Prerequisites for bio-based plastic

Projections shows that there exists potential for an increased extrac-tion of biomass in Sweden. Researcher that have examined forestry, agriculture and water highlight a potential increase of approximately 152 TWh annually where forestry account for 130, agriculture 20 and water 1,5 (RISE, 2018). These numbers should however be taken with a grain of salt, as the researchers have made several assumptions on e.g. different time horizons for the different raw material sources and there are restrictions of, amongst others, technological, eco-nomic, political and market-based character.

5.7.1 Exploitation of Swedish forest for plastic

“Plastic from forest” may entail by-products from forestry in the form of branches and treetops or residues and by-products from industrial processes. For branches and treetops, there exists a theoretical avail-able volume, but it is not currently extracted from the forest, primarily due to high transportation costs (Skogsindustrierna², 2018). In the context, it is worth highlighting that one alternative may be to leave the by-products in the cutting area, which means that a resource is added in the form of a carbon supplement to the biological cycle.

Concerning residues and by-products from forestry, almost 100 percent is being used today to produce process steam, but also to produce different chemicals and energy. The forest industry works continuously with increasing energy efficiency and the industry in-creases the efficiency with approximately one percent annually. With an increased efficiency, the possibilities of producing and further refining the by-products increases. Skogsindustrierna (2018) believes that it is essential to let the market control the use of raw material, residues and by-products.

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5.7.2 The companies’ efforts

Borealis and Perstorp are two examples of Swedish plastic manu-facturers that work with different project for renewable plastic. Borealis is the only manufacturer of PE in Sweden with facilities in Stenungs-sund. The PE that is currently manufactured in Stenugnssund com-prise of exclusively fossil raw material. It would be difficult to shift the production to bio-PE with only the existing facility. For that to happen, large amounts of bio-naphtha, which is currently not viable, would be required. Otherwise, a whole new process for processing the biomass would be needed and that would entail large investment costs.

Perstorp works with developing plastic formulations that are based on a combination of renewable and biodegradable raw material, e.g.

different kinds of starch, bio-based polyhydroxybutyrate (PHB) and fossil-based polybutylene succinate (PHB) together with the com-pany’s product Capa (based on the fossil and biodegradable polycapro-lactone, PCL) to apply it in different products. The technology for renewable Capa exists, but only in lab scale and not an industrial one.

To scale it up to a commercial level is costly and that is the same for most bio-based locations. Perstorp is therefore engaged in several research projects to find green routes to raw chemicals.

5.7.3 Swedish research on plastic from forest and agriculture Currently, utilising raw material from forestry and agriculture for manufacturing of plastic is still in the research stage. Different pro-jects are ongoing to investigate the possibilities of these raw materials.

One example is Skogskemi, a collaboration project between the forest and chemicals industries as well as academic partners, where three supply-chains were examined under a three-year period to develop drop-in chemicals from Swedish forestry to the chemical industry.

Two Swedish clusters participated, Kemiklustret in Stenugnsund and SP Processum’s biorefinery cluster in Örnsköldsvik. Three supply-chains were included based on forest raw material and the potential for upscaling to demonstrations – butanol, methanol and olefins, where olefins (ethylene and propylene) are relevant for plastic manufac-turing. The foremost conclusions from the project was that:

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• The technology exists even if upscaling must be proven for cer-tain steps.

• To be introduced, economic motivations are required.

• There are greater possibilities within the fuel area, from an eco-nomic perspective, but the uncertainty regarding the conditions is large.

• Application within chemicals and materials is currently difficult to compete with fuel, due to the support that exists for the latter.

New business models may be required.

Since Skogskemi, efforts on methanol have continued through Skogs-metanol while the effort on olefins have continued through Närodlad plast. Efforts on butanol is run by Perstorp, which has an interest in the product and is evaluating different possibilities for continuation.

Another example is the research programme STEPS – Sustainable Plastic and Transition Pathways, which is ongoing till 2020 with the target of developing plastic that is based on bio raw material. Agri-cultural products, algae and forests are possible sources for the raw material. The plastic within the project shall have desireable qualities, but also be recyclable.

5.7.4 Next generation renewable plastic

To allow a transition to renewables, it is necessary to widely examine the development of alternatives to plastic from fossil raw material, apart from the biomass that is currently utilised. One interesting example is the possibility of manufacturing plastic from carbon dioxide.

Carbon dioxide from raw material is about reducing the stable carbon dioxide first, to e.g. methanol or methane, and then refine it further. For this, hydrogen is one example that is being used. The production of hydrogen is done by cleaving water, a process riddled with large energy losses due to the overpotential that is needed for the electrolysis. Still, several initiatives and research studies show promising results. Vattenfall is for instance working for a renewable manufacturing of methanol and olefins (ethylene and propylene) from carbon dioxide and hydrogen (from water, sun or wind power).

This technology would mean a smaller land area could be used to

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produce bio-based raw material and thus entail a decreased risk of competing with food production.

Currently, the company Covestro is already using up to 20 percent carbon dioxide to produce PUR. The company has used this tech-nology in their manufacturing facilities since 2016³. Researchers from Stanford University have investigated polyethylene furandicarboxy-late (PEF) from carbon dioxide and inedible plant material (agri-cultural waste and grass) with promising results (Banerjee et al., 2016).

One approach is to transform fructose from corn syrup to FCDA, a technology that Coca Cola and other companies have developed.

Instead of using sugar from corn, the Stanford researchers have exper-imented with furfural, a compound developed by agricultural waste, which has been used for several decades. Approximately 400 000 tons is produced annually for resins, solvents and other products.

5.8 Environmental consequences