Brent Westbrook
Commercial Director, Mitsubishi Chemical Group
Imagine a world where we grow the materials used to make single-use items and return them back to the soil after we are done with them. This scenario is not only possible, it is already happening on a small scale across the world—through the use of biobased and compostable bioplastics. Bioplastics are plastics made from plants and/or are in some way biodegradable. Biobased bioplastics are a renewable material, meaning that the feedstocks needed to make them can be replenished in a short period of time, and therefore cannot be easily depleted.
What positive environmental benefits does the use of biobased and compostable bioplastics provide? To answer this question, we first need some background on our waste system.
Landfills led to consequences
Widespread use of landfills in the USA didn’t happen until the 1940s. Landfills helped resolve challenges caused by open dumping and are a helpful way to keep litter out of trouble areas. Without landfills, and central municipal waste collection, we would live in a world where our land and waterways are contaminated with unsightly and potentially harmful litter.
However, landfills have had an unintended negative consequence. They have created a convenient way for residents to dispose of all waste, including beneficial recyclables and carbon-rich organic waste like food and yard scraps, and compostable products.
At about the same time landfill use became widespread, the adoption of plastic for single-use items was also growing. Both changes provided convenience, and in many cases lighter-weight plastics had an environmental benefit over their heavier glass or metal counterparts. However, the make-take-waste process was treating valuable materials as waste by placing them into landfills where they would last for hundreds of years. This is a major problem for organic waste, as well. Disposed of in a landfill, it ultimately goes through anaerobic decomposition (exposed to little or no air) and produces methane— a greenhouse gas more than 28 times stronger than carbon dioxide.
What is the solution?
Where plastic can be recycled, it should be. However, with applications where food packaging and agricultural products become too contaminated with food/yard residue, designing the package with compostable bioplastics and sending the item, after use, to a compost facility offers a novel end-of-life alternative. Aerobic decomposition in compost (which exposes the waste to air) produces carbon dioxide instead of methane, providing an added benefit to the environment when compared with landfill disposal.
According to the Environmental Protection Agency (EPA) website, although 24% of municipal waste is food waste, only about 5% is composted. Increasing this composted percentage is possible, just as it was with yard trimmings. In the 1980s, virtually 0% of yard trimmings were composted; by 2018 that number grew to 63%. It is important that we work as a society to ensure the carbon-rich nutrients in our food scraps and yard trimmings are returned to the soil – compostable bioplastics can help accomplish that.
Along with reducing methane emissions from landfills, biobased and compostable bioplastics can also reduce carbon emissions during the growth and manufacturing process and help to improve soil quality when composted.
Growing the plants that are partially or fully used as bioplastic feedstock helps keep the earth cooler and remove carbon dioxide from the atmosphere through the processes of transpiration (taking in water and emitting vapor) and photosynthesis (the use of sunlight to absorb carbon dioxide) that all plants go through.
Composting biobased, compostable bioplastics at the end of life would reduce municipal waste sent to landfills and in turn reduce methane emissions caused by decomposition. Compostable bioplastics bring carbon sources to the compost it is added to. If these compostable products carry food or yard waste, they can bring those organic nutrients to the compost too. This addition improves soil health, thus reducing flooding, erosion, and giving plants vital nutrients to grow healthy.
The cycle begins again when new plants grow from the compost soil, further cooling the earth and pulling more carbon dioxide from the air. This is truly a circular economy, and we must strive to achieve it for the good of our planet and our grandchildren.
References:
1. https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/national-overview-facts-and-figures-materials
2. https://www.epa.gov/gmi/importance-methane
