From Peter Hilbert
Dresden. In the past few days, the long-awaited rain has arrived, providing fresh water for meadows and forests and causing the level of the Elbe and other water bodies to rise again. Nevertheless, this year again drought characterized the picture in the Dresden Elbe Valley for a long time. And this has been the case for a long time.
This is also reflected in the fact that Dresden's groundwater levels are still half a meter below the long-term average. This makes it all the more important for the Sachsen-Energie company to find solutions. After all, water consumption has been rising for years, explains spokeswoman Nora Weinhold.
Demand: Up to 162,000 cubic meters daily
Whereas in 2011 an average of around 102,000 cubic meters of drinking water was consumed daily, in 2015 this figure had already risen to 112,000 cubic meters. Last year, the consumption curve had already risen to an average of 124,013 cubic meters. The 2022 consumption record was reached on the hot July 20 with 162,687 cubic meters, explains the spokeswoman. Rising trend.
The trend was mainly due to industry, which was growing strongly. Bosch, for example, had built a new microchip factory in the Rähnitz industrial park Airportpark. Now builds Infineon is also significantly expanding its Dresden site. At the southeast corner of the plant on Königsbrücker Straße, a new building is being constructed for around 1,000 additional jobs by 2026. Now the Taiwanese chip manufacturer TSMC to build another plant in the Rähnitz industrial park., in which 2,000 jobs will be created.
The entire microelectronics industry in the north of Dresden already requires about 30 percent of Dresden's water, Weinhold points out. That is about as much as the Tolkewitz waterworks can treat. It has a capacity of up to 35,000 cubic meters a day.
The solution: well water for Infineon
It may seem like a contradiction that so far this year, on average, only about 114,000 cubic meters of drinking water are being consumed daily. But it is not. That's because there is an initial solution in which industrial water extracted underground flows directly into the Infineon plant. "The Saloppe water intake is designed in such a way that up to 900 cubic meters of water can be pumped every hour from bank filtrate of the Elbe," explains the spokeswoman. At full production, that would be 21,600 cubic meters a day. But that's not how much is needed at the moment.
By the middle of last year, 15 wells up to 20 meters deep had been drilled. This took place in the 1.2-kilometer-long area between the Saloppe and the Albrechtsberg Castle. Groundwater and bank filtrate from the Elbe flows through a coiled wire filter up to five meters high into the stainless steel pipe of the well and is pumped to the top. At the top, well pits were still built, but they remain below the surface.
The practice: Old Saloppe line is used
The water flows into a 50-centimeter collection pipe that runs to the Saloppe access road. A connection to the Infineon plant is available with a pipe that starts on Brockhausstraße at the Saloppe. It was already used when the waterworks in the Saloppe was still operating until 2008.
At the Hosterwitz elevated tank next to Fischhausstraße, industrial water has been pumped directly to the Infineon plant by three pumps since the end of last year. It is then treated in various stages until it reaches ultrapure water in the chip factory.
The fact that drinking water is no longer supplied there has several advantages. Saxony Energy project manager Reinhard du Vinage explained in the spring that this would save resources for the costly treatment process. In addition, substances added to the drinking water according to the ordinance would have to be removed during the treatment for the special purposes of the plant. That is no longer necessary. "Around 90 percent of the industrial water is returned to the natural water cycle in purified form after the production process by Dresden's municipal drainage system," says spokeswoman Weinhold, pointing out another aspect.
The remaining work on the Saloppe has now been completed. This means that the Elbe cycle path can be reopened. The replacement bike path will then be removed within two weeks.
The perspective: Innovative industrial water system
But it won't stop at the saloppe solution. "In the next ten to 20 years, the demand for industrial water by semiconductor manufacturers is expected to at least double due to the ambitious EU expansion plans," explains Weinhold. The share of water required by chip manufacturers is thus expected to be around 50 percent of Dresden's total water requirements in 2030. Water consumption will increase accordingly.
For this reason, Sachsen-Energie is planning an innovative industrial water system on behalf of the city. Ultrapure water can then be treated by the companies themselves. "By providing additional industrial water, we are also responding to the announced construction of a new semiconductor factory by the Taiwanese manufacturer TSMC together with other companies in the industry," she explains.
The extensive approval process has already begun, he said. Details of the industrial water system cannot be published until the authorities give the green light for the technological solution being planned. The date is still open.