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Walheim sewage sludge treatment plant

Questions and answers concerning the sewage sludge combined heat and power plant

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Below you will find answers to the most frequently asked questions. If you cannot find any suitable answers to your questions here, please do not hesitate to contact us at .

Questions about the plant

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In order to ascertain this, an extensive noise exposure forecast was conducted as a guide. The findings revealed that the additional acoustic load resulting from the operation of the plant meets all legal requirements and can be classified as “not relevant” according to noise control guidelines (TA Lärm).

How loud is the plant?

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The plant does not smell – this is assured by the sophisticated design. The air (so-called combustion air) needed to incinerate the sewage sludge is extracted from all odorous plant sections, creating a vacuum within the plant. The vacuum means that no odorous air can escape. In addition, the sewage sludge is delivered via airlocks, which are also extracted by suction. All of the extracted air is then fed into the incineration process, which reliably destroys all odors. During plant downtimes (for overhauls), the exhaust air is cleaned using suitable filter technology so that even then no odors can develop.

How strong is the smell from the plant?

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Most of the building will be between 26 and 35 meters tall. At its highest point it will be about 38 meters tall. The chimney will be 56 meters tall.

How tall will the building be?

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Yes, the plant is safe. It is being planned in accordance with all legal regulations, guaranteeing safe operations. Due to the operating materials and chemicals used, the sewage sludge CHP plant does not fall under the Major Accidents Ordinance (Störfallverordnung). Fire, explosion and flood protection aspects are being examined in various expert reports and the plant is being designed accordingly.

Is the new plant safe?

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The plant will operate around the clock. The sewage sludge is scheduled to be delivered from Monday to Friday between 6 a.m. and 6 p.m. Deliveries until 10 p.m. and on Saturdays will only take place in exceptional cases.

How long will the plant be in operation?

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Most of the sewage sludge recycled in the plant comes from northern Baden-Württemberg.

Where does the sewage sludge come from?

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As operators of sewage treatment plants where sewage sludge is a waste product, municipalities throughout Germany are faced with the challenge of having to dispose of between seven and eight million metric tons per year.

Who is responsible for the sewage sludge?

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The sewage sludge recycling plant will be operated by EnBW AG.

Who will operate the plant?

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Yes, the plant can locally generate green energy in the form of heat and sufficient electricity to meet its own supply needs.

Can energy be generated by the plant?

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On behalf of the Federal Network Agency, EnBW is obliged to operate the Walheim coal-fired power plant until April 2023 at the latest. We are complying with this obligation in full. The personnel planning at the site is designed for operation until April 2023. There is a lack of skilled operating personnel for operation beyond that date. Within the scope of regulatory possibilities, it was not possible to train appropriate operating personnel. From today's perspective, continued operation after April 2023 is not possible.

Would it be possible to operate the EnBW Walheim site as a coal-fired power plant beyond the winter of 2022/2023 due to the current energy crisis?

Questions about the project

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It is expected that around 20 posts will be needed to operate the sewage sludge CHP plant. Then there are posts linked to the operation of the plants already on the site, such as the gas turbine plant.

What will it mean in terms of the number of jobs if the project goes ahead?

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The plant will be housed in a new building that will be built on the site of the power plant’s existing coal dump. This is due to the status of Walheim’s coal-fired blocks as a grid reserve power plant, which means that it is currently not possible to use existing buildings for regulatory reasons.

Are there any plans to expand/convert the existing power plants?

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According to air quality control regulations, the immissions produced by the power plant are classified as irrelevant. This means that there will be no negative impact on humans, animals or the environment.

How will the project impact on local wine growing and the agricultural land in the area?

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Stuttgart Regional Council is the approval authority.

Who is responsible for approving the project?

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Current calculations assume investments for the project in the upper double-digit million range.

What does the construction of the CHP plant cost?

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Construction is expected to start in spring/summer 2024, depending on the course of the approval process, and assuming this is the case, commissioning after a two-year construction phase at the beginning of 2027 seems realistic

How long will the construction phase last?

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Yes, all EnBW sites where planning rights exist for a power plant and sites which are located in northern Baden-Württemberg were considered in order to ensure that the sewage sludge can be recycled as locally as possible. In evaluating and comparing all location options, Walheim emerged as the most suitable location for the sewage sludge CHP plant.

Were other sites considered for the construction of a sewage sludge CHP plant?

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Unfortunately, this is not possible. In regional planning policy, the entire power plant site is designated as a “priority area for regionally significant power plants.” Accordingly, any kind of use that conflicts with this policy is not permitted. Furthermore, the gas turbine located on the site will continue to operate, which means that it cannot be used for residential or commercial purposes for the time being.

Couldn’t the power plant site be used for residential or commercial areas following the decommissioning of the coal blocks?

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Since a power plant already exists at the site, it has an excellent infrastructure. It is conveniently located in terms of transport, which reduces unnecessary transport for the disposal of sewage sludge. Due to the upcoming coal phase-out, the existing power plant will no longer be needed in the future; the new sewage sludge utilisation plant will be a sensible subsequent use of the site without having to use up new land. Qualified employees are already available at the site for the operation of a complex plant.

Why was Walheim chosen as the location?

Questions about the impact on the environment and daily life

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The operation of the sewage sludge combined heat and power plant will generate additional emissions. At the same time, the decommissioning of the coal blocks will eliminate all emissions generated by the operation of the coal blocks. As a result, fewer airborne pollutants will be released into the environment in the future.

That’s because compared to the coal blocks, the sewage sludge CHP emits just 2% of the previous quantities of dust, NOx and mercury pollutants into the environment every year.

By complying with stricter emission limits than required by law, the resulting immissions of the power plant are irrelevant according to air quality control regulations. This means that there will be no negative impact on humans, animals or the environment.

Will the air quality improve or deteriorate?

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No, there will be no wastewater diverted into the Neckar. The wastewater produced in the sewage sludge CHP will be pretreated in the power plant before being discharged into the sewage treatment plant in Bietigheim-Bissingen.

Will wastewater from the power plant be discharged into the Neckar?

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Much of the sewage sludge that will be delivered to Walheim in the future is already being transported via the B27. As such, the volume of traffic is not expected to increase noticeably. Above all, there will be no delivery traffic passing through the center of Walheim. An average of 60 lorries per day are expected to drive to the power plant site to deliver the sewage sludge and remove all operating materials, especially the vapours.

How many trucks will drive through Walheim?

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There is currently no established process for recovering phosphorus from the ash. It is therefore not yet possible to say which method will be used and how dangerous it is.

How dangerous is the production of phosphorus?

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The sewage sludge can only be delivered by truck because the sewage treatment plants that provide the sewage sludge do not have the infrastructure to transport it by ship or rail. The cost of transferring it to ship or rail elsewhere would be too prohibitive due to the Walheim plant’s small supplier radius.

Alternative methods of transport are being explored for the removal of the ashes and, if possible, other transport routes will be used.

Are there alternative methods of transport to delivery by truck?

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Yes. Municipal sewage sludge mainly comes from the products that each of us flushes down the lavatory every day. Accordingly, sewage sludge is a biogenic fuel and the energy generated from it (electricity and heat) is largely carbon-neutral.

Is the energy obtained from the sewage sludge “green”?


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