Incineration with energy recovery

Incineration with energy recovery is a thermal waste-treatment technology that reduces the volume and hazard of waste while harnessing the heat generated during combustion to produce electricity, steam or hot water. It is one of the energy recovery options within the EU waste hierarchy, placed after recycling and before final disposal in landfill.

In today's context of ecological transition, this technique plays a complementary role in the integrated management of municipal and industrial waste, especially for fractions that are non-recyclable or have no material value, helping to reduce reliance on landfilling and to generate low-carbon energy.

How the process works

Incineration with energy recovery involves several stages:

1. Reception and storage: waste arrives at the plant and is stored in enclosed bunkers with controlled ventilation.
2. Feeding the furnace: an automatic system feeds the waste into a rotary kiln or moving-grate furnace.
3. Combustion: the waste is burned completely at temperatures above 850°C for at least two seconds.
4. Energy recovery: the heat generated raises steam in boilers, which is converted into electricity or district heating.
5. Flue-gas treatment: cleaning systems remove particulates, heavy metals, dioxins and furans.
6. Management of secondary residues: ash, slag and sludge are stabilised and sent to controlled landfills or metal recovery plants.

Types of facility

• Municipal solid waste plants: handle the non-recyclable fraction of household waste.
• Industrial facilities: treat hazardous or clinical waste with a high calorific value.
• Mixed plants: combine the treatment of sludge, rejects from recycling plants and industrial waste.

Applicable regulation

European Union

• Directive 2010/75/EU on industrial emissions.
• Directive 2008/98/EC (Waste Framework Directive).
• Regulation (EU) 2020/852 on the EU green taxonomy.
• Regulation (EU) 2019/1021 on persistent organic pollutants.

Spain

• Law 7/2022 on waste and contaminated soil for a circular economy.
• Royal Decree 815/2013 on industrial emissions.
• Regional waste management plans.
• Integrated Environmental Authorisation (AAI) required for every incineration plant.

Advantages of incineration with energy recovery

Environmental

• Reduction of waste sent to landfill.
• Destruction of hazardous pollutants.
• Generation of low-carbon energy.
• Highly regulated emissions control.

Economic

• On-site energy generation.
• Lower disposal costs.
• Local job creation in operation and maintenance.
• Recovery of metals from slag.

Risks and challenges

1. Air emissions: potential release of dioxins and furans if not properly managed.
2. Ash management: slag and fly ash require special treatment.
3. Social impact: negative perception among nearby communities (the 'NIMBY' effect).
4. Competition with recycling: it must not displace efforts towards prevention and material recovery.

Environmental control and cleaning systems

Modern incineration plants use advanced technology to ensure compliance:

• Bag filters to capture particulates.
• Lime and activated-carbon injection to neutralise acid gases and absorb heavy metals.
• Wet and catalytic scrubbing to reduce NOx and dioxins.
• Continuous monitoring of emissions and furnace temperature.

Emission limits are set in Annex VI of Directive 2010/75/EU and are periodically reviewed by the European Commission through best available techniques reference documents (BREFs).

Position in the waste hierarchy

Within the European hierarchy, incineration with energy recovery is classified as recovery (operation R1) if it meets the established energy efficiency requirements. If it does not, it is considered disposal (operation D10). Improving technological and energy performance is therefore key for these facilities to be integrated effectively into the circular economy.

Relationship with the circular economy

Incineration with energy recovery complements recycling by managing waste that cannot be recovered as material. Its integration into the circular economy is based on:

• Harnessing residual calorific value.
• Recovering metals from slag.
• Minimising final landfilling.
• Generating energy for local communities.

However, it should remain the last option before landfilling, respecting the management hierarchy set by the EU. Where it does not meet efficiency criteria it functions closer to a controlled landfill in hierarchy terms.

Opportunities for improvement

• Optimising energy performance through cogeneration or district heating networks.
• Greater transparency in environmental data and public participation.
• Carbon capture technologies (CCUS).
• Use of by-products such as slag as recycled aggregates.

Conclusion

Incineration with energy recovery is an essential tool in modern waste management, combining controlled treatment with the generation of useful energy. With strict environmental regulation, technological advances in emissions control and increasingly efficient cogeneration models, it is consolidating as an intermediate transition option towards the circular economy and climate neutrality.

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