A different perspective on plastics
Plastics: industrial heavyweights
In 2015, 322 million tonnes of plastics were produced throughout the world. A high figure, although it does not come close to steel, of which 1.62 billion tonnes were produced in the same year. Nevertheless, plastics remain a heavyweight in the economy, particularly in Europe which produced some 58 million tonnes in 2015, equating to 18.5% of world production. The old continent is just behind China, which recently became the world's leading producer. In Europe, the plastics industry accounts for over 1.5 million direct jobs across close to 60,000 companies, with a total turnover of 340 billion Euros. Finally, European plastics do well in export, and reel in over 16 billion Euros in trade.
Polymers in the service of society
Plastics have become ubiquitous due to their increased and indispensable presence in our daily lives. Without them, it would be difficult to reduce the weight of our means of transport and thus make them less polluting. Without their contribution to insulation, the energy efficiency of many buildings would be greatly reduced. Many industries need polymers: 40% of the production is intended for the packaging industry, then the construction industry (20%), the automotive industry (9%), the electronics industry (6%) and finally comes the agricultural industry at 3%. The bottom line would be fantastic were it not for the 25 million tonnes of waste generated in Europe each year. Fortunately, there is rapid progress in this area and there are ever more solutions to be found.
Europe: a good student, but great disparities
Just a few decades ago, waste was not a problem. Either it was dumped in open-air landfills or, at best, it was burned in giant incinerators. Some visionaries invested in plants able to convert the heat from burning waste into electrical energy or heating. Since that time, many countries have understood the benefits of recycling, and in particular those linked to recycling plastics. Some believe that progress is too slow, but progress is happening nonetheless. However, landfilling used plastics remains the preferred option in many European countries. In 2014, 30 % of plastic waste produced in Europe* was landfilled, 40 % was incinerated and only 30% was recycled.
The performance remains noteworthy as, over less than 10 years, the landfilling of plastics has decreased by close to 40%, the recycling rate has increased by 64% and the rate of energy recovery has increased by 46%. Europe is therefore on the right track and there is good reason to believe that no more polymers will be landfilled in a dozen years' time. This is not good news for the environment or for the economy as plastic waste remains a formidable resource which it would be a shame to do without. * of course, this is simply an European average as there remain wide disparities between countries. Some countries have legislated on the matter and opted to prohibit the landfilling of plastics. Those countries achieve recovery rates close to 100%. At the other end of the scale, such rates hardly exceed 10%.
Waste too precious for a simple bin
To date, there were only two methods for recovering plastic waste: Incineration, sometimes unfortunately without energy recovery, which consists of burning the waste in household waste incinerators. The calorific potential of polymers is unrivalled and a polyethylene milk bottle has the same yield as a litre of oil. Of course, current incinerators meet all anti-pollution standards in force. Another option: recycling the waste into a material whose properties are as close to those of a virgin material. In more technical language, this conversion is called material recovery. Recyclers have various solutions available to them. Grinding down the material, washing it, calibrating it and converting it into granules so that it may once again be converted into new products.
Plastic waste can also be recovered using chemical processes. The processes make it possible to recover the raw materials used to make a polymer: either the basic monomer, or a basic petrochemical product, and to re-use them. This is called chemical recycling.
Recycling, a decision not to be taken lightly
Recovering plastics through recycling is not as easy as it might seem. First of all, they have to be collected. This is a crucial step which depends exclusively on the goodwill of all involved, i.e. industry and households. Then comes the matter of transport, whose cost and environmental impact have to be taken into account. Plastics owe some of their success to their light weight, and collecting a tonne of plastic obviously requires collecting more bottles than for a tonne of glass! Next, they need to be sorted, and this is particularly difficult given the wide range of plastics and the fact that each polymer has its own specific properties. Although it is fairly simple to sort single-material plastics, such as PET water bottles for instance, sorting objects made from various plastics is another matter entirely. In some cases, it is more economically and environmentally profitable to recover energy* from them.
* Find out more in the "Plastics viewpoints." section containing the interview with Michaël Kotschan
The sorter sharpens its eyes
However, sorting techniques are rapidly evolving. Steinert, a German company specialised in designing sorting machines, recently started selling a totally revolutionary model. To date, sorting materials such as plastics only required plunging them into a bath. Given that each polymer has a specific density, they would float or sink. At this stage, almost all that needs to be done is to collect them individually. This is a simple technique that is not always appropriate for polymers with very similar densities. Some machines are able to use optical scanning to recognise certain polymers, although they are as yet unable to differentiate between black-coloured plastics. The component at fault, the carbon black used to blacken plastics, absorbs the visible and infrared wavelengths of the optical beam.
The scanning system on Steinert's latest sorter distinguishes between materials by comparing their electromagnetic spectrum against a stock of references stored in a piece of analytical software. The analysis' reliability is guaranteed by using an ultra high definition camera able to precisely analyse the electromagnetic frequency of each of the homogenates. This enables the slightest variations in materials to be detected. The sorter is therefore able to distinguish between the various plastics and polymers (PE, PP, PVC, PS, etc.) within a flow of waste that can reach up to 1 tonne/hour.
Collecting used plastics for sorting and recycling is evidently a matter of goodwill. Some industries have high performance ratings, such as the construction industry which is the second largest consumer of polymers after the packaging industry. Out of the 10 million tonnes of plastics that it uses every year, almost half is made of PVC. Although it is of great service, the material had a rather negative image twenty years ago, as it was considered to be non-recyclable. The industry therefore took the bull by the horns and put all efforts into making PVC recyclable with its VinylPlus programme. That objective has been achieved, and the industry is extremely effective in terms of sorting and recycling processes, leading to potentially over 800,000 tonnes of PVC being recycled every year by 2020.
Manufacturers sometimes get involved in recycling too. Solvay, for instance, uses its Move4earth™ process to convert complex textile waste, such as the fabric used in airbags made from a combination of polyamide and silicone. Using a novel chemical process to separate the two constituent materials, Solvay carries out high-quality recycling of polyamides (PA6.6) without any significant loss of the material's properties. Solvay also produces a high-quality recycled polyamide intended for the automotive, construction, household appliances and leisure industries. A lifecycle assessment conducted on those recycled plastics shows 26% of the carbon footprint, savings in non-renewable resources, and a 69% reduction in water consumption compared to the use of virgin materials. Move4earth™ will be used to process the cuts from airbag production, with the prospect of soon processing used airbags.