Corn ethanol is turning out to be a lousy future investment for America, said plant scientist and renewable energy expert David Tilman during a presentation at Brown University on Tuesday.

Not only does it not help reduce carbon emissions or make a significant dent on our dependency on foreign oil, diverting corn for ethanol is wreaking havoc on the price of the staple crop.

In the past couple of years, the price of corn has nearly doubled to $4 a bushel.

“It’s not the technology we want to base an energy-efficient, environmental-friendly economy on,” said Tilman, a professor of ecology at the University of Minnesota who has been studying renewable energy sources from plants for the last five years.

If the United States dedicated all its corn to ethanol production, it would satisfy only 12 percent of the U.S. demand for gas, Tilman said in a 2006 report in the Proceeding of the National Academy of Sciences, one of the world’s most prominent scientific journals.

Environmental benefits are also negated once energy requirements for fertilizer, the harvesting process, transportation and refining are factored in, rendering corn ethanol production no better at cutting carbon than gas, Tilman says.

The fundamental problem is not ethanol itself, but inefficiencies in the process of making it compared to its energy yield.

Only 20 percent of every gallon of ethanol is “new” or created energy, Tilman says.

When that figure is combined with the efficiency rate of ethanol when it burns — creating 35 percent less energy than gasoline — ethanol loses even more of its potency as an effective alternative fuel, Tilman said.

For it to be competitive with gas for consumers, ethanol would have to be 35 percent cheaper.

The federal government protects the domestic production of ethanol with a 51-cent blending subsidy and high tariffs on imported fuel, but still the industry is already lagging from low demand.

Archer Daniels Midland, the largest U.S. ethanol producer, has seen its stock fall 20 percent since the summer of 2006.

Automaker General Motors is a strong proponent of ethanol, having made more than 2 million “Flex Fuel” vehicles that can run on E85, a fuel blend of 85 percent ethanol and 15 percent gasoline, or gas.

The “Live green, go yellow” campaign launched about two years ago by GM encourages young Americans to create grass-roots support for ethanol to support renewable fuel and reduce greenhouse gases.

The campaign’s Web site sells E85 merchandise such as yellow T-shirts and hats bearing the slogan “Live green, go yellow” for about $15 apiece.

Tilman says this type of promotion is misleading.

“One of the dilemmas we have is automobile companies advertising corn ethanol as a clean fuel,” Tilman said. “Its whole life cycle is not very green and not very clean.”

Scientists and corporations have already recognized many of the flaws of corn ethanol and are investing millions into research to develop more efficient, less polluting biofuels from other forms of organic matter from corn stover to prairie grass.

Research at the University of Rhode Island, led by visiting professor in the department of cell and molecular biology Albert Kausch, is focusing on ways to genetically modify prairie grasses to optimize their use as a biofuel.

The grasses show a lot of promise, Tilman and Kausch say, because they require little to no fertilizer and grow well in poor, marginal soil.

If they can be broken down with inexpensive enzymes and efficiently fermented into alcohol, the grasses could contain several times more energy than corn ethanol and sugar cane biodiesel used in Brazil, with far fewer environmental impacts.

Both scientists agree that the technology is still several years away, but it does offer hope for homegrown clean, renewable fuel.

Rhode Island investors are getting into the ethanol business.

In October, the group that governs the Quonset Business Park approved a $135-million proposal to build an ethanol refinery.

It is unclear if the plant will have the capability to refine other types of biomass, but Tilman said the investors should consider it.

“I would advise holding off on a corn ethanol plant right now,” Tilman said. “I would suggest investing in some of the new technology.”

Tilman has drawn decisive conclusions from his research, mainly relating to sustainability.

The United Nations projects the population to reach 9 billion by 2050 and energy demands to double.

He insists that countries cannot afford to use fertile land to grow a fuel source and the world population cannot be supported when food is used for fuel.

Tilman does not think that ethanol is a failure, but is a preliminary experiment into the potential of biofuels.

“In defense of what happened, it was an interesting idea and it wasn’t until the last few years that it became clear that it was not giving us very much new energy and it doesn’t have the environmental benefits originally thought,” Tilman said. “We need a lot of different solutions.”

ngarcia@projo.com