President Bush's goal of boosting production of renewable and alternative fuel to 35 billion gallons in 2017 from 5 billion last year poses a huge challenge to the biofuels industry.

"That's an astonishing number," John Raineri, who leads DuPont Co.'s effort to boost biofuel production, said in an interview yesterday.

Today, Bush is scheduled to visit DuPont's Experimental Station near Wilmington to bring attention to that research.

The only way to achieve the president's goal, Raineri said, is through cellulosic ethanol, which uses cornstalks, wood chips, and other nonfood materials instead of corn kernels.

At the sprawling Experimental Station, DuPont scientists are in the third year of a four-year, $38 million effort - also involving university researchers and other companies - to develop a cost-effective biorefinery that can produce ethanol and other chemicals from the entire corn plant.

During the tour, Bush will see the lab where DuPont scientists use enzymes to break the corn- plant fibers cellulose and hemicellulose into different kinds of sugar. In another lab, researchers are tweaking a bacterium to convert as much xylose as possible into ethanol.

Yeast is among the workhorses of ethanol production, eating corn sugars and giving off ethanol and carbon dioxide, but it will not consume xylose, the sugar from hemicellulose.

Raineri declined to say what percentage of the xylose is being converted. That yield is key because, if it is not high enough, it might not be cost-effective to collect the massive amounts of plant material needed for cellulosic-ethanol production. How that collection process will work and how the materials will be stored for year-round use are among the unknowns in the renewable-fuels puzzle.

In October, DuPont teamed with Broin Cos., of Sioux Falls, S.D., to build a pilot plant. The two companies have applied for a piece of the $160 million the Bush administration plans to contribute over the next three years to the construction of up to three biorefineries.

"The fact that we're moving out of the lab . . . gives good credence that we're well along the curve, but we still have a ways to go," Raineri said.

Contact staff writer Harold Brubaker at 215-854-4651 or hbrubaker@phillynews.com.