What are the three types of feedstocks for bioplastics?

If we’re going to achieve a circular economy in the chemicals industry, we’re going to need more than recycling of fossil-fuel-based plastics – but how do we get bioplastics from biomass? Jed Thomas

Bioplastics are shaking up the plastics industry, offering a renewable alternative to fossil-based materials.

But where exactly do these eco-friendly plastics come from? The answer lies in a mix of natural sources, ranging from sugars and plant oils to waste materials and even captured carbon dioxide.

Bioplastic production relies on three main types of feedstocks: carbohydrate-rich crops, lipid-based sources, and non-food biomass.

Each of these offers a unique pathway to producing sustainable plastics, but not all are created equal in terms of efficiency and environmental impact.

Could new plastics make recycling feasible?

A number of experts remain opposed to plastic recycling - but not because they oppose recycling or circularity as principles. Instead, their concern is that our economies produce far too many, fa... Read More

Carbohydrate (sugar) feedstocks

Sugars and starches are among the most common raw materials for bioplastics, thanks to their ability to ferment into building-block chemicals.

Sugarcane, sugar beets, and corn syrup are widely used to produce polylactic acid (PLA) and polyhydroxyalkanoates (PHA) through microbial fermentation.

The process converts glucose into lactic acid or polyester granules, which then form biodegradable plastics. While effective, there’s an ongoing debate about whether using food crops for plastics competes with food production.

Another key carbohydrate source is starch, which comes from crops like corn, potatoes, and cassava. Thermoplastic starch (TPS) is directly converted into bioplastic films, or it’s blended with other biopolymers like PLA to improve strength and flexibility.

However, starch-based plastics can be sensitive to moisture and prone to brittleness over time.

For a more sustainable option, some bioplastics use cellulose, a major component of plant cell walls.

Wood pulp and agricultural residues are valuable sources of cellulose-based biopolymers, such as cellulose acetate, which finds use in textiles and coatings. Nanocellulose, a newer innovation, adds strength and biodegradability to plastic composites.

The main challenge with cellulose-based materials is the complex processing required to extract and modify the polymer.

Lipid (fat and oil) feedstocks

Oils and fats provide another important route to bioplastics, particularly for flexible and durable materials.

Vegetable oils from soybeans, palm, and rapeseed undergo chemical modification to produce bio-based polyurethanes (PU) and polyester precursors. Some bacterial strains can even convert these oils directly into PHA, making them an alternative to sugar-based feedstocks.

However, large-scale use of vegetable oils raises concerns about land-use change and deforestation, particularly with palm oil.

A promising alternative is microbial lipid synthesis, where engineered microbes like Yarrowia lipolytica and Chlorella algae produce oils that can be converted into plastics.

While still in development, this method could reduce dependence on traditional crops and offer a more sustainable lipid source.

Cellulose feedstocks

One of the most exciting shifts in bioplastic production is the move toward non-food biomass. Lignocellulosic materials, which include forestry residues and agricultural waste like wheat straw and corn stover, provide a sustainable source of sugars for biopolymer synthesis.

A key example is polyethylene furanoate (PEF), a next-generation bioplastic made from 5-hydroxymethylfurfural (HMF) derived from cellulose. Additionally, lignin, a byproduct of wood processing, is being explored as a source of bio-based aromatics for polymer production.

Industrial and municipal waste streams are also gaining traction as bioplastic feedstocks. Some bacterial strains can ferment food waste and sewage sludge into PHA, offering a circular economy approach to plastic production.

Additionally, gasification processes can convert waste biomass into syngas, which serves as a precursor for methanol-to-olefins (MTO) technology used in plastic synthesis.

The challenge here lies in dealing with the variable composition of waste streams and optimizing conversion efficiency.

Could biofuels become a feedstock for renewable plastics?

In a world where plastic pollution has become a critical environmental issue, the search for sustainable alternatives is more pressing than ever. Bioplastics, made from plant-based or other biologi... Read More

Bonus: CO₂ feedstock

Beyond traditional biomass sources, advancements in synthetic biology and electrochemistry are opening up new possibilities for bioplastics.

One approach involves converting captured CO₂ into polymer precursors using electrochemical processes.

For example, ethylene and methanol derived from CO₂ can be used to produce polyethylene or polyesters, reducing dependence on plant-based sources.

Another innovative method uses methanotrophic bacteria, which consume methane and convert it into PHA.

This approach not only creates biodegradable plastics but also provides a way to mitigate methane emissions. While promising, these technologies are still in the early stages of commercialization and require significant investment to scale up.

[[Pr: 63818:2028-01-01]]

Each type of feedstock comes with its own advantages and challenges.

Carbohydrate-based feedstocks are well-established and scalable but face criticism for competing with food production.

Lipid-based sources offer flexibility but come with sustainability concerns.

Lignocellulosic and waste biomass feedstocks are among the most sustainable but require complex processing.

Meanwhile, CO₂-based and methane-based methods hold long-term promise but are still developing.

The future of bioplastics depends on balancing efficiency, sustainability, and economic feasibility.

While sugar and starch-based materials dominate the market today, the next generation of bioplastics is likely to shift toward waste-based and CO₂-derived sources.

As technology evolves, a combination of these feedstocks will play a role in reducing our reliance on fossil-based plastics and creating a more circular, sustainable economy.