Corn ethanol is no better fuel than gasoline, and it may even be worse for air quality, according to a new University of Minnesota study.

The study, released Monday, is the first one to estimate the economic costs to human health and well-being from three different fuels -- gasoline, corn-based ethanol and cellulosic (plant-based) ethanol -- its authors say.

Scientists and economists looked at life-cycle emissions of growing, harvesting, producing and burning different fuels, and concluded that ethanol made from switchgrass and other plant materials is far better than either corn ethanol or gasoline.

"Our study shows that if we're really going to make choices in the best interest of the public, we need to look not only at what's cheapest to produce, but what are the costs to the public in terms of environmental and health effects," said Jason Hill, research associate in applied economics and a resident fellow at the U's Institute on the Environment.

Ethanol is a $6 billion industry in Minnesota, according to state estimates. The Minnesota Department of Agriculture calculated that the 17 ethanol plants in the state produced 670 million gallons of ethanol in 2007 and provided 26,000 "direct impact" jobs.

The university's study will be published in this week's issue of the Proceedings of the National Academy of Sciences and was posted online on Monday afternoon at the PNAS site.

No love from ethanol backers

Ethanol advocates said they haven't seen the study and will need time to understand how the conclusions were reached.

"I'm stifling a yawn," said Mark Hamerlinck, communications director for the Minnesota Corn Growers Association. "It would be news if the university had anything positive to say about corn ethanol. It's how they make a living over there."

His comment was an apparent reference to a controversial paper published by the university a year ago that said the exploding demand for biofuels will change the landscape and worsen global warming if farmers around the world clear forests and grasslands to grow more corn, soybeans and sugar cane.

In the latest study, the health concern comes mainly from microscopic particulates in the air, which are produced when fossil fuels are burned. They accumulate in the lungs and can cause a variety of respiratory and other problems.

The fine particles, similar to soot, are produced from the earliest stages by the farm equipment used to plant, fertilize and harvest the corn, or the drills and pumps used to extract and transport crude oil to refineries.

From 19 cents to $1.45 a gallon

The study concluded that the total environmental and health costs of making a gallon of gasoline was about 71 cents, compared with a range of 72 cents to $1.45 for corn-based ethanol, and 19 to 32 cents for cellulosic ethanol, depending upon the technology and type of plants used.

A major difference between corn-based and "cellulosic" ethanol is that biorefineries producing corn ethanol need to purchase electricity, while those producing cellulosic ethanol can burn the plant waste and generate their own power, the study said. That adds another source of air pollution to corn ethanol as well.

Whatever its benefits, Hamerlinck said, cellulosic ethanol cannot yet be made on a large scale.

He doesn't understand why researchers "bash" corn ethanol. It's a domestic source of fuel, he said, and farmers should be given more credit for developing and investing in it.

"If folks in their ivory towers at the university continue to pummel this industry, it doesn't do anyone any good" except perhaps for oil-rich countries around the world, Hamerlinck said.

Hill said that the study is not biased against corn ethanol.

"We're not coming at this with any preconceived notions of what the best fuel should be," he said. "We're just investigating and trying to take an independent look at the underlying factors and consequences of global energy and food use."

Tom Meersman • 612-673-7388