The environmental friendliness of bioplastics is frequently praised, but do they live up to the hype?
Since the 1950s, the globe has created more than nine billion tonnes of plastic. With over 9 million additional tonnes entering the waters each year, 165 million tonnes of it have defiled our ocean. Since only about 9% of plastic is recycled, the majority of the remaining plastic either pollutes the environment or is left in landfills, where it can take up to 500 years for it to decompose while releasing hazardous chemicals into the soil.
Raw ingredients derived from petroleum are used to make traditional plastic. Some claim that bioplastics, which contain 20% or more renewable resources, could be the answer to the problem of plastic pollution. Reduced reliance on fossil fuel supplies, a smaller carbon impact, and quicker decomposition are some of the benefits of bioplastic that are frequently mentioned. Additionally, bioplastic is less hazardous and free of bisphenol A (BPA), a hormone disruptor that is frequently included in conventional plastics.
Researching bioplastics at Columbia University's Earth and Environmental Engineering Department, Kartik Chandran asserts that they are "a significant improvement" over conventional plastics.
Bioplastics are not yet the panacea for our plastic problem, it turns out.
How Biodegradable are Bioplastics?
Since there is frequently misunderstanding while discussing bioplastics, let's first define a few concepts.
Degradable - All plastic, including conventional plastic, is degradable, however just because it can be reduced to tiny pieces or powder does not mean the materials will ever revert to their original state. Traditional plastics with certain compounds decay more quickly. Plastic that is photodegradable degrades more easily in sunshine; plastic that is oxo-degradable degrades more swiftly under heat and light.
Biodegradable - Under the correct circumstances, microbes may totally degrade biodegradable plastic into water, carbon dioxide, and compost. The term "biodegradable" suggests that the decomposition takes weeks to months to complete. Durable bioplastics are those that disintegrate slowly, and non-biodegradable bioplastics are those manufactured from biomass that are difficult for microorganisms to break down.
Compostable - Plastic that is compostable will decompose in a composting facility. At the same rate as other organic materials in the compost pile, microorganisms break it down into carbon dioxide, water, inorganic chemicals, and biomass, leaving no hazardous behind.
Types of Bioplastic
Currently, bioplastics are utilised in non-disposable things including carpet, plastic pipes, phone casings, 3D printing, automobile insulation, and medical implants in addition to disposable items like packaging, containers, straws, bags, and bottles. According to projections, the worldwide bioplastic market will increase from $17 billion this year to about $44 billion in 2022.
The two primary categories of bioplastics are.
In most cases, the sugars in maize starch, cassava, or sugarcane are used to make PLA (polylactic acid). It is edible, carbon-neutral, and biodegradable. The components of corn break down into starch, protein, and fibre when it is submerged in sulphur dioxide and hot water to make plastic. After the kernels are processed, the starch and corn oil are separated. Similar to the carbon chains found in plastic made from fossil fuels, the starch is made up of lengthy chains of carbon molecules. The building block for plastic, a long-chain polymer (a big molecule made up of repeating smaller units), is created by combining several citric acids. Polyethylene (used in plastic films, packaging, and bottles), polystyrene (Styrofoam, and plastic cutlery) and polypropylene can all appear and function like PLA (packaging, auto parts, textiles). One of the biggest businesses making PLA under the Ingeo trademark is Minnesota-based NatureWorks.
Microorganisms that generate plastic from organic sources, often genetically altered, make polyhydroxyalkanoate (PHA). The microorganisms receive high levels of carbon but are deficient in nutrients like nitrogen, oxygen, and phosphorus. When they run out of the other nutrients they require to develop and reproduce, they make PHA as carbon reserves, which they store in granules. The PHA produced by the microbes, which has a chemical composition resembling that of conventional plastics, may subsequently be harvested by businesses. PHA is frequently used for medical applications including sutures, slings, bone plates, and skin substitutes because it is biodegradable and won't harm living tissue. It is also utilised for single-use food packaging.
The Side Effects of Bioplastic Production
Although it is usually believed that bioplastics are more environmentally friendly than conventional plastics, a 2010 study from the University of Pittsburgh discovered that this wasn't always the case when the materials' life cycles were taken into account.
Seven conventional plastics, four bioplastics, and one made from both fossil fuels and renewable sources were all compared in the study. The fertilisers and pesticides used to produce the crops and the chemical processing required to convert organic material into plastic, according to the researchers, led to higher levels of pollution during the creation of bioplastics. Additionally, the bioplastics consumed a lot of land and had a greater impact on ozone depletion than regular plastics. Because it incorporated the harmful effects of both agriculture and chemical processing, the hybrid plastic known as B-PET was determined to have the highest potential for hazardous effects on ecosystems and to contain the most carcinogens. It also received the lowest score in the life cycle study.
Over the course of their lifetime, bioplastics do emit much fewer greenhouse gases than conventional plastics. Because the plants that produce bioplastics absorbed the same amount of carbon dioxide as they grew, there is no net increase in carbon dioxide as they decompose. According to a 2017 study, switching to PLA made of corn instead of conventional plastic would reduce U.S. greenhouse gas emissions by 25%. The study also found that traditional plastic production utilising renewable energy sources might cut greenhouse gas emissions by 50 to 75 percent; however, bioplastic production using renewable energy in the future showed the most promise for significantly lowering greenhouse gas emissions.
Other Problems
Although biodegradability is a benefit, most bioplastics require high temperature industrial composting facilities to degrade, and only a small number of cities have the equipment to handle them. Because of this, bioplastics frequently end up in landfills, where they may emit methane, a greenhouse gas 23 times more potent than carbon dioxide, when they are denied oxygen.
Bioplastics can contaminate batches of recovered plastic and damage recycling infrastructure if they are not properly disposed of. For instance, the entire batch can be rejected and dumped in a landfill if recycled PET (polyethylene terephthalate, the most common plastic, used for water and soda bottles) is contaminated with bioplastic. Therefore, several recycling streams are required in order to appropriately dispose of bioplastics.
Because the crops that create bioplastics can also be used to feed people, the land needed for their production competes with that needed for food cultivation. By 2019, according to the Plastic Pollution Coalition, more than 3.4 million acres of land—an area greater than Belgium, the Netherlands, and Denmark put together—will be required to cultivate the crops in order to satisfy the rising worldwide demand for bioplastics. Additionally, the farm equipment's use of petroleum results in greenhouse gas emissions.
Because of the complicated process required to transform corn or sugarcane into the constituent parts of PLA, bioplastics are also highly expensive; PLA can cost 20 to 50 percent more than equivalent materials. However, costs are decreasing as businesses and academics come up with more effective and environmentally responsible ways to make bioplastics.
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