Biobased Materials and Sustainability
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. Top
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. Top
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. Top
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. Top
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. Top
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. Top
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. Top
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. Top
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. Top
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. Top