Switzerland: Sustainable energy supply for Grob’s vegetable cultivation

It will probably be in the second quarter of 2018 that the pumping tests of the geothermal plant in Schlattingen will start. The plant should sustainably contribute to the energy supply of the family vegetable farm Grob. In recent months, after an oil spill, various protective measures for additional water treatment, water control, recording, water regulation and an oil filter have been installed and tested. During the approximately one-year long pumping tests, the long-term effects on thermal water are investigated under realistic conditions by varying the pumping rates.

Picture: Grob vegetable cultivation

The Grob family vegetable farm in Schlattingen has historically been heated through natural gas and oil. The total energy consumption of the farm is about 20 GWh per year, which corresponds to about 2 million liters of heating oil. In the future, the family-owned company intends to use the warm, approximately 60o deep underground water for heating the greenhouses, which was collected in the two wells that were built after the project started in 2010. The cooled and treated water will be discharged into the Rhine, in compliance with all legal requirements. For this purpose, a closed draining system and various protective measures were implemented. Last year, oil was discovered in the artesian thermal water. The examination of the oily admixtures by a specialized laboratory shows that it is natural oil, which occurs in the sediments of Northern Switzerland in small quantities.

With the now installed measures for the treatment of the deep underground water, with filter and oil separator, the oil is completely separated and retained. For the pumping test above Diessenhofen, an oil barrier will also be installed in the Rhine as a preventative measure. The pumping test is resumed only after the installed treatment plants have been tested and approved, and the required cantonal permit has been issued.

The results of the pumping test provide the basis for the license application for long-term use and to confirm the operating concept. Based on the data collected, the responsible authorities of the canton of Thurgau are expected to decide in 2019 whether and in which way the well with the thermal water can be used permanently.

An inspection unit will still be closely involved. The license application is subject to the ordinary authorization procedure, and all data is publicly accessible.

For more information:
matthias.knill@konsulenten.ch