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Bio-based, yes… more sustainable? That depends: a closer look at the LCA of PLA.

Perrine Sébastien

Faced with the climate emergency and the growing concerns surrounding fossil-based plastics, bio-based plastics are now emerging as a promising alternative. Among them, PLA (polylactic acid), a biodegradable polymer, holds a central position in the market, with an annual production of 700 kT in 2022 (according to the OECD Data Explorer).

Here, we explore the following question: do bio-based plastics truly help reduce dependence on fossil resources?

To answer this question, the life cycle assessment (LCA) of PLA production from various biotic resources, conducted as part of the Bio4HUMAN project, provides a multi-stage and multi-criteria analysis covering major challenges linked to the bio-based sector

PLA: the leading bio-based plastic on the market

PLA is currently the most widely used bioplastic in the world (according to Global Growth Insights, 2025), used in packaging and nonwoven textiles for insance . The chemical synthesis of PLA from fossil-based resources does exist but remains marginal (10% of global lactic acid production) because it is more complex, more energy-intensive, and unsuitable for food, pharmaceutical, and medical applications (Angelin Swetha et al., 2023).

Bio-based PLA is produced from fermentable sugars (glucose), which are converted into lactic acid via fermentation and then polymerised. This glucose can originate from different biotic resources:

  • Food crops (corn, sugarcane, cassava, etc.),
  • agricultural organic waste
  • household organic waste.

The PLA production pathway, regardless of the feedstock used, follows similar stages:

Sugars and starch are extracted from the biotic feedstock after drying, grinding, and removal of fibrous components. Cellulose can also be converted into fermentable sugars (e.g., via enzymatic hydrolysis) when necessary.

For biotic resources with low sugar content but high starch content, chemical hydrolysis is used to convert starch into fermentable sugars.

The resulting sugar is fermented into lactic acid through homo- or hetero-fermentative microbial processes, which may co-produce lactic acid, ethanol, acetic acid, and acetate.

by precipitation as calcium lactate followed by solvent extraction.

Lactic acid is polymerised via enzymatic polymerisation, azeotropic dehydration, polycondensation, or ring-opening polymerisation.

Plastic processing (extrusion, injection molding, blow molding).

The sugar, starch, fibre, and water of biotic resources therefore influences the production process and, consequently, the associated environmental impacts. Upstream impacts also vary significantly due to agriculture and pre-treatment stages associated with each resource.

PLA production from different biotic feedstocks.

From agricultural feedstocks.

Currently, maize is one of the primary feedstocks used for PLA production worldwide, due to its high starch content.

Sugarcane, mainly cultivated in Brazil and Asia, also offers a high sugar content and is widely used.

The energy required for production can even be generated from the combustion of non-usable agricultural residues (bagasse), which could represent a promising approach for reducing environmental impacts.

What if it were produced from waste?

Producing PLA from organic waste or biowaste is often seen as an optimal solution. Indeed, it has several advantages:

  • valorisation of existing waste streams (no associated impacts),
  • no competition with food resources,
  • reduced land use.

The diagrams below represent each production pathway studied, which are necessary for building the life cycle inventories.

Table 1. Different PLA production processes. The crossed-out steps are not included in the process and highlight the differences between production pathways.

PLA production from

Associated process

Maize

Sugar Cane*

Biowaste

Fruit waste*

*L’allocation économique a attribué 57,6 % des impacts aux 22 kg de PLA produits (à partir d’1 tonne de déchets traités).
34,9 % sont attribués à l’éthanol, 0,6 % au gypse et 6,9 % à l’électricité (lorsqu’elle est produite).

Life Cycle Assessment (LCA) will make it possible to identify the nature and sources of impacts associated with PLA production and to draw conclusions on which biotic feedstocks should be prioritised in order to minimise, as far as possible, the environmental impact of this bio-based plastic.

How does LCA HELP SELECTING bio-based MATERIALS and reduce their environmental impact ?

Comparative LCA results

Based on these processes, we were able to model the synthesis of bio-based PLA in SimaPro, using the ecoinvent 3.10 (Cut-Off) database, from cradle to gate.

Each production method presents its own advantages and disadvantages, with a variable impact on fossil resources, which can sometimes be higher than that of PE or PET (fossil-based plastics). A more detailed analysis is available in deliverable D5.2 of the Bio4HUMAN project, and our main conclusions are presented below.

Parameters influencing environmental impacts

LCA highlights several key parameters:

  • The biotic ressource (type, origin) influences the share of impacts associated with the raw material.
  • Production from biowaste is more favourable compared to sugarcane or corn, which are associated with impacts on acidification, particulate matter emissions, climate change, ecotoxicity, eutrophication, and land use due to agricultural activities.
  • The energy mix (electricity and heat) accounts for a variable share of impacts depending on the country of production.
  • Production impacts from corn, sugarcane, or biowaste can be significantly reduced by optimising the energy source. However, when energy is of fossil origin, the impact on fossil resource depletion remains substantial.
  • The process yield influences the amount of energy and consumables required.
  • Production from biowaste with low sugar or starch content is therefore not recommended, as it may cause greater environmental impacts than conventional processes.

Beyond production, the impact of PLA across its entire life cycle

Compared with a fossil-based plastic, a bio-based material may exhibit more limited mechanical performance. It therefore requires more material for the same application, which inevitably increases overall impacts.

  • Bio-based plastics should be prioritised when their performance is suitable for the intended application.

One of the main advantages of PLA lies in its end-of-life. It is biodegradable and therefore compostable, avoiding incineration at the end of its life cycle. It can also improve soil structure, promote water retention, root development, and microbial activity.

It should however be noted that PLA is industrially compostable, but not biodegradable in natural environments. If waste management is inadequate, the environmental benefits associated with its biodegradability are lost. Other bio-based plastics available on the market may better address this issue, such as PHA.

Towards a more rational selection of bio-based plastics

The LCA of PLA has highlighted that the environmental impact of bio-based plastics is directly linked to the nature and valorisation potential of the biotic resources used.
The analysis shows that not all PLA production pathways are equivalent, and that an LCA integrating feedstock, energy, use phase, and end-of-life enables informed decision-making, covering the full range of issues associated with bio-based materials.

In conclusion, dependence on fossil resources is reduced if and only if the production process uses a limited amount of energy (as in agricultural feedstocks with high starch and sugar content), or renewable energy sources (biowaste).

The inventories used in this study are drawn from the scientific literature and generic databases; they do not therefore necessarily reflect all the processes and production conditions of PLA. To obtain results representative of a specific product or process, it is recommended to carry out a specific life cycle inventory as well as a Life Cycle Assessment (LCA) tailored to the system under study.

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