Decades ago, plastic production boomed worldwide because of its cheapness and durability. A material with endless potential to become any shape, size, and thickness, and best of all – it lasts forever. Now, scientists are desperately trying to engineer a replacement plastic that does the opposite: disappears.
Bioplastics are becoming an increasingly popular alternative to petrochemical plastics. Bioplastics are not new to the market: Henry Ford made the first-ever soybean car in the 1930s. But now, large corporations are starting to use bioplastics in their products. Coca-Cola has released a PlantBottle, Lego has committed to only manufacturing bricks made from sugar-cane and even Reebok has created corn-based sneakers. Bioplastics are advertised as a green alternative because they can break down over time, unlike current petrochemical plastics which will never biodegrade. What’s more, they produce fewer overall emissions than other plastics and are made from renewable, organic sources.
Have our plastic-panic prayers been answered? Can we stop worrying about the marine ecosystem? Not quite yet. Unfortunately, Bioplastics aren’t as leafy green as we’d hoped. Studies have shown that bioplastics are in many ways more environmentally damaging than normal petrochemical plastics.
What Are Bioplastics?
The majority of plastics we use today are made from petrochemical products, such as oil, gas and coal (fossil fuels). These plastics are non-renewable and do not degrade, which is why our oceans are slowly becoming plastic soups. Bioplastics use biodegradable materials such as corn starch, sugars, wood chips, organic waste and vegetable oils as their main component – which have the ability to naturally break down over time. The two most popular and widely used bioplastics today are called PLA and PHA:
PLA (Polylactic Acids) Produced from the fermentation of starch from crops such as corn, sugarcane or cassava.
PLA’s look and feel like most petrochemical plastics. They’re the most commonly used bioplastic and create items such as plastic film, food packing, disposable cutlery and textiles. PLA is biodegradable, but only in high temperatures – at least 60°c, and it can take up to 6 months to fully break down.
PHA (Polyhydroxyalkanoates): Produced from the bacterial fermentation of sugars from carbon-based feedstocks
PHA’s are widely used as thermoplastics, because they can endure temperatures of up to 180°c. PHA’s are popular for medical use in devices such as sutures and cardiovascular patches, as well as single-use food items. PHA’s can be both biodegradable and compostable.
Bioplastics are predominantly produced from agro-based feedstocks, such as corn starch and sugarcane. These feedstocks require large amounts of land and water to grow. As the world currently struggles for space for more agricultural land, manufacturers are having to use pre-existing farmland to meet the growing demands of these materials. This raises another important debate: Should we be using agricultural land to grow crops for plastics rather than food, with an increasing global population and land scarcity?
Several studies have determined that the production of feedstocks for bioplastics could produce more environmentally damaging pollutants than using traditional petrochemical plastics. Some of these damaging elements include, but are not limited to:
Fertilizers and pesticides used for growing crops
The runoff from fertilizers and pesticides from agricultural use have polluted waterways, rivers and oceans causing eutrophication, or toxic ‘dead zones’, killing all aquatic life.
A study by the University of Pittsburgh found that the most common sugar-based plastic in the United States (PLA-NW) exhibited the maximum contribution to eutrophication.
Carbon emissions from farming
It is predicted that one third of global carbon emissions comes from agriculture, which is around 6 billion tonnes per year. Agriculture is the world’s second largest greenhouse gas contributor after the energy sector. For crop cultivation, most emissions come from field burning of crop residues, fuel use for farming machinery, incorrect manure management and natural/synthetic fertilizers used in soils.
Deforestation to allow space for crops such as sugarcane to grow
Some of the most biodiverse regions on the planet have been cleared for sugarcane production. Brazil, the largest sugarcane producer in the world, could double its deforested areas from 5.7 to 11 million hectares in the next ten years due to increasing demands for foods, biofuels and bioplastics. This means habitat loss for thousands of species alongside the loss of vital carbon absorbing trees.
Large amounts of water needed to grow crops
Farming accounts for 70% of the worlds freshwater usage. By 2050, the global water demand of agriculture is estimated to increase by a further 19%. With threats such as rising global temperatures and disrupted rain/snow patterns, we are already facing a worldwide threat of water shortage. A study has demonstrated that if we were to completely change from fossil-based plastics to bio-based plastics, it would account for an extra 3% to 18% of the global annual average water footprint.
Biodegradability & Recycling
It’s common to think that bioplastics will eventually decompose in a pit of soil and feed a blossom tree in the garden of Eden. In fact, advertising has encouraged this idea, filling our screens with images of bottles sprouting from plants as natural as a stick of corn. Of course, this is entirely inaccurate. To understand how bioplastics degrade, it’s important to outline the different ways things break down and what specific conditions they need to do so.
Degradable – A degradable material can break down into tiny pieces but will never disappear. The material components will never separate and return back to their natural sources i.e. back into carbon, water, and oxygen. This includes all fossil-fuel based plastics, which slowly break down in the ocean or in landfills into tiny pieces, leaching out absorbed toxins into the environment.
Biodegradable – Most bioplastics fall under this category. A biodegradable material can break down into water, CO2 and compost by microorganisms under the right conditions (high temperatures, oxygen, light).
However, most waste depots need special facilities to break down biodegradable materials, which is only affordable in some wealthier countries. Most biodegradable plastics end up in landfills, where they cannot break down. Landfills are absent of oxygen and light, which are needed for organisms to break down bioplastics. They remain in their manufactured forms, and leech out methane into the atmosphere (a gas 23 times more harmful than CO2).
Compostable – Breaks down naturally in compost sites, which must have the right conditions (oxygen, sunlight, natural temperatures). Compostable materials do not break down in landfills, due to the lack of oxygen needed for decomposition.
Not all bioplastics are biodegradable. To achieve this status, the material must decompose in weeks to months. Anything longer than this, and it is considered ‘durable’ and non-biodegradable.
Many of the bioplastics we use today are considered ‘durable’ bioplastics. They cannot biodegrade in the ocean, and instead break down into microplastics, which find their way into all marine life and even the human body. Bioplastics are mostly recyclable – but only with their own kind. Biodegradable plastic cannot be mixed with petrochemical plastics in the recycling process – if one snuck in, the lot would be considered ‘contaminated’ and dumped into landfill.
Once discarded, plastics release carbon (or methane) as they degrade. And as we know, excess carbon dioxide in the atmosphere is the primary cause of climate change. A promising property of bioplastics is that they emit less carbon dioxide than petrochemical plastics when they break down. The carbon emitted when they degrade is equal to the carbon once sucked up by crops whilst they were growing – the carbon is returned back to the environment, adding no extra gas to the atmosphere. In contrast to this, their fossil fuel-based cousins release extra carbon that has been trapped underground for years in the form of oil and gas.
Are Bioplastics The Answer To The Plastic Epidemic?
Whilst bioplastics are touted for their ability to biodegrade, tackling the issue of eternal plastic waste, they address an array of environmental concerns beyond plastic pollution. Like many environmental crises of our time, we’re confronted with one environmental issue versus the other; environmentally taxing farming to produce crops versus using our limited amount of fossil fuels; energy intensive composting of bioplastics versus having a plastic that will never, ever disappear. How do we weigh these things up, and who decides what’s most important?
The truth is, we shouldn’t have to be deciding whether deforestation is worse than an ocean full of plastic. Until we find a damage-free plastic alternative, we must hit the emergency stop button on our plastic use. A recent study outlines how the entire lifecycle of plastic production poses a dangerous threat to human health. Right now, we need to dramatically reduce the amount of plastics we use, and eventually cut out damaging plastics altogether. Finding a 100% environmentally friendly alternative to plastic is the hope for us all – but until then, we must reduce and reuse.