Shredding corn stover could produce more ethanol at less cost

February 24th, 2009 - 3:31 pm ICT by ANI  

Washington, Feb 24 (ANI): A Purdue University researcher has found a way to produce more ethanol at less cost, by shredding corn stover instead of chopping it.

According to Dennis Buckmaster, an associate professor of agricultural and biological engineering, Purdue University, by shredding corn stover, there is better access to cellulose, which is the main part of plant cell walls necessary to make ethanol.

By shredding corn stover instead of chopping, as is commonly done, about 40 percent less energy is needed to gain access to more of the material stored in the plant.

You cant just use a big chunk of cellulosic material. You need small particles, Buckmaster said. What we want is access to whats in there, he added.

Using a technique employed in food processing and other industries to measure cell damage, Buckmaster put chopped and shredded corn stalks in water and compared the amount of leachates in each solution.

A leachate is any plant substance that is dissolved out of a plant or soil when it is placed in water.

According to Buckmasters results, shredded corn stalks produced about 11 percent more leachates than chopped and 5 percent more than stalks that had been chopped and put through a roller.

Buckmaster said that those differences are all the more impressive when considering the energy savings tied to shredding, giving ethanol makers potentially more cellulose for less cost.

He added that shredding corn stalks increases the surface area of the plant material. And because stalks can be shredded along the grain of the plants, like splitting a log with an ax, it takes less energy.

The current chopping method, he said, is like putting the log on its side and trying to chop it with the same axe.

It takes much less force to shear the plant material in the direction of the fibers, Buckmaster said.

Plants can be chopped again after storage to increase surface area, but that would raise energy costs beyond what is already spent at harvest.

Shredding corn stalks produced pieces of different sizes, but even the largest pieces of shredded material produced about as many leachates as the smallest shredded pieces.

When comparing the chopped materials, the largest pieces produced fewer leachates than the smallest pieces.

The shredded material, even with the long particles, gives you more access to plant nutrients, Buckmaster said.

Buckmaster said that the next step in his research is to compare shredded and chopped cellulosic material to see which produces more ethanol. (ANI)

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