Water Resource
GRI 103, 303-1, 303-2; 303-3, 303-4, 303-5
SASB IF-EU-140a.1, F-EU-140a.2, IF-EU-140a.3 / SDG6
Responsible water management and water conservation is essential for natural ecosystems and local communities as well as for our society. Water management is governed by the Environmental Safety and Protection Policy, which includes an Environmental Management System in accordance with ISO 14001:2015. Within the framework of EMS in water management, as in other areas of environmental protection, we identify environmental risks and create conditions for their prevention and elimination.
Large combustion plants require significant amounts of water for the production of process water and technological water, cooling, power generation, wastewater treatment and hygiene purposes. The largest volumes of water within CEZ Group are utilised in the operation of coal, CCGT and nuclear power plants. Energy potential of water is utilized for electricity generation in hydroelectric power plants. During the operation of energy sources, the needs of other water users are respected - to ensure sufficient flows of streams for recreation and sports, for flooding floodplain forests and other functions of watercourses and ecosystems linked to them. The impacts of operations of the production units are determined by the scope of valid permits for water abstraction and wastewater discharges issued by the local government.
The permit conditions are set out using a combined approach based on:
- indicators reflecting water status,
- environmental quality standards, taking into account the specification of the best available techniques,
considering the use of surface water affected by wastewater (e.g., for bathing or drinking water production) so that the abstraction or discharge of wastewater does not have a negative impact on water conditions.
In the case of surface water withdrawals, we participate in the management of watercourses by paying fees to river basin managers for the water withdrawn.
Great consideration is given to water retention in the landscape in order to stabilize the level of groundwater and to the use of nature-based solutions. Examples include numerous polders in the areas of reclamation or the retention tanks at the Dukovany nuclear power plant, where the groundwater level is recharged from rainwater, which slowly percolates into the groundwater reservoirs.
In 2023, all surface water and groundwater abstraction permit conditions as well as wastewater and mine water discharge conditions were met.
Reports on compliance with the conditions of the integrated permits are published regularly through the relevant authorities. CEZ Group reports data relevant to abstraction, accumulation (storage) and discharge. This Sustainability Report also includes office buildings in which water management is represented only by drinking water consumption and wastewater quantities, which are mainly transferred to third parties. The quantity of water consumed and discharged from production facilities is measured by meters whose accuracy is tested according to metrological rules. The quality of water is determined by analyses of water samples taken and analysed by accredited bodies or a certificated bodies in line with good laboratory practice relating to analytical testing of relevant parameters and to sampling of the required type of wastewater.
Water is used responsibly to minimize the impacts on its quality and quantity in all areas of operations. Before use, water is chemically and mechanically treated to reduce its possible contamination and to ensure the required water quality necessary for the utilization in a power plant operation. After use, a part of the used water is recycled in the plants to minimize the amount of surface water withdrawn. Groundwater is used in minimal quantities at CEZ Group. It is used for the production of drinking water, or in cases where the use of surface water is not suitable.
Water consumption per generated electricity and heat stays is maintained at 1.40 m3/MWh.
Total amount of discharged water including flow for once-through cooling systems decreased from 7.91 m3/MWh to 5.65 m3/MWh. The volume of discharged wastewater excluding once-through cooling systems increased from 0.71 m3/MWh to 0.74 m3/MWh.
We reuse wastewater when possible. In 2023, the volume of wastewater reused in power plant operations was 7.5% of process water consumption. Wastewater from the nuclear plant Temelín is reutilized in the hydroelectric power plant Kořensko, II, where 2,098.56 MWh was produced in 2023.
Several production units are located in water-scarce areas as defined by Aqueduct - Water Risk Atlas. Water consumption in these areas is related to the operation of biogas plants, office buildings and photovoltaic power plants. In water-scarce areas, were taken from suppliers 2.98 thousand m3, which represents only a fraction of 416,869 thousand m3 of total water withdrawal.
Surface water is an indispensable resource in the generation of electricity for CEZ Group facilities and an indispensable cooling medium. Around three-quarters of the total surface water withdrawn is used for once-through cooling systems. The water used in this way is returned to the watercourses immediately downstream of the abstraction point.
Water from the cooling systems is also used to power water turbines when leaving power plants. Examples include hydroelectric power plants Mělník and Kořensko II. Another example of harnessing the potential of water to generate electricity is the use of the wastewater discharge turbines in Ledvice and Prunéřov.
Withdrawals of surface water for CEZ Group’s operations do not significantly impact the water volume of the watercourses involved. Maximum surface water withdrawal of plants with circulation cooling ranges from 0.02 to 8.3% of the natural flow capacity, and we can evaluate the withdrawal impacts as negligible or low. A greater impact on the flow is represented by the maximum withdrawal of surface water for the Dukovany nuclear power plant in the amount of 30.22% of the natural flow in the last year. The surface water withdrawal is carried out from the Dalešice water reservoir on the Jihlava river, which is also a recipient of wastewater. This reservoir is also used as a pumped storage hydro power plant.
| Water Withdrawn, Discharged and Consumed | Unit | 2021 | 2022 | 2023 |
|---|---|---|---|---|
| Total amount of water withdrawn | ths. m3MWh | 525,431 | 578,996 | 416,869 |
| Water withdrawn per electricity and heat generated | m3/MWh | 8.15 | 9.32 | 7.05 |
| Total amount of water discharged | ths. m3MWh | 443,277 | 491,821 | 334,126 |
| Amount of water discharged per electricity and heat generated | m3/MWh | 6.88 | 7.91 | 5.65 |
| Total water consumption | ths. m3MWh | 82,154 | 87,178 | 82,743 |
| Water consumption per electricity and heat generated | m3/MWh | 1.27 | 1.40 | 1.40 |
Note: The volume of water discharged does not include the volume of mine water discharged (7,519 thousand m3), which is considered to be groundwater, surface water and rainwater.
In 2023, only about 29% of withdrawn surface water was used for technological purposes. There is no identified impact of surface water withdrawal on biodiversity in protected areas and on the presence of specially protected plant and animal species.
Production sources withdraw surface and ground water and generally maintain small buffer reserves of both raw water and treated surface water for their own use – these are in the order of thousands of m3 at the most.
A specific case of water storage/reservoir storage is the reservoirs of pumped storage hydroelectric plants. A permanent water supply reserved for energy storage in times of surplus is maintained at the volume displayed in the following table.
| Reservoir | Water storage ths. m3(Ml) | Location |
|---|---|---|
| Homole | 427 | 49°50'25.99"N, 14°25'04.05"E |
| Dalešice | 16,150 | 49°08'21.32"N, 16°06'25.62"E |
| Dlouhé stráně | 2,720 | 50°04'54.98"N, 17°10'22.72"E |
The retention of surface water and its storage in the reservoirs can generally be considered as an anthropogenic factor affecting water status and ecosystems by changing the morphology of watercourse channels. Simultaneously, however, reservoirs fulfil other essential complementary functions serving local communities. In order to protect against the effects of the increasingly significant climate change, reservoirs are used to buffer flood waves and to ensure minimum sanitary flows as laid down in the operational schedules approved by the local authorities. In times of drought, they provide the basic living conditions for aquatic flora and fauna in water ecosystems. Some reservoirs are used not only by the local communities for various sporting activities, including fishing, but also for shipping transportation.
Wastewater is recycled with the aim to reduce the consumption of surface water. CEZ Group reuses wastewater from cooling tower blowdown, sand filter and gypsum washing, seepage water, and drainage water if the quality of the wastewater is sufficient for new use. Rainwater is captured where possible. In 2023, we achieved to reuse wastewater and rainwater in a volume equivalent to approximately 7.5% of the total amount of surface water abstracted for technological purposes.
The significant decrease in the values of the parameters water withdrawn and water discharged per electricity and heat generated is due to the decrease in production at the once-through power plants (Mělník and Skawina power plants) in connection with lower production, mainly of electricity, and partly also to the commissioning of the new cooling tower at the Hodonín power plant. Water consumption for the once-through cooling system decreased by 35% compared to the previous year.
Wastewater in the CEZ Group mainly consists of water from once-through cooling systems and other technological water incl. water from circulating cooling and a small volume of sewage wastewater. Before its release into a watercourse, industrial wastewater is treated, and its quality and amount are monitored. Sewage wastewater is discharged into municipal sewage systems managed by water and sewage management companies, or it is treated in a company water treatment plant and returned to a watercourse. Wastewater that is or could be contaminated with oil is discharged through oil separators. Wastewater from once-through cooling systems, rainfall, drainage, and other similar outlets which do not necessitate treatment are discharged directly to a watercourse. Neither priority nor priority hazardous substances as defined in the Water Framework Directive are discharged from CEZ Group facilities.
Wastewater discharges are subject to conditions set by relevant authorities. Groundwater protection requires that wastewater from electricity generation is only discharged into surface watercourses. Wastewater from once-through cooling systems represents most of the volume of wastewater discharged, and conditions for its discharge are carefully maintained to ensure the safety of life and development of aqua biotic ecosystems. CEZ Group carries out regular monitoring of discharged wastewater at all outlets. For some indicators, continuous monitoring is implemented. Our goal is to monitor the quality of wastewater and to respond promptly to any risk of quality deterioration. We regularly report the results of monitoring to relevant authorities.