This article previously appeared via De Kleur van Geld
Near Groningen, a large solar thermal park was commissioned last year. Special panels do not generate electricity here, but heat—enough for 2,600 households. It is no coincidence that this was realized near Groningen, as an alternative to natural gas. “With this project, everything came together.”
At sunset you can spot roe deer there, and you see all kinds of birds. Herbs and plants grow in abundance. Since the former dredging depot in Dorkwerd was transformed into a solar thermal park, all kinds of flora and fauna have discovered the site. But more on that increase in biodiversity later.
The largest solar thermal park in the Netherlands was completed at the end of last year, just north of the city of Groningen. Area developer K3, supplier TVP Solar, and Novar, a developer of green energy systems, built a park here with 24,000 solar collectors that together can supply 37 megawatts of sustainable heat. Enough to provide heating and hot water for 2,600 households. Financier Triodos Bank was also closely involved in the realization of the park from the very beginning.
“We have all invested heavily in sustainable energy in recent years, such as solar and wind power. But in addition, we still face a major challenge: making Dutch homes free of natural gas,” says Harold Hofenk, Relationship Manager Energy & Climate at Triodos Bank. “This is one of the innovative projects with which we are taking steps to make that happen.”
“What concerns us, this is the future of sustainable heat.” – Jelmer Pijlman, Director of Novar
How solar thermal works
To generate heat, special panels are used, just as with electricity generation. Inside these panels are tubes through which water flows. The water flows from panel to panel and is heated further by the sun each time. Via a special heat exchanger, the heated water is transferred to the district heating network. The network contains a buffer tank in which heat produced during the day is kept at temperature for use in the evening. There is also a buffer that stores heat generated in summer and makes it available in winter—when there are fewer hours of sunshine.
“It’s a very elegant system,” says Jelmer Pijlman, Director of Novar. “We use innovative vacuum panels. Because of the vacuum, the water comes into as little contact as possible with the outside air, so very little heat is lost.” Solar thermal technology has already been applied in Denmark. Pijlman adds: “There are also a number of projects in the Netherlands on a much smaller scale. This is the first large park in our country and the third-largest in the world.”
Living warmly with district heating
A district heating network is a network of underground pipes through which hot water flows. The water comes from a central heat source, such as residual heat from a factory, geothermal energy, or—like in Dorkwerd—solar heat. The hot water is transported to homes via insulated pipes. Each home has a heat exchanger that extracts heat from the water to heat the house and produce hot tap water. The cooled water then flows back to the source to be reheated.
Because the heat is generated sustainably, this results in far less CO₂ emissions than traditional heating. It is therefore a good alternative to the use of natural gas. District heating networks are a reliable heat supply. The Netherlands has around 500 district heating networks. Altogether, about 515,000 households are connected to one. A collective district heating network in a neighborhood or district is, for one third of the built environment, the best solution at the lowest cost to make the Netherlands natural-gas-free by 2050.
Why Groningen
The location, a former dredging depot, first came into view seven years ago as a potential solar power park. Pijlman explains: “Through the public utility Warmtestad, we understood at the time that there was also a challenge to generate sustainable heat. Especially in Groningen, because of earthquake sensitivity, there is a desire to switch to natural-gas-free solutions. That’s when we proposed the idea of working with solar thermal energy.” For financing, Novar turned to Triodos Bank. Hofenk says: “This project fits us well, because it truly involved pioneering. We are already quite advanced when it comes to sustainably generating electricity, but we still have steps to take when it comes to heat.”
That heat is less developed also has to do with the fact that it is much more complicated. “It really works very differently from solar panels,” Hofenk explains. “If you generate electricity, you can sell it relatively easily. You can, so to speak, generate it in Groningen, feed it into the electricity grid, and take it out again in Maastricht. You can’t transport heat over long distances, because it cools down too much. So you can only generate heat if there is a customer nearby, for example—as is the case here—in the form of a district heating network.” For Triodos, that customer was crucial. “After all, you want to be sure that the heat generated is actually used. The district heating network for Groningen was already in place, so for this project everything came together.”
What made the project challenging was that everything had to be reinvented. “This was the first time a solar thermal park of this scale was built in the Netherlands,” says Pijlman. “That meant we had to start from scratch in every respect, and that there was also no existing knowledge at the municipality and provincial level. That naturally makes the permitting process more complex. For example, we—quite rightly—received many technical questions about the safety of the panels.” Novar also encountered practical issues during construction. “The site is a former dredging depot, and the sludge lies here in a large mound. We encountered quite a few uneven spots, sometimes even car tires and bicycles in the sludge.”
Nature comes to life
Local residents were involved in the plans, Pijlman says. “The site is nicely elevated, which means you can hardly see it from street level. At the request of residents, we added extra greenery. The surrounding community also made efforts to designate part of the area as nature. Of the 22 hectares the site covers, we use 12 hectares for the panels and 10 hectares for greenery.”
Since then, nature has flourished here, Pijlman observes. “We sowed herb mixtures, and because there are hardly any people on the site, nature has all the space it needs. It’s a wonderful bonus that this sustainable development also strengthens biodiversity.”
Only the beginning
There is a great deal of interest in the technology from both within the Netherlands and abroad. As far as Hofenk and Pijlman are concerned, this is only the beginning. “Over the past year we’ve done a lot to fine-tune the panels and the technology,” says Pijlman. “Heat was already being generated, but we are now really moving toward our maximum capacity. Now that we know how to realize this, we are of course also looking around for other suitable sites. As far as we’re concerned, this is the future of sustainable heat.”
To work more with solar thermal energy, more district heating networks are also needed. “After all, you have to be able to supply that heat somewhere,” says Pijlman. “Unfortunately, the rollout of district heating networks in the Netherlands is still not progressing very quickly. In that respect, Groningen truly had a forward-looking vision, and they are now reaping the benefits. Hopefully, catch-up efforts will be made, because we are ready to further roll out solar thermal energy.”
