FAQs: Biobased Materials and Sustainability
- What are biobased materials?
- What are biopolymers?
- How are biopolymers made?
- What are the major feedstocks for biopolymers?
- What kinds of biopolymers are currently being made?
- Who makes biopolymers?
- Why is it important to shift our economy to biobased materials?
- What are some of the concerns about biopolymers?
- Are all biodegradable plastics made from biobased polymers?
- Are biopolymers being combined with non-biobased materials?
- How do biopolymers compare to petroleum-based plastic polymers on an environmental basis?
- How could the sustainability of biopolymers be improved?
- Are there government policies to promote biobased materials in the US?
- What is being done to support industry leaders whose products meet high standards?
We define a “biomaterial” or a “biobased material” as any material made from current living organisms (as opposed to non-renewable fossil fuels that are made from prehistoric plants), including agricultural crops and residues, trees, and algae. “Sustainable biomaterials” are those that are (1) sourced from sustainably grown and harvested cropland or forests, (2) manufactured without hazardous inputs and impacts, (3) healthy and safe for the environment during use, and (4) designed to be reutilized at the end of their intended use such as via recycling or composting. Top
Biopolymers are macromolecules derived from plants, trees, bacteria, algae, or other sources that are long chains of molecules linked together through a chemical bond. They are generally able to perform the functions of traditional petroleum-based plastics. They are often degradable through microbial processes such as composting, but this will depend on how they are produced.
Biopolymers exist in nature as cellulose (in cotton, wood, wheat, etc.), proteins, starches, and polyesters. The potential for using these materials to make synthetic polymers was identified in the early 1900s, but they have only recently emerged as a viable material for large-scale commercial use. Top
Biopolymers occur naturally or can be produced through several different processes such as genetic modification of plants, starch conversion, or microbial conversion. The most commercially available biopolymer, polylactide (PLA), is produced from lactic acid through fermentation of dextrose, which is extracted from a starch source material.
Currently, most biopolymers are made in large biorefinery systems. For example, PLA is produced at a plant near the Cargill wet mill corn refinery in Blair, Nebraska. This plant produces the dextrose used as a feedstock, but also turns out sweeteners, corn oil, and other corn-based products. Top
While biopolymers can be made from an almost unlimited range of biobased materials, most of the currently marketed biopolymers are made from starch.
Corn is currently the primary feedstock, with potatoes and other starch crops also used in lower amounts. As an example of the quantity needed, roughly 2.5 lb of corn (15% moisture) is required to make one pound of polylactic acid (PLA). Top
While there are many applications and production approaches for biopolymers, the primary commercial product available now is polylactic acid (PLA). Currently produced from corn by NatureWorks, LLC., which is owned by Cargill, PLA is increasingly used in food and product packaging, clothing, carpeting and bedding materials, plastic component fabrication, and disposable food service items.
ADM, in a joint-venture with Metabolix, will soon begin commercial production of polyhydroxyalkanoate or PHA plastic, which is produced through a fermentation process that converts glucose into a polymer. DuPont produces Sorona polymer, 1,3-propanediol (PDO), from a combination of biobased and fossil-fuel based materials. PLA and the other biopolymers are able to substitute for fossil-fuel based plastics in many applications.
NatureWorks is the largest producer of PLA, with a 300 million pound capacity production facility. Other companies manufacturing biobased plastics include Dupont, BASF, Eastman, Proctor & Gamble, Novamont, Polargruppen, and Cereplast.
Societal benefits from a shift to biobased plastics could be enormous. Biobased materials have the potential to produce fewer greenhouse gases, require less energy, and produce fewer toxic pollutants over their lifecycle than products made from fossil fuels. They may also be recyclable or composted (depending on the biomaterial and how it is produced), reducing waste streams to already crowded landfills or to incinerators.
As the cost of petroleum increases, making products with biobased materials is increasingly attractive. Increased demand for agricultural and forest-based feedstocks also offers new resource-based economic development opportunities for farmers and struggling rural communities and manufacturing sectors.
However, many of these advantages are not inherent in the material. They all depend on ensuring that biobased products meet minimal standards for the safe production, use, and end-of-life disposition.
Making the transition from a petroleum-based to a biobased economy also gives us an opportunity for product standards to ensure that impacts on the environment, health, and society are included.
There are some significant and valid concerns about biopolymers. For example, the current use of genetically modified corn as a feedstock for PLA is a major concern to many, as are the environmental impacts of producing corn.
Who owns the biorefining facilities and the scale of these facilities are significant issues for rural communities that are looking to biobased production as a foundation for new and sustainable economic development.
The inclusion of potentially harmful materials in manufacturing raises other concerns.
Recycling and disposal of these products are potential problems, especially impacts on the current recycling and disposal infrastructure. For example, bottles made with polylactic acid (PLA) can contaminate the recycling of polyethylene terephthalate (PET) bottles. Most recycling technologies are unable to distinguish between the two types of plastic. Many recyclers therefore oppose the use of PLA until the recycling technology is capable of weeding out products made with PLA.
These concerns need to be addressed so that the benefits of biopolymers are maximized without impeding their commercial viability. This will likely require a combination of policy incentives and regulations, private-public engagement and support, and market development that supports economic, environmental, and social objectives.
No. While 100 percent biopolymers are generally biodegradable and compostable, not all biodegradable and compostable plastics are made from biopolymers. Some biodegradable and compostable materials are produced entirely from synthetic polyesters and other non-biobased feedstock, while others are a combination.
Commercial products that contain biopolymers can have varying amounts of biobased feedstock/resin in the final product depending on the formula a manufacturer uses. For example, a product may be a mixture of one or more biobased resins such as corn and sugar as well as fossil-fuel based resin. In addition, converters (???) or manufacturers of intermediate and final products will sometimes use non-biobased additives including metallic heat stabilizers, plasticizers, inks, pigments, or other inorganic or man-made additives to enhance performance and broaden applications for use.
Conventional plastics are manufactured from essentially nonrenewable petroleum and natural gas byproducts. A small percentage of these products are recycled, and the remainder end up at landfills or incinerators. Other negative impacts include air and water pollution from manufacturing and incineration, worker exposure to toxic chemicals, and health risks to consumers from the use of fossil fuel-based plastic in cooking and food storage, especially when hormone-disrupting chemicals leach into foods and beverages.
Biopolymers are made from annually renewable biobased materials that can be recyclable, biodegradable, and/or compostable. While there are outstanding questions concerning overall energy use, greenhouse gas emissions, GMOs, and impacts from crop production, biopolymer production in general is an immature technology with many opportunities for improvement, whereas technologies to make conventional plastics such as PET are more than 60 years old.
While biopolymer production and use already present some positive benefits for the environment and society, there is much room for improvement in the biopolymer lifecycle. If feedstocks were produced in ways that conserve resources, protect the environment, and provide fair returns for farmers, biopolymer production could help improve the ecological and economic health of the countryside. Manufacturers can also be encouraged to meet environmental and health standards in the production of biobased production. Municipalities and retailers can support and promote consumer education and recovery and composting infrastructures.
The Federal Biobased Products Preferred Procurement Program can help to build market share and increase the sustainability of the biopolymer sector. For information, see www.biobased.oce.usda.gov/public/index.cfm.
The Sustainable Biomaterials Collaborative (SBC) has developed sustainability guidelines for bioplastics as well as purchasing specifications for compostable biobased food service ware. Large institutional buyers that use the purchasing specifications will preferentially buy products from companies that meet high standards, thus expanding markets for these products.
FAQs: End of Life
- Should biobased materials be composted or recycled?
- Are there special concerns about recycling biobased plastic bottles?
- Are there special concerns about recycling biobased bags?
The advantages and disadvantages of composting biobased materials depend on the material, the product, and the infrastructure.
When recycling systems exist and are successful, composting the product or package will lose the front-end inputs that were used in its extraction, refining and production although this must be weighed against the costs of transportation and recycling.
However, because bioplastics otherwise hold so much promise, research should be encouraged to develop and commercialize means to recycle rather than compost PLA to approximate the net value of PET. If that can be done and is corroborated by major recycling programs, pilot programs may be appropriate to validate such systems in a test. Based on what is presently commercialized in the market, however, there is much controversy about the introduction of bioplastic predicated upon composting at the end of the life for bottles where there is an existing and successful recycling system.
Potential PLA bottle manufacturers are urged to develop systems to successfully and economically recycle bioplastic bottles to overcome the challenges posed to the current recycling program before there is widespread production. This is in contrast to other applications such as cutlery, cups and utensils or which there is presently no flourishing recycling infrastructure.
In most recycling facilities, it is difficult to separate biobased PLA (polylactic acid) from PET (polyethylene terephthalate), which is the most widely used plastic in plastic bottles. PLA contamination degrades the ability to recycle PET. While technology exists to separate PLA from PET, it is costly and not commonly used.
Bottles made from PET are extremely valuable for current recycling programs. That high value would be completely lost if there were significant PLA contamination, given current recycling technologies.
Many recyclers therefore oppose the use of PLA until the recycling technology is capable of weeding out products made with PLA. Even after technologies to detect and sort PLA are in widespread use, recyclers would still incur additional sorting costs to remove the PLA contaminant.
Currently, all biodegradable/compostable bags available on the market contain a large percentage of fossil-fuel-based plastics. They also present similar challenges to existing plastic recycling systems as do bottles. Unless appropriate infrastructure is in place for collecting compostable materials, biodegradable bags for retail applications should be avoided(as should other single-use fossil-fuel based bags).
One excellent application for biodegradable bags is to collect foodwaste for composting. Indeed, food scrap composting programs and use of compostable bags are expanding, most notably in the San Francisco Bay Area and some other key cities.
While much traditional plastic film is technically recyclable and demand for this material is high, only a tiny portion is actually being recycled (less than 1% nationally). One reason is that traditional plastic film is not economically recyclable or compostable in household curbside collection programs.
When this material is mixed with recyclables or organics at curbside, it becomes a major contaminant in recycling and composting programs. As curbside organics collection programs expand to include many types of compostable materials, compostable bags and film products have the potential to reach higher recovery levels than their petroleum-based counterparts.
- How might the production of agricultural feedstocks for biobased materials affect the environment?
- Are the feedstocks genetically modified?
- Are there sustainability standards for agricultural feedstocks?
Production impacts of agricultural feedstock vary significantly, depending on the practices and inputs used by the farmer. In general, conventional corn and other annual crops utilize high levels of fertilizer and other inputs. Widespread use of GMO varieties can result in increased herbicide resistance in weeds and pollen drift. Production practices can result in soil erosion and chemical and nutrient run-off that degrade water quality, soil health, and wildlife habitat.
On the other hand, corn can be produced in a manner that conserves soil, provides wildlife habitat, and does not impair water quality. Farming approaches that minimize commercial inputs and tillage, utilize crop rotations, and maximize soil cover and biodiversity are successfully used by many farmers. Most corn production in the US falls somewhere in between these two examples, with the majority of farmers working to minimize their environmental impacts without reducing their overall production.
Approximately 52% of corn acres in the US were planted in 2005 with genetically modified varieties, with a higher percentage in Nebraska and Iowa, where most of the corn used to make PLA is grown. GMO traits in available corn varieties are focused on insect resistance (Bt) and herbicide tolerance. Therefore, while much of the corn currently used to produce PLA is genetically modified, the traits are not specifically focused on PLA production and GMO corn is not required for PLA production. There has been discussion of specifically modifying corn and other crops to produce biopolymers or to increase convertible materials for biopolymer production, but to date these have not been introduced.
Organizations such as the Institute for Agriculture and Trade Policy (IATP) are developing and promoting the use of sustainability standards for biopolymer feedstock production. For more on IATP’s Sustainable Standards, see their website. Agricultural and rural policies proposed by broad coalitions could encourage sustainable feedstock production and economic development.