Sugar cane grows on less than a million acres in Louisiana, Florida and Texas. But if Edward Richard's research pans out, the crop will be growing on additional acreage in additional states as a dedicated biomass crop called energy cane.
Richard, research leader at ARS's Sugarcane Research Unit, Houma, LA, crossed cold-tolerant sugar cane varieties grown in the Himalayan foothills with domestic varieties, producing lower-sugar plants that don't need tropical weather.
“They have higher fiber levels and they have tremendous hybrid vigor, so they can produce high biomass yields,” he says.
“What we see as the greatest potential is that biomass is not all cellulose. A lot is sugar, and it's so easy to take sugar and add a little yeast to it and you have ethanol. Some of the fiber can be used to co-generate electricity used to power the facility. The remaining cellulose material, what we call bagasse, could be used with the cellulosic technology to convert to ethanol as well,” Richard says.
He and colleagues have established trials growing energy cane in northern Mississippi, Oklahoma, Arkansas, California, Alabama, Georgia and northern Florida. “We think we have a crop that can be grown in areas outside of the traditional sugar-growing areas of the country,” he says.
The University of Illinois is also testing the crop, which is propagated by laying the whole mature stalk in the ground and covering it with soil. “It's a much slower process to establish a field than planting seed,” Richard says. “But once the industry is going, you can ramp it up relatively quickly and get more than one yearly harvest from a planting.”
He expects energy cane varieties will have a stand life of seven to eight years with a 15-ton dry yield, 4 tons of which would be sugar. With 80 lbs/acre of nitrogen applied, it can be harvested the first year at full yield. Richard has planted it on everything from sandy to heavy clay soils. “It needs moisture but just at certain times of the year.
“We're hoping that this is a crop that can be grown in the South where our corn yields are not as great as those in the Midwest. This crop could give growers a higher ethanol yield than corn in some of our Southern states.”
He's also researching crops that produce at other times of the year — helpful in keeping biorefineries supplied year-round. “Sweet sorghum is one we're looking at. We should get some really good yields with it and it can be harvested with the same equipment used to harvest sugar or energy cane.”
Tropical maize and miscanthus are two other possible companion crops. It's possible to cross miscanthus, which offers cold-tolerance, with sugar cane to produce novel new bioenergy feedstocks as well.
In January, Verenium Corp. announced it will build a commercial-scale plant in Highlands County, FL, with a goal of producing 36 million gallons of cellulosic ethanol from Florida-grown crops, including sugar or energy cane and sweet sorghum, by 2011. The corporation has an agreement with Lykes Bros., which will provide feedstock from 20,000 acres adjacent to the building site.
Verenium also has a demonstration plant in Jennings, LA. “I think they're looking at 1.5 million gallons of ethanol from it in 2009. Sugar cane fiber is going to be one of the main feedstocks for it,” Richard says. ?