Groningen, a city in the Netherlands that traces its roots back to the eleventh century, is taking a modern approach to sustainably heating its homes and residences. Last week, it opened what officials said is the largest solar thermal park in the country and the third largest in the world.
Located just outside city limits in the village of Dorkwerd, the Dorkwerd Solar Thermal Park has 24,000 solar collectors that capture sunlight and convert it to heat, rather than electricity like a traditional solar panel would.
A control system pumps water through underground pipes and into the solar collectors, which warm the water to 203 degrees Fahrenheit (95˚C). The warm water is transported back to the control station and through a heat exchanger where the heat is transferred to a roughly 211 cubic-foot (6,000 cubic meters) on-site buffer tank (the cool water is sent back to the collectors to repeat the process).
From there, WarmteStad, the city’s public utility, pumps the warm water to the Zernike Heating Plant and into its underground pipe network where it will heat an expected 2,600 homes and businesses. The system also provides hot water.
An underground reservoir was also built at the heating plant. Located 574 feet (175 meters) below ground, it can store up to 60.8 million gallons (230 million liters) of hot water. This enables heat to be stored underground during summer months when production is high and extracted during winter when demand is high but solar production is lower.
An alternative to geothermal in earthquake-prone regions
Home to one of the largest natural gas fields in western Europe, decades of gas production have left the Groningen region prone to earthquakes. As gas is removed from the porous sandstone layer deep underground, the pressure drops causing the surrounding rock to compact. This causes existing geological faults to slip, triggering earthquakes.
The region has experienced more than 1,400 tremors since the early 1990s, many of which have damaged homes and businesses. The Dutch government permanently shuttered the gas field in 2023.
It was quickly determined that a geothermal heat system, which, like gas production extracts and injects fluids deep underground, was not viable and could exacerbate seismic activity.
This drove WarmteStad, the Groningen Water Company and developers Novar, K3 and TVP solar to pursue a solar thermal solution.
The Dorkwerd Solar Thermal Park “demonstrates that Groningen can lead the energy transition despite seismic concerns. This project is a testament to innovation, courage, and collaboration,” said Jelmer Pijlman, director of Novar.
Novar, a green energy systems company that aims to have a 4-GW renewable energy portfolio by 2030, was the primary developer.
A public-private partnership
The nearly 55-acre site was built on a former dredging depot owned by K3 and its subsidiary Grondbank GMG, which specializes in processing soil and other dredged materials.
The solar installation covers 30 acres (12 hectares). The remaining 15 acres (10 hectares) were developed into a nature reserve that includes native plant species. The area will eventually be open to the public, according to Novar.
TVP Solar, a Swiss company, provided the high efficiency solar collectors and vacuum technology that enable production even on cloudy days or during winter, when there are fewer hours of sunlight.
“A project of this scale and complexity can only be achieved through intensive cooperation between governments, public utilities, and market players from the outset,” said Dick Takkebos, director of WarmteStad. “And that’s exactly what happened here.”
U.S. solar thermal future in question
The largest solar thermal plant in the U.S. is the Ivanpah Solar Electric Generating System, which commenced operations in the Mojave Desert in 2014. The 392-MW facility provides electricity to both Pacific Gas & Electric (PG&E) and San Diego Gas and Electric (SDG&E).
In January, it was announced that two of the facility’s three units would be shuttered in 2026 due, in part, to an inability to compete with lower-priced photovoltaic technology.
Similar, smaller facilities are still operating in Arizona, California and Nevada.
