(CNN) -- Donald Stedman has never been a fan of ethanol. Stedman, a chemistry professor at the University of Denver, said there are several problems with the alcohol fuel, one being that it messed up the fuel pump in a car he uses.
Brooke Coleman is a big fan of ethanol. Coleman, executive director of the Advanced Ethanol Council, said there are a lot of misconceptions about the type of fuel. He's also experienced an engine-part failure that a mechanic blamed on ethanol, but he said he's sure there were other issues that caused the shutdown.
The two men are on different sides of a debate on a fuel that is increasingly under a political and public microscope.
The debate over ethanol can be heated. The government mandates the amount that is produced in the United States each year, and the Environmental Protection Agency recently granted a waiver, allowing the percentage of ethanol that can be used in some cars to rise from 10% to 15%.
The government is also funding more pumps that can distribute various blends of ethanol, including E85 (85% ethanol).
The Obama administration wants to see 36 billion gallons of ethanol in fuel tanks in 2022. This year the standard is 12.6 billion gallons of corn ethanol, which the industry expects to exceed, with other renewables to contribute a little more than 2 billion gallons.
While politicians and experts take sides on the issue, some drivers are just looking for reassurance that ethanol is not a bad idea in their vehicles.
John O'Dell, who writes about green cars for the popular auto website, Edmunds.com, said that while there isn't a whole lot of discussion on ethanol on the main site, the primary thing users want to know is, "Is it safe to put in my car?"
"Ethanol is alcohol," he said. "And alcohol is corrosive to a number of things, including metal and rubber parts. So vehicles have to have fuel systems designed to be hardy enough to handle ethanol, and most everything on the road today is OK to take the current blends."
Richard K. Perrin, a professor of agricultural economics at the University of Nebraska, said he's not seen any experiments at his school that showed harm up to E15 (15% ethanol).
"And I am aware of three studies (elsewhere) that showed no harm," he wrote in an e-mail.
On the green car section of the Edmunds site, users seem more concerned about the fact that in the United States, we use mostly corn to make ethanol, which has consequences on the food supply and the land.
This is where the experts often disagree. Detractors, such as Stedman, call all ethanol a bad idea that hurts the environment, hurts the economy and hurts people.
Those who are for more widespread use of ethanol said it can improve national security, improve our ability to make home-grown fuel and improve our health by steering us away from an energy source that is becoming increasing harder to get to and dirtier to extract.
"Ethanol, by the time it's all said and done, almost doesn't save any oil," Stedman said. Farm equipment doesn't run on ethanol, he said. Petroleum-based fertilizers are used. Ethanol must be transported on trucks because it would corrode the rubber rings in a pipeline.
The ethanol industry just transfers the oil use, he said.
Ethanol also harms the ozone, he said. Stedman has invented a roadside air quality monitor that measures the emissions of 5,000 to 6,000 cars daily in the Denver area. The professor said the data he collected showed that hydrocarbon emissions were greatest on days when the temperature was higher than 95.
"And it jumped a whole lot more in years when there was a lot of ethanol in the fuel than it did in years when there was no ethanol in the fuel," he said. "Now correlation doesn't prove causation, but the fact of the matter is that there is an incredibly good correlation with (higher emissions) and ethanol."
Coleman said that ethanol, while not perfect, is a much better option than oil, especially the types of extreme energy sources that oil companies are going after today.
"People just don't understand the trade-off," he said. "What are we using instead? And the answer is a really dirty petroleum-based molecule, because the oil industry is getting dirtier and dirtier on the margins. Light sweet crude is depleting quickly, and now the industry is going after heavy crude and tar sands and thermally enhanced oil."
That's what ethanol is replacing, he said. Advocates such as Coleman and Georgia Tech professor Marilyn Brown said there are going to be better sources for ethanol than corn.
"It's not our long-term solution because of the competition with feed, and fuel competition, but it is prompting us to put into place a refueling infrastructure that could be used with cellulosic ethanol," made from other types of plant material such as timber waste or switch grass.
Cellulosic ethanol was belle of the renewable fuels ball in 2007 when President George W. Bush touted it during the State of the Union address. But today there are only a handful of demonstration plants producing a few million gallons of ethanol.
Charles Wyman, a professor of chemical and environmental engineering at the University of California, Riverside, said the sources of cellulosic ethanol are more widely available. Trees and grass can be grown just about anywhere.
Costs are also low, about the equivalent of 60 cents per gallon, he said. But the big challenge right now is the capital costs. To build a plant costs several hundred million dollars.
"The first few plants would cost quite a bit, but after that costs would come way down," he said.
Coleman, the ethanol advocacy group director, said there are about 50 "advanced" biofuels projects at some point of development, with about a dozen ready and just waiting on financial backing.
Everything was slowed by the recession, he said. A new round of policy battles didn't help. Each side said the other has powerful lobbies working to thwart the other. Advocates said oil companies lose a dollar every time they gain one. Detractors said the corn industry is doling out large campaign contributions.
Both sides can only seem to agree on a few things. Oil is getting harder to extract, and ethanol from corn, while a logical solution to the gas shortages of the 1970s, is no longer the best ethanol option.