Biofuels could be a crucial weapon against both rising temperatures and dwindling global oil supplies. They are made from organic material such
as plants, so they essentially recycle existing carbon in the
atmosphere instead of releasing new carbon from the depths of the
earth; they are also, in principle, endlessly renewable. But the
best-known biofuel, ethanol, is looking decidedly unpromising right
now. Today most ethanol in the United States is made from corn, using
an energy-intensive process that may not actually save a lot of fossil
fuel, and in any case America cannot produce enough ethanol from corn
to really matter.

Scientists have long tried to devise an
efficient way to make ethanol from a wider range of raw materials,
especially waste products rather than food. The U.S. government has
calculated that the country could generate 1.4 billion tons of biomass
a year. This could make 100 billion gallons of fuel or more, enough to
meet much of America’s demand for motor gasoline. One approach to
tapping into all that biomass focuses on cellulose, the material that
gives plant cells their strong walls. The cellulose is converted into
sugar and then from sugar into ethanol. But despite decades of
research, the technology is still far from commercially viable.

Now
several companies, including Coskata and Range Fuels, say they have
cracked the problem. They are pursuing a different strategy, one that
turns any carbon-rich matter into a gas, which is then converted to
liquid fuel. This approach can use any organic material, so the
potential sources for this fuel are virtually unlimited. Soon, the
companies claim, they will be able to refine vast quantities of noncorn
ethanol. Coskata even predicts they will do so for as little as $1 a
gallon.

“In the Southeast there is enough biomass from wood
products alone to make 10 to 15 billion gallons of fuel a year,” says
Mitch Mandich, CEO of Range Fuels, based in Broomfield, Colorado, the
firm building what may be the first U.S. plant to make next-generation
ethanol commercially. The refinery, in Soperton, Georgia, will open
late next year, and Range Fuels is already scouting locations for more
plants. Meanwhile, other firms here and abroad have announced plans to
make ethanol from pine trees, from the contents of a city dump, even
from the carbon monoxide generated by steel mills.

Making liquid
fuels from gasified carbon-rich matter isn’t actually a new idea, but
it has never before been practical for biomass. The first step,
gasification, usually requires either pure oxygen, which is expensive,
or regular air, which introduces nitrogen that is costly to remove.
Range Fuels has designed a system that delivers oxygen cheaply through
steam and converts all the raw material into a gas in just 20 minutes.
“Under those conditions you get a very high conversion of all the
carbon in the biomass into various gaseous products,” says Arie
Geertsema, Range Fuel’s chief technical officer. The process also
reduces by-products such as carbon dioxide and slag, the company says.

The
gas that comes out, called syngas, is a mixture of mostly carbon
monoxide and hydrogen. Traditionally, syngas is converted to liquid
fuel by means of a catalyst; Range Fuels is tweaking the catalyst to
improve this procedure as well.

Some competitors are going
further. To boost efficiency, they are ditching the catalyst entirely
and enlisting bacteria to ferment syngas into ethanol. “The amount of
ethanol produced by chemical catalysis is around 70 or 80 gallons per
ton,” says Wes Bolsen, chief marketing officer for Coskata, located in
Warrenville, Illinois. (Coskata generated headlines recently by
attracting an investment from General Motors.) The company can produce
more than 100 gallons of fuel per ton based on lab experiments because
bacteria make more ethanol: “We aren’t producing butanol, propanol,
hexanol, octanol, and all the other alcohols,” Bolsen says.

Bolsen
also points to estimates by the National Renewable Energy Laboratory
(NREL) that the high pressure and high temperature required for syngas
cleaning and catalytic conversion add about 30 to 40 cents to the cost
of a gallon of fuel. In contrast, Coskata says its process works at
relatively low pressure and temperature: about twice atmospheric
pressure and 97 degrees Fahrenheit.

But building a system to turn
any carbon into ethanol is one thing; finding a steady diet for such an
omnivore is another. Take trash, for instance. Many environmentalists
are eager to harvest fuel from bald tires and junk plastic. Yet Range
Fuels’ fancy new ethanol plant, which will eventually pump out 100
million gallons of fuel a year, will feed mostly on wood chips. “What’s
nice about wood chips is that they’re pretty uniform. You’re not
sorting out hearing aid batteries from it,” says Samir Kaul, a
principal at Khos­la Ventures, a venture capital firm started by Sun
Microsystems founder Vinod Khosla. Khosla Ventures is financing at
least three ethanol producers, including both Range Fuels and Coskata,
and so is sensitive to practical issues. “Garbage is risky,” Kaul says,
“and when you scale a technology for the first time, you don’t want to
add risk where you don’t have to.”

Surprisingly, the other
problem with trash is that there may not be enough of it. Coskata
estimates that municipal solid waste is less than 10 percent of all the
available biomass—too little, perhaps, to make developing a sorting
process worthwhile, at least at the outset.

Other sources of
waste are more promising. The government biomass study that came up
with 1.4 billion tons of annually available biomass identified farming
and timber residues (cornstalks and the unusable parts of logged trees)
as the source for nearly half of the nation’s bioenergy. The trick will
be cheaply delivering these leftovers to the ethanol plant.

Range
Fuels initially hoped to feed its refinery with leaves and small limbs
that the timber industry cannot process. The Georgia Forestry
Commission reports that each year loggers leave behind some 8 million
tons of waste wood, including too-small living trees, within a 75-mile
radius of the new refinery—enough for four of Range Fuels’ plants. But
getting that material to the refinery has proved difficult. “The timber
industries are really not set up to do that,” says Range Fuels’ Mandich.

Nobody
has yet figured out how to compact forest leftovers for transport.
“Have you ever tried to move your leaves in the fall?” asks Richard
Hess, a scientist studying the problem at Idaho National Laboratory.
“You fill up this garbage sack and it doesn’t weigh anything. That’s
the problem. It takes a lot of energy to move air.” Still, Hess expects
optimized handling systems will be ready by 2012, meeting the
government’s goal and in time for a wave of new refineries. “We’re rich
in opportunities to make fairly epic gains,” he says. Until then Range
Fuels will source its wood chips from whole trees—not a waste product
at all, but a commodity used to make paper pulp.

It might not be
long before the ethanol companies are paying to get more biomass waste
headed into their plants. According to Richard Bain, a researcher at
NREL, the estimated cost of producing a gallon of ethanol stands at
$2.10 today. By 2012 this should fall to $1.33—at least for those
companies using steam to turn biomass into syngas (several firms, he
says, have developed this technology). At the same time, the steep
price of gasoline—and corn—means that next-generation ethanol can be
profitable even if its price doesn’t reach what Khosla Ventures’ Kaul
calls the “holy grail” of $1 a gallon. Freed from the bad rap of corn
ethanol, bio­fuel-powered cars could then drive us toward a better
future.