Better Biofuel: Corn with No Ears

Fields of corn surround the Golden Grain Energy ethanol plant, Thursday, June 30, 2005, in Mason City, Iowa. Credit: AP Photo

Ear-less corn holds heaps of sugar that could be turned into ethanol and other biofuels, a new study finds.
 
When grown in the Midwest, this "tropical maize" lacks nutrient-needy cobs, so the crops require less nitrogen and other fertilizers.

"Corn is a short-day plant, so when we grow tropical maize here in the Midwest the long summer days delay flowering, which causes the plant to grow very tall and produce few or no ears," said Fred Below, a crop scientist at the University of Illinois.

What the plants do produce could be a jackpot for the biofuels industry. Below found that the ear-less stalks store 25 percent or more of sugars in the form of sucrose, fructose and glucose.

Conventional corn and other dedicated energy crops store their sugars as more complex molecules, including starches and cellulose. Scientists must treat these substances with enzymes to convert them into sugars that can be fermented into alcohols such as ethanol.

The tropical-maize stalks store simple sugars, so no processing is needed. In addition, storing simple sugars is more cost-effective for the plant, because it takes additional energy to form complex starches. The energy savings could result in more available energy (simple sugars) per acre of tropical maize.

"In terms of biofuel production, tropical maize could be considered the 'sugarcane of the Midwest,'" Below said. "The tropical maize we're growing here at the University of Illinois is very lush, very tall and very full of sugar."

Sugarcane grown in Brazil produces lots of sugar with minimal nitrogen fertilizer, and as is the case for the tropical maize, the sugars can be converted into ethanol without the middle processing steps needed for complex sugars, he said.

The svelte stalks are also easier for farmers to integrate into their current operations than other dedicated energy crops because they can be easily rotated with corn or soybeans.

• Ethanol: Energy Panacea or False Promise?
• Top 10 Emerging Environmental Technologies
• Power of the Future: 10 Ways to Run the 21st Century