Plastic is a fundamental part of our daily lives. It’s in the camera capturing this moment, the device you’re using to read this, the clothes we wear, and even the milk jug in your fridge. This is because plastic is an incredible invention—it’s flexible, durable, adaptable, and inexpensive. However, despite these advantages, plastic has significant downsides. It leaves a massive carbon footprint, disrupts natural ecosystems, and is so widespread that it’s found in the food we eat and the air we breathe. Some suggest we should stop using plastic altogether, but given its integration into our lives, that’s easier said than done.
So, what if we could find a better alternative to plastic? How close are we to reinventing it? The journey of most plastics begins with petrochemicals, which are transformed into materials like “nurdles”—small plastic pellets. These pellets can be melted into packaging or molded into items like water bottles. Plastics are polymers, which means they are made of many small molecules linked together to form large macromolecules. For example, ethylene gas can be polymerized into polyethylene, a common plastic used in various applications.
Polyethylene is just one of many types of plastics, each with unique properties suited to specific uses, from packaging to clothing. The biggest challenge in replacing plastic is finding a material that can perform all these functions. An ideal material would have all the benefits of plastic but be sustainable to produce, use, and dispose of. This means it should be both bio-based and biodegradable. Bio-based refers to the source of the carbon in the material, ideally from renewable resources like plants or waste biogas. Biodegradable means the material can be broken down by microorganisms like bacteria and fungi at the end of its life.
PLA, or polylactic acid, is a type of plastic that is bio-derived, biodegradable, and compostable. It’s currently the most widely available biopolymer, but it primarily breaks down in industrial composting environments, which require specific conditions like high heat and pressure. This presents a challenge similar to recycling, as it requires significant infrastructure.
Molly and her team at Mango Materials are working on a different type of biopolymer called polyhydroxyalkanoates (PHAs). PHAs are naturally occurring biopolyesters that bacteria have evolved to store carbon. Although identified over a century ago, commercializing PHAs has been challenging due to the difficulty of producing them on a large scale.
About a decade ago, Molly’s team at Stanford began exploring the use of methane as a feedstock for producing PHA. Methanotrophs, bacteria that consume methane, can potentially produce PHA. This process involves using waste methane from landfills and wastewater treatment plants, making it a sustainable option.
Mango Materials utilizes existing infrastructure, such as anaerobic digesters, where methanogens produce methane from waste. This methane is then used in fermentors where bacteria grow and produce the biopolymer. The process involves two stages: reproduction of the organisms and transformation of carbon into the biopolymer within their cell walls. Once ready, the polymer is harvested and can be turned into various products.
In an ideal future, anaerobic digestion could convert waste into fuels and energy, creating a more resilient economy by using waste as a resource for everyday materials. Currently, Molly’s team is focusing on products like fibers for textiles, small packaging items, and even 3D-printed tools for space use. By building demand and refining their production process, they aim to eventually produce items like plastic bags.
PHAs offer versatility, with the ability to be tailored for different applications and biodegrade in various environments, including home composts. If we can scale up the production of PHA using waste facilities worldwide, we could significantly reduce our reliance on petrochemical plastics.
We are on the brink of a technological leap forward. The technology for next-generation plastics exists; the challenge lies in developing the necessary infrastructure. Once this is in place, bioplastics and compostable plastics will become more prevalent. With the right alignment of production costs and infrastructure, the future of sustainable plastics looks promising. As these materials become more economically viable, we can expect significant progress in the coming years.
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Research the different types of bioplastics, such as PLA and PHA, and their potential applications. Prepare a presentation to share your findings with the class, focusing on the benefits and challenges of each type. Highlight any recent advancements in bioplastic technology.
Participate in a debate on whether society should aim to completely eliminate traditional plastics or focus on improving recycling and bioplastic alternatives. Prepare arguments for both sides and engage in a structured debate with your peers.
Analyze the case study of Mango Materials and their innovative approach to producing PHA using methane. Discuss the potential environmental and economic impacts of their method. Consider the scalability and feasibility of implementing this technology globally.
Conduct a hands-on experiment by composting different types of bioplastics, such as PLA, in a controlled environment. Monitor and document the decomposition process over several weeks. Share your observations and conclusions with the class.
Participate in a workshop where you design a product using bioplastics. Consider the entire lifecycle of the product, from sourcing materials to disposal. Present your design and explain how it addresses the challenges of sustainability and functionality.
**Sanitized Transcript:**
Plastic is everywhere. From the camera recording me right now, to the device you’re watching this on, the clothes that we’re wearing, the gallon of milk you drank straight out of this morning, and the fridge that you put it back into. But that’s because it’s a pretty awesome invention. Plastic is flexible, durable, tunable, and it’s cheap. However, for all of plastic’s advantages, it has an obvious dark side. It has a massive carbon footprint, wreaks havoc on our natural ecosystems, and is so pervasive that it’s literally showing up in the food we eat and the air we breathe. Some would argue that we just need to quit plastic cold turkey. But because we’re so wrapped up in it, that might be easier said than done.
But what if we could upgrade to something better? How close are we to reinventing plastic? The life cycle of most plastics starts with petrochemicals, which are used to form some kind of source material, like these pellets called “nurdles.” These plastic pellets can be melted into something like plastic packaging or blow molded into a water bottle. That bottle might go somewhere else, where a label gets put on top of it, and then it gets filled.
Plastics are polymers. “Poly” means many, and “mers” means parts. So, basically, small molecules are chained together to make a really large molecule, or a macromolecule. Some of these macromolecules can be shaped using heat and pressure, and that’s what plastics are. You can start with ethylene gas, polymerize it into polyethylene, which is a type of plastic, and use it in various shapes and forms.
Polyethylene is just one of countless types of plastics with different properties, each perfectly suited for their application, from sealing a house to lining a car, shipping a product, wrapping produce, keeping your soda carbonated, or your clothing from crumbling when you sweat. Packaging is the largest consumer of polymers, or plastics. We interact with them every day. And that’s one major challenge of reinventing plastic: finding a replacement that can do all these things.
A miracle material would possess all the incredible properties of plastic but be sustainable to produce, use, and dispose of, meaning it’s both bio-based and biodegradable. Bio-based refers to where the carbon in the material comes from. Is it rapidly renewable? Is it from plants or waste biogas? Biodegradable refers to what happens to a material at the end of its life. Can it be broken down by microorganisms like bacteria and fungi?
PLA, or polylactic acid, is one of the plastics that is bio-derived, biodegradable, and compostable. Right now, PLA is the most widely available “biopolymer” on the market, and you might already be familiar with it. However, one of the challenges is that PLA generally will only break down in industrial composting environments, which require high heat and high pressure.
Industrial composting is a challenge for the same reason that recycling is: it’s expensive and requires massive infrastructure to be built from the ground up. If you throw a recyclable soda bottle in the wrong bin or a ‘compostable’ PLA cup in your backyard, the plastic is still stuck and won’t break down. That’s why Molly and her team at Mango Materials are focused on a different kind of biopolymer—one that degrades naturally, but only when you want it to: polyhydroxyalkanoates (PHAs).
Polyhydroxyalkanoates are a family of naturally occurring biopolyesters. It’s the way bacteria have evolved over billions of years to store carbon in case of famines. PHAs were identified in bacteria over a hundred years ago, but the challenge has been how to commercialize them. Typically, using bacteria to produce PHA in their cell walls required feeding them something like sugar or vegetable oils, which can be difficult at large scales.
However, over a decade ago, Molly and her research team at Stanford started to explore another idea: what if we used methane? There are naturally occurring methanotrophs, or bacteria that can consume methane, and they could potentially produce PHA. This is an ancient carbon storage mechanism in organisms.
Now, there has been ongoing success in validating whether waste methane can be used and what properties can be obtained from compounding or formulating the polymer correctly. The major challenge for any next-generation material is to be able to compete with petroleum-based plastic products.
For example, if you go to a dollar store, you see items priced around $1. The product itself has to be less than $1, along with the packaging, which has to be very cheap to succeed in the market. To drive a competing material’s costs down that far, it would have to be incredibly easy to produce. According to Mango, that “thin air” is the methane wafting from landfills and wastewater treatment plants.
Mango Materials is able to utilize existing infrastructure. The tank behind me is called an anaerobic digester, where organisms called methanogens live and eat waste to produce methane. Behind that, we have the fermentor where the bacteria grow and make the biopolymer. This process happens in two stages: first, the organisms reproduce, and then they transform the carbon to build up the biopolymer inside their cell walls.
Once the bacteria are ready, the polymer is harvested from their cell walls. The goal is to turn it into various products, generally in pellet form.
In an ideal future, anaerobic digestion could convert materials to fuels and energy. Local, decentralized facilities could collect waste and anaerobically digest it to methane, creating a more resilient economy by using waste as a feedstock for everyday materials and products.
For Molly and her team today, those products include fibers for textiles, small packaging items, and even 3D-printed tools for use in space. By gradually building demand and improving their production process, they believe they’ll soon be able to work with something like plastic bags.
One of the amazing things about PHAs is that they can be tailored for various applications, offering different mechanical properties, processing capabilities, and end-of-life biodegradability. PHAs can also biodegrade in home compost or even in environments without oxygen, providing reassurance that they won’t pollute indefinitely.
So, if we can mentor methane-munching microbes to produce PHA at scale using waste facilities worldwide, gradually build the capacity to compete with petrochemical plastics, and watch as our landfills become valuable resources, how close are we to reinventing plastic?
We are experiencing a technological leap forward. The technology for the next generation of plastics is already here; it’s the infrastructure that needs to be developed around it. Whether it’s bioplastics, compostable plastics, or processing, once the infrastructure is in place, we’ll have the next generation of plastics taking over.
We’re very close to replacing petroleum and polluting plastics. These materials are already available. If everything falls into place, we could see significant progress in just a few years. There’s a sweet spot between technology and economics. Sustainable plastics are going to grow from here on—there’s no doubt about that. Once the production costs and infrastructure align, I see a bright future for bioplastics.
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Plastic – A synthetic material made from a wide range of organic polymers such as polyethylene, PVC, etc., that can be molded into shape while soft and then set into a rigid or slightly elastic form. – Researchers are exploring new methods to recycle plastic efficiently to reduce environmental pollution.
Bioplastics – Plastics derived from renewable biomass sources, such as vegetable fats and oils, corn starch, or microbiota, rather than fossil-fuel plastics which are derived from petroleum. – The development of bioplastics is crucial for reducing our reliance on fossil fuels and minimizing plastic waste.
Biodegradable – Capable of being decomposed by bacteria or other living organisms and thereby avoiding pollution. – Scientists are engineering biodegradable materials to replace conventional plastics in packaging industries.
Sustainable – Involving methods that do not completely use up or destroy natural resources, allowing for long-term environmental quality. – Sustainable agricultural practices are essential for maintaining soil health and ensuring food security for future generations.
Methane – A colorless, odorless flammable gas that is the main constituent of natural gas, contributing significantly to the greenhouse effect. – Reducing methane emissions from livestock is a critical step in combating climate change.
Polymers – Large molecules composed of many repeated subunits, which can be natural, like DNA and proteins, or synthetic, like plastics and resins. – The study of polymers is fundamental in developing new materials with unique properties for industrial applications.
Ecosystems – A biological community of interacting organisms and their physical environment. – Understanding the dynamics of ecosystems is vital for conservation efforts and biodiversity management.
Composting – The process of recycling organic waste into a rich soil amendment through natural decomposition. – Composting not only reduces landfill waste but also enriches soil fertility, promoting healthier plant growth.
Carbon – A chemical element that is the fundamental building block of life, forming the basis of organic chemistry and playing a crucial role in the Earth’s climate system. – Carbon sequestration techniques are being developed to capture and store atmospheric carbon dioxide to mitigate global warming.
Alternatives – Options or choices that serve as substitutes for conventional methods or materials, often with the aim of reducing environmental impact. – Researchers are investigating alternatives to fossil fuels to create a more sustainable energy future.
