From Discards to Resources – Understanding Plastic Recycling

In this blog post, we will review the current state of plastic materials and circularity.
Plastics - Essential Materials
Plastics have become essential materials in many applications due to their versatility to meet a variety of functions and demands. 
• Lightweight and energy efficient

• Plastic packaging weigh about 15% compared to most of the metals and glass, lowering transportation emissions
• Less energy to produce compared to metals and glass, however feed is fossil fuel dependent

• Helps extend shelf life of food products – flexible and tight sealing

• Reducing spoilage and waste

• Medical and Healthcare applications – reduce risk of contamination, crucial in single-use items

• Sterilizable, lightweight, disposable, transparent

• Consumer electronics – insulating, durable, customizable shapes and color, impact resistance
• Construction and building materials – resistant to weathering and rot, durable and insulating
• Safety and sports equipment – impact resistant, lightweight, durable and flexible
• 3D printing and prototyping – can be melted, shaped to create detailed complex shapes
• Agriculture – protecting crops from extreme weather, better environmental control improving yields and availability, reduce water evaporation
• Automotive and Airspace – lightweight improves fuel efficiency, corrosion and impact resistant making them safe and economical
• Textiles – can be engineered for breathability, insulating, easy to maintain, durable
• Infrastructure – durability, corrosion resistance, easy to install, lightweight – requires less maintenance than metals

Plastic Waste and Circularity
Key to tackling plastic waste is to create circularity.
Plastic Waste
• Environmental and health challenge

• Does not decompose naturally – can persist for hundreds of years
• Nearly a third of the plastic package waste is lost in the environment (nearly 58 million tons based on 2022 data)

        • Breaks down to microplastics – entering food chains and contaminate ecosystem

• Additives and production can involve toxic chemicals – potentially harming human health and environment

• Not sustainable, given the growing demand for materials
• Challenge for managing waste – diversity of polymer types and composites, low economic value
• Less durable under extreme conditions of high temperatures and UV light – limits lifespan and reusability
Circularity
• Keep the materials in use longer at maximum value
• Recover and regenerate 

• Use as a resource minimizing environmental impact
• Decoupling the demand growth from feedstock resources

Design Innovation – Plastics Materials & Products
To achieve circularity, there is a need for innovations in both the plastic materials as well as product designs.
• Extend lifetime of plastic materials – self healing, slowing deterioration
• Reducing material usage – enhanced performance and design
• Refillable and recyclable packaging 
• Ease of repair to extend life, and dismantling for recycling
• Increase recyclability of plastics – degradability on demand, one type of material for packaging
• Biodegradable plastics
• Non-toxic additives and chemicals

Recycling Technologies Overview
In 2022, recycled materials (mostly mechanical) contributed nearly 36 million tons (about 9% of the global production).
Mechanical Recycling 

• Mostly for PET, HDPE, PP
• Energy efficiency - high
• Carbon efficiency - moderate to high
• Limited by contamination, degradation

Pyrolysis

• Mixed and contaminated plastics
• Energy efficiency - low
• Carbon efficiency - low
• Produces fuels

Depolymerization

• Mostly for PET, Nylons, polyesters
• Energy efficiency - moderate
• Carbon efficiency - moderate to high
• High cost

Solvolysis

• Contaminated, multilayer plastics ​
• Energy efficiency - moderate
• Carbon efficiency - moderate to high
• Expensive, limited commercial availability

Thermal (Gasification, Incineration)

• Mixed and unrecyclable plastics
• Energy efficiency - moderate
• Carbon efficiency - low
• Not circular

Biological

• PET
• Energy efficiency - likely high
• Carbon efficiency - likley high
• Early stage of development

Many technologies are still in the early stages of development and commercialization. As these technologies mature, performance and efficiency will likely improve.

Allocation Approach
Mass balance and allocation methods offer flexibility in incorporating recycled materials. While mass balance accounting can include both high-value chemicals and fuels, the latter is subjective in sustainability terms because it doesn't support closed-loop recycling and results in CO₂ emissions. Mass balance for fuels has a role in current waste management and transition strategies. Clearly distinguishing between recycled content allocated to fuels versus chemicals can help increase transparency.