Heat from an extinct volcano could be piped into homes under a plan in the Dutch city of Bolsward.
The Netherlands may be known for windmills but Ynze Salverda is no fan of the wind turbines proliferating across the country. He believes sustainable energy could be generated underground using residual warmth from the Zuidwal volcano deep under the Wadden Sea.
“It started as a crazy idea,” said Salverda, a board member of Stichting Ontwikkeling Geothermie Friesland (Stogef), a community initiative. “These big wind turbines put a lot of pressure on our landscape but when there is no wind we have a problem. I have a background in the oil and gas world, I knew that there were a few volcanoes, and the [increased] temperature is going to the coast.”
The Netherlands’ history as a major gas extractor means it has huge amounts of subsurface data. “We found out that there is a layer of porous stone, it’s nice and warm, about 90C, so wouldn’t it be an idea to use geothermal energy,” he said. “We want to take it in our own hands and work with the local government. Just like food, we need energy to be reliable, affordable and it should not be commercialised. And that’s the whole idea.”
Using a geothermal “doublet” technique, water can be pumped up from the ground in a production well and the heat extracted in a heat exchanger before the water is reinjected via an injection well.
The public energy company Energie Beheer Nederland believes 25% of Dutch heat demand could eventually be met by geothermal energy. There are 26 working non-volcanic geothermal energy projects, mostly heating greenhouses between The Hague and Rotterdam, and a national mapping project and plans to more than double geothermal production by 2030.
Phil Vardon, a professor of energy geomechanics at Delft University of Technology, is leading the science programme for a 2.5km-deep geothermal project being drilled in Delft to heat the university campus plus the equivalent of 10,000 houses.
“The volcano is a bit of a gimmick, but what it does seem to have done is to increase the temperature locally,” he said. “You can see this on temperature maps interpolated from drilling projects. One thing that isn’t so good is the ability for the water to flow – there’s a relatively limited thickness reservoir.”
Still, Energiewerkplaats Fryslân, a network of professionals supporting local energy initiatives, has published an “exploratory investigation” into the potential of 500-metre or 3km-deep structures plus a district heating system, with a total estimated cost of between €143m and €188m. Johannes Lankester, the project leader, is positive, even if the local area would have to raise 30% of the total. “Technically, it is certainly very achievable,” he said. “The heat is there but we want ownership as a community. In Frisian, we call this MienskipsEnergie [community energy].”
The local council of South-west Friesland wants to set up this public heating network and develop more alternative energy sources and is appealing for government and European help. “In around 2027 we hope to drill for geothermal heat for Bolsward,” a spokesperson said. “Geothermal is a good additional source in the desired energy mix.”
However, the Dutch mining regulator is understood to be looking carefully at mining risks in the wake of a scandal around earthquakes caused by gas extraction in Groningen. A spokesperson said there was “too little known about the initiative to estimate the risks”.
Diana Tronco, the chief executive of Inco-Drilling and an adviser to the project, believes it has potential. “There are some cases like in Groningen where people are afraid of drilling, but the advantage of geothermal is that if you drill two wells, one to extract water [and one to] inject it back, there’s a balance,” she said.
