What is thermal utilisation?
Thermal utilisation refers to the recovery of energy from suitable waste fractions through processes involving high temperatures. Under certain technical and legal conditions, waste can be used to generate heat, electricity or process energy. The actual suitability of a waste stream depends, among other things, on its composition, calorific value, moisture content, contaminant load, recyclability, legal requirements and the plant technology used.
Thermal utilisation processes
Thermal utilisation processes include, in particular:
- Incineration: Suitable waste is incinerated under controlled conditions in order to generate thermal energy. Depending on the plant, this heat can be used to generate electricity, supply district heating or support industrial processes.
- Pyrolysis: Waste is treated at high temperatures with little or no oxygen. Gaseous, liquid or solid products may be generated, the use of which depends on the material, the process and the quality of the products.
- Gasification: Waste is treated at high temperatures with a limited supply of oxygen. This can produce synthesis gas, which may be used further for energy or material purposes under suitable conditions.
Suitable materials
Only suitable waste fractions are considered for thermal utilisation. Suitability depends primarily on calorific value, moisture content, contaminant content, recyclability and legal requirements. Possible material groups include:
- Household, commercial or municipal waste, provided that it has been appropriately pre-treated and is suitable for the process.
- Waste-derived fuels from suitable fractions, for example from paper, textile or wood-processing operations, provided that quality and emission requirements are met.
- End-of-life tyres or rubber-containing fractions, where utilisation is legally permissible and the plant used is designed for these materials.
- Non-recyclable plastic fractions, provided that material-recycling options have been assessed and thermal utilisation is technically and legally suitable. It should be noted that plastic content can cause fossil CO₂ emissions.
- Certain dry biogenic waste fractions, provided that thermal utilisation is appropriate in the individual case. For wet organic waste, biological processes such as anaerobic digestion or composting may also be suitable options.
Materials that are unsuitable or only of limited suitability
Not all materials are suitable for thermal utilisation. Hazardous waste, contaminated materials or substances subject to special legal requirements may only be treated in authorised plants and in compliance with the applicable regulations. Waste with a low calorific value or high moisture content may be unsuitable for thermal processes or may require pre-treatment. It should also be assessed whether reuse or material recycling should take priority for environmental and economic reasons.
Classification within waste management
Thermal utilisation is one possible recovery method, but not the only one. Depending on the type of waste, reuse, mechanical recycling, biological treatment, anaerobic digestion, mechanical-biological treatment or other processes may be more suitable. The choice of process should be based on a careful analysis. This should take into account the composition of the waste, contaminant content, energy content, recyclability, legal requirements, costs, emissions, residues and available sales or utilisation opportunities.