Biopolymers and the dream of a green petrochemical industry

By Fabiana Frayssinet, August 13, 2012. Source: Tierramerica

RIO DE JANEIRO – Brazil leads global production of biopolymers, an industry that generates fewer greenhouse gas emissions than fossil fuel-based plastic manufacture. But “green plastics” made from sugarcane have a sour aftertaste.

Braskem ethylene bags labeled “I’m green”.
Photo: Braskem

The leap to industrial-scale production of green polyethylene was made by a factory established two years ago in the Polo Petroquímico do Sul (Southern Petrochemical Hub), located in the Triunfo municipality of the southern state of Rio Grande do Sul, with an annual output capacity of 200,000 tons.

Green plastic is a thermoplastic resin made from the country’s abundant sugarcane-derived ethanol and produced with technology developed by the Brazilian company Braskem, one of the largest petrochemical producers in the world.

Braskem – whose production is still primarily based on oil – claims that green polyethylene has the same properties as its petrochemical relative, but that the difference between the two is their environmental impact.

“Up to 2.5 tons of carbon dioxide are captured and stored per ton of green plastic produced,” Marcelo Nunes, renewable chemicals director at Braskem, told Tierramérica.

This material also has great versatility for applications in a range of industries, including hygiene and cleaning, food, cosmetics, and automobiles.

“It’s made from sugarcane, a raw material that’s 100 percent renewable,” he added.

Braskem assures that with the production of this polyethylene and other sustainable products in the same line it is contributing to reducing carbon dioxide by more than 750,000 tons a year, or the equivalent to planting and maintaining more than five million trees a year.

The next step for the company will be to build its first green polypropylene plant and launch production in 2013.

Green polypropylene – which in its petrochemical version is the second most widely used thermoplastic resin in the world – will also be made from ethanol and will have much the same environmental advantages as polyethylene, Nunes said.

The volume of green plastic produced is marginal compared to conventional resins. But, according to Nunes, it is very important for Braskem, whose “goal is to become a global leader in sustainable chemical production by 2020.”

According to environmentalist José Goldemberg, a professor at the Electrotechnical and Energy Institute of the University of São Paulo, green plastics are a good investment as they are a substitute for basic raw materials from the petrochemical industry, such as naphtha (benzene or petroleum ether).

Naphtha is the leading input in the petrochemical industry and accounts for almost 50 percent of global ethylene production, although in some regions, such as the Middle East and North America, gas is more widely used.

“Using sugarcane as a substitute for products made from naphtha is a major step in the road to sustainability,” Goldemberg told Tierramérica.

In his 2009 article “Polietileno verde, um sinal positivo” (Green Polyethylene, a Positive Sign), Eduardo Athayde, director of Worldwatch Institute- Brazil, agreed, noting that this plastic produced with Brazilian technology set the stage for “the petrochemical industry to start operating under the new rules of a low carbon economy.”

“While it’s not biodegradable yet – because the product obtained using renewable ethanol as a substitute for fossil fuels is exactly the same as a petrochemical-based polymer – it is a step forward in line with greenhouse gas reduction recommendations,” he added.

Compared to crude oil, sugarcane has not had an impact yet on the petrochemical industry.

But “in time there will be a need to find a substitute for oil and natural gas in polymer production. The sooner the better,” Roberto Kishinami, expert on climate change and sustainable use of natural resources, told Tierramérica.

A consultant for organizations such as the Democracy and Sustainability Institute and ActionAid, Kishinami fears that the massive use of sugarcane for fuel or petrochemical production will favor extensive monoculture of this crop.

Nunes disagrees. “Only 0.02 percent of the country’s arable lands are planted with sugarcane crops for green plastic manufacture. Moreover, this production does not affect food crops, as is the case with some corn-based plastics, for example.”

But Luiz Jacques Saldanha, an agricultural engineer and environmental activist from Rio Grande do Sul, says that “calling this process green just because its source of carbon comes from a plant is highly misleading.”

“It changes food production, with another commodity joining soybeans in furthering huge monoculture plantations, the greatest tragedy of the 21st century in terms of global productive land use,” he added.

For Saldanha, biopolymers are another form of greenwashing, a term used to describe new marketing practices aimed at highlighting a product’s alleged environmental benefits.

He argues that the source of carbon – whether oil, coal, ethanol or any other source – does not “make these molecules green.”

“They can’t be considered green because they are not biodegradable, so they remain in the environment for a long time, polluting ecosystems,” he said.

He also questions the plasticizer used in the process of industrialization of green polyethylene and polypropylene.

“As monomers, these are still considered the least problematic resins. But, like all resins used in the production of consumer goods, they contain plasticizers such as bisphenol A,” which is a contaminating additive.

Green plastics, like any plastics, “must be recycled and never released into the environment,” he cautioned.

Only time will tell if the effect of green plastics on the environment will leave a sweet or sour aftertaste. But that is only if sugarcane does become the star raw material of Brazil’s petrochemical industry. Right now, the “sugar- chemical” industry is still a distant dream.

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