Feedstock for the production of bioplastics

Although the term “bioplastics” suggests materials of natural origin, in fact, today some bioplastics are also produced from fossil resources. This possibility, in fact, is allowed by the definition of the term “bioplastics”. The feedstock used in the production of bioplastics, therefore, may derive from biomass or fossil resources, although the first class is the most represented.

The two different types of feedstock for the production of bioplastics are analysed in detail. For convenience, it is, first of all, the least represented source, i.e. fossil resources.

Fossil resources as feedstock for bioplastics

As mentioned above, the number of bioplastics produced from fossil resources is rather limited. As of today, in fact, PBAT and PCL can be mainly included in this class.

Bioplastics obtained from these sources are defined as “non-biobased”. However, since they are bioplastics, and must comply with the definition, they will necessarily be “biodegradable”.

Biomass as feedstock

Most of the bioplastics known today are derived from biomass. In particular, they are derived from biomass rich in carbohydrates.

Bioplastics obtained from this type of feedstock are defined as “bio-based”. They can also be “biodegradable” or “non-biodegradable” according to the definition of bioplastics. Their ability to biodegrade strongly depends on the chemical structure of the material, regardless of whether they are, in fact, bio-based. It must be remembered, in fact, that the bio-based property does not necessarily imply that of biodegradability! [If you want to go deeper into this concept, I suggest to connect to the section dedicated to the types of bioplastics].

Types of biomass

The biomass needed for the production of bioplastics, in turn, may have different origins. In general, it can come from agriculture or the food industry, but further specifications are needed.

The 1st generation feedstock

Today, bioplastics are mainly produced from food crops of plants rich in carbohydrates (e.g. corn, sugar cane, beet, potato, etc.). These represent the 1st generation feedstock. The latter are currently the most efficient in the production of bioplastics, as they are the ones that require the least use of soil, while still allowing high product yields. However, the use of these crops may soon compete with the main purposes for which they are grown, i.e. human and animal feed.

The problems linked to the 1st generation

However, the use of these crops may soon compete with the main purposes for which they are grown, namely food and feed.

In 2019, global bioplastics production capacity amounted to 2.11 million tonnes. This resulted in approximately 0.79 million hectares of land. As a result, the area needed to grow sufficient raw materials for bioplastics production is about 0.02% of the global agricultural area.

Source: European Bioplastics
Land use for the production of bioplastics
Land use for the production of bioplastics

Although the use of soil for bioplastics may seem limited, a number of other factors need to be considered that could make this value unsustainable. First of all, a probable development of underdeveloped countries would lead to an inevitable increase in the demand for food soil, also considering the high population of these countries. Then we must consider the effects of climate change, which could make some of the areas currently used for agricultural purposes unavailable. Finally, it is necessary to anticipate the effects of recent environmental regulations, aimed at the circular economy, but also at the reduction of traditional plastics. These, in fact, will certainly lead, in the coming years, to an increase in alternative materials, including bioplastics. Consequently, in the absence of other sources of biomass for the production of bioplastics, there will be an increase in demand for soil for this purpose.

The 2nd and 3rd generation feedstock

This made it necessary to search for new feedstocks whose use did not compete with other main purposes. The sustainable supply of the necessary raw materials is the key to sustainable development.

This leads to 2nd generation feedstock. These are generally products with a high ligno-cellulosic content, therefore not intended for food use. In general, these raw materials represent the non-edible by-products of food crops (e.g. straw, corn stalks, sugar cane waste, etc.).

A further development takes place with 3rd generation feedstock. These, in fact, are obtained from the cultivation, above ground, of algae and microorganisms, which process waste biomass. The introduction of this generation feedstock therefore limits the problems of land use discussed above.

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