Cogeneration of heat and power

Cogeneration is the simultaneous production of electricity and useful heat. In a regular power plant, the heat remaining in the generation of electricity is released to the environment, mostly through cooling towers or cooling water, whereas in a cogeneration plant, the heat is recovered for use in homes, businesses, and industry. Significantly, cogeneration plants can achieve energy efficiency levels of around 90%, and small cogeneration facilities can also be an effective way to supply energy to remote areas without the need for expensive grid infrastructure.

A trigeneration plant, or combined cooling, heat and power (CCHP), produces cooling (air conditioning) as well as heat and electricity.

Promoting cogeneration in Europe

Cogeneration can significantly help improve energy efficiency as efficiency gains can be achieved in a technologically neutral way, particularly by making use of waste heat and cold from waste incineration, power generation and industry, as well as district heat and cold transmission installations with low losses.

In line with the Energy efficiency directive, the Commission may require EU countries to carry out a comprehensive assessment of the potential for efficient heating and cooling, including the assessment of the potential for cogeneration.

Cost-benefit analyses of the cogeneration

The Energy Efficiency Directive requires EU countries must to ensure that a cost-benefit analysis is conducted of the potential of using cogeneration when they plan to build or substantially refurbish

• a heat or electrical installation with a total thermal input exceeding 20MW
• an industrial installation generating waste heat with a total thermal input exceeding 20MW
• a district heating and cooling network exceeding a total thermal input of 20MW. In this case, the intention is to see if it is cost-effective to utilise waste heat from nearby industry

Exemptions

In certain cases, the facilities exceeding 20MW thermal input described above may be exempt from a cogeneration cost-benefit analysis. Specifically

• facilities that are expected to operate for less than 1500 hours/year over a 5 year period, for instance, back-up electricity installations and peak load power plants that are only turned on during very high levels of demand
• nuclear power installations
• installations located close to a geological site for carbon capture and storage

EU governments are required to notify the European Commission of these exemptions. The notifications are available and listed per country below. 

High-efficiency cogeneration

The Energy Efficiency Directive lays down a common definition of high-efficiency cogeneration. To fit the definition, a cogeneration plant must fulfil two conditions. First, it should deliver primary energy savings compared to separate production of heat and electricity in new power plants and boilers. Secondly, the cogeneration plant should fulfil carbon dioxide emissions criterion, limiting maximum allowable carbon dioxide emissions for the plant’s energy output, measured in grams of CO₂ per kWh of output energy.

To determine the primary energy savings of the cogeneration, the directive establishes a calculation methodology that involves comparison of the electrical and thermal efficiency of the cogeneration plant, with the reference efficiency values for the separate production of electricity and heat. The Commission regularly reviews these reference efficiency values based on the latest developments in the electricity and heat generation technology. The latest study to evaluate the reference efficiency values for the separate production of electricity and heat was completed in 2023 and presented in a meeting of Group of Experts on the Energy Efficiency Directive. In the preparation of delegated act on the review of reference efficiency values, a dedicated public consultation was held.

Cogeneration data

According to Article 35(3) of the Energy Efficiency Directive, EU countries are required to report their cogeneration data annually. This data is collected, processed, and published by Eurostat in following data tables

• Capacities, production, fuel used and energy savings in combined heat and power by type of plant, generation technologies and primary energy savings levels
• Number of combined heat and power units by type of plant, generation technologies and primary energy savings level
• Fuel used in combined heat and power 

Assessments of the high-efficiency cogeneration potential

As a part of the heating and cooling assessments pursuant to Article 25(1) of the Energy Efficiency Directive, EU countries shall regularly assess their potential for high-efficiency cogeneration. These assessments can be accessed on the heating and cooling page.

Recommendations for implementation

The Commission has published several documents to support EU countries in implementing the legislation relevant for cogeneration, namely

• Commission Recommendation setting out guidelines for the interpretation of Article 26 of the Energy Efficiency Directive on heating and cooling supply 
• Commission Staff Working Document on promotion of efficiency in heating and cooling in the Energy Efficiency Directive 2012/27/EU 
• Commission Staff Working Document on interpretation of the Cogeneration Directive 
• Detailed guidelines for the calculation of electricity from cogeneration