The Koepchenwerk is a historic pumped storage power plant on the Hengsteysee in Herdecke, which was put into operation in 1930. It is considered one of the first large pumped storage power plants in Germany and was named after the engineer Arthur Koepchen, who developed the idea for this type of electricity storage. The power plant was designed to use excess electricity in times of low demand to pump water into a higher storage basin. When energy demand increased, this water could then be fed back through turbines to generate additional electricity.
The Koepchenwerk was active until 1994, before being replaced by a more modern plant. The old plant is now a listed building and is an important industrial monument that represents the history of energy supply in the Ruhr area. Visitors can explore the impressive technology and architecture on guided tours. The site also plays a central role in the International Garden Exhibition 2027, where the restored plant will be presented as a cultural attraction.
The facility is located on the northern shore of Lake Hengstey and also offers an excellent view of the Ruhr Valley. The area around the Koepchenwerk is a popular local recreation destination with a wide range of leisure activities such as hiking and cycling.