Energy recovery

Energy recovery (in Spanish, valorización energética) is one of the waste treatment options set out in the European waste hierarchy, placed below recycling and above landfill disposal.

It is a process that makes use of the energy content of non-recyclable waste, turning it into electricity, heat or alternative fuels. Although it often generates debate, it is an intermediate solution that reduces the amount of waste sent to landfill and recovers resources that would otherwise be lost.

What is energy recovery?

Energy recovery involves subjecting waste to processes such as combustion, gasification, pyrolysis or anaerobic digestion to obtain usable energy. Key principles include:

• It should only be applied to non-recyclable waste.
• It can reduce waste volume substantially (often cited at up to around 90% for incineration).
• It generates by-products (ash and slag) that require proper management.

Applicable rules

European Union

• Directive 2008/98/EC (Waste Framework Directive): sets the waste hierarchy and the definition of recovery.
• Directive 2010/75/EU on industrial emissions: environmental control requirements for incineration plants.
• Regulation (EU) 2020/852 (EU Taxonomy): helps define which recovery projects can be considered sustainable.

Spain

• Law 7/2022 on waste and contaminated land for a circular economy.
• Regional waste management plans.
• Integrated environmental authorisations (AAI) for recovery facilities.

Energy recovery technologies

1. Incineration with energy recovery: controlled combustion at high temperature, producing electricity and heat.
2. Co-incineration in cement kilns: waste used as an alternative fuel in kilns, replacing petroleum coke.
3. Gasification and pyrolysis: thermochemical processes that convert waste into synthesis gas; still developing, with potential for lower impact.
4. Anaerobic digestion: biological treatment of biowaste, producing biogas and digestate for agricultural use.

Benefits of energy recovery

• Environmental: less landfilling, use of the energy content of waste, and lower methane emissions than landfills.
• Economic: production of electricity and heat, job creation at recovery plants, and savings in municipal waste management.
• Social: greater local energy self-sufficiency and integration with district heating systems.

Criticisms and controversies

1. Pollutant emissions (NOx, dioxins, heavy metals) that must be tightly controlled.
2. Competition with recycling if incineration is prioritised.
3. Limited social acceptance near plants.
4. Ash and slag that require specific management.

Relationship with the circular economy

Although energy recovery ranks below recycling in the hierarchy, it plays a role in a circular economy system: it reduces dependence on landfill, generates energy from non-recyclable fractions, and can make use of by-products (such as ash valorised in construction). Even so, it should be applied as a last resort, without displacing investment in prevention and recycling.

Future challenges

1. Increasing the energy efficiency of plants.
2. Reducing emissions and improving public perception.
3. Prioritising prevention and recycling over recovery.
4. Innovating in lower-impact gasification and pyrolysis technologies.

Energy recovery is a necessary tool within modern waste management, reducing landfilling and using the energy content of non-recyclable fractions. It is a complementary solution that should be applied with sustainability, transparency and efficiency to support European goals on decarbonization and waste reduction. At Manglai we help companies measure their environmental impact and prepare credible sustainability reporting. Discover how Manglai can help you.