Cheap Plastic Made from Sugarcane

Crude replacement: This Brazilian sugarcane could supersede oil for making plastic.
Credit: Dow Chemical

ENERGY

Dow Chemical is building a plant to make polyethylene from sugarcane at costs that rival petrochemical production.

• BY KEVIN BULLIS

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Making plastic from sugar can be just as cheap as making it from petroleum, says Dow Chemical. The company plans to build a plant in Brazil that it says will be the world's largest facility for making polymers from plants. 

The project will begin with the construction of a 240-million-liter ethanol plant, a joint venture with Mitsui, that is set to begin later this year. By the beginning of next year, Dow will finish engineering plans for facilities that will convert that ethanol into hundreds of thousands of metric tons of polyethylene, the world's most widely used plastic.

Bio-based chemicals production has grown quickly in recent years, but it still represents just 7.7 percent of the overall chemicals market. Production has been limited in many cases to specialty chemicals or niche products. But Dow now says chemicals made from plant feedstocks may be ready to compete head-to-head with petrochemicals made in large volumes.

Most large-volume chemicals are made from petroleum. About 80 million tons of polyethylene are made annually around the world. But high oil prices have increased the costs of petrochemicals. And in Brazil, long-standing government support for sugarcane ethanol production has allowed the industry to drive down costs, making ethanol competitive with fossil fuels. Making polyethylene from sugar "would not necessarily be attractive in other regions," says Luis Cirihal, Dow's director of renewable alternatives and business development for Latin America.

The technology for converting ethanol into ethylene, the precursor for polyethylene, is not new. "The dehydration process for converting ethanol to ethylene has been known since the 1920s. The only thing that's really new here is the scale," Cirihal says. The new plant will have a polyethylene production capacity comparable to production at a petrochemical plant. Though the exact production levels aren't yet settled, they will be on the order of "what you have heard before," he says, referring to a proposed Dow project that would have made 350,000 metric tons of polyethylene from sugarcane. (That proposal relied on a partnership that ended as a result of the recession.) It will be bigger than a 200,000-ton sugarcane-to-polyethylene plant operated by Brazil-based Braskem.

The new plant won't be the first time Dow has invested significantly in bio-based plastics. A decade ago, it partnered with Cargill to make corn-based plastics. But Dow pulled out of that venture in 2005 after the market for the bioplastic failed to take off. Cirihal says that Dow is now taking a different approach. The earlier plastic was a new material, and proved difficult to market and distribute. He says that's why Dow decided to make a common material with an established market this time. The sugarcane-based polyethylene will perform just as well as oil-based polyethylene, he says.

Cirihal says Dow is keeping costs down by doing every part of the process, from growing the sugarcane to producing the polymers. This makes it possible, for example, to provide energy to run the plant with biomass left over from producing sugar from sugarcane. While he says the plastics produced will be competitive with petrochemicals, he also says the company hopes to charge more for the product because of the significant demand for low-carbon, sustainable materials.