Sugarcane plays role in development of green polyethylene, Sugarcorn

By Erin Voegele | February 04, 2009
Brazil is the world's top sugarcane-based ethanol producer. According to the Renewable Fuels Association, the country produced more than 5 billion gallons in 2007. A new project being undertaken by Braskem, a Brazilian thermoplastic resin producer, will seek to convert a portion of that ethanol into green polyethylene.

Braskem's board of directors recently approved the Green Polyethylene Project, which will produce ethylene and polyethylene from sugarcane-based ethanol. An investment of 500 million reals ($211 million) has been allotted for the project, located at the Southern Petrochemical Complex in the state of Rio Grande do Sul.

According to Braskem spokesman Nelson Lataif, the process of producing polyethylene from sugarcane is simple in concept. "Sugar in the form of sucrose is extracted from the sugarcane and fermented to produce ethanol," he said. "This is dehydrogenated to ethylene, which is subsequently polymerized to polyethylene. The challenge is achieving the level of purity required."

The facility will have the capacity to produce 200,000 tons of ethylene and polyethylene on an annual basis. The project won't be integrated with an ethanol plant. "Braskem will purchase [ethanol] as a commodity," Lataif said. The process will utilize approximately 400,000 tons of ethanol each year, producing one ton of ethylene from every 1.8 tons of ethanol.

According to information released by Braskem, the design of the project is complete. The detailing phase and construction are expected to begin in 2009, and operational start-up is scheduled for 2011. Braskem has also reserved the project's critical equipment, such as the feed gas and refrigeration compressors. To finance the operation, the company plans to pay 30 percent with its own funds and is seeking financing for the remaining 70 percent.

The company has identified demand for 600,000 tons of green polyethylene and estimates the chemical will command a price premium of 15 percent to 30 percent over the price of polyethylene made from nonrenewable materials. The project could be the first of additional larger-scale projects being analyzed by the company.

While sugarcane-based ethanol production is highly efficient and widespread in Brazil, its potential is limited in the U.S. This is largely due to economic factors and the fact that most agricultural land in the U.S. isn't ideal for sugarcane growth. Still, at least one U.S. company is working to overcome some of these barriers.

Seattle-based Targeted Growth Inc. is developing a new crop referred to as Sugarcorn, a hybrid cross between sugarcane and corn. The plant contains genes from Midwestern corn, tropical maize and sugarcane, resuilting in a corn variety that doesn't flower to produce grain but instead produces sugar in its stalks.

The company has been developing the crop for approximately three years. Researchers are currently working to increase sugar yields, increase the plant's hardiness and develop ways to prevent the plant from being pollinated by nearby crops of traditional corn. The ultimate goal is to develop a sugar crop in the U.S. that will be competitive with sugarcane for ethanol production.

Unlike sugarcane, Sugarcorn doesn't require more water than tradition corn. It also requires less nitrogen fertilizer. One major difference between corn and Sugarcorn is the way Sugarcorn must be harvestedwith a biomass harvester, similar to the way sugarcane is harvested. The stalks would be gathered and crushed to extract the sugary juice. This juice could then be fermented into ethanol. In addition, the remaining biomass material could be processed through a cellulosic technology.

During the 2008 growing season, Targeted Growth tested the growth of Sugarcorn in Illinois and Indiana. During the 2009 growing season, the company will test the crop in plots across a larger region of the U.S., from Indiana to Nebraska and Minnesota to Florida.