LCA of by-products, bioplastics and biocomposite agricultural product

From July 2015 to June 2018, NaturePlast has participated to the COPROPLAST project (with the funding of Normandy region and FEDER) with the partnership of AGRIAL cooperative.
The purpose of the COPROPLAST project was to propose to the different actors in the field of plastics industry, alternative solutions integrating the use of local waste / by-products as filler into different polymer matrixes.
As a part of the project, a life cycle assessment* (LCA) has been carried out in order to determine the improvement of the environmental impact of the biocomposite and by-product produced during the project.

To be the most significant, 4 polymer matrixes and 6 by-products from the project have been studied:

  • Fossil-based polypropylene, “standard” plastic material.
  • Biobased polyethylene, material derived from the bioethanol industry in Brazil and having the same properties as its equivalent fossil-based one.
  • PLA (polylactides), biobased material from maize starch or sugar cane and biodegradable.
  • PBS (Polybutylene succinate), material partially biobased also from maize starch or sugar cane and biodegradable.

And:

  • Wheat sorting waste, from seeds sorting.
  • Barley sorting waste, from seeds sorting.
  • Corn cob, from cereal activities.
  • Carrot sorting waste, from vegetables cutting activities.
  • Leek green leaves, also from vegetables cutting activities.
  • Carrot press cake, from vegetables pressing for soup fabrication.

The environmental impact of these matrixes and by-products was studied from “cradle to gate”, meaning from the production of raw material (renewable or fossil) and the production of each by-product to the obtention of the compounds mixing both matrixes and by-products. The methodical choices used for this study lead to an impact repartition between products and agricultural by-products under a mass allocation.

Six indicators have been selected so as to have a relevant representation of the component environmental impact:

  • Climate change: Quantify the anthropic emission of greenhouse gas which can disrupt climatic cycle at a terrestrial scale – kg CO2 eq.
  • Acidification: Indicate the acidification potential of areas (soils and surface waters) induced by acidifying substances emissions (SO2, NOx, NH3, …) – mole H+ eq.
  • Aquatic eutrophication: Introduction of nutriments (Nitrogen and Phosphate emission) which favor algal development and harm the aquatic fauna and flora – kg P or N eq.
  • Energy resources depletion: Evaluate the non-renewable energy resources depletion – MJ.
  • Soils occupancy: Quantify the space necessary to the different production steps – m² eq.
  • Water consumption: Evaluate the quantity of water drawn in the ecosphere – m3.

The indicators of soils occupancy and water consumption have an important uncertainty because the data available are not precise, notably when it comes to the fossil-based PP which provide a reliable comparison on those points.

 

By-products obtention

 

When studying the by-products obtention, it was seen that plants cultivation but also the transformation step at NaturePlast have a strong impact on the Acidification, Eutrophication and Climate change indicators.

The transformation steps necessary to the plastic processing (drying, grinding, sieving) are also responsible for the high impact on the energy consumption, notably for the by-products with a high humidity content (it can be more than 80%) like the carrot sorting waste and the leek green leaves.

Carrot press cake is the most effective by-product on the selected indicators followed by wheat and barley.

 

coproduits

by-products

 

Matrixes production

The study of the matrixes production has shown that biobased versions are more performing on the criteria of Climate change and Energy but have a disadvantage on Acidification and Eutrophication.

Regarding the criteria of Climate change, the positive impact of biobased matrix is emphasized when biogenic carbon is considered (carbon which is captured by the plants for their growth). Indeed, biobased matrix are 60% more performing than fossil-based PP.

 

 

 

Biocomposites study

One of the first goals of the introduction of by-products into a plastic matrix is to lower its environmental impact. Considering biogenic carbon for both matrixes and by-products, it has already been observed that no matter the percentage of by-products introduced for biocomposites production, the environmental criteria are positively impacted. Furthermore, the use of biobased matrixes allows to be more performing (notably with PLA and biobased PE), even if a fossil-based compound will still remain relevant compared to only the matrix.

 

by-products

 

Example of an end-product

 

In order to illustrate in a more precise way the potential gain in real conditions, one of the applications targeted by the project has been specifically evaluated. It concerns insulators for electric fences from the company Chapron:

 

by-products

 

As this product has a long duration of use (around 10 years), biodegradable versions have to be proscribed and incineration with energy recovery is here considered as end-of-life. So, the comparison is made between a fossil-based PP, a PP + wheat composite and a bio PE + wheat composite.

 

produits

 

The use of an entirely biobased compound has an important advantage on the criteria of Energy and Climate change when compared to PP and its wheat compound. The impact reduction on these criteria with respect to PP is about 40%. Nonetheless, Eutrophication and Acidification criteria are negatively impacted by the use of by-products, for the reasons raised above.

 

Lessons

 

This life cycle assessment has demonstrated the environmental advantage to use by-products with biobased matrix, or not, notably from an Energy and Climate change point of view. It was also a way to identify some negative aspects like Eutrophication and Acidification, those two criteria being impacted by the agricultural origin of the biobased matrixes and by-products.
Indeed, the first generation of biomasses (sugar cane, cereals, etc) cultivation from which derived the biobased matrixes and by-products drives bad results on these two indicators. Nonetheless, numerous production projects of biobased matrix from new generation of biomass (cellulose, organic wastes, waste water, etc) are on going and should make available in the short term these solutions.

The other improvement points that have been brought to light during this study are the different by-products treatment processes (drying, grinding, sieving) that need to be carefully chosen in order to reduce even more the environmental impact of its biocomposites.

 

About us: NaturePlast is a french company based in Normandy (IFS-14), specialized in bioplastics. With more than 10 years of experience in this field, the company has the most extensive portfolio of raw materials and biobased and/or biodegradable compounds in Europe. With its daughter company BiopolyNov, they provide support to industrialists from the origin to the industrialisation of their innovative project. Thanks to their R&D expertise acquired during the years, NaturePlast and BiopolyNov are renowned major player in the development and production of formulations for clients and collaborative projects.

*Life Cycle Assessment has been realized by O2M Conseil Company.