Bio-based vs. Fossil-based plastics

As industries seek to reduce their environmental footprint, biobased plastics have emerged as a promising alternative to fossil-based materials. Derived from renewable resources, these plastics offer the potential to reduce dependence on fossil fuels, lower carbon emissions, and contribute to a more sustainable future. However, the viability of biobased materials as a complete replacement for fossil-based plastics remains a topic of debate. This article consolidates some insights on the recyclability, mechanical performance, and long-term sustainability of biobased and fossil-based plastics. It discusses whether biobased materials alone can drive a sustainable future or if we still need fossil-based plastics in the mix.

The Future of Biobased Plastics: Sustainability Potential and Limitations

Biobased plastics have clear environmental benefits, primarily in reducing dependency on fossil fuels and lowering carbon emissions. For instance, biobased PP, PA, and PET have similar properties to their fossil-based equivalents and can be processed through existing infrastructure. However, there are inherent limitations:

• Cost and Scalability: Biobased plastics often come with higher production costs and complexities, particularly for specialized high-performance materials. While large-scale production could help reduce costs, the price gap between biobased and fossil-based plastics remains a barrier for widespread adoption.
• Recycling Challenges: While even fossil-based composites and high-performance polymers are too very difficult to reprocess and find economically viable recirculation pathways, the recyclability of less complex and more widely used biobased plastics is generally on par with fossil-based materials, provided they are chemically identical. However, biobased plastics with unique compositions (e.g., PLA, PHA, PBS or PBF) require separate re-processing streams, which can complicate logistics for its recirculation, and reduce the economic viability of a closed-loop system. Something similar applies to fossil-based polymers that use natural fibres fillers. Natural fibres could be great alternatives to fillers like carbon or glass fibre, however, they are even more difficult to recycle since there are yet very few fossil-based polymers with natural reinforcements, and yet, adding natural fibers, even when it helps to reduce the associated impacts to fillers, they do not solve the degradation problem of polymers.
• Lifespan & Biodegradability Considerations: A common misconception is that bio-based materials are inherently biodegradable or compostable, but this is not always the case. Many bio-based materials lack biodegradability, and even those marketed as biodegradable or compostable often fail to break down in home composting systems. Standard testing conditions for certification require controlled environments with specific temperatures, moisture, acidity, and oxygen levels—conditions rarely achieved outside of industrial composting facilities. For example, PLA typically needs temperatures above 55°C to degrade properly, making it unsuitable for most home composts. On the other hand, to meet performance demands like durability under chemical, thermal, or mechanical loads, bio-based materials are often modified with additives. These additives can hinder biodegradability, complicate recyclability, and even contaminate recycling streams when mixed with fossil-based materials. The issue of additives, however, is not exclusive to bio-based plastics—fossil-based materials also rely heavily on them, which similarly reduces recyclability.
• Resource Constraints: Producing biobased plastics at scale demands significant agricultural land, often relying on monocultures that can compete with food production, degrade soils, and harm biodiversity. Currently, less than 3% of global farmland is used for bio-materials and biofuels, with no major expansion expected soon. However, many regenerative and mixed-crop practices, while more sustainable, still have lower yields than industrial monocultures. Additionally, some biopolymers depend on specific crop-growing conditions—such as humidity, soil pH, and temperature—to ensure sufficient yield and material quality, adding to the challenges of scaling biobased materials sustainably.

Fossil-Based Plastics: Still Necessary for Some Applications

Despite the environmental impact of fossil-based plastics, they remain essential in various high-performance sectors. Polymers like PEEK, POM, ABS and PA are critical in applications that demand superior mechanical strength, chemical resistance, and thermal stability —properties that biobased plastics currently cannot match at the same scale or cost. For such applications, fossil-based materials are still, regrettably, the best choice.

While biobased plastics are a step in the right direction, a mixed approach that combines biobased materials with reduced fossil-based plastic consumption is more realistic for achieving long-term sustainability goals.

However, the challenge lies in reducing the consumption of these plastics while maintaining performance standards. The best waste is the one that has not been created, thus, avoiding the production of brand-new products with virgin materials, should be a priority. Key strategies to make fossil-based materials less unsustainable include:

A. Design for Sustainability

Designing products with recyclability and resource efficiency in mind is one of the most impactful ways to reduce the need for both fossil-based and biobased plastics. This includes:

• Using fewer materials overall and opting for designs that require less plastic.
• Use additive manufacturing as a repair tool for certain broken plastic components.
• Selecting materials that can be easily recycled within existing systems, including biobased plastics that are chemically identical to fossil-based alternatives.
• Encouraging mono-material products that simplify the disassembly and thus the recycling process and minimize contamination.
• Increase product longevity, through more robust designs, topological optimization and improving their repairability.

B. Improve Reprocessing Infrastructure

All materials can be reprocessed... with the proper infrastructure. However, very few regions in the world have enough infrastructure to make the recirculation of materials a viable and really sustainable solution. To ensure that both biobased and fossil-based plastics are reprocessed effectively, investments in sorting technologies and recycling systems are necessary, and that cannot be the responsibility solely of the government: companies creating the products that require these kinds of materials should support the initiatives, for instance, with Extended Product's Responsibility programs that create synergies with recyclers and waste managers, beyond a financial contribution. Enhancing the quality and efficiency of recycling systems can help reduce the need for virgin plastic production, lowering both fossil-based and biobased plastic consumption.

• Mixed Material Recycling: Developing processes that allow for mixed streams of fossil-based and biobased plastics—especially when they are chemically identical—can maximize recycling efficiency.
• Chemical Recycling: This process can be particularly useful for high-performance plastics and for cases where mechanical recycling alone is not sufficient. It can break plastics down into their monomers, enabling them to be reprocessed into new plastics without losing quality. However, it has its environmental trade-offs, and could be very energy and overall resources intensive.

C. Shift Toward Circular Economy Models

A circular economy model can significantly reduce the need for virgin materials by promoting reuse, repair, and recycling. For biobased and fossil-based plastics alike, the focus should be on maintaining the value of the materials for as long as possible through efficient product design, recycling, and end-of-life management.

D. Innovativation in Materials.

Sustainability fosters innovation (and vice versa). Emerging materials like nanomaterials and those engineered through molecular design offer promising alternatives to traditional polymers. These innovations enable precise control over material properties, such as strength, flexibility, and conductivity, while often reducing resource use and environmental impact. For example, graphene-based nanocomposites and molecularly tailored biopolymers can provide superior performance in applications ranging from electronics to medical devices. While still in early development, these advanced materials have the potential to overcome the limitations of conventional plastics, paving the way for more sustainable solutions.

A Balanced Future

While biobased plastics are an important component of a more sustainable future, they cannot entirely replace fossil-based plastics in all applications, particularly in sectors demanding high-performance materials like mobility, MedTech or security. The future of plastic sustainability lies in reducing the consumption of both fossil-based and biobased plastics through smarter design, improved recycling, and circular economy practices.

While biobased materials offer a promising path toward reducing reliance on fossil-based plastics, they are not a universal solution. Their production, recyclability, and environmental impact depend on factors such as the source materials, processing methods, and application requirements. In high-performance applications where user safety is a priority, to mention some as mobility or MedTech, there is still a long pathway to run.

Challenges like reliance on agricultural land, limited biodegradability, and additives affecting recyclability highlight the need for a balanced approach. Reducing fossil-based plastics will require not only scaling up sustainable biobased alternatives but also optimizing recycling systems, adopting circular design practices, and improving transparency in material labelling, regardless of the origin (bio-based or fossil-bassed) of the material.

In parallel, innovative materials like nanomaterials and those engineered through molecular design present exciting alternatives. These materials enable precise control over performance properties while potentially reducing environmental impacts. Advanced solutions, such as graphene-based nanocomposites and molecularly designed biopolymers, could complement biobased and recycled plastics, addressing some of their limitations. By combining biobased innovations with cutting-edge material research and systemic improvements in waste management, we can work toward a more sustainable and resource-efficient future.

Biobased plastics can significantly contribute to reducing our carbon footprint and reliance on fossil fuels, but a holistic, balanced approach that integrates both biobased and fossil-based plastics, while emphasizing reduction, reuse, and recycling, altogether with the development of innovative materials, is essential for achieving true sustainability.