Plants fuel new petrol

Cellulosic ethanol may help solve oil 'addiction'

GOLDEN - In his short list of solutions to American oil "addiction," President Bush in his State of the Union address discussed hydrogen power, hybrid gas-electric vehicles and something called "cellulosic ethanol."

If Bush visits the National Renewable Energy Laboratory in Golden this week as expected, he might get a glimpse of what NREL's biomass researchers have been up to for the past two decades. It's all about cellulosic ethanol, or ethanol made from plant waste.

NREL biomass engineer Andy Aden
Andy Aden, of the National Renewable Energy Laboratory, displays a container of fibrous cornstalks that are used to create cellulosic ethanol. Marty Caivano/Daily Camera

A mouthful today, cellulosic ethanol could be a tankful tomorrow. A recent federal report concluded that America's forests and croplands produce enough energy to replace 30 percent of petroleum consumed by 2030. That would take about a billion tons of biomass - mainly from agricultural and forest waste, although fast-growing grasses also could end up in gas tanks.

Whether America can convert piles of sawdust, forest slash, cornstalks or switchgrass into billions of gallons of usable motor fuel and, possibly, valuable industrial chemicals, will rest to no small degree on the efforts of NREL researchers.

NREL has been leading the basic research effort to turn biomass such as crop waste and wood chips into usable ethanol since the 1980s. It leads the virtual National Bioenergy Center and employs about 90 researchers.

Recent layoffs at NREL cost two biomass researchers their jobs; 32 jobs were lost altogether, but are being restored. A row of brewery-scale fermentation bins in the biomass research lab's pilot plant have gone unused for more than a year because of a lack of research money.

But that could change, depending on the impact of congressional earmarking, which cut NREL's budget $28 million this year. The Bush administration's 2007 budget proposes to increase cellulosic ethanol research $59 million, a 65 percent increase over 2006.

The president wants to make cellulosic ethanol "practical and competitive within six years" and ramp up production to replace the equivalent of three-quarters of Middle East oil imports by 2025. It is a tall order: There are about 100 ethanol refineries in the United States today, and none produces cellulosic ethanol.

Without cellulosic biomass, there's little hope of displacing all that petroleum, said Don Stevens, a biomass researcher at the U.S. Department of Energy's Pacific Northwest National Laboratory and vice president of the Biomass Energy Research Association.

"It's very difficult to see how you get to having a major impact on biofuels in the United States if you do not use these kinds of fuels ," Stevens said.

Pulpy biomass packs plenty of punch: Look at the muscles on a bull or a rhinoceros. The issue is in the packaging.

The 4 billion gallons of ethanol produced last year in the United States came from the sweet starches in corn kernels, which are broken down into the simple six-carbon glucose - table sugar - with relative ease. Ferment it and you get ethanol.

Wood chips and other cellulosic biomass contain glucose, but also xylose, a five-carbon sugar stubborn to break down. Cellulosic biomass also contains lignin, the cement that holds wood together and keeps cornstalks from flopping like beached seaweed.

Pound for pound, wood chips and corn chips contain about the same energy. But cellulosic biomass effectively locks it in.

"It's the difference between graphite and diamonds," said Andy Aden, a process engineer in NREL's biomass research group. "One is brittle; the other is the hardest substance on Earth."

NREL's biomass research in the 1980s and 1990s focused on figuring out just which sugars and chemicals various stalks, husks and wood chips contained and how to best unlock the energy. More recently, NREL has taken to optimizing the processes needed to convert tangled corn waste into a sweet xylose molasses and, finally, highly refined cellulosic ethanol.

Among the lab's recent triumphs, together with industrial partners, was the reduction in cost of enzymes central to biomass breakdown by a factor of 20, Aden said. Such enzymes, produced by bioengineered microbes, were previously so pricey that they only made sense when making high-end products such as stone-washed jeans.

NREL's biomass research now aims to help ethanol producers and chemical companies bring cellulosic biomass from research labs to full-scale production. The vehicle would be the biorefinery.

Aden says NREL hopes to help companies build biorefineries and make cellulosic ethanol as cheap as the corn-kernel variety within five to 10 years. A gallon of cellulosic ethanol would cost about twice that of corn ethanol now.

But biorefineries would make more than high-grade hooch for vehicles. They would be biomass-based chemical plants capable of generating fuels , power and diverse chemicals in the same big house.

NREL already is working with industry on pilot plants. DuPont, NREL, Michigan State University and John Deere are working on a four-year, $38 million Integrated Corn-Based Bioproducts Refinery effort. It aims to produce fuels , chemicals and power by using corn plants , stalk to silk.

NREL also is working with Abengoa Bioenergy, a St. Louis-based subsidiary of the Spanish conglomerate. Gerson Santos, Abengoa Bioenergy's director of research and development, said his company wants to have a refinery capable of producing cellulosic ethanol by 2010 or 2011.