“Get rid of gas through solar heat”

it stimulates the economic growth of Groningen. If residents can purchase their energy cheaper, they will have more money left over for other things. In addition, we are a pioneer, and therefore attractive to the business community and interested parties.” The solar thermal park in Groningen will be the largest solar thermal park in the Netherlands. “And even the third largest in the world. In Groningen we are a forerunner in the Netherlands and Europe in the application of this technology for district heating. They have only gained experience with this in Scandinavian countries. We learn a lot especially from Denmark.”

10,000 households

It is precisely that learning, experimenting and pioneering that Dick finds great. “Solar thermal is a heat source with a future. It is a clean, sustainable, innovative and safe solution for Groningen’s heat supply. With our heating network, we want to provide a total of more than 10,000 households with sustainable heat by 2026. This solar thermal park will soon supply heat for 2,500 of those 10,000 households. And the ambitions for the heating network will expand even further in the following years to approximately 20,000-25,000 households in the north of the city. The different neighborhoods will be connected in stages and they will switch off the gas.”

The first 5,000 Groningen households have already been connected to the heating network. In the future, we hope to provide as many homes as possible in and around the city of Groningen with truly sustainable Groningen heat with our new and clean techniques.

Summer and winter

It all sounds very logical, but how do you ensure that the heat from the park reaches Groningen households? And what about the difference between summer and winter? “To get the heat to the people, we use the existing heating network. On a sunny day, the water in the solar collectors can quickly rise to around 85 degrees. As much as possible, that heat goes directly to the neighborhoods so that people can shower with it or turn on the heater. We store heat that is not used immediately in seasonal storage. This storage is located deep underground.”

Storing the heat is very important. “In the summer the sun shines a lot and a lot of heat is generated, but we need less heat. In winter there is little sun, but we do need a lot of heat. By storing it underground, we always have sustainable heat.”

Seasonal storage

The seasonal storage consists of sand layers full of groundwater at a depth between 50-250 meters underground. This groundwater can be heated by the solar collectors to a temperature of 45 degrees. “The temperature is well maintained due to the insulating effect of the ground. The storage contains approximately 230,000 m2³ to water. You can compare that with a container of water the size of 200 Martini towers. And then also underground.”

In winter, that heat is then removed from storage. “We then heat the water with electric heat pumps to about 70-80 degrees, the temperature required for the heating network. This means that the neighborhoods always have sufficient heat in both winter and summer.”

“And that’s exactly what you want. The first 5,000 Groningen households have already been connected to the heating network. In the future, we naturally hope to provide as many homes as possible in and around the city of Groningen with real sustainable Groningen heat with our new and clean techniques,” Dick concludes.