PORTLAND, OR – There isn’t enough cropland in the entire U.S., nor sufficient water for irrigation, to grow the feedstock required to produce a fraction of the nation’s near-term automotive biofuels needs.

That is the cheery message outlined here by scientists who, when pressed, suggest algae production has the greatest potential for mitigating fossil-fuel dependence with biofuel alternatives.

“The bloom is pretty well off the ethanol rose,” says Jan Kreider, author, consultant and founding director of the University of Colorado’s Center for Energy Management.

As the auto industry advocates greater use of ethanol blends such as E85, Kreider and a colleague sound the feedstock alarm here during a sustainable mobility seminar sponsored by Toyota Motor Sales U.S.A. Inc.

Meanwhile, the auto maker is making plans to market a pair of E85-compatible vehicles: the ’09 Tundra pickup and Sequoia fullsize SUV.

With this move, Toyota joins a party in full swing. To date, Detroit auto makers have put about 7 million flex-fuel vehicles on U.S. roads.

But neither corn, nor soybeans, nor switchgrass have the potential to make a significant dent in the nation’s usage of 390 million gallons (1.5 billion L) of gasoline per day, Kreider claims.

If corn were planted in every corner of every farm in the U.S., and those crops were harvested solely for ethanol production, it would supply just half of the nation’s near-term blended automotive fuel needs, Kreider says.

Similarly, sowing the nation with soybeans would generate just over 12% of the nation’s requirements.

Switchgrass, he adds, portends slightly greater yields but demands irrigation.

The problem? “There is no more water,” Kreider says.

More than half of the nation’s arable land requires some degree of irrigation beause most of the precipitation occurs east of the Mississippi River.

“We’ve had our fun,” adds Tim Barnett of the Scripps Institute of Oceanography, noting Lake Mead, a key reservoir and recreation area in the Colorado River basin has lost more than half its volume and is 15 ft. (5 m) lower than this time last year.

Supporting adequate feedstock production would require “multiple Colorado Rivers,” says Kreider, who ironically cites algae, a water plant, as the alternative that shows “the most promise.”

Land- and water-use requirements are miniscule and manageable compared with resources such as switchgrass. Meanwhile, test crops grown at a pilot site in Arizona produced higher-than-expected yields.

And because algae thrives on carbon dioxide, it could be grown in bioreactors co-located with coal-to-liquid plants, because they emit large quantities of the gas. And there is sufficient coal in the U.S. reserve to last 150 years, Kreider says.

The down side? Coal-to-liquid plants consume 1 billion tons of water annually.

Kreider also is down on the prospects for cellulosic ethanol, claiming the world’s network of pilot plants have produced “mixed results” and made no data available for scientific review.

But even if the biofuels production wrinkles were ironed out, “enormous” logistical problems remain. The corrosive properties of the fuel itself eliminate pipelines as a means of shipment.

“You need to actually think all of this through,” Kreider says.