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Survey for critical raw materials in Malawi East African Rift geothermal areas

In autumn 2023, an expedition to Malawi was undertaken within the framework of the research project “CRM-geothermal”. Within „CRM-geothermal“ we are looking for an environmentally friendly co-production of critical raw materials together with the provision of geothermal energy. In the East African Rift System (EARS), high levels of rare earth elements (REE), Sr, Ba and Mg are expected in waters and solids in areas with alkaline volcanic rocks, while other critical elements, including helium, have been sought in other localities. In particular, the eastern branch is the most juvenile sector and has increased geothermal potential related to hot fluids migrating along permeable faults. Malawi was traversed along the eastern arm of the EARS from north to south to collect gas, water, rock and sediment samples associated with natural hot springs. On site, physical and chemical parameters were measured in-situ and documented together with the geology, infrastructure and domestic use of the hot site. Detailed measurements were carried out in different labs in Potsdam and Bremen.

CRM-geothermal - gas geochemical results of pump tests at borehole GWDD-001 of Cornish Lithium Company, Cornwall, UK

The EU funded project “CRM geothermal”, aims to establish an overview of the potential for raw materials in geothermal fluids for a large range of CRM elements across the EU and third countries. Due to its economic importance, Helium is closely monitored, in view of its relevance for possibly emerging digital applications [1]. Therefore, during a project-related pump test on borehole GWDD-001 of the Cornish Lithium Company in United Downs, Cornwall, UK from 20/06/2023 to 22/06/2023, an gas monitoring was conducted. This comprised the logging of gas composition and the measurement of the gas-water ratio during the pumping operation. Main focus was the examination of Helium content in the course of the pump test. In addition, experiments addressing the option of online-helium extraction via a membrane-based gas extraction method, were performed. A conventional gas sampling for lab-based analyses of bulk gas composition and noble gas concentration was completed as well. The results are reported here.

Viscosity of pure and mixed NaCl and CaCl2 aqueous solutions at 293 K to 353 K and 0.1 MPa

This project has been funded by the German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV, grant agreement No. 0325217), the European Union's Horizon 2020 Research and Innovation Programme (grant agreement No. 850626) and the Helmholtz Association. In the context of the German national geoscientific large-scale infrastructure project GeoLaB (https://www.geolab.kit.edu/english/index.php). This data publication presents newly acquired viscosity data for synthetic aqueous solutions of sodium chloride (NaCl) and calcium chloride (CaCl₂), which have been prepared in a single salt and mixed form. The solutions covered a wide range of concentrations and mixing ratios representative of those encountered in geothermal settings. The data presented here span temperatures between 293 K and 353 K at ambient pressure. The measured data were obtained at the Laboratory for Fluid physics at GFZ German Research Centre for Geosciences.

Dissolved organic compounds in geothermal fluids used for energy production

This data was collected to write an extensive review on organic compounds in geothermal fluids as part of the REFLECT (Redefining geothermal fluid properties at extreme conditions to optimize future geothermal energy extraction). The data is mainly focussed on geothermal sites were organic compound data was reported in the literature. It includes data from the literature (Feldbusch, 2016; Vetter, 2012; Brehme et al., 2019; Westphal et al., 2019; Sanjuan et al., 2016) as well as own data that was analysed at the GFZ German Research Centre for Geosciences in section 3.2 (Organic Geochemistry). It comprises 130 samples from 19 different sites including DOC, organic acid anion as well as main inorganic anion concentrations, well depths, and reservoir temperatures of various geothermal sites in Europe. Due to confidentiality agreements Site names are all given in ID’s which are fully explained in the publication “Organic compounds in geothermal fluids – a review” when available. Sample ID’s are also given if the samples, both from the literature or own samples were measured at GFZ German Research Centre for Geosciences. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement nº 850626 (REFLECT).

Density of pure and mixed NaCl and CaCl2 aqueous solutions at 293 K to 353 K and 0.1 MPa

This study, which has been funded by the German Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV, grant agreement No. 0325217), the European Union's Horizon 2020 Research and Innovation Programme (grant agreement No. 850626) and the Helmholtz Association in the framework of the national German geoscientific large-scale infrastructure project GeoLaB (https://www.geolab.kit.edu/english/index.php), reports on newly acquired density data of synthetic aqueous solutions of sodium chloride (NaCl) and calcium chloride (CaCl₂), which have been prepared in a single salt and mixed form. The solutions span a wide range of concentrations and mixing ratios that are geothermally encountered. The data presented here cover temperatures between 293 K and 353 K at ambient pressure. The measured data were obtained at the GFZ German Research Centre for Geosciences.

Dissolved organic compounds in geothermal fluids used for energy production – part II

This dataset comprises 47 fluid samples from 11 geothermal sites (Germany, Austria, Iceland, Turkey, Netherlands, Belgium, French West Indies). The samples were collected within the REFLECT project (Redefining geothermal properties at extreme conditions to optimize future geothermal energy extraction). The focus with these analyses were on the organic compound composition of the fluids, since they are rarely included in the analyses of fluids taken from geothermal power plants. Understanding the organic compound composition of geothermal fluids might help to better understand chemical reactions within the fluids and might help to mitigate problems that arise with the operation of a geothermal power plant such as mineral precipitation (scaling) and corrosion of the casing and pipes.