With increasing fossil fuel prices, geothermal energy is an attractive alternative energy source for district heating and for heating industrial greenhouses. An important benefit of geothermal energy is that it has almost zero greenhouse-gas emissions, making it a sustainable energy source.
The Dutch horticultural firm A+G van den Bosch, in the greenhouse area in Bleiswijk, near The Hague, has shown entrepreneurial courage by developing the First geothermal heating plant ever in the Netherlands. The enterprise currently heats 7.2 ha of tomato greenhouses with warm water coming from a successfully drilled geothermal doublet that reaches into Lower Cretaceous aquifers at 1,700 m depth. TNO was closely involved in the pre-drill geological uncertainty assessment that led to the final drilling plan for the doublet. The aquifer had to apply to a diversity of constraints. The water temperature had to be as high as possible; it had to have a proper thickness and properties, tectonically stable and finally no producing oil field had to be in the way.