Authors: Laua Wiman, Kirsi Immonen & Anna Leinonen, VTT
Plastics are troubled by several sustainability challenges. Most plastics are produced from finite fossil raw materials. When they are incinerated after use, they emit greenhouse gases, and when they are not incinerated, they too often end up in the environment. Biobased plastics, made from renewable sources like plants or carbon containing side streams from other industries, offer a possible technical solution. When burned, they only release the amount of greenhouse gas they absorbed while growing. Some biobased plastics can also break down naturally in the environment, though not all of them do.
The main sustainability trade-off with biobased plastics is that many of their raw materials (e.g. corn, sugar beet) are also food, and cultivating enough raw materials for a large-scale biobased transition requires vast amounts of land. The common concerns are, therefore, that biobased plastics raise food prices by diverting edible food and productive agricultural land to materials production, or that materials production otherwise requires immense land use change. For instance, Brizga et al. (2020) estimate that replacing all current fossil plastics with biobased alternatives could require 54% of current corn production and a land area the size of France (which would amount to 1.2 % of global agricultural land, Ritchie and Roser 2024). These estimates are based on the agricultural yields of raw materials for different plastic types.
However, a biobased transition can feature many types of change regarding material choice, technology, and supply chains. Furthermore, comprehensive projections of land use and food impacts depend on more than just the choices of material types and their land-use requirements. To illustrate this point, and to inform the discussion on plastics sustainability, we conducted a light, back-of-the-envelope scenario analysis that highlighted often-ignored variables of the transition. The results indicate that it is possible to envision a large expansion of biobased plastics with quite modest global land area requirements – and therefore, presumably, modest food and land use impacts. Biobased plastics could therefore contribute to the overall sustainability of plastics, at least if the transition is governed appropriately.
A social-technical transition has many moving parts
Equally important to land use estimates is understanding which uncertainties drive land use effect. We highlighted five variables, which were also the foundation of our scenario analysis. In brief, we assume it is the year 2050, and:
- 25% of plastics are biobased, as per SystemIQ’s (2022) net zero scenario (the demand variable)
- Total plastics use doubles to 800M by 2050, as projected e.g. Dokl et al. 2024 (demand variable)
- There are three possible splits of broad material types (material split variable)
- There is a high amount of plastics-to-plastics recycling of biobased materials (the secondary sourcing variable)
- A significant amount of biobased raw materials stem from novel non-agricultural sources, such as industrial side-streams (e.g. waste oils), carbon capture and use, or algae farming (the non-agricultural primary sourcing variable)
From this sequence of assumptions – demand, material splits, and secondary and non-agricultural primary sourcing – an amount (mass) of biobased raw material is ‘left over’ to be agriculturally cultivated. This mass times the land use factor equals total land use requirement:
- The land required per mass of materials produced is the mean value from Brizga et al. (2020), 1.18 ht/t (the land use factor)
As a result, we get a figure for total land use requirements.
Each variable in the chain of assumptions is uncertain for different reasons. Our choice was to use optimistic recycling assumptions non-agricultural sourcing assumptions to represent what is possible with effective circular economy governance. By contrast, the assumptions of material splits (steering maximum feasible recyclability), demand increase, and land use factors were more moderate in the sense that other assumptions could have led to lower land use requirements. Nonetheless, the results for land use requirements that we calculated could for the most part be described as modest.
Good transition governance can moderate land use impacts
Today, biobased raw materials use about 0.06% of global agricultural land (European Bioplastics 2025). Across all our transition scenario variations, biobased raw materials required 0.1 – 3.4% of global agricultural land (global agricultural land spans 48 million km2, as per Ritchie and Roser 2024). Therefore, our results span far on both sides of the 1.2% of agricultural land estimated by Brizga et al. (2020). But this is where the important work of scenario analysis begins: the next step is to understand what makes a difference to the uncertainty range.
If we excluded the optimistic extremes of non-agricultural sourcing assumptions (since some of these solutions are today emerging rather than established), the lower end of the range draws in: 0.9 – 3.4% of global agricultural land. If we additionally excluded the non-mainstream ‘stagnation’ scenarios where global plastics demand does not rise from today’s state, the range narrows further: 1.3 – 3.4%. One step further, if we only use the most likely (diverse) material split and pessimistically low recycling behaviour assumptions (well below technical feasibility), the land use requirement is 2.8 – 3.4%.
Overall, land use requirement is strongly steered by total demand, recycling, and novel sourcing – not only the land use factors that are the typical focus of the discussion (and which we kept constant in these calculations). With good governance of demand, recycling, and sourcing, land use requirement and sustainability problems that stem from it can be controlled.
Is our main result range, 0.1 – 3.4% of global agricultural land, a lot or a little? Would its impacts on food price and land use change be modest, devastating, or something in between? We cannot answer these questions systematically way here. Much depends on where the land for cultivation is taken from (e.g., do we cut down forest to cultivate raw materials?), how different effects get valued (which amounts of trade-offs are deemed acceptable, and by who), and which groups take on which impacts.
However, we think this land requirement range can be described as low, because today about 80% of agricultural land is used for the pasture and feed of livestock (Ritchie and Roser 2024). Livestock is a notoriously low efficiency calory and protein source relative to its environmental footprint – or its emission impact and, evidently, land use requirement. A global sustainability transformation entails a dietary shift (especially in wealthy economies) toward plant-based diets, so we should expect the 80% figure to come down in a reasonable ‘sustainability’ scenario.
It is not clear that all land used for pasture or feed cultivation is easily repurposed for raw materials cultivation, but where feasible, it would be intuitively preferable to cutting down forests or displacing food production. When evaluating the land use impact of biobased plastics and debating the appropriate scale and form of the transition, we should place the agricultural shift into the context of the much broader question of a dietary shift. Good governance that emphasizes circular economy principles and avoids land use change can find a sustainable role for biobased plastics.
The documentation for this scenario analysis, including numeric assumptions and their sources, is available at Research Gate, link here.