Water from the depths of the Upper Rhine Rift can be used to generate heat and electricity, but similar mineral-rich waters are also essential for the formation of ore deposits in the region. Scientists at the Karlsruhe Institute of Technology (KIT) investigate the transport of energy and substances in the rift system in order to understand the formation of ore deposits and the formation of undesired mineral deposits in geothermal power plants.
The thermal springs and geothermal power plants in the Upper Rhine region offer researchers the opportunity to examine both the transport of heat and metals for ore deposits. Both processes, which so far have rarely been considered together, are to be examined holistically in the EMURG project (stands for Energy and Mass flux in the Upper Rhine Graben ) over the next three years.
Using geothermal water, deposits in pipes in geothermal power plants as well as ore samples and sintering from the Black Forest and the Kraichgau, the scientists research current and fossil energy and material flows in deeper layers of the Upper Rhine Rift. To do this, they look at the physicochemical properties of the water, measure its pH value and temperature and examine whether it is oxidized or reduced. They also determine its main and trace components as well as its isotopic composition. "We use some of the parameters to understand where the fluid - which contains around 100 to 130 grams of dissolved solids per liter in addition to water as its main component - comes from, which route it took and which rocks the fluids reacted with," explains Professor Jochen Kolb, Professor for Geochemistry and Mineral Resources at the Institute for Applied Geosciences (AGW) of KIT. The German Research Foundation (DFG) is funding the project for three years by financing a PhD position and with material resources.
"We know from previous studies that the Jura had fluids similar to those in the Upper Rhine Rift, and we are trying to understand whether the same processes are still taking place in the hydrothermal systems as they were about 180 million years ago," explains Kolb. “Based on the knowledge gained, it will be possible to compare all similar systems with the Upper Rhine Rift,” says the geologist.
In addition, the scientists want to get more detailed information about what causes the undesirable mineral deposits - called scalings - on the pipes of geothermal systems and how they can be prevented. Because of the precipitation and corrosion, the pipes of the geothermal power plants must be regularly serviced and replaced.
Understanding the underground heat and material flows is also crucial for the extraction of raw materials in the future. "We want to provide industry with methods for assessing the current potential of deposits," says Kolb. They could help to find raw materials that are important for the energy and mobility transition, such as germanium, gallium, lithium, indium, cadmium or cobalt, which are currently 100 percent imported. "The thermal water in the Upper Rhine region contains a relatively large amount of lithium; its extraction would give geothermal energy an additional benefit," says Kolb.
The researchers want to use rock and fluid samples to understand where the respective metals come from and how large the resource of the coveted technology metals is in the Upper Rhine Rift. Research at the AGW is integrated into the think tank “Industrial Resource Strategies” at KIT, which is supported by the state of Baden-Württemberg and industrial partners.
Possibilities of future raw material extraction by looking at hydrothermal systems that were active in the history of the earth are also the focus of four other research projects of the AGW, which the DFG supports with doctoral positions as well as travel and material costs. In Namibia and South Africa, the scientists are researching exemplary rare earth deposits, and within the DFG priority program “Dynamics of Ore Metals Enrichment - DOME” they are looking at the formation of igneous titanium and zirconium ores using the example of deposits in Greenland and Russia as well as the Mobility of gold and other metals in fluids related to active volcanism in the Greek archipelago of Santorini. The DFG is funding the five projects with around one million euros.
As “The Research University in the Helmholtz Association”, KIT creates and imparts knowledge for society and the environment. The aim is to make significant contributions to the global challenges in the fields of energy, mobility and information. To this end, around 9,300 employees work together on a broad disciplinary basis in the natural, engineering, economics, humanities and social sciences. KIT prepares its 24,400 students for responsible tasks in society, business and science through a research-oriented university course. The innovation activity at KIT bridges the gap between knowledge and application for social benefit, economic prosperity and the preservation of our natural foundations of life.