Wesley Verschoof is the manager of Sport centrum De Blinkerd and Patrick Wagemans is the project leader on behalf of the Municipality of The Hague. They are both responsible for this project. They looked at this energy transition option a couple of years ago, before the gas crisis started. In that time, it didn’t look really worth the investment. But as soon as the gas prices went up, they looked at this idea again. An external agency made the calculations, and everybody realized that saving 170.000 m3 of gas per year is worth every investment in this project.  

How does it technically work? 

The Blinkerd will utilize sewage thermal energy, also known as riothermia or the slightly different aquathermy. Sewage water has a temperature of about 18°C in the summer and 12°C in the winter. It's a stable and reliable heat source. In the center of the buffer tank at the sewage pumping station, a submersible pump is installed to draw up the dirty but warm water and push it through a 100-meter-long pipe placed under the ground from the pumping station to the sport facility and back. 2 Other pipes are wrapped around this ‘dirty water pipe’. 1 pipe is carrying coolant (glycol) and the other pipe is filled with clean water that will be heated during the ‘flow’ within the pipe. The clean water pipe and the coolant pipe flow into the sports complex. The dirty ‘water’ will flow back to the buffer tank.

Storage in the ground 

This part of the heating plan was introduced in a later stage of the project. In summer, the sewage provides higher temperatures. In winter the temperatures are lower and more extra heat is required. To prevent heat loss, the heat will be stored in the ground at a depth of 200 meters. Two wells are drilled: one for storing heat in the summer and retrieving it in the winter, and the other for returning cooled water to the ground. This system is called aquifer thermal energy storage (ATES) and is already used to heat and cool The Hague's city hall.