More energy efficiency in recycling

The plastic pollution of the oceans, the melting of the polar ice caps and the extreme weather events of recent years make it all too clear: we do not have a second world in our trunk and must actively protect ours. One way to preserve the foundations of life on our planet for future generations is to use finite and renewable resources sparingly. Recycling plays an important role in this.

But most processes for reusing materials still have decisive disadvantages in terms of energy efficiency. In the following, we will show you how recycling can become even more energy-efficient and thus better in the future.

Not all recycling is the same

The recycling loop is the path a product takes from use to recycling to reuse.

Collecting yogurt pots in the yellow bag so that new yogurt pots can be made from them again - this is generally the understanding of the recycling cycle. But with plastics in particular, reuse does not work so smoothly in many cases and, in the worst case, consumes a lot of energy. In general, experts distinguish between three recycling processes:

Material recycling
This term describes the royal road of the circular economy. Ideally, a material is collected and reprocessed so that it can be used again for the same purpose. This works optimally in the case of glass, which is melted down and processed into new glasses and bottles. Waste paper can be recycled into new paper products just as easily.

However, the mechanical recycling of plastics poses challenges for recyclers:

Mechanical and chemical recycling processes for plastic When plastic is materially recycled, its chemical structure, i.e. the structure of the polymers, is retained. The material is merely cleaned, shredded and reprocessed into new plastic parts.

Here, recyclers use dry-mechanical processes in which the plastic parts are separated from impurities by screening, magnetism, electrostatics as well as near-infrared spectroscopy.

The following washing of recycled materials removes

food residues and labels so that the plastic can be ground and melted. Finally, the last remaining impurities are filtered out in the melt, for example wood fibers or plastic grades with higher melting temperatures.

As an alternative to the recycling route described, plastics can also be liquefied with special solvents that retain their polymer structure. In this state, pollutants, additives and foreign plastics can be effectively filtered out. The remaining plastic is unmixed and forms the basic material for new products.

Plastics recycling requires single-variety collection The mechanical recycling of plastics is energy-efficient and produces high-quality recyclates. The catch: In order for plastic waste to be suitable for the process, the plastics must be collected or separated from one another in as single-variety a manner as possible.
Raw material recycling
During the feedstock recycling of plastic, its polymer chains are dissolved under the action of thermal and chemical processes. What remains are monomers or petrochemical base substances that are chemically very similar to natural gas and crude oil.

These products are either used in the manufacture of new plastics or for other industrial purposes, such as gas as a reducing agent in metal production.

A reducing agent aims to remove an unwanted substance from the raw material. Natural gas can be used to extract the substances necessary for steel production (carbon monoxide and hydrogen gas).

How is feedstock recycling of plastics to be evaluated? Compared to mechanical recycling, the process has a decisive advantage: It is also suitable for mixed and contaminated plastic fractions. It thus expands the circular economy by a portion that cannot be recycled and increases the recycling rate overall.

The disadvantage: The chemical processes used to break down the plastic polymers - e.g. pyrolysis, gasification and solvolysis - require high temperatures and sometimes operate under pressure. They therefore consume significantly more energy than mechanical recycling.
Energy recovery
Some mixed, contaminated or polluted plastics cannot be recycled either as materials or as raw materials - the only option here is incineration. The goal: to use the resulting energy while selectively separating out substances that are harmful to the environment. Here, filter systems remove the acid gases and scrubbers absorb metal salts from the slag.

To make recycling more resource-conserving and energy-efficient, it is desirable to reduce the energy recovery sector in favor of mechanical recycling.


Material recycling	Raw material recycling	Energy recovery
Yields recyclates of high quality. Here, plastic products can be recycled back into new plastic products. Requires the clean and sorted collection of plastic waste.	Suitable for mixed and contaminated waste. Increases the recycling rate by this sector. Consumes more energy than the recyclable recycling due to the thermal processes.	Suitable for contaminated and polluted plastics. Destroys plastic as a reusable raw material.

Germany: Which recycling process has which share?

Since 1994, the amount of plastics recycled has more than quadrupled, from 1.4 million tons (1994) to 6.24 million tons (2019). Material recycling accounts for 46.6 percent of this, with mechanical recycling accounting for 46.4 percent and feedstock recycling for only 0.2 percent.

52.8 percent of waste is recycled for energy, i.e. processed in waste incineration plants or used as substitute fuel. Only 0.6 percent of recycled waste ultimately ends up in a landfill.

Different recycling rates depending on origin

How well plastic waste can be recycled also depends on who collects it: For example, recycling rates for waste from the plastics processing and plastics producing industries are 94 and 82 percent, respectively. Commercial end users produce waste from which 47 percent plastic can currently be recycled.

In the yellow bag of private households , the recycling rate reaches just 33 percent. The reason for the disparity: While industry can collect the material cleanly and sorted by type, private consumers end up with mixed and contaminated waste.

The perspective: For a higher recycling rate and a better energy balance, it must be possible to separate more plastic from household waste that can be materially recycled.

What is the current energy balance in recycling?

With a view to a sustainable circular economy, recycling only makes sense if reprocessing a material consumes significantly less energy and other raw materials than creating the same material from scratch. But how do the different materials, which are particularly important in the packaging sector, fare here?

Glass: In the production of container glass, i.e. screw jars and bottles, a recycling rate of 90 percent is required by law. No wonder, because glass can be easily sorted out of household waste and is collected by the end consumer in waste glass containers.

Here, the advantage of recycling lies primarily in saving the raw materials required for glass production, for example sand, limestone, feldspar and soda. In terms of energy, waste glass recycling offers an advantage of only 0.2 percent per percent of waste glass. At 90 percent recycling, this results in an energy saving of 18 percent compared with new production.

Paper: One kilogram of new printer paper, approx. 200 sheets, requires around 5 KWh of energy and 50 liters of water in its production. If, on the other hand, it is produced from recycled paper, only 50 percent of the energy consumption and 33 percent of the water volume are required. In addition, recycled paper saves around 2.2 kg of wood as a resource per kilogram - 1.2 kg of waste paper is needed instead.

As a consumer, you can best recognize recycled products by their respective seals, for example the "Blue Angel", which certifies products made from 100 percent recycled paper.

Plastics: Here, the energy savings depend on which recycling process is used. In the case of raw material recycling, processes such as pyrolysis (combustion in the absence of oxygen) naturally require a lot of energy, while mechanical recycling is much more energy-efficient. Experts speak here of a possible reduction of 80 percent in CO2 emissions compared to the new production of petroleum-based plastics.

Aluminum: This metal is considered to be endlessly recyclable - provided that identical alloys can be collected by type. Compared with new production, up to 95 percent of the necessary energy can be saved during recycling.

How could energy efficiency in recycling be further increased?

Recycled glass saves 18 percent energy, secondary aluminum up to 95 percent and only 46 percent of plastics can be recycled in an energy-saving and valuable way - the eco-balance of recycling across the different material classes is very heterogeneous. What can be done to increase the energy efficiency of reuse?

Use green electricity: If electricity and heat consumption cannot be reduced during recycling, it does make a crucial difference which energy source is used. The higher the Share of wind and solar energy the greater the reduction in CO2 emissions.
For aluminum produced with petroleum energy versus aluminum produced with green energy, the difference is significant: 25 kg of CO2 versus 0.5 kg of CO2 per kilogram of metal produced.
Improved recycling processesFor reprocessing, recovered paper is boiled for several hours, mechanically shredded and treated with further processes, for example blowing in air to remove color residues. Here lies high potential for improved energy efficiency in innovative processes.
One of these is so-called eutectic solvents, which can dissolve long cellulose fibers from wood and waste paper for paper production in an environmentally friendly and energy-saving manner. Improved processes in the paper industry are particularly desirable because the industry currently accounts for 5 percent of total industrial energy consumption.
Other raw materials: Choosing more sustainable raw materials does not have to compromise the recyclability of a material, but does reduce primary CO2 emissions. Example: Plastics such as PET from vegetable raw materials can be recycled just as well as their petroleum-based counterparts.
In paper production, cellulose from fruits that waste in the food industry or alternative raw materials such as stone meal can replace wood as a raw material, saving energy and water.

You are curious about more information about recycling and interested in our packaging options? Just ask us, we are looking forward to your message.

Conclusion: Energy-efficient recycling needs clean waste separation, improved practices and green energy

Depending on the material class, recycling poses specific challenges for recyclers. In the paper and glass industries, recycling rates are high - here, the environmental opportunity lies primarily in the use of green energy and the development of new, more efficient manufacturing methods. For plastics, the problem settles earlier in the recycling cycle, at the point of separation and collection.

Here, methods need to be developed for recovering different types of plastic from household and commercial waste in a single sort so that a higher proportion is available for valuable recycling. We monitor the recycling sector and inform you regularly about innovations.

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