29th November 2023

Thermal recovery - energy instead of waste

As of 1 January 2024, not just the sun, wind and water, but also waste will be considered a renewable energy source in Germany. What may be surprising at first turns out to be a clever idea upon closer inspection. The thermal recovery of waste is a kind of disposal with added value. It saves resources, works regionally and, thanks to sophisticated filtration, is hardly a burden on the environment. Even the circular economy benefits: when plastics come to the end of their life, they provide energy once again through incineration.

Amager Bakke

The Amager Bakke waste incineration plant supplies heat to 150,000 households and electricity to 62,500 homes each year.

Germany has led the way. Under the new Gebäudeenergiegesetz (GEG – Building Energy Act), thermal discharge from waste incineration will be classified as a renewable energy source. And it’s about time. After all, power plant incinerators don’t simply produce heat. They reduce waste to a minimum, destroy pollutants, relieve landfills and, incidentally, generate plenty of energy. Thanks to technological achievements, this has been done cleanly since the 1990s.

Around 50 million tonnes of waste are incinerated annually in Germany, about 12 per cent of the total amount of waste. The process produces more than 30 million megawatt hours of electricity, district heating and process steam per year – equivalent to about five per cent of the electricity produced annually. The declaration as a renewable energy source is the next step on the road to energy independence and can accelerate the departure from fossil fuels such as oil, gas and coal.

Regional processing with added value

Around 70 waste incineration plants are located in German conurbations. They process waste without it having to travel long distances, feed the energy they generate into the grids quickly, and work cleanly thanks to sophisticated filters. They are even suitable as local recreation areas, as the example of Copenhagen shows. The Amager Bakke waste incineration plant supplies heat to 150,000 households and electricity to 62,500 homes each year. At the same time, the generating plant, known as ‘CopenHill’, is a popular leisure destination with a ski slope, viewing platform and climbing wall. The thermal recovery also produces resources itself and is therefore part of the circular economy. When waste is incinerated, slag and bottom ash are left over. These residual materials are then used in the construction industry as substitutes for sand and gravel.

Thermal recovery as part of the circular economy

ALPLA is one of the world’s leading companies in recycling used plastics and invests millions of euros every year in establishing and expanding regional ‘bottle-to-bottle’ cycles. A consistent design for recycling, state-of-the-art facilities, projects about returning bottles and awareness campaigns extend the life of the materials, reduce waste and turn potential waste into a valuable resource.

But in order for the cycle to work and meet the high requirements, some virgin material is continually needed to refresh the material supply. If plastics lose too much quality or become too contaminated after repeated use, thermal recovery turns the reusable material back into energy. This, of course, also applies to waste materials and residues during the sorting and recycling processes. The recovery is worthwhile in terms of energy: one kilogram of plastic (PE or PET) has a calorific value of between 25,000 and 46,000 kilojoules – significantly more than wood pellets (18,000 kilojoules). In addition to resource-saving energy generation, the thermal recovery of plastic waste also reduces waste volumes. There are even uses for the emissions, as they can be collected using a separation technique and then prepared for use in plant breeding or in the chemical industry.

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