As state lawmakers move on legislation to provide incentives for using biofuels instead of gasoline, several University of Wisconsin professors said they are concerned corn-based ethanol may not be a practical large-scale fuel source.

But even so, it may pave the way for future advances in Wisconsin's growing biofuel industry, experts said.

Some opponents of corn-based ethanol say producing the fuel is actually a net loss of energy. However, Tom Jeffries, a UW bacteriology professor, said such theories are false.

For each unit of energy put into corn-based ethanol production, Jeffries said, people generally produce 1.36 units of energy. This ratio, even with improving technology, is "within 80 to 90 percent of what they're going to accomplish."

Cellulose-based ethanol — made from sources such as cornstalks and wood — could generate a better energy ratio, "something like 6 units for every unit you put in," Jeffries said.

However, he added gasoline shipped from the Middle East has about a 100-to-1 ratio.

And Paul Weimer, a UW microbiology professor, said purely comparing the economic differences between ethanol and gasoline is unfair.

"All you have to do with gasoline is pull it out of the ground, transport it and refine it," Weimer said. "Gasoline's better because it's already made."

Yet unlike fossil fuels, Weimer said ethanol is renewable and carries many social benefits. Weimer said ethanol reduces dependence on oil providers and promotes economic growth, all while reducing greenhouse-gas emissions.

While livestock farmers may suffer from the rise in corn prices, Bill Tracy, chair of the UW Department of Agronomy, said grain farmers stand to gain from the use of ethanol.

However, Tim Donohue, another UW bacteriology professor, said in order to sustain America's growing biofuel industry, farmers will have to diversify their crops.

"We have to get away from just using corn kernels to using cobs and stalks … (and) woods and grasses," he said.

Possible alternative sources, Weimer added, could also include pulp mill waste, cheese whey, alfalfa and switch grass.

Jeffries said he thinks the corn-based ethanol trend will soon transition to cellulose-based, though he added "getting the ethanol out of cellulose is what's hard."

While the energy ratio for cellulose-based ethanol is much greater, Weimer said the technology "is just not there" and "frankly won't be reached any time soon."

"Once the technological barriers have been overcome and [ethanol] can be produced in an economically sensible manner," Weimer said, ethanol should be a "functional replacement" for gasoline.

Jeffries said it would take sustainable high prices in petroleum for ethanol to catch on, noting the volatility of oil prices in the past.

"If petroleum prices stay about $40 to $45 a barrel, and if financial people … are convinced it's going to be there, you'll see a lot of investment in renewable energy technology," Jeffries said. "If it drops between $30 and $35 a barrel, people are going to go bankrupt."