"The problems we see are on the other end," Erickson said. "Will we have enough infrastructure to transport these biofuels? Will the automobile industry make enough flex-fuel vehicles (specially designed to run on gas or high-ethanol blends)?"

If the goal can be achieved, though, it will translate into major energy security gains, by decreasing foreign oil imports, and environmental benefits, by helping wean the nation from carbon-emitting fossil fuels, its proponents say. That holds true for these small-scale projects as well, which will use a variety of sources to create the fuels and are planned for construction in Boardman, Ore.; Commerce City, Colo.; and Wisconsin Rapids, Wis., in addition to the Missouri plant, DOE representatives say.

"With all of these projects, the amount of fossil fuel used to produce the biofuels is significantly less than that associated with gasoline -- on average as much as 90 percent less over the lifecycle," according to a recent DOE statement.

But policymakers and industry leaders should be cautious about investing in widespread production before all the environmental impacts have been assessed, said Jason Hill, co-author of a recent article, published in the journal "Science," that questioned whether traditional ethanol production might actually increase greenhouse gas emissions. This could occur if land is converted to cropland to grow feedstock for renewable fuels, the authors of the study said.

"It's a really good thing to get these pilot facilities up and running," Hill told UPI. "The warning is that when we scale that up to commercial size, the land use change becomes critical."

Cellulosic ethanol -- from waste products and high-cellulose crops -- probably won't be as harmful as traditional ethanol, Hill said, but some, particularly energy crops, could still require land use change.

"Where is it going to come from?" he asked. "If it's from our fertile land, where are those crops being displaced to? If not, it's going to come from our reserve land or it's going to come from other land."

And all of those scenarios represent land use change.

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