Question 1

How loud is construction work at the plant?

Accepted Answer

An expert survey conducted to determine the expected construction noise during the day has shown compliance with the legal requirements of the General Administrative Regulation for Protection against Construction Noise (AVV Baulärm) in all construction phases, taking into account the noise protection measures.

During nighttime work, such as concrete finishing, the noise rating level is limited to a maximum of 47 decibels based on the A-weighted scale (dB(A)) in compliance with noise protection measures applicable to residential areas under planning law. According to current case law, no health hazard is expected from construction noise at night, even without noise protection measures.

Question 2

How long will the construction phase last?

Accepted Answer

The construction phase (building work and commissioning) will last about three years, depending on approval processes.

Question 3

How loud is the plant during operations?

Accepted Answer

A comprehensive noise forecast has shown that the noise generated in the course of operating the plant complies with all legal requirements. The noise emissions are at least six decibels (dB) below the maximum limit laid down by noise control regulations (TA Lärm).

Various noise protection measures are being taken to comply with the permissible limits, including the installation of a noise barrier for the container handling zone. In order to ensure permanent compliance with the legal noise limits, official acceptance testing will also be carried out as soon as the power plant is commissioned.

Question 4

At what times will the plant be in operation?

Accepted Answer

The plant will operate around the clock. The sewage sludge is scheduled to be delivered from Monday to Friday between 6 a.m. and 8 p.m. There will only be Saturday deliveries after public holidays – as is the case for the garbage collection, for example – or in exceptional cases. Since sewage sludge is continuously produced during wastewater treatment in sewage treatment plants, no seasonal fluctuations are expected during operation of the plant.

For temporary interruptions to operations, such as during the annual inspection, EnBW has devised a fallback concept, which involves the sewage sludge being used in other incineration plants or temporarily stored. On-site storage in Walheim outside the designated plant areas is not possible under licensing law, partly for safety reasons, but also to ensure environmental protection at the site.

Question 5

Is the plant safe?

Accepted Answer

The plant is safe because it has been designed in compliance with all legal regulations to ensure safe operation. Various expert reports consider fire, explosion and flood protection scenarios, and the system is built and operated accordingly:

In the event of faults affecting air quality, operations at the plant are temporarily suspended. This prevents any environmental damage.
Fires and smoke formation are effectively prevented and safely extinguished in an emergency. A fire safety certificate confirms compliance with building regulations.
Explosions are also prevented. The explosion protection concept meets all legal requirements.

The materials and chemicals used or produced by the plant are not classified as “hazardous substances” under the Major Accidents Ordinance (StörfallVO). Following decommissioning of the coal blocks, the plant will continue to be classified as an operating area in the lower class as per the StörfallVO (it was previously classified in the upper class).

Question 6

How tall is the plant?

Accepted Answer

The buildings at the plant will be up to 36 meters (m) tall. Its chimney will be 50 meters tall, measured from the power plant’s new level of 180.2 meters above standard zero (“Normalnull” or N.N.).

Question 7

Does the plant smell?

Accepted Answer

Thanks to the use of sophisticated technology, the plant does not smell: The air needed to incinerate the sewage sludge (so-called “combustion air”) is extracted from all odorous areas of the plant, creating a vacuum. This vacuum prevents any odorous air from escaping.

The sewage sludge itself, the smell of which is only perceptible in the immediate vicinity, is in turn delivered via airlocks, for which there is also an extraction system. All of the extracted air is then fed into the incineration process, which destroys all odors. During plant downtimes – when it is being overhauled, for example – the exhaust air is cleaned using filters so that even then no odors can develop.

Despite the sewage sludge’s very low potential for odor, additional protective measures are taken when transporting it, with all vehicles equipped with covers that effectively retain odors. In addition, the vehicles will travel directly from the sewage treatment plants to the CHP plant without any intermediate stops.

Question 8

What impact will the plant have on air quality?

Accepted Answer

The operation of the sewage sludge CHP plant will generate emissions. At the same time, the decommissioning of the site’s coal blocks will eliminate all emissions previously generated by the operation of the coal blocks. As a result, fewer airborne pollutants will be released into the environment in the future.

The new plant was put out to tender in anticipation of the latest standards of the 17th Regulation on the Implementation of the Federal Immission Control Act (BImSchV), as amended in 2024, and it exceeds its requirements.

Equipped with state-of-the-art filter technology, the planned plant also meets all air quality control regulations (TA Luft), precluding any harmful environmental impact and soil changes. This has been confirmed by independent expert surveys in the course of the approval process and is being reviewed by the responsible licensing authority.

Measurements will still be regularly taken and transparently documented in line with legal requirements to ensure the safe and environmentally friendly operation of the plant.

Question 9

Which pollutants are measured and how often are checks carried out?

Accepted Answer

The power plant will be strictly monitored. We continuously measure parameters such as total dust, carbon, sulfur oxides, nitrogen oxides, mercury, ammonia and carbon monoxide. Although it is not required by law, we also continuously record nitrous oxide (N2O) emissions. The built-in measurement equipment is tested by independent, officially recognized bodies and regularly calibrated.

In addition to continuous monitoring, substances such as heavy metals or dioxins are kept under observation in the chimney by carrying out individual measurements on a periodic basis. These are done on a recurring six-monthly or annual basis, and even more frequently during the first year of operation.

There is currently no legal standard or measurement regulation for so-called forever chemicals (PFAS) in relation to sewage sludge recycling plants. However, we are giving the responsible authorities (such as the LUBW) the opportunity to take on-site samples in order to gain scientific insights into how these substances degrade.

Question 10

Where can the measurement data be viewed and what happens if any of the figures exceed the threshold values?

Accepted Answer

The plant is set up so that the target value in the course of normal operations is always below the legal thresholds. In the event of any deviation from a target value, the control system or the control center intervenes. However, if a daily average threshold value is exceeded, it will be reported to the responsible licensing authority (Stuttgart Regional Council) no later than the next working day.

The emissions monitoring findings are generally summarized in an annual report for the licensing authority. We publish the emissions data once a year on our EnBW website to make sure that the public are given transparent information.

Question 11

Will groundwater be extracted and will the groundwater level change as a result?

Accepted Answer

EnBW would like to use the existing wells at the site for the plant’s water supply. As part of the approval process in line with immission control regulations, EnBW has examined the potential impact of this water extraction on the environment. The results show that the water extraction will not cause the groundwater level to drop.

EnBW also attaches great importance to the responsible use of water resources and ensures that the legal requirements are fully met. In a separate application for a permit in accordance with water law, all relevant aspects are therefore presented in detail and submitted to the responsible authorities for careful inspection.

Question 12

How does the former coal storage facility affect the groundwater?

Accepted Answer

Analyses performed by a specialist company have shown that the higher values recorded in a small number of places do not pose a danger to the groundwater. This assessment is based on the results of an accredited laboratory and the maximum permissible pollution levels.

A soil sample at a depth of four to five meters, taken outside the construction site and the coal storage area, detected slightly elevated heavy metal values. These probably come from foundry sands in the backfill materials. They cannot have any impact on the groundwater because a sample taken directly below the first was within normal limits when tested for heavy metal content. Groundwater was not encountered in the course of drilling.

Soil samples from the construction site were also tested. The result shows that the soil mixed with the coal dust contains more carbon, increasing the sample’s TOC (total organic carbon) content and loss on ignition value (proportion of organic and combustible substances). Since these naturally occurring substances are considered harmless, however, the presence of coal dust in the soil does not pose a problem from a toxicological perspective, although it does mean that the soil cannot be reused freely. There is thus no proof that the soil quality has been impaired as a result of coal being stored on the construction site.

The coal residue present as a result of the site’s former use as coal storage facility was removed prior to the actual excavation work and placed in heaps outside the construction site for declaration purposes.

Question 13

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

Accepted Answer

All emissions from the plant are very clearly below the values laid down by air quality control regulations (TA Luft). Accordingly, they have no relevant impact on the wine-growing areas, the agricultural soils and the municipal areas of Walheim and Gemmrigheim. There is therefore no negative impact on humans, animals or the environment.

Question 14

Where does the required sewage sludge come from?

Accepted Answer

Most of the sewage sludge delivered to Walheim and recycled at the plant comes from municipal sewage treatment plants in northeastern Baden-Württemberg, where it is a waste product. The plant is capable of processing up to 180,000 metric tons of dewatered sewage sludge annually, plus an additional 5,000 metric tons of dried sewage sludge. The dewatered sewage sludge consists of about 75 percent water and 25 percent solids. An average truckload of sewage sludge contains around 18 metric tons of water. About 36 truckloads of sewage sludge are delivered every day in the course of normal operations.

Question 15

How will the wastewater produced by the exhaust vapor be disposed of?

Accepted Answer

Before the sewage sludge is incinerated in the plant, it undergoes an efficient drying process. The wastewater produced by the exhaust vapor during this process is carefully collected, condensed and treated. Only the water content that remains after the drying process ends up being incinerated along with the solids. This resource-saving process improves energy efficiency and minimizes the environmental impact. Based on current plans, the wastewater produced by the exhaust vapor will then be transported by truck to the sewage treatment plant in Heilbronn, where it will be professionally treated. As a further option, EnBW would support the construction of a pipeline to the treatment plant in Nesselwörth for this wastewater.

Question 16

What does the transport of sewage sludge to and from the plant mean for traffic?

Accepted Answer

Sewage sludge is already being transported today, so this is a case of rerouting traffic rather than creating additional traffic. The construction of the plant in Walheim will lead to a considerable reduction in the total mileage because sewage sludge currently has to be transported over very long distances, sometimes up to 500 km, to Lippendorf brown coal power plant near Leipzig.

Much of the sewage sludge that is set to be brought to Walheim in the future is already being transported via the B27. No noticeable increase in the volume of local traffic is therefore expected. Above all, no delivery traffic will pass through the center of Walheim. An average of 60 trucks per day will visit the power plant site to deliver the sewage sludge and take away all operating materials, particularly the wastewater produced by the exhaust vapor. You will find further information in the answer to the question about the route.

EnBW has also commissioned an independent report to examine the potential impact of the project on local transport. It looked at several traffic counts as well as official data. The findings revealed that although additional traffic is created, there is no negative impact on the traffic junctions’ ability to cope. EnBW is also prepared to talk to the municipalities about a sewer force main to Nesselwörth sewage treatment plant in order to reduce truck traffic.

Question 17

Can traffic be reduced by drying the sewage sludge beforehand?

Accepted Answer

Although drying sewage sludge can reduce traffic, the quality of the sewage sludge is significantly influenced by how a sewage treatment plant is operated and managed. EnBW and its transport partner MSE therefore have no direct influence on any processes or optimization measures within the sewage treatment plants. Rather, as service providers, they are responsible for professionally recycling the sewage sludge that has already been produced.

The degree of dryness essentially depends on two key factors, one of which is the technical capabilities of the sewage treatment plants, the other being the composition of the sewage sludge. Both are under the control and responsibility of the sewage treatment plant operators.

EnBW nonetheless supports all efforts by sewage treatment plant operators to increase the degree of dryness, not least because a higher degree of dryness also means less transport volume, which in turn leads to fewer truck journeys and lower environmental pollution levels. EnBW is therefore prepared to engage in constructive dialogue with all partners. The aim is to work together to find the most efficient and environmentally friendly solutions for the entire process chain.

Question 18

What route do the trucks take?

Accepted Answer

Since an increase in traffic can be stressful for the affected residents, the necessary journeys and routes of the trucks were examined in a traffic report. A comparison of the estimated additional journeys with the current traffic volume has found that the additional volume is in the low single-digit percentage range and is therefore not considered significant. Most vehicles will travel along the A81 and via highways:

Traffic will not pass through Walheim itself, but will instead take the B27 and drive along Mühlstraße directly to the access road leading to the power plant site.

Traffic will also not pass through Gemmrigheim, but will instead travel along the K1625 north of the town and over the Neckar bridge.

In Kirchheim, the majority of the traffic will only travel through the southern industrial area before turning onto the B27 coming from the Neckar bridge via Max-Eyth-Straße. Only a small, unavoidable part of the traffic will use the B27 passing through the town.

Question 19

Are there any alternatives to delivery and collection by truck?

Accepted Answer

The sewage sludge can currently only be delivered by truck because the sewage treatment plants that provide the sewage sludge do not have the necessary infrastructure to transport it by ship or rail. The cost of transferring the sewage sludge to ships or trains elsewhere is very high due to the small delivery radius around the plant in Walheim. EnBW is nonetheless continuously examining the rail transport option, depending on the location of the sewage treatment plants.

Rail transport was also considered for the removal of the sewage sludge ash, but there are no plans to examine this option in greater depth for the time being. This is partly due to the fact that the exact location of the future southern German recycling plant has not yet been determined. In addition, transporting the ash by rail would only have a minor effect on efforts to reduce traffic.

Instead, the focus of the investigations is on looking at alternative transport routes for the wastewater produced by exhaust vapor (from the drying process). One particularly environmentally friendly option would ideally see it being channeled to the Bietigheim-Bissingen sewage treatment plant via a pipeline. EnBW is also looking at the possibility of transporting the wastewater by rail to Heilbronn. Even if neither of these two options are viable, an application to transport the sewage sludge by truck has been submitted and approved so that operations can run smoothly for now.

Question 20

Who is responsible for disposing of the sewage sludge?

Accepted Answer

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

Question 21

Why is the task of recycling sewage sludge not spread over several locations?

Accepted Answer

Decentralized treatment or incineration of sewage sludge in many small plants is neither economically nor technically feasible. In Baden-Württemberg, there is not yet enough capacity to incinerate sewage sludge, which is why it currently still has to be transported over long distances. The quantities of dewatered sewage sludge and dry sludge agreed with the partner company for sewage sludge ash recycling also correspond to the sludge volume from our catchment area and reflect the actual proportion produced in municipal sewage treatment plants.

The fluidized bed incinerator technology chosen for the new plant is safe, reliable, economical and meets the current legal requirements for controlling air pollution. Compared to older systems, it also features improvements that reduce environmental pollution caused by odors and harmful emissions. These include the ability to take delivery of the sewage sludge in the building with airlocks, activated carbon filters for silo air extraction and treatment of the wastewater produced by the exhaust vapor. Alternative processes such as pyrolysis or hydrothermal carbonization have generally only been tested on a small scale. They require additional energy and are therefore less efficient, not to mention further disadvantages in terms of reliability and the usability of the ashes.

Question 22

Why was Walheim chosen as the location for the plant?

Accepted Answer

EnBW examined all its sites in northern Baden-Württemberg where planning rights exist for a power plant so that it could recycle the sewage sludge as locally as possible. Walheim proved to be the best location for the new plant:

Since there is already a power plant on the site, it has an excellent infrastructure.
The site is conveniently situated, reducing unnecessary journeys to dispose of the sewage sludge.
Due to the impending coal phaseout, the existing power plant on the site will no longer be needed, freeing it up for a new purpose.
The new sewage sludge recycling plant is a sensible way of using the existing site without having to develop new land.
There are already well-qualified employees on the site who can operate the new plant
During the construction phase, the location of the site on the Neckar makes it possible to transport major components along the water that are too big to be transported by road.

Question 23

Were alternative locations to Walheim also examined?

Accepted Answer

EnBW concentrated its search on the northeastern part of Baden-Württemberg. There is an as yet unmet need here to recycle regional sewage sludge. Both industrial sites and existing power plants owned by EnBW were considered. The advantage here is that no new areas of land are sealed, existing infrastructure can continue to be used and investment costs are kept as low as possible. With this in mind, Marbach, Obrigheim, Heilbronn and Walheim came under consideration:

Marbach and Obrigheim were ruled out due to a lack of space and unfavorable conditions relating to planning law as well as the staff composition and infrastructure.
Heilbronn didn’t have the required planning permission. Furthermore, due to a lack of space, the plant could not be completed in time for the construction of the fuel switch project (which involves replacing coal power plants with modern H2-ready combined cycle gas turbine plants).
Walheim was therefore chosen as the most suitable location (see question above).

A new building in a different location would require a higher level of investment and involve a more complex approval process – both factors that would have a negative impact on the profitability of the project. The same also goes for sites at existing sewage treatment plants because EnBW does not own any.

Question 24

Will the phosphorus from the sewage sludge be recovered in Walheim?

Accepted Answer

In so-called mono-incineration plants, the sewage sludge is incinerated on its own without any other fuels. The phosphorus is then recovered from the ash by specialized companies elsewhere rather than on-site, ensuring that EnBW and its subsidiary MSE meet all legal requirements. What’s more, the companies are making an important contribution to the circular economy and the conservation of resources with this process. After conducting a thorough economic and environmental analysis, EnBW has therefore decided against building a phosphorus recovery plant in Walheim.

The reason for this lies in the requirements for economic operation: Such plants need at least 30,000 metric tons of sewage sludge ash per year. However, only about 20,000 metric tons are produced at the Walheim site, which means that an additional 10,000 metric tons of ash would have to be delivered from other plants. These additional loads would significantly increase traffic in the region. Out of consideration for local residents and with responsible site planning in mind, EnBW has therefore decided not to build a phosphorus recovery plant in Walheim.

As part of a development partnership, some of the sewage sludge ash is treated at a plant in Schkopau. The rest will eventually be processed at a future plant in southern Germany. Until this plant goes online, the ash will be safely stored at an interim storage facility via approved recycling paths. In line with the current legal situation, phosphorus must also be recovered from this temporarily stored ash, which can easily be done from a technical perspective.

Question 25

Who will cover the cost of recycling the phosphorus?

Accepted Answer

If operators of municipal sewage treatment plants put the task of recycling their sewage sludge out to tender, the cost of subsequent phosphorus recycling from the ash is already included in the price. In this case, there are no additional recycling costs for the treatment plants supplying the sewage sludge.

Question 26

Who is responsible for approving the project?

Accepted Answer

Stuttgart Regional Council is the approval authority. EnBW is working closely with the responsible authorities to secure all the necessary permits in good time. If there are delays in the approval process, however, this could affect the project timetable. This will not have any bearing on the planned investment for the time being.

In order for the plant to be operated in compliance with all legal regulations, the Federal Immission Control Act requires a second partial permit in addition to the first partial permit already granted for the construction of the plant. EnBW is planning to submit the corresponding application in 2026. Permits in accordance with water law are also required, covering the environmentally friendly discharge of water into the Neckar, for example.

Question 27

How much is it costing to build the plant?

Accepted Answer

EnBW is bearing all the costs for the construction of the plant. The project is therefore being developed without public funding. Current calculations assume an investment in the lower treble-digit million range. This investment demonstrates EnBW’s long-term commitment to establishing a sustainable circular economy in Baden-Württemberg.

Question 28

What will the new plant mean in terms of the number of jobs?

Accepted Answer

It is expected that around 20 posts will be needed to operate the new plant. Then there are the other posts needed to operate the existing on-site facilities, such as the gas turbine plant.

Question 29

What are the advantages for residents of Walheim?

Accepted Answer

The future CHP plant presents a wide range of opportunities for Walheim and its residents:

Once the plant is commissioned, trade tax will rise again to a similar level as in previous years when the coal power plant was still in operation, which means that a mid-range six-figure sum will flow into the municipal treasury every year – income that will benefit the entire community and thus all Walheim residents.
The long-term retention of the location will secure jobs in the region. It is expected that around 20 posts will be needed to operate the new plant. Then there are the other posts needed to operate the existing on-site facilities, such as the gas turbine plant.
The promised dismantling of the prominent chimney currently in place will improve the landscape. The new chimney will only stand 50 meters (m) tall, measured from the power plant’s new level of 180.2 m above standard zero (“Normalnull” or N.N.).
A possible pipeline to the Bietigheim sewage treatment plant would simplify the process of transporting the wastewater produced by the exhaust vapor during sewage sludge incineration. This would allow Walheim to decommission its own municipal sewage treatment plant, which would render its costly modernization measures unnecessary and reduce wastewater fees.
The environmentally friendly heat generated secondarily by the plant is available as a sustainable energy source for a municipal local heating network – one important potential way of achieving the energy transition at local level. The plant is being built with the necessary technical setup for heat extraction, including a connecting pipeline.

Question 30

Will the coal power plant continue to operate alongside the new plant?

Accepted Answer

On behalf of the Federal Network Agency, EnBW was required to operate Walheim coal power plant in the so-called grid reserve until March 31, 2025. Both the Walheim 1 block and the Walheim 2 block have now been officially decommissioned since April 1, 2025.

Question 31

Are there any plans to expand or convert the existing plants?

Accepted Answer

The new plant will be housed in a building that will be specially constructed on the site of the former coal dump, which has been cleared. Due to the status of the old Block 2, which is set to remain in operation as a grid reserve power plant until the end of March 2025, the use of existing buildings is not possible for regulatory reasons.

Question 32

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

Accepted Answer

The entire power plant site is designated in regional planning policy as a “priority area for regionally significant power plants.” Accordingly, any kind of use that conflicts with this policy is not permitted.

In addition, the gas turbine on the power plant site will continue to operate independently of the decommissioning of the coal blocks, which means that it cannot be used as residential or commercial space.

Question 33

What technology has been used as a basis for the plant?

Accepted Answer

The state-of-the-art plant is designed for the mono-incineration of sewage sludge using fluidized bed technology. This method of recycling sewage sludge is reliable, efficient and established in Germany.

EnBW and its subsidiary MSE are constantly monitoring all aspects of the market and new industrial development opportunities. There is evidence that incineration has historically been the main and most reliable way to dispose of municipal sewage sludge – and remains so. This is also reflected in the approach taken by almost all municipalities in Germany, particularly where plants are built by municipal consortia. At present, the method is being successfully used at 23 of 28 existing plants in Germany.

One particular advantage of the technology is the high quality of the ash produced, forming an optimal basis for future phosphorus recycling. The technology is also constantly evolving, which means that the planned plant in Walheim features significant improvements compared to older sewage sludge mono-incineration plants with a stationary fluidized bed. One example of an improvement is the flue gas cleaning system, which effectively reduces pollutants and comfortably meets the stricter emission limits introduced in 2024, in some cases even falling below them.

More modern methods, such as pyrolysis, have not yet been technically perfected and are highly susceptible to failure, which can compromise the safe disposal of sewage sludge. Most of them are still undergoing testing and cannot yet be scaled up.

The decision to build a central sewage sludge treatment plant also has economic advantages: The optimized processes help to keep operating costs low compared to running several smaller, decentralized plants. This cost-efficiency will directly benefit local residents because it helps to keep municipal wastewater charges stable.

Question 34

Can electricity and heat be generated by the plant?

Accepted Answer

Since energy is released during sewage sludge incineration, the plant can generate sufficient electricity to meet its own supply needs as well as useful heat. To this end, the plant is technically equipped with a waste heat boiler, a steam turbine and a heat extraction option. The plant generates a surplus of electricity and heat. According to the approval application, it thus meets the definition of a combined heat and power plant pursuant to the 4th and 17th Regulation on the Implementation of the Federal Immission Control Act (BImSchV).

Question 35

Can the plant play a key role in energy generation?

Accepted Answer

Dewatered sewage sludge, such as that which comes from sewage treatment plants, is still a very moist fuel (approx. 75% water content) and also contains components of substances that cannot be used for energy purposes, such as sand. A large part of the energy from the sewage sludge incineration is therefore used directly in the plant, especially the heat for drying the sewage sludge prior to incineration and the electricity generated to meet the plant’s own needs.

If the delivered sewage sludge meets the necessary criteria, the plant does not require any additional fuel and generates more electricity than it needs itself. This makes the planned concept in Walheim sustainable because other technologies used to recycle sewage sludge are not self-sufficient in energy terms and require fossil fuel.

Question 36

Will the plant replace the power generated by the previous coal-fired blocks at the site?

Accepted Answer

With an electrical output of around 1.7 megawatts (MWe), the plant efficiently uses the process heat produced during sewage sludge treatment to generate electricity. Around 0.3 MWe of this is fed into the public power grid, with the remaining amount used to operate the plant. The plant is therefore not intended to substitute the electricity generated by the previous coal-fired blocks at the site, which together supplied around 250 MWe.

Rather, the project represents a forward-looking realignment of the Walheim site, with the existing infrastructure still being put to practical use while at the same time making an important contribution to the regional circular economy. This transformation typifies the shift away from conventional electricity and heat generation to integrated, sustainable solutions aimed at mastering the challenges of our time.

Question 37

How can the heat generated during sewage sludge incineration be used?

Accepted Answer

Some of the heat generated is used internally to increase efficiency, while excess heat could be used externally. The plant is therefore being built with the necessary technical setup for heat extraction. A district heating pipe has already been built near the site boundary with Walheim and could be extended from there. The plant can continuously extract up to four megawatts of thermal output (MWth). With a typical heating load of 16 kW for older houses, around 250 houses could be supplied exclusively with heat – or even more depending on the condition of the buildings.

In Walheim, however, there is currently no local heating network, which means that there are also no concrete pipeline route plans. The results of the municipality’s ongoing municipal heat planning process will determine whether one will be built. EnBW is therefore offering support to create such a network. The exact conditions and prices for supplying heat also need to be discussed because they will depend to a considerable extent on the number and location of households participating. EnBW already operates local heating networks nearby, which could potentially be supplied by the plant if Walheim cannot devise its own local heating concept.

Question 38

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

Accepted Answer

Municipal sewage sludge mainly comes from the waste that is flushed down the lavatory every day. It is thus a biogenic fuel and the electricity and heat generated from it are largely carbon-neutral and therefore “green.”

Plant capacity	around 180,000 t/a of dewatered sewage sludge (equivalent to 50,000 t/a of dry matter) and around 5,000 t/a of dried sewage sludge
Dry matter content of delivered sewage sludge	20-30% dry matter
Throughput	approx. 20 metric tons of dewatered sewage sludge per hour
Operating time	over 8,000 hours per year
Electrical output	approx. 1.7 megawatts electrical
Local heating	up to 4 megawatts thermal

End of Q2 2028	Commercial commissioning
Q3 2027	Start-up phase
2026	Installation of plant technology
June 2025	Receipt of the 1st partial permit
Q2 2025	Start of shell construction work
February 2025	Bored piles for the foundations
October 2024	Approval for advance construction work to begin
November 2023	Completion of documentation for the approval application
March 2023	Approval application checked by the authorities to ensure it is complete
February 2023	Approval application submitted
26 October 2022	Scoping meeting* held by Stuttgart Regional Council
Start of 2022	Dialogue with the municipality
2020/2021	Early public consultation process, presentation to the Municipal Council, expert reports produced

Walheim sewage sludge combined heat and power plant

Sewage sludge utilisation

Project introduction

Technology

Specifications

Approach

Project phases

Construction Diary

Frequently asked questions