What Are the Benefits of Biodegradable Plastic?

by John Brennan

    In the recently emerging field of green chemistry, researchers try to find more environmentally friendly chemicals and processes for industrial use (see References 1). One product of interest is biodegradable plastic, which is designed to break down in the environment (see References 2). Biodegradable plastics could help deal with the problems posed by plastic waste, as many types can be added to compost heaps, keeping them out of landfills completely.

    Types of Biodegradable Plastic

    One biodegradable plastic is poly (beta-hydroxybutyrate-co-hydroxyvalerate), or PHBV. Under the right conditions, bacteria can degrade this form of polyester to carbon dioxide and water in as little as six months. Polylactic acid, or PLA, is made from starch and can biodegrade under certain conditions. Another promising alternative is polyhydroxyalkanoic acid, or PHA, which can be fully composted. (See References 2)

    Reduced Demand for Fossil Fuels

    Most synthetic polymers are made from petroleum derivatives, so they increase fossil-fuel consumption (see References 2). Plastics like PLA, PHBV and PHA are made from biomass, so they can reduce the demand for crude oil and other fossil fuels. Moreover, in many cases the lifecycle greenhouse gas emissions associated with biodegradable plastics may be less than those associated with traditional plastics. (See References 3)

    Reduced Volume of Municipal Waste

    Biodegradable plastic has the potential to significantly reduce the volume of municipal waste generated in the U.S. and worldwide. Since it can be composted, biodegradable plastic could be collected together with food scraps or yard waste and diverted to compost heaps. (See References 3) The resulting compost can be used as garden or agricultural fertilizer (see References 5). Conventional plastics may take centuries to break down and are often difficult to recycle, whereas biodegradable plastics can be broken down quickly into useful soil amendments (see References 3, 5 and 6).


    Biodegradable plastics only break down rapidly under the right conditions, like the conditions found in a compost heap. The landfill environment is poor in oxygen and moisture and discourages degradation, so if bioplastics are added to landfills, they may remain intact and fail to break down. They are also difficult to recycle and hence should be kept separate from other recyclable materials. For biodegradable plastic to be beneficial, it should be composted, not thrown away. (See References 3 and 4)

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