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Green Polyethylene: bringing renewable raw materials to the traditional plastic industry
Leonora Novaes, Green PE Commercial Leader,
Braskem, Sao Paulo, Brazil
Abstract.
The Green Polyethylene helps to reduce climate change and greenhouse gases effects because the production of
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one kilogram of Green PE captures and fixes 2.5 kg of CO2 from the atmosphere. The favorable carbon footprint is a result of
combination of sugarcane energetic efficiency, technology improvements in the ethanol business in Brazil and our commitment
to this technology. When the Green PE carbon footprint is compared with the one from oil-derived PE, the environmental
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advantage is even bigger: For every kilogram of petrochemical PE produced, 2.5kg of CO2 are released to the atmosphere.
Additionally, the Green PE production reduces in approximately 70% the energy consumption in the cycle (sugarcane to
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polymerization), when comparing to the petrochemical cycle (oil to polymerization) to produce petrochemical PE .
Sugarcane is recognized as the most efficient raw material to produce renewable energy, especially if compared to
corn and sugar beet. Furthermore, the sugarcane energetic efficiency will improve even more due to the significant changes
taking place in the Brazilian sugar and ethanol business, driven by flex fuel technology in light vehicles. The increasing use of
mechanized harvesting and bioelectricity generation are examples of this process. We can transfer all the sugarcane
environmental advantages to the production of Polyethylene, the world’s most used plastic.
One very important factor is the easy transition from petrochemical to Green PE, because it does not require any
adjustment in processing equipment as well as in final product design. This is true for all the applications and market segments
where PE is presently used, including flexible packaging for food and non-food applications.
The process starts when the sugarcane crop captures the carbon dioxide from the atmosphere and metabolizes it to
produce sugar to be fermented to ethanol, through photosynthesis. The proprietary high yield dehydration technology, used to
produce ethylene and butene monomers from ethanol and butanol respectively, is very simple. It includes a catalytic reaction
initial step followed by a purification stage that produces very high purity polymer grade ethylene and butene.
As mentioned, these monomers are used to produce a number of commercial grades of bio-polyethylene (HDPE,
LLDPE, LDPE) at a very competitive cost using standard polymerization technologies. These polymers can be then
transformed into different products, with the same processing equipment used now in the plastics industry and with the same
performance characteristics customers expect from PE. This is a clear advantage over other biopolymers, which may require
significant investment and changes. Properties of these resins will be presented in the Conference.
After their end-of-life, bio-polyethylenes can be reused, recycled or incinerated to generate energy, with the main
advantage of having neutral carbon emissions.
As mentioned, Green Polyolefins help to reduce global warming and greenhouse gas effects. The bio-polyethylene
Life Cycle Assessment shows the capture of 2.0-2.5 tons of CO2 per ton of polymer versus the release of 2.5 tons of CO2 per
ton of fossil polyethylene produced.
This ability to reduce the carbon levels of the atmosphere is higher than in any other biopolymer because and it is the
consequence of the high biomass productivity of the sugarcane used both as feedstock (sugar) and energy source (bagasse),
the high efficiency of the dehydration technology and the high capability of the polyethylene molecule to store carbon.
An added advantage is the generation of water, a byproduct during the dehydration step, which is recycled and used
in other steps of the process.
Despite some negative publicity, the ethanol industry in Brazil has a good record for respect of nature. Brazil has
22% (340 MM hectares) of the global farming land. As of 2010, only 18.6% of this land is used for agriculture. Sugarcane crop
occupies 7.8 MM ha. of which 3.4 MM are used for ethanol production. As a comparison soybean fields use 22MM ha. and
corn fields another 14 MM ha. Livestock uses 220 MM ha. as pasture.
The state of São Paulo is the leading state in the country in ethanol production with 60% of the total Brazilian output
and it is more than 2.000 km away from the Amazon Forest.
Bio-based ethylene and polyethylene are being produced in a pilot scale and are under evaluation in a broad set of
applications globally. A 200 ktons/year plant, now in its final construction state in Brazil, is expected to be in operation by the
last quarter of 2010.
Braskem filled recently 5 patents applications in this field.
1 Life Cycle Analysis conducted by Espaço Eco Foundation (from the cradle to Braskem’s gate).
2 PE Petrochemical life cycle analysis (from cradle to the petrochemical gate) from PlasticsEurope