Carbon Management Implications for R&D in the Chemical Sciences and Technology (2001) / Chapter Skim
Currently Skimming:
11. Commodity Polymers from Renewable Resources: Polyactic Acid
11. Commodity Polymers from Renewable Resources: Polyactic Acid
Pages 166-184
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 166... ...
This chapter addresses those questions and draws generalizations that can be applied to other chemical products made from renewable resources. MANUFACTURING OF PLA The raw material for PLA manufacturing is any fermentable sugar.
|
From page 167... ...
Consumers' reports indicate that the products actually work well, and they appreciate the products being made from renewable resources. Of course when consumers indicate that they appreciate a product made from renewable resources, they expect that there should be some measurable advantage regarding the environment compared to traditional petroleum-based products.
|
From page 168... ...
Research for CO2 in the atmosphere HO CH2 HO CH 2 O Enzyme Hydrolysis O OH OH O O H2O HO OH OH OH n Dextrose Starch Fermentation (glucose) O O 2 HO O OH Chemical Processing O H CH3 H CH3 n lactic Acid PL A H2O FIGURE 11.2 The processing route to PLA combines bioprocessing and chemical processing
|
From page 169... ...
Market Potential In the long term, PLA can compete successfully in several markets with an annual volume of more than 6.6 billion pounds. With technology improvements in manufacturing and processing, these markets Carpet Tiles Apparel Industrial Fibers and Non-wovens 8 2000 FIGURE 11.3 Typical PLA fiber applications.
|
From page 170... ...
These chemicals add an additional 3 billion to 4 billion pounds and market value of $1 billion to $4 billion per year to the estimated PLA value. Why didn't CD initially target traditional chemicals based on renewable resources?
|
From page 171... ...
With modern biotechnology, bioprocessing, and chemical processing technology, more focus should be on creating environmentally friendly processes and 50% cost reductions. The lesson is that just because something is made from renewable resources does not make it better.
|
From page 172... ...
However, like all manufacturing processes, the production of PLA requires energy. The question is, Does the energy required to drive the processing cause more carbon dioxide emissions than the amount of carbon dioxide fixed in PLA?
|
From page 173... ...
Conventional plastic materials use fossil resources. Both petrochemical-based plastics and PLA require process energy.
|
From page 174... ...
If the plastic is made from petrochemicals and incinerated, then fossil resources are being converted to carbon dioxide emissions. If the plastic is PLA and it is incinerated, then the carbon is converted back to CO2.
|
From page 175... ...
"PLA year 1" data were generated using assumptions based on the process technology to be deployed in Cargill Dow's production facility currently under construction. "PLA year 5" and "long-term" data assume improvements in process technology and alternative energy sources that further optimize production efficiencies for PLA.
|
From page 176... ...
In our analysis, we charged all of the agricultural 3200 3000 2933 2800 PET PLA Year 5 2600 KJ/1000 Bottles 2400 2258 2200 2000 1970 2000 1800 1640 1600 1400 1400 1300 1200 Incineration Recycle to non- Recycle to Bottle Anaerobic bottle Digestion FIGURE 11.13 Fossil resource use in PLA bottles compared to polystyrene bottles in various waste disposal systems.
|
From page 177... ...
This means that less water has to be removed from the product -- hence, less energy input to evaporation and lower carbon dioxide emissions. To my thinking, a general rule would be that a commercially viable industrial product produced from renewable resources using fermentation and biotechnology must have yields greater than about 45 42 40 Polystyrene 35 PLA Year 5 kg / 1000 cups 30 27.6 27.8 25 18.4 20 16.3 16.4 15 10.8 10 8.1 5 0 0 0 Up to cups Landfill Incineration Composting HT Anaerobic Modern digestion FIGURE 11.15 Carbon dioxide emissions of PLA cups compared to polystyrene cups on a cradle-to-grave basis.
|
From page 178... ...
Our long-term goal is to eliminate fossil fuel resource use, the source of carbon dioxide emissions.
|
From page 179... ...
We find ourselves forced to develop appropriate agricultural data, because the practices that farmers employ impact our environmental profile. SUMMARY PLA uses fewer fossil resources and emits less carbon dioxide in its manufacturing than the petrochemical-based products it replaces.
|
From page 180... ...
Henton, Patrick Smith, and Jed Randall, Tom Bremel, NIST, and DOE. NatureWorks PLA is a registered trademark of Cargill Dow LLC.
|
From page 181... ...
It is quite an efficient process. Tom Baker, Los Alamos National Laboratory: Can you tell us something about the kind of footprint you would need for plants when PLA cup production becomes very large?
|
From page 182... ...
Patrick Gruber: Third World countries are trying to figure out what infrastructure they should build. This includes chemical processing systems, bio-processing systems, food processing systems and, of course, waste disposal systems.
|
From page 183... ...
The others ought to be burned if the better value is to burn them. Richard Wool, University of Delaware: Where, along the chain of reactions, are you expending your highest fossil fuel energy, in terms of conversion processes?
|
From page 184... ...
Richard Wool: How much fossil fuel energy is expended in breaking the starch down into sugars? Patrick Gruber: I have the numbers for total percent of the PLA, but I don't remember exactly.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.