas in their process. Iogen is targeting agricultural residues such as wheat
straw and corn stover for their initial commercial demonstration.
� Artist’s rendering of proposed rice straw-to-ethanol facility.
� Groundbreaking ceremony for BCI’s bagasse-to-ethanol plant in Jennings, Louisiana.
Municipal solid waste—an untapped resource for bioethanol. �
Fungal production of cellulase. �
Current U.S. ethanol pro-
ducers use only the starch
in the corn kernels. The
fiber left from that pro-
cessing, however, plus the
cobs, husks, and stalks all
contain sugars that can
also be made into ethanol.
■ Bioprocessing—a strategy ofadding, improving and combiningbiological process steps
A strategy that reflects past and future
accomplishment
Today we talk about our strategy for future technol-
ogy improvements in terms of “bioprocessing,” but,
in fact, this is not a new approach. Bioprocessing
captures the approach that we have taken over the
past few decades, as suggested by the illustration
above. Dilute acid hydrolysis reached the limits of its
capabilities after several decades of research that led
to the construction of a plant during World War II
and further refinements in the 1950s. At that time,
the biological steps were limited to the conversion
of glucose to ethanol by conventional industrial
yeast. Early in the 1970s, research began on the use
of cellulase enzymes to hydrolyze cellulose—an
approach that offered higher yields and elimination
of unwanted side reactions. The 1980s saw dramatic
improvements in enzyme performance, and the first
efforts to consolidate biological hydrolysis and glu-
cose fermentation. Today, we have taken biopro-
cessing of ethanol from biomass one step further by
genetically engineering microbes capable of ferment-
ing hemicellulosic sugars as well as cellulosic sugars.
What will bioprocessing mean for tomorrow’s tech-
nology? The exact form is not clear. We are attacking
the technology on several fronts—by applying new
biotech tools to improve cellulase enzymes and con-
tinuing to enhance the fermenting organisms.
The Marketplace
So, what does all this technology improvement mean
for the marketplace? Before the introduction of
microbes capable of handling multiple sugars,
ethanol from biomass was projected to cost about
$1.58 per gallon for the enzyme process. Today, that
cost is projected at around $1.16 per gallon. This
cost assumes access to moderately priced feedstocks
(at around $25 per dry ton), and reflects a combina-
tion of the best results reported by various research
groups in industry and in the private sector. The fuel
ethanol market currently supports a price of any-
where from $1.00 to $1.40 per gallon. Though the
high capital investment and higher risk of deploying
new technology are still hurdles to be overcome, it
is clear that the new bioethanol technology is poised
for commercial introduction.
Today’s fuel ethanol market represents 1.5 bil-
lion gallons per year in sales. This market is now
constrained—because of cost—to the use of ethanol
as a blending agent in gasoline, with only limited
sales of “E-85”—85% ethanol fuel. As technology
costs drop, bioethanol will add sales of anywhere
from 6 to 9 billion gallons year. With the blend mar-
ket saturated at this level of ethanol sales, we will
then set our sites on the bulk fuel market—compet-
ing head-to-head with gasoline at ethanol costs of
around $0.60 per gallon.
For more information contact:
Robert Wooley, Biofuels Technology Manager,
National Renewable Energy Laboratory
[emailprotected]
(303) 384-6825
Produced for the U.S. Department of Energy
(DOE) by the National Renewable Energy
Laboratory, a DOE national laboratory.DOE/GO-102000-1109 • August 2000
Photo Credits: Page 1: Warren Gretz, NREL/PIX02268; Warren Gretz,NREL/PIX05790; Warren Gretz, NREL/PIX03246. Page 2: Min Zhang,NREL/PIX06812; Warren Gretz, NREL/PIX00947. Page 3: Warren Gretz,NREL/PIX03479; Arkenol, Inc., NREL/PIX07008; Dynamic Graphics, 066009;Blane David Faul, NREL/PIX06544; Warren Gretz, NREL/PIX03287.
T OF ENERGYD
EPA
RTMEN
U
E
NIT
ED
STAT S OFA
ER
ICA
M
Acidhydrolysis
Enzymeproduction
Enzymeproduction
Enzymeproduction
Biological step
Non-biological step
Enzyme hydrolysisGlucose-to-ethanolHemicellulose sugars-to-ethanol
Enzyme productionEnzyme hydrolysisGlucose-to-ethanolHemicellulose sugars-to-ethanol
Today
Tomorrow?
1980
1950
1970
Enzyme hydrolysisGlucose-to-ethanol
Hemicellulosesugars-to-ethanol
Enzymehydrolysis
Glucose-to-ethanol
Hemicellulose sugars to disposal
Glucose-to-ethanol
Hemicellulose sugars to disposal
Projected Cost of Ethanol
($1997 per gallon)
1980s
$1.58
1990s
$1.16
2010
$0.82
Printed with a renewable-source ink on paper containing atleast 50% wastepaper, including 20% postconsumer waste.
