30 Spotlight Photo: Too van Velzen Thermal storage at the VU Two wells have been drilled 160 meters underneath the VU Amsterdam’s New University Building. They do not deliver oil or gas, but warmth and cold. Once they are charged at least, and that will take a while. The charging is underway but will not be completed until next year from when the wells will be full of heat and cool. Strangely, the wells will have collected their temperatures from each other. This sounds mysterious and for many people it still is, according to Rooske Gaal, (energy coordinator at the Energy Coordination Centre of the VU Amsterdam and the Amsterdam medical centre VUmc). ‘It works somewhat like a refrigerator. A refrigerator also expels warmth from the back. Warmth is stored in underground sources during the summer months when cool air needs to rise to the buildings above. In the other way around, the cold well fills up in the winter months when warmth flows upwards. After a year of charging with and external help, the system will work independently. Possibly aided with above-ground installations at peak demands.’ Solar panels From 2004 to 2006, the VU Amsterdam already installed thermal storage under its Training Centre for Health and Wellness. Why is the second system only being installed now? ‘The need for gas-free heating only developed recently. Three years ago a number of scenarios were considered for that goal.’ Solar panels were also part of the plan, but they only offer part of the solution: ‘Even if we lay solar panels all over our roof, we will only be able to generate eight percent of the electricity we need. Thermal storage offers more energy but installation is complicated. You need to dig two wells and adapt the systems in the building, as different temperatures come out of the ground than from gas-fuelled heaters and electric air conditioning.’ Postage stamp In addition, when installing the heat exchanger storage system, you need to be very careful, especially in Zuidas. Reservoirs must not be too close to each other or they might leak heat. ‘You need to take precautions in this postage-stamp-size area of Amsterdam’, says Rooske. All the large consumers in the area do offer an advantage: they can exchange warmth and cold. ‘A circular connection can be installed around the reservoirs to supplement needs and to share external sources.’ In 2006 O|2 and Acta installed a pipe to pump cool water from thirty meters deep in the Nieuwe Meer lake. Gaal: ‘And in the future we will probably extract heat from waste.’
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