Bioplastics are plastics in which all carbon is derived from renewable feedstocks. They may or may not be biodegradable. Biobased plastics contain both renewable and fossil-fuel-based carbon. The percentage of biobased ingredients and the conditions under which the biobased product may biodegrade, if at all, vary widely.
According to the American Society for Testing and Materials (ASTM), a biobased material is:
an organic material in which carbon is derived from a renewable resource via biological processes. Biobased materials include all plant and animal mass derived from CO2 recently fixed via photosynthesis, per definition of a renewable resource.
Products on the market are made from a variety of natural feedstocks including corn, potatoes, rice, tapioca, palm fiber, wood cellulose, wheat fiber and bagasse. Products are available for a wide range of applications such as cups, bottles, cutlery, plates, bags, bedding, furnishings, carpets, film, textiles and packaging materials. In the US, the percentage of biobased ingredients required for a product to be referred to as biobased, is defined by the USDA on a product-by-product basis. ILSR has recommended that the USDA set a minimum threshold of 50 percent biobased content for products to be considered biobased.
A biodegradable material is, according to the Biodegradable Products Institute (BPI), "where under the right conditions the microbes in the environment can break down the material and use it as a food source". In other words, a biodegradable plastic is completely mineralized by microorganisms. Biodegradable plastics are not necessarily biobased. Biobased and biodegradability are not the same. Some biobased products can biodegrade in municipal or commercial composting facilities, home composting, and aquatic and roadside environments, others will only biodegrade in very specific environments and some will not biodegrade at all. In North America the BPI is the third-party certifier for products that are compostable in commercial composting facilities. To receive the BPI Compostable Logo, products must meet the ASTM Standards D6400 (for Compostable Plastics) or ASTM D6868 (for Compostable Packaging). According to the BPI, to be certified, a product must:
- Disintegrate rapidly during the composting process (so that no large plastic fragments will wind up on the composters' screens when the process is finished).
- Biodegrade quickly under the composting conditions.
- Not reduce the value or utility of the finished compost. The humus manufactured during the composting process will support plant life.
- Not contain high amounts of regulated metals.
Bioplastics have many benefits over petro-plastics, but several challenges also lie ahead.
Potential Benefits of Bioplastics, Problems with Petro-Plastics
|Benefits of Biopolymers||Petro-Plastic Woes|
|Can replace many harmful conventional plastics||Non-renewable (geological timeframes to produce but 1 to 10 years to consume)|
|Can be fully biodegradable (capable of being utilized by living matter)||Health impacts (polymers differ)|
|Can be made from a variety of renewable resources||Generally nonbiodegradable with devastating affects on ocean life|
|Can be composted locally into a soil amendment||Demand and production skyrocketing|
|Can contribute to healthier rural economies||Plastics industry supports more drilling|
|Recycling and reuse low|
Challenges with development and widespread acceptance of bioplastics include: