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Green plastics

February 18, 2010

Companies worldwide are developing plastics from renewable sources for use in everything from sushi containers to lipstick tubes and toys. Plastics made from plant waste, in particular, promise a real revolution.

A green toy truck made of bio-based plastic
Safe to play with - green plastics are used in a range of productsImage: Green Toys Inc.

Plastics, a fundamental material in modern life, play a central role in global efforts to wean the planet off oil and fight climate change. And it's easy to see why, since most traditional plastics are made from petroleum.

It's estimated that four percent of the world's crude oil reserves are used to manufacture plastics and making just one kilogram of plastic releases six kilograms of carbon dioxide into the air. 

Add to that dwindling global oil resources, and it's not difficult to see why green alternatives to fossil-based plastics have made a splash in recent years, especially in the packaging industry.

"Organic" sells

Called green plastics or bioplastics, they're usually made from plants such as sugarcane, wheat, corn and potatoes as well as renewable biomass sources such as vegetable oil.

Sugar cane
Bioplastics are also made from sugar cane wasteImage: CC / Rufino Uribe

From cell phone casings, disposable cups and shoes to nappies, shopping bags and flower pots -- there's hardly a household product that isn't being targeted in efforts to develop green plastics.

Experts say it's all part of a growing demand for sustainable products, triggered by a boom in organic food in recent years.

"Nowadays, it's far better to have an 'organic' image than a conventional one. And companies are capitalizing on it," said Norbert Voell, a press spokesman at Duales System Deutschland GmbH, a company that runs Germany's national recycling scheme.

"It's much better to know that your organically-grown vegetables bought at the supermarket come in eco-friendly containers than in harmful conventional plastic."

Big business

That thinking has prompted plastic producers to invest millions in green research and production techniques.

Major players include American agricultural giant Cargill, Italian company Novamont and German chemical giant BASF. Corn-based biodegradable plastic with polylactic acid (Pla) is used by some of the biggest supermarkets and food companies, including Wal-Mart and Coca Cola.

Green plastics are also big business in Brazil, the world's leading sugar producer. Petrochemicals giant Braskem is using the country's booming sugarcane ethanol industry to make green plastics.

Plastics from sugarcane waste

That has stirred concerns that much like biofuels, making bioplastics contributes to deforestation, uses vast quantities of water and takes over land previously used to grow crops for human consumption.

"The concerns raised by bioplastics production are similar to the debate on palm oil," Norbert Voell said, referring to the large-scale clearing of forests in parts of South East Asia to make way for lucrative palm oil plantations.

But smaller projects have hit on a new way to ease those doubts and at the same time tap the country's soaring sugarcane sector.

A German-Brazilian project at the Senai-Climatec institute in Salvador de Bahia is making plastic from the massive amounts of sugarcane waste produced in the country's ethanol factories.

The project, which draws on the expertise of another German firm called Tecnaro, uses so-called bagasse which is usually burned and releases large amounts of carbon dioxide into the atmosphere.

It's hoped that this bagasse-based plastic can in future replace petro-plastic in another booming sector in Brazil -- the automobile industry.

Still just a niche market

Despite the seemingly dizzying rise of green plastics, they account for less than one percent of the total global plastic market. And according to European Plastics, a Berlin-based umbrella organization of the bioplastics industry, that number is not likely to grow beyond more than five to ten percent in the coming years.

Sushi in a plastic container
Some sushi containers too are made from bio-based plasticImage: Sysoev - Fotolia

"The slow growth is because of high production costs but also because of the inferior processing and thermo-mechanical properties of bioplastics compared to petrochemical ones," Michael Niaounakis, an expert on polymers at the European Patent Office at The Hague, said.

A lighter carbon footprint?

Experts say bioplastics hold real potential for lowering greenhouse gas emissions and making a significant contribution to halting global warming since their production requires less energy than petroleum based-plastics and they contain no harmful toxins.

But first, reliable scientific studies need to be carried out about their sustainability.

"Simply being produced from renewable sources doesn't necessarily make plastic better for the environment," Gerhard Kotschik of the German federal environment agency said.

"You need to look at the entire life-cycle of production -- right from the cradle to the grave -- to determine whether bioplastics are really more eco-friendly than oil-based ones."

The plastic project based on sugarcane waste in Brazil could help answer that question.

Author: Sonia Phalnikar 
Editor: Nathan Witkop

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