Water and soil are important foundations of life for humans, animals and plants and consequently are an indispensable part of nature. They therefore deserve special protection from pollution and excessive use. Whenever it is essential to use water, it should always take place in harmony with one another and in a way that offers the best possible protection to the ecosystem.
Water is used as a resource within the EnBW Group for, among other things, the operation of our hydropower plants and the supply of drinking water. However, it is our conventional power plants that have the most significant impact on water as a resource. For the operation of these plants, water is withdrawn from watercourses for use in cooling systems and as process water and then fed back in. The water we use is treated and, where possible, recirculated as cooling water in order to reduce the amount of freshwater required. EnBW actively contributes to the efficient use of resources and the prevention of water and soil pollution through the environmental management systems certified according to ISO 140010ISO 14001: international ISO standard for environmental management systems and EMAS0EMAS: Eco-Management and Audit Scheme, voluntary environmental management system in accordance with Regulation (EC) 1221/2009 that have been set up within the Group.
Content
Wastewater management
Freshwater and wastewater is monitored at the company using two primary methods: continuous and discontinuous measurements. This includes measurements of quantity, temperature, oxygen and pollutants. Continuous measurements are monitored internally on a quarterly basis and reviewed by external experts or specialists at regular intervals of 3 to 5 years. These continuous measures not only ensure constant monitoring but also help us to maintain the quality of the water and to comply with permissible limits for the amount of wastewater we discharge.
Discontinuous measurements, especially pollutant measurements, are carried out by in-house laboratories and accredited external laboratories. They determine the parameters to be tested and analyze whether legal guidelines and standards are being met.
The technology used for the measurements and the frequency at which they are carried out comply with legal requirements. These requirements can be found in, among other things, the Water Resources Act (WHG), the Wastewater Ordinance (AbwV) and the self-monitoring regulations imposed by the federal states (e.g., EKVO Baden-Württemberg). Additionally, all permits issued in accordance with water law are strictly monitored by the authorities. This procedure ensures that the monitoring of wastewater at the company is not only consistent but also meets all legal requirements. It also guarantees that insufficiently treated or purified wastewater is not discharged back into water bodies.
A key component of the work carried out at our main water users is annual monitoring of their wastewater management within the framework of our environmental management systems. Our systems are certified according to ISO 14001 and EMAS. This ensures that our environmental management systems are continuously improved and meet the highest environmental standards. Annual reviews by the authorities supplement our internal and external controls and ensure that all processes are documented in a transparent and traceable way.
In addition, water and wastewater data from EnBW companies are collected and recorded in a central environmental database as part of our annual reporting.
Reducing water usage and wastewater
EnBW uses various methods to reduce, reuse and recycle wastewater. By installing modern closed-loop cooling systems and reusing operational wastewater, we are able to reduce the consumption of freshwater. Additionally, measures such as the recirculation of cooling water and the optimization of wastewater treatment plants help to improve water recycling. Annual monitoring and certification according to ISO 14001 and EMAS also help us to further reduce wastewater and the amount of water withdrawn for operational purposes.
The following section describes the procedures used at EnBW's main sites.
Innovative procedures help reduce water consumption
Most EnBW power plants already use modern closed-loop cooling systems. These reduce water demand by approximately three times compared to so-called continuous flow cooling. Furthermore, evaporation processes using less water result in more efficient cooling.
However, the best way to reduce water usage at our sites is to completely replace water cooling at our power plants. This is particularly evident at the Stuttgart-Münster power plants, where the fuel-switch plants that are currently under construction will be operated in future with modern air-cooling systems that will replace parts of the water cooling system. The new Marbach 4 grid stabilization plant and the new HKW3 power plant block in Stuttgart-Gaisburg also use air cooling systems.
In the Heilbronn and Altbach/Deizisau power plants, the new fuel-switch plants use water-saving closed-loop cooling systems.
EnBW’s plans to phaseout the use of coal by 2028 will also reduce water demand at our operational facilities. Unlike coal-fired power plants, the new gas-fired fuel switch plants no longer require water-intensive processes such as flue gas desulfurization and ash wastewater treatment.
Saving freshwater through reuse and recycling
It is possible to conserve freshwater by using operational water as cooling water. For example, wastewater from the ash wastewater treatment plant and wastewater from the full demineralization plant (VEA wastewater) at the Altbach/Deizisau power plant is reused in the cooling tower supplementary treatment plant. At the Heilbronn power plant, rainwater and operational wastewater are collected and also fed into a cooling tower supplementary treatment plant (KZA) as a freshwater substitute.
Furthermore, the condensate water required at our sites for the water-steam process in the turbines is cleaned after passing through a condensate treatment plant so that this recycled water can be fed back into the water-steam process.
Reusing and recycling cooling water reduces both the withdrawal of surface water and the discharge of wastewater. In recent years, we have been able to recycle and reuse more than 10% of our total wastewater every year at our plants.
Using the measures described above, including both the reduction and the reuse and recycling of wastewater, we have also been able to reduce the water withdrawal intensity (volume of water withdrawn per unit of energy produced). The water-saving production processes described here lead to lower overall water consumption and have a positive impact on both wastewater and the volumes of water extracted or withdrawn.
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Key figures
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2023
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2022
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Key figures
Total waste water0Total wastewater: wastewater from direct and indirect discharge (in million m³)
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2023
6.5
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2022
6.6
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Key figures
Water recycling and reuse (in million m³)
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2023
0.8
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2022
1.1
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Key figures
Water recycling rate (in %)
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2023
11
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2022
14
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Risks due to water scarcity and heatwaves
EnBW has developed emergency and crisis scenarios, along with corresponding escalation levels, for a variety of risks, including flooding, to protect operational facilities at various stages. A dedicated department with specialists in emergency and crisis management has been firmly established within the group for this purpose. EnBW assesses and monitors the risks related to water availability within its integrated risk management system (iRMA). For water risks, particularly those related to heat and low water levels, EnBW has developed its own emergency and crisis scenario in cooperation with the authorities that is applied when needed and describes the challenges of operating thermal power plants from EnBW's perspective.
Prolonged drought causes river levels to fall and the remaining river water heats up even faster as a result. Heat, drought and short rainfall events lead to increased algae growth, which in turn raises the risk of oxygen deficiency.
These different situations cause various impacts and correlatory effects. Restrictions on cooling water withdrawal and return at coal-fired power plants due to high temperatures or low water volumes lead to a reduction in cooling capacity and thus lower power generation. The reduced generation capacity in the transmission system operator's grid can impact the stability of the system and make it necessary to take countermeasures. The generation capacity of hydropower plants is also likely to fall due to the lower water flow. Ships are also forced to carry less cargo, which leads to bottlenecks in fuel supply and a further reduction in generation. Finally, the risk of oxygen deficiency means that aeration measures have to be taken at hydropower plants and this also reduces power generation.
Due to the increased frequency of heatwaves, the water flow and temperature in the Rhine and Neckar rivers has become an increasing focus of concern. Supported by predictive water balance and thermal modeling, EnBW, as an operator of thermal power plants, strives to meet the requirements of water ecology on the one hand and security of supply on the other to the best of its abilities and introduce remedial measures in cooperation with authorities. From an operational perspective, power plant deployment can also be planned according to water flow forecasts. A water balance and thermal model set up by the authorities has now become an established tool for simulating the impact on power plant deployment, and allows EnBW to adjust its operations to comply with ecological limits where necessary. An increase in the number of heatwaves could extend the periods when thermal power plants are unavailable for use due to the legal regulations. Nevertheless, the security of supply must be ensured at all times.
Impact of water withdrawal on the local population
The impact of water withdrawal for operational purposes on the environment, particularly the local population, has been thoroughly examined and taken into account in the approval procedures for issuing water permits. The withdrawal of water by EnBW has no impact on the local population. This also applies to EnBW's groundwater extraction facilities because they are not located within drinking water protection areas.
Groundwater is extracted at some EnBW power plant sites for use as process and cooling water.
The extraction of groundwater is subject to strict regulations and the provisions of the Water Resources Act (WHG). Minimum water levels must be maintained at all times. Therefore, EnBW carries out regular measurements to ensure that the water does not fall below these minimum levels.
In general, EnBW only extracts as much water as is absolutely necessary for operational purposes to avoid jeopardizing the operation of the facilities on the one hand and to minimize the amount of water extracted on the other. This approach also minimizes the charges for water usage and wastewater based on the water usage fees in each federal state.
These measures help to minimize the impact of water extraction on local users of the groundwater and promote the sustainable use of water.
Water use in water-stressed areas
Approximately 60% of EnBW's main power plant sites are located in areas with high water stress according to the WWF Water Risk Filter0WWF Water Risk Filter - Maps - as of December 2024, but they only account for about 15% of the total water withdrawal.
Around 40% of EnBW's main sites are located in areas with low or medium water stress and account for about 75% of the total water withdrawal.
The following main power plants are located in areas with high water stress:
- Altbach/Deizisau combined heat and power plant
- Heilbronn combined heat and power plant
- Walheim power plant
- Marbach power plant
- Stuttgart-Münster combined heat and power plant
- Stuttgart-Gaisburg combined heat and power plant
- Lippendorf power plant
It is important to note that all of the sites mentioned above that are located in areas with high water stress predominantly use surface water. The WWF classification is based on an assessment of groundwater and surface water resources. This classification of “water stress” does not fully reflect our actual usage conditions.
Our modern closed-loop cooling and wastewater utilization methods help to reduce freshwater withdrawal at our power plant sites, especially in areas with high water stress. We also plan to reduce the amount of water withdrawn even further in the future. Most of the water is withdrawn by EnBW at sites with low or medium water stress.
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Key figures
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2023
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2022
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Key figures
Total water withdrawal at Group0Total water withdrawal includes water withdrawn or extracted from surface/river water, well water/groundwater and drinking water. (rounded to million m³)
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2023
904
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2022
1.131
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Key figures
of which total water withdrawal by main power plants in areas with high water stress (rounded to million m³)
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2023
139
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2022
186
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Key figures
of which total water withdrawal by the Altbach/Deizisau power plant (rounded to million m³)
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2023
11
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2022
14
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Key figures
of which total water withdrawal by the Heilbronn power plants0Heilbronn power plants includes the Walheim power plant, Marbach power plant and Heilbronn combined heat and power plant. (rounded in million m³)
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2023
62
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2022
107
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Key figures
of which total water withdrawal by the Stuttgart power plants0Stuttgart power plants includes the Stuttgart-Münster and Stuttgart-Gaisburg combined heat and power plants (rounded to million m³)
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2023
58
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2022
53
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Key figures
of which total water withdrawal by the Lippendorf power plant0Lippendorf power plant: Includes the volumes of withdrawn water that are applicable to EnBW’s share of the electricity generated and marketed as part of the shareholder structure. (rounded to million m³)
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2023
8
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2022
12
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Key figures
of which total water withdrawal by the main power plants in areas with low or medium water stress0Main power plants under low or medium water stress: Rostock power plant, Rheinhafen steam power plant in Karlsruhe, power plants operated by Stadtwerke Düsseldorf AG, Awista waste incineration plant (Düsseldorf) and Ulm power plant. (rounded to million m³)
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2023
693
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2022
869
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Examples of water and soil protection
Water protection
To protect the environment, our power plants that use oil are equipped with oil-impermeable catchment and protection systems and are regularly inspected. This provides effective protection against pollution of the soil and water in the event of an incident at the plant. In environmentally sensitive areas, we have been installing transformers filled with ester fluids for many years when it is time to replace old transformers. In contrast to mineral oils, ester is only classified as being “generally hazardous to water.”
Conventional transformers in which mineral oil is used as an insulating and cooling agent are not permitted, for example, in water protection areas or in areas with stricter fire protection requirements. EnBW has been investigating transformers that use vegetable oil as an insulating agent since 2010. In June 2016, the EnBW subsidiary Netze BW started a major field test in which 102 of its stations in Baden-Württemberg were equipped with “eco-transformers“ containing vegetable oil instead of mineral oil. Our subsidiary Netze BW operates a total of around 26,500 local transformer stations, which convert electricity from medium voltage to the low voltage commonly used in households and businesses.
The major advantages of vegetable oils are that they are biodegradable and only classified as being “generally hazardous to water.” There are thus ecological advantages to operating a transformer in drinking water protection zones that uses vegetable oil. In addition, natural esters have a significantly higher flash point than mineral oils. This means that bio-oil transformers can also be installed in difficult conditions with respect to fire protection standards, such as urban areas with high population densities. Vegetable oils can be produced from renewable raw materials grown in Germany such as rapeseed or sunflowers and could become a cost-efficient alternative to standard insulating materials based on crude oil in the foreseeable future.
Corrosion protection measures
Overhead line masts made of steel are at risk of corrosion due to weathering, just like all other steel structures. In order to protect them from rust in the best possible way, they are galvanized and/or provided with protective coatings. The protective coating is renewed or repaired as required as part of maintenance work, so that the masts are kept stable and functional.
The surface of the masts is cleaned and repainted using special procedures. Today, EnBW's electricity grid operators, TransnetBW GmbH and Netze BW GmbH, only use environmentally friendly paints that do not impair soil and water functions.
Enclosure and ground cover
It is possible that the coatings on older masts still contain problematic substances. In order to avoid any danger to the environment, EnBW's electricity grid operators, TransnetBW GmbH and Netze BW GmbH, take the following protective measures:
- The masts are enclosed during cleaning.
- The ground under the masts is covered with a protective sheet over a large area.
- In sensitive locations, scientific institutes also take soil samples in order to identify any need for action that may be necessary based on the laboratory results.
These measures prevent the spread of problematic substances and the risk of damage to people and the environment.