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Emissions of Pollutants

GRI 103, 305-7; SASB IF-EU-120a.1 / SDG3, SDG12

We closely monitor emissions to air from our sources according to current regulations for emission and air quality monitoring and the EMS system. Emissions are continuously measured in large combustion plants; in medium combustion plants (up to 50MW), periodic measurements are performed in line with legislation, or, if not available, emissions are calculated using emission factors. CEZ Group reduces the air pollutants using innovative technologies following best available techniques (BAT):

  • SO2 emissions are reduced using limestone technologies: In large facilities, wet limestone washing of flue gas is used; in small facilities, a semi-dry method with absorption in the lime slurry is used. Emissions are further reduced by replacing fossil fuels with biomass in combustion units.
  • NOx emissions are reduced by primary measures in combustion processes or by reduction techniques with ammonia water or urea.
  • Particulate matter (PM) emissions are reduced in our facilities by electrostatic precipitators or fabric filters; their efficiency is over 99%.
  • Since 2020, we have been installing technologies to capture mercury (Hg) in all our coal-fired power plants1. Since August 2021, we have been continuously monitoring mercury emissions in large combustion plants.

1) Production sites that will stop heat production by 2030 are exempt from the installation.

Between 2019 and 2023, we have reduced SO2 emissions by 74%, NOx emissions by 50%, and we are well on track to reach our target VISION 2030. The use of BAT technologies has led to a 65% reduction in particulate matter emissions in the same period.

Emissions and Specific Emissions of Air Pollutants
Emissions and Specific Emissions of Air Pollutants Unit 2021 2022 2023
Particulate matter (PM) t 823 635 558
Particulate matter per electricity and heat generated kg/MWh 0.013 0.010 0.009
Sulfur dioxide (SO2) t 7,812 6,323 5,381
Sulfur dioxide per electricity and heat generated kg/MWh 0.121 0.102 0.091
Nitrogen oxides (NOx) t 14,306 12,964 11,619
Nitrogen oxides per electricity and heat generated kg/MWh 0.222 0.209 0.196
Mercury (Hg)1 t 1.110 0.706 0.562
Lead (Pb)2 t 0.896 1.177 0.609
Volatile organic compounds (VOC)2, 3 t 17 25 22
Persistent organic pollutants (POPs)2, 3 kg   32 13

1) Continuously measured since 2021, previously one–off measurements.
2) Determined by one–off measurements.
3) Newly reported pollutants.

All of the monitored air pollutants emissions were reduced in 2023 compared to 2022. The amount of PM was reduced by 12%, SO2 by 15%, NOx by 10% and mercury by 20%.

We monitor pollutants and take measures to prevent their emissions from open-cast coal mines. We take both active and passive measures to reduce particulate emissions. Active measures include scraping or fogging equipment, mine speed restrictions, soil stabilizers and process innovations. Passive measures include terrain protection bunds, forest belts and isolation walls around mines. We pay particular attention to the prevention of fires in our mining operations. Sites prone to spontaneous combustion are treated with heavy machinery to prevent the oxidation of coal-bearing areas and the development of fires. By agreement, we provide regular cleaning of roads and areas for the inhabitants of the villages near the mines.

Air Pollution Monitoring


Beyond the scope of legal obligations, CEZ Group has provided accredited monitoring of air quality near large combustion facilities since 1994, which measures pollution with NOX, SO2, and particulate matter of different sizes (PM10 and PM2.5). The data are delivered to the Czech Hydrometeorological Institute, which publishes them in the information system on air quality in Czechia. The results of air pollution monitoring are published on the CEZ Group website.

An independent accredited laboratory also monitors air and noise pollution in municipalities affected by the operations of CEZ Group’s lignite mines. Monitoring stations in these locations provide a continual measurement of particulate matter, especially PM10. The results of the measurements are shared with the affected municipalities and governmental agencies.

Wastewater Management

GRI 306-3:2016

The residual heat is transferred to the cooling water and then to the aquatic environment by means of once-through cooling systems or cooling towers. The effluent from the once-through cooling systems, which uses approximately 70% of the total water withdrawn, represents the majority of the effluent discharged. We handle discharged water so that it does not change the conditions in watercourses that are important for the life and development of biotic communities.

Water other than from once-through cooling systems or drainage water, is treated to meet all requirements set by the water authorities before discharge to surface water. Further, water is monitored for pollutants at the outlets; selected pollutants are monitored continuously. We regularly report the results of the monitoring to relevant authorities and river basin managers.

Wastewater streams can be contaminated with a variety of water pollutants; the main parameters monitored for water pollution from CEZ Group's large combustion plants include pH, temperature, TSS (insoluble solids), petroleum hydrocarbons and RAS (dissolved inorganic salts). For E-PRTR monitoring, the following parameters are monitored: N (total), P (total), As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, halogenated organic compounds (AOX), PAHs, TOC, chloride (as total Cl) and fluoride (as total F).

The importance of each parameter depends on the quality of the raw water, the specific plant configuration and the processes used.

The only recorded incidents with leakage of hazardous substances to the environment were oil spills from distribution transformers in 2023. These are most often caused by transformer leaks or weather events (trees falling into the lines and the transformer being knocked to the ground). We try to prevent these situations:

  • Regular bi-annual transformer leakage checks, with transformers replaced if oil drops (leaks) are detected.
  • Trimming and felling of trees that are in the protection zone of the lines or at risk of falling on the lines.
  • In areas at risk in terms of water protection, transformers with a sealed vessel are preferred.

The oil spill occurred when a tree fell on a power line, leakage approximately 100 litres of transformer oil into a local watercourse. It was not possible to remediate the water pollution due to the inaccessibility of the distribution transformer station during flood state. The pollution was washed away by the floods. A subsequent assessment of the incident by a hydrogeologist concluded that the spill did not affect the quality of either surface or ground water. No fish or other organisms are known to have died as a result of the accident during the flood.

A technical fault caused a leak of about 200 litres of heating oil at the heating plant in Dvůr Králové nad Labem. The oil leaked into the plant's sewer system and into the municipal sewer system, where it was captured. No environmental impact was found. A fine of CZK 75,000 was imposed by the supervisory authority. Based on the evaluation of the fault, corrective measures were taken, which, in addition to eliminating the fault and cleaning the sewerage system, included checking the condition of the distribution system and installing an oil detection system for early warning of fuel oil leaks.

Following oil spills at the Mělník power plant in previous years, an early warning system for oil leaks was installed, thereby reducing the risk of possible contamination of surface water (the Labe River).

Soil Pollution

GRI 306-3:2016

In connection with the operation of the distribution system, a total of 1,035 litres of oils from distribution transformers leaked into the soil, mostly in connection with falling trees into power lines, technical defects or traffic accidents with damage to transformer masts. In all cases, immediate measures were taken through the Integrated Rescue System, or subsequent remediation measures were carried out by an external professional company.

Prevention of Serious Accidents

For all production sites, we have a protocol declaring that the limits of hazardous chemicals specified in the Directive 2012/18/EU of the European Parliament and of the Council on the control of major-accident hazards involving dangerous substances have not been exceeded.