Kenneth A. Gravois and Keith P. Bischoff
If you bought gas at the pump or paid a utility bill lately, then you know the high costs of energy are affecting many people. There are likely to be many solutions for achieving energy alternatives, and agriculture is being looked upon for several sources of alternative energy, and sugarcane is one.
Sugarcane is a popular feedstock for ethanol production in Brazil, and many think sugarcane can be a valuable energy source in an emerging biofuels market in the United States. Ethanol can be manufactured from the sucrose produced in sugarcane’s sweet stalks or from the conversion of bagasse – the fibrous pulp remaining after sucrose is extracted from the stalks.
Obtaining energy from bagasse is nothing new to the Louisiana sugar industry. Bagasse is typically burned as a fuel in boilers that produce steam, which is the main energy source for operating factory equipment used to produce raw sugar. Some sugar factories produce excess steam to operate turbines that generate electricity for the factory.
With these possibilities in mind, three high-fiber sugarcane varieties were released on April 25, 2007. The LSU AgCenter, in cooperation with the U.S. Department of Agriculture-Agricultural Research Service and the American Sugar Cane League, released L 79-1002, HoCP 91-552 and Ho 00-961.
L 79-1002 is characterized as having high fiber content (about 25.5 percent) and low sucrose content. The typical commercial sugarcane variety has fiber content in the range of 11 percent to 13 percent with high sucrose content. L 79-1002 is a cross between CP 52- 68 and Tainan. CP 52-68 was the most widely grown sugarcane variety in the 1960s, and Tainan is a clone of Saccharum spontaneum
– a wild form of sugarcane that has been used to incorporate vigor and disease resistance in Louisiana’s modern sugarcane varieties.
Some of these early-generation hybrids can be used to produce clones with high fiber content. These clones usually have vigorous growth, excellent ability to produce for several years, a more erect growth habit, better cold tolerance and large quantities of biomass. Biomass includes soluble solids (sugars) and insoluble solids (fiber, which is composed of cellulose, hemicellulose and lignin) – components that can be converted into ethanol.
HoCP 91-552 and Ho 00-961 have fiber content about three to four percentage points higher than commercial sugarcane varieties along with comparable sucrose content. These varieties could serve a dual purpose: as a source for both raw sugar and fiber.
Two companies, Verenium Corp. and TR Energy Growers LLC, have planted small acreages of L 79-1002. Verenium plans to use the L 79-1002 fiber as a feedstock in pilot-scale operations to produce ethanol through cellulosic conversion technologies. TR Energy Growers will use the fiber produced by L 79-1002 as a dehydrated boiler fuel as it co-generates electricity.
As new biofuel technologies and applications emerge, the Louisiana sugar industry should be well-poised to produce energy as well as sugar, a product that has sustained the south Louisiana economy for more than 200 years.
Kenneth A. Gravois, Graugnard Brothers Professor and Resident Coordinator, and Keith P. Bischoff, Andrew P. Gay Professor, Sugar Research Station, St. Gabriel, La.(This article was published in the spring 2008 issue of Louisiana Agriculture.)