Energy
It’s the holy grail of renewable-energy research: a liquid
fuel that can be harvested sustainably, burned cleanly, and doesn’t come from an
unstable part of the world.
And maybe, just maybe, it will be manufactured at a plant
near you.
The fuel in question is ethanol. Specifically, cellulosic
ethanol. Ethanol is an alcohol made from fermenting sugar that can be burned as
a fuel in internal combustion engines.
To make traditional ethanol, from corn, requires a lot of
fossil fuel. Enough that the energy output from the resulting ethanol isn’t a
lot more than the energy needed to make it. According to some scientists,
traditional ethanol may actually produce less energy than it takes to make it.
Cellulosic ethanol is different. Instead of using the sugars
that naturally occur in corn, makers of cellulosic ethanol create those sugars.
They do that by using enzymes to convert cellulose — tough fibers that make
up a large portion of organic matter — into the sugars.
Once it’s broken down, the sugar made from cellulose can be
fermented in much the same way corn starch is. This means that cellulosic
ethanol is actually a bit more complicated to make than traditional ethanol.
But that’s offset by the fact that cellulose is much more widely available than
corn starch. Just about any plant is made of the stuff. Corn has to be planted,
cultivated, fertilized, and harvested. It takes up a lot of land, causes
erosion, and requires plenty of fossil energy to be burned as fuel or used as
fertilizer at each step.
On the other hand, switchgrass, for example, only has to be
harvested. Wood chips, a byproduct of the forest industry, might be even easier
to come by, depending on where you’re located.
In December, in one of his last acts as governor, George
Pataki announced state funding for an ethanol demonstration plant to be built
in Greece. New
YorkState is
kicking in $14.8 million for the plant, which will produce half a million
gallons of cellulosic ethanol a year. The partners involved in the plant are
matching that money. Mascoma, the lead company, is contributing most of it.
Other partners include Genencor, a biotech company with a presence in Rochester;
CornellUniversity;
ClarksonUniversity,
and Khosla Ventures, a venture-capital company founded by Sun Microsystems
co-founder Vinod Khosla (an ardent proponent of ethanol and frequent backer of
ethanol-related companies).
“What we hope the demonstration leads to is a commercial
facility, says Larry Bouchie, a spokesperson for Mascoma. While this pilot
plant might produce up to 500,000 gallons a year, the goal is a plant that
produces millions. This plant is simply a halfway point between the lab and
that goal.
“Mascoma is trying to move very quickly from an R and D
company” to a production company, Bouchie says. “We’re trying to fast-track
this out of academia.”
Right now, Mascoma is working on turning its research into
processes that can reproduce what happens in a lab on an industrial scale. If
that can’t be done efficiently, the technology won’t be worth much in the long
run. One of the ways of accomplishing that is by streamlining things.
“We’re trying to reduce the number of steps involved,” says
Bouchie. “We’re hoping to use one or two enzymes to keep it at one or two
steps.” Whittling down the number of enzymes needed to complete the
ethanol-making process will ultimately (if it succeeds) make it cheap and
efficient enough to commercialize.
David Wu believes a one or two-enzyme “cocktail” to process ethanol is possible. Wu, a professor
of biochemical engineering at the University
of Rochester, has no connection
with any of the players in the proposed Greece
plant, but he’s devoted his career to researching the same technology.
When the name Mascoma comes up, he beams in recognition.
He’s aware of their research, as they surely are of his. It’s because of
research like his that the Greece
plant is a possibility. Wu, among others, helped map the genome of a bacteria
species called Clostridium thermocellum. It’s an anaerobic bacterium you might
find growing in a compost pile. Its function in nature is decomposing organic
matter — exactly what ethanol makers need to do. And it’s from this species
that many of the most promising enzymes for cellulosic ethanol come.
Now Wu is working to pair different enzymes with the genes
that trigger their production in the first place. If all goes according to
plan, researchers should be able to genetically engineer a microorganism
perfectly suited to the twin tasks of breaking down cellulose, then fermenting
the resulting starches and sugars. Multiple microorganisms, actually.
Isolating the genes “would allow us to custom design a
particular microorganism for a particular substrate,” says Wu. (By substrate he
means the substance being converted to ethanol.) In other words, you could
engineer one strain of bacteria for switchgrass, another for wood chips, and
still another for municipal waste. But that’s easier said than done. Wu
estimates that in nature, one dead tree could be decomposed by tens of
thousands of different enzymes. Even in a controlled lab, and focusing only on
his one species of Clostridium, at least a hundred different genes and about as
many enzymes are related to the process of breaking down cellulose.
He and other researchers are closing in on the right enzyme
cocktails or “super enzymes,” but “there’s room for improvement,” he says. “In
the next three to five years, people are going to see better enzymes.”
Wu’s interest in
the field that would eventually become his life’s work began in the 1970’s,
during the first energy crisis. But by the time he was finishing up his PhD at
MIT in the mid 80’s, oil prices had plummeted. The issue was off the public’s
radar and no longer in the forefront of the minds of many who funded research
grants. Still, ever since the early 90’s, Wu’s Rochester
lab has had a steady stream of funding from places like the Department of
Energy, the US Department of Agriculture, and the National Renewable Energy
Laboratory.
Now, it seems to him the situation has reached something of
a full circle. “We’re facing a similar problem to what we faced in the 70’s,”
he says, in terms of ever-growing demands on the world’s energy supply.
There are some differences this time around, though. There’s
more competition, he points out, especially from China’s
booming economy. And there’s also a different ecological climate — literally.
“In the 70’s, we were not so aware of the greenhouse effect,”
he says. “Now we’re going through it, in my opinion.”
But according to Wu, not all the change since the first
energy crisis has been bad.
“We now have the recombinant DNA technology we didn’t have
in the 70’s,” he says. Without that technology, his work isolating the genes
that produce the best enzymes wouldn’t have been possible.
“So the problems have become more severe, but our capability
to tackle them has expanded,” he says. “There’s both challenge and promise.”
Wu is clearly enthusiastic about the possibility of ethanol,
particularly cellulosic ethanol, to play a key role in the energy supply of the
future. In addition to his research, he’s on the editorial board of Industrial
Biology, for example, a journal that has put glowing stories about the fuel on
several of its recent covers.
But not everyone is as bullish about the alcohol’s
potential.
Robert Bryce is the managing editor of Energy Tribune, an
industry newsletter. He criticized a Pataki subsidy for a traditional ethanol
plant in a City Newspaper article last spring, and his views aren’t much
different about the cellulosic variety.
“My opinion on cellulosic ethanol’s pretty simple: Where’s
the beef?” he writes in an e-mail. “Everybody talks about cellulosic ethanol
and how it will be wonderful, but the energy input numbers just don’t work.
They’re talking about turning what is essentially hay into motor fuel. Sure.
I’ll believe it when I see it.” And by “see it,” Bryce clarifies in a
subsequent conversation, he means on a commercial scale, and without government
subsidies.
“No matter how much ethanol we produce,” he says, “we’re
still going to be part of the global oil market. We cannot divorce ourselves
from it.”
Cornell Professor
David Pimentel drew national attention in 2005 when he and a colleague
published a study claiming that ethanol took more energy to produce than it
contained. He shares Bryce’s skepticism, if not his blunt approach.
“I must admit that I wish that it were true,” says Pimentel,
referring to the promises of ethanol’s potential. “I still support all the
research going on.”
And while he seems to be interested in the kind of research
Wu is doing, Pimentel is skeptical of ethanol, no matter how it’s produced, as
a way out of our energy crunch.
“I’m for the use of biomass in a reasonable way,” he says.
But then, to put that in perspective, he adds: “We already get 3 percent of
energy from woody biomass.” That’s in the form of woodstoves, boilers that burn
wood, and even a wood-fired electricity plant. At 3 percent, he says, woody
biomass is already contributing the same percentage of energy as hydro power.
The problem, then, isn’t one of supply, but of demand run amok. Even if this
nation made a seismic shift toward using biomass, like ethanol, as a primary
energy source, that wouldn’t slake our thirst for energy.
“We are burning twice as much fossil energy as all the
plants in the US
collect,” he says. “We should be focusing on conservation.”
This article appears in Jan 3-9, 2007.
