Fifteen years ago the country started making ethanol from sugar cane Now the Brazilians use 50 percent less gasoline and pay less for transportation fuel when they fill up with ethanol a
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AMERICAN SOCIEWY FOR ENGINEERWG EDUCATION == NOVEMBER 2006
Can engineers serve up enough
cellulosic ethanol to quench our thirst for foreign oil?
RUNNING ON
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OULDN’T IT BE GREAT if we could grow our own fuel? That thought proba- bly occurred to many Americans this year, particularly those in the seemingly end- less fields of the heartland Despite recent declines, gasoline prices stubbornly stuck around $3.00 per gallon for much of 2006 Now, engineers, investors and even President Bush are saying the solution to the country’s energy woes could be harvested from America’s fruited plain in the form of biofuel
After decades of being dismissed as too expensive and impracti-
cal, biofuel—ethanol, diesel and other combustible liquids made from plants —is coming back into fashion And it doesn’t look like biofuel will be slipping into obscurity anytime soon, thanks to his- torically high prices at the pump, the war in Iraq, instability in the Middle East and growing demand for fuel from developing nations such as China
\t the moment, biofuel accounts for roughly 3 percent of U.S transportation fuel, little more than a proverbial drop in the bar- rel, But by 2025, the U.S Department of Energy (DOE) would like biofuel to account for 30 percent of what we put in our tanks
While there are several different types of plant-derived fuel, etha- nol—the alcoholic component of beer, wine and spirits —consti- tutes 99 percent of all the biofuel in the United States ‘To reach DOE's ambitious goal, engineers say we will have to rethink everything about ethanol, from crop growth to fuel distribution It’s a challenge, they say, that will require the expertise of bioen- gineers, agricultural engineers, chemical engineers and systems
engineers alike
Brazil is the best example of a biofuel success story Fifteen years ago the country started making ethanol from sugar cane Now the Brazilians use 50 percent less gasoline and pay less for transportation fuel when they fill up with ethanol and ethanol- gas blends But Brazil’s success with ethanol fuel isn’t something
that can simply be copied The country’s agricultural conditions,
inexpensive land and cheap labor make Brazil an ideal location for producing large amounts of ethanol from sugar cane inexpen- sively, explains Robert C Brown, a professor of thermal science
and engineering at lowa State University
than sugar cane, so ethanol producers in this country use corn as their primary feedstock From an energy standpoint, however, corn isn’t the most energy-efficient source
of ethanol Given the choice of growing an acre of corn, soybeans
or switchgrass, which would yield the most transportation fuel?
That's the homework question that gets engineering students in
Brown’s Fundmentals of Biorenewable Resources course scratch- ing their heads and poking at their calculators
“It's really a trick question,” Brown confesses Since they're in lowa, most of the students choose corn, he says But after some
back-ofan-envelope calculations, the students discover that an acre of switchgrass could yield almost twice the biofuel as an acre
of corn Brown’s simple homework exercise points to larger issues for ethanol The Energy Information Administration estimates that Americans currently consume 400 million gallons of gasoline ev- ery day If ethanol producers are ever going to meet that kind of demand, they are probably going to have to turn to switchgrass and other cellulosic sources of ethanol, such as crop waste and wood chips, says Daniel Kammen, director of the Renewable and Appro- priate Energy Laboratory at the University of California, Berkeley There are several problems in pinning our transportation fuel goals solely to corn-based ethanol ‘To begin with, the payoff in energy efficiency for switching from petroleum products to corn-
based ethanol isn’t all that big To make one gallon of ethanol
using current farming and production methods, it takes around 0.7 gallons of nonrenewable fuel, according to a recent study from Kammen’s group
Another problem is that we use corn for other things Using
The energy return on cellulosic ethanol blows corn-based fuel away Every gallon of nonrenewable fuel invested could produce more than 8 gallons of cellulosic ethanol, according to Kammens study
corn-based ethanol to fuel our cars means increased demand and higher prices for corn and corn-based products The ramp-up in ethanol production has already driven up corn prices by more than 20 percent this year, pushing up the cost of livestock feed and soft drink sweeteners as well Rising com prices, along with a
5]-cent tax credit on each gallon of corn-based ethanol fuel sold,
have some wondering just how economical an alternative the fuel really is
Corn-based ethanol could probably displace up to 10 percent
of total gas in this country, Kammen says While that’s not bad, it's not the coup everyone is hoping for “Ultimately, if we really want
to make a big dent in petroleum use we need to look at broaden- ing our feedstock base to use cellulosic materials,” says Charles F, Wyman, professor of chemical and environmental engineering at University of California, Riverside, who works on renewable en-
ergy technologies It's not just academics who see a future for ethanol made from cellulosic material logen, a Canadian biotech company, has al-
ready built a demonstration-scale cellulosic ethanol plant in Ot tawa President Bush, during his 2006 State of the Union address, stressed the need to develop cellulosic technology “Our goal is to make this new kind of ethanol practical and competitive within
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logen’s Ottawa plant,
where bales of wheat
straw are brought in
for ethanol production
six years,” he said
“L think cellulosic ethanol is a powerful option that has been
underappreciated,” Wyman says “Now, because of high gas prices,
people are realizing that there aren't many other options.” Cellu-
losic materials, also known as biomass, cost very little, he explains
And unlike corn, we've got sources of cellulosic ethanol in abun-
dance Hardy switchgrass, for example, thrives in the Great Plains
and Southeast, resisting floods, droughts, pests and disease “That
material is virtually unused,” Wyman notes Corn stover, the leftover
husks and stalks from corn normally left to rot in the field, is another
good source of cellulosic ethanol, he adds
The energy return on cellulosic ethanol blows corn-based fuel away Every gallon of nonrenewable fuel invested could produce more than 8 gallons of cellulosic ethanol, according to Kammen’s study
He estimates that with engineering improvements
in fuel efficiency and cellulosic ethanol produc-
tion, the fuel could replace 35 to 40 percent of the
gasoline consumed in the nation “The potential is truly huge,” he says
Huge Promise, Huge Problems
S PROMISING AS cellulosic ethanol looks on paper, there’s a lot that needs to
be done before Americans can fill their
tanks with the stuff The United States currently
has no commercial industry devoted to making cellulosic ethanol, and the largest precommerical plant—logen's Ottawa demonstration facility—only makes 700,000 gallons of cellulosic ethanol annu- ally That’s about 0.25
gasoline consumption
percent of Americans’ daily Cellulosic ethanol also needs to be cost com- petitive In June, Michael Pacheco, director of the
National Bioenergy Center, told the Senate Com-
mittee on Energy and Natural Resources that with
current technology, the cost of producing cellulosic
ethanol is twice that of corn-based ethanol To bring the cost of cellulosic ethanol close to gasoline, he said
ducing, collecting and converting biomass
Engineers are already hard at work tackling
will require revolutionary approaches for pro-
those challenges They range from molecular prob- lems—how to break down cellulosic plants cheaply and efficiently—to infrastructure issues—how to
get ethanol produced in the agricultural heartland
to the coasts, where demand is greatest
Since ethanol production literally starts in the field, agricultural engineers are on the front lines
of making cellulosic ethanol viable An acre of perennial grass or
woody crop currently produces about 335 gallons of ethanol, ac- cording to the DOE If agricultural engineers can boost biomass vields, the DOE estimates an acre of crops could produce up to 1,000 gallons of ethanol
After the president named switchgrass as a source for ethanol
in his State of the Union address, the crop has gotten a lot of at- tention But according to Larry P Walker, biological and envi- ronmental engineering professor at Cornell University, engineers need to look at which sources work best for a particular region In
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some areas, it makes sense to grow switchgrass, but in other areas,
different grasses or even trees may be the best source of ethanol
“Whatever we do needs to be sustainable,” Walker adds Con- sequently, engineers also have to figure out how to get the most out of cellulosic crops without depleting nutrients in the soil or fostering erosion
Even with cellulosic crops harvested and in hand, engineers still face one of their biggest challenges: converting that recalci- trant material into fuel Ethanol is made by fermenting sugars
In corn and sugar cane, that sugar is easily accessible to the mi-
crobes that can turn it into ethanol, which is why those crops are popular choices for ethanol feedstocks In cellulosic materials, the sugar is stored as cellulose, a long chain of sugar molecules,
and hemicellulose, a random mix of five- and six-carbon sugars
Both the cellulose and the hemicellulose have to be convert-
ed into their constituent sugars before they can be fermented into ethanol “These materials are not easy to break down,” Wyman explains, which is one of the reasons cellulosic ethanol produc- tion is far behind that of corn or sugar cane ethanol, despite its enormous potential
Once the cellulose and hemicellulose have been stripped out
of a plant, material called lignin remains Lignin can’t be convert-
ed into eth
nol but it is the secret to cellulosic ethanol’s big en-
ergy payoff “We can burn the lignin to generate heat, so we don't have to bring in any fossil fuels” to produce ethanol, Wyman says
“In fact, you generate more heat and electricity than you need.”
Bioengineers are taking a few different approaches to overcome
the high costs inherent in breaking down hardy cellulosic materi- als Researchers in industry and academia are trying to genetically engineer more robust, less expensive enzymes for processing cel- lulosic biomass UC Berkeley’s Kammen points out that cellulosic feedstocks are usually a mixture of different plants “You need dif- ferent enzymes to digest all that stuff,” he says
Lee R Lynd, Dartmouth University engineering professor and chief scientific officer at cellulosic ethanol start-up company Mas- coma, for example, has been working to genetically engineer a
cellulose into sugars and then ferment those sugars into ethanol
[his type of “consolidated bioprocessing” could radically cut the cost of producing cellulosic ethanol, Lynd says
Another approach is to genetically modify the cellulosic crops
themselves so that they are easier to process A team at Purdue University is trying to make genetically engineered hybrid poplars that have either modified lignin or less lignin altogether The cel- lulose in these low-lignin trees, should be easier to break and will likely yield more ethanol per acre
“There are two areas where engineering is meeting challeng- es,” Walker points out “There's the basic R&D process of convert- ing cellulosic material into ethanol, but there is also a systems engineering approach that considers infrastructure, resources and transportation.” Engineers need to examine cellulosic ethanol from a broad perspective, he explains Where does it make the most sense to build production facilities—in the rural areas where
the crops are or in the urban areas where there’s high fuel de- mand? Ethanol can’t travel through the pipelines we use for gas,
so what's the most efficient way to transport it?
Renewable energy experts have been saying cellulosic ethanol
has been just around the corner for at least a decade Now, how-
ever, they think the time has come to build facilities that pump the fuel out on a commercial scale
“Unless you have the will to put the necessary infrastructure
in place, all the biomass in the world doesn’t mean anything,”
Iowa State’s Brown explains ‘The big question, he says, is whether companies will invest the hundreds of millions of dollars that are needed to build commercial-scale plants in the next five to seven years Brown believes that window of time is critical After that, he believes we'll start to see shortfalls in transportation fuels that drive
the prices of already costly gasoline even higher
Some are making the investment Abengo Bioenergy is cur- rently building the world’s first commercial-scale cellulosic eth-
anol plant in Babilafuente, Spain And a handful of U.S.-based companies have announced they will either build new plants or retrofit old ones to produce ethanol from biomass In February
the Bush administration announced it would contribute $160 mil- lion dollars to construct up to three biorefineries The DOF, has already received more than 75 applications for the funds
The administration’s recent interest in cellulosic ethanol pleases
biofuel experts, but they say they're still not convinced that renew- able energy is a priority in Washington Getting enough funding,
they say, is still one of their biggest challenges “I don’t think that
Trang 5“There are two areas where engineering is
meeting challenges,”
Walker points out
“There’ the basic Re*’D
process of converting cellulosic material into ethanol, but there is also
a systems engineering
approach that considers infrastructure, resources and transportation.”
nol tanks rang@in size
CO orca
grass thrives in the Gfeat Plains ang Southeast
the government is investing in this
in a way that's serious,” Lynd says
To illustrate this point, he contin-
ues, one need only to compare
the amount of funding for cancer
research ($4.75 billion) to that for
renewable energy ($342 million)
in Bush’s federal budget for fiscal
2007 “The disparity is large,” Lynd asserts, “and yet those problems are
arguably of similar importance.”
Not Enough Funding
F THE $342 million budgeted for renewable
energy, about $149 mil-
lion is set aside for biofuel-related programs While that’s a $60 mil- lion increase over 2006, it’s still
far less than the $330 million devoted to coal research and $347
million for nuclear power R&D, both of which are mature tech-
nologies “We are underfunding energy research across the board,”
Kammen says “When you want to ramp up a promising technolo-
gy like cellulosic ethanol, you have to ramp up funding,” even if the
private sector ultimately takes over the technology's development
Aside from holding cellulosic ethanol technology back, Lynd
thinks another problem has arisen from a decade of underfunding
renewable energy —a manpower shortage “We're not training the people we need,” he says Now, with investors and venture capital- ists clamoring for commercial-scale cellulosic ethanol facilities,
Lynd worries that there aren’t enough engineers with the expertise
to build top-quality biomass refineries
Lynd has a few ideas for filling the pipeline with engineers with renewable energy know-how “Engineering educators need to de- velop their curriculum to include examples from the so-called bioeconomy in traditional courses that will reach more students, not just specialized courses that attract students who are already interested,” he explains
Getting students involved in relevant research experiences,
Lynd says, is another good way to foster interest in renewable ener-
gy Kammen agrees “You really don’t learn about which problems are more important just by sitting in the lab,” he says To focus on the energy issues facing the world today, students at the Renew-
able and Appropriate Energy Laboratory combine research with
outreach Past projects include developing sustainable biomass energy in Zimbabwe's eastern highlands and in Cuba
“We need to get away from the perspective of applied research
competing with basic research,” says Kammen, who was trained
as a physicist “You can do basic science and engineering as well
as applied research and field research Exceptional advances in
engineering really come from that mis Kammen agrees that there aren’t enough engineers working in
renewable energy, but in his experience it’s not because students aren't interested in the field; it's because there aren’t enough edu- cational programs for them He says that the graduate program at
UC Berkeley's Energy and Resources Group, an interdisciplinary program in which Kammen isa professor, receives 200 applications
each year for just 15 to 20 spots There are enough qualified appli- cants in that pool, he says, to host a class three times that size
“The students that come to these programs want to change the world,” Brown says As director of the Office of Biorenewables at Towa State, he helped established the nation’s first graduate pro- gram to offer advanced degrees in biorenewable resources Stu- dents in the program concentrate on biorenewables while also
completing degree requirements in a more traditional engineer-
ing field like chemical engineering or agricultural and biosystems engineering Having graduated about a dozen students since its inception in 2002, Brown thinks the program is still small In an
effort to expand, he is currently helping to set up a consortium
with the University of Idaho and the University of Kentucky
The recent interest in biorenewable energy signals how impor- tant biology is going to be for the next generation of engineers, Brown notes “In the past, we have tended to let those biological problems be solved by scientists, which is fine until you try to take
those solutions and make them into a practical process,” he says
“We need to engage more engineers in looking at the biological issues of the bioeconomy There is tremendous potential in this area and we need to start thinking creatively.”
Bethany Halford is a freelance writer based in Baltimore
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