Producing bioplastics

Growing awareness of the toxicity of plastics and increasing government regulation of plastic waste has led to a surge of interest and investment in bioplastics.

Bioplastics are plastics made from renewable biological material, usually plants, waste, or microorganisms rather than petroleum or natural gas. Many bioplastics can be far more beneficial to the environment than plastics made from fossil fuels, but others can be no better than the original. It depends on how bioplastics are made.

To produce bioplastic, polymers (complex chains of molecules) are extracted from biomass to be formed into plastic products. That biomass can include corn, sugarcane, vegetable oils, and other edible sources called first-generation biomass. Producing bioplastic from first-generation biomass on land that could otherwise be used to grow food is controversial, as it can compromise food security.

So-called second-generation biomass includes wastes from agriculture, industry, cooking, food, foresting, and municipal landfills. Since it is not edible, its production doesn’t take the place of food production. And, unlike fossil plastics, bioplastic polymers can also be made from reused or recycled bioplastics, making them part of a circular economy; bioplastics derived from wastes are carbon-neutral, giving second-generation bioplastics the “lowest global warming impact overall.”

Third-generation largely refers to seaweed, cyanobacteria, and microalgae. The latter can be cultivated in wastewater, including municipal water treatment facilities, meaning its cultivation doesn’t threaten other land uses. Third-generation bioplastics are less studied, as most have yet to reach commercial viability, but they hold great promise to reduce carbon emissions even further. Cyanobacteria and algae remove more CO2 from the atmosphere than they produce as biomass, meaning their use as feedstocks for bioplastics is carbon-negative.

Depending on its molecular structure, bioplastic may or may not be biodegradable: roughly 60% isn't.20 This confusion has led to criticism of bioplastics from environmental groups, bans in cities like San Francisco, and low adoption rates due to a lack of options for their disposal.21

Some of the confusion and criticism stem from the fact that the terms “bioplastic” and “biodegradable” can mean many different things. Listed in order of least sustainable to most, products labeled “bioplastic” can be any of the following:

petroleum-based but biodegradable, made from plants and renewable sources but not biodegradable, biodegradable but made from renewable first-generation sources such as edible crops biodegradable and made from second- or third-generation sources such as wastes or microalgae.

With no clear definitions, consumers are not only confused but they may also be convinced that the products they are buying are better than they actually are. Clarity in definitions, such as those of the European Union’s Product Environmental Footprint standards, is a step in the right direction toward greater bioplastic adoption and less greenwashing.

The bioplastics industry is young; in 2022, bioplastics represented only 1% of the world’s plastic production but the industry is expected to grow by 10% to 14% in a few years.  There is currently no standardization for sourcing raw materials, types of plastics, or labeling what is biodegradable or compostable. This makes it difficult for consumers to judge whether they are doing anything environmentally beneficial by choosing bioplastics over fossil-based ones.