Geothermal fluids often carry high amounts of elements that the EU considers as 'critical' raw materials (CRM). Preliminary calculations show that even a single well has the potential to produce single-digit percentages of the EU needs. Combined extraction of heat and minerals maximises returns on investment, minimises environmental impact, requires no additional land use, leaves no mining legacies, has near-zero carbon footprint, and enables domestic supplies of CRM. To assess overall supply potential, CRM-geothermal will enlarge an existing geothermal fluid atlas by collecting new data and sampling wells for their CRM content in Europe and East Africa. The potential of different geological settings for combined extraction will be evaluated. Extraction/separation techniques exist, but need to be adapted to the harsh conditions of such systems (high temperature, pressure and salinities). Combinations of materials and flow-schemes will be assessed at lab-scale to optimise systems for different geothermal settings and CRM. A modular, mobile plant will be developed and deployed at existing geothermal sites to conduct pilot studies, investigating upscaling and system integration. The technological developments will be accompanied by assessments of environmental and social impacts to ensure good governance. An UNFC/UNRMS compliant reporting template will be developed to create trust among investors, regulators and the public. The project will advance key reference points for stakeholder engagement, in order to obtain and maintain a 'social license to operate'. Combined extraction creates new business opportunities for both SMEs and larger companies, and its economics under likely future market developments will be investigated with a view to proposing suitable business models. CRM-geothermal will open up a potentially huge untapped resource and deploy solutions to help Europe fulfil the strategic objectives of the EU Green Deal and the Agenda for Sustainable Development.

The efficiency of geothermal utilisation depends heavily upon the behaviour of the fluids that transfer heat between the geosphere and the engineered components of a power plant. Chemical or physical processes such as precipitation, corrosion, or degassing occur as pressure and temperature change with serious consequences for power plant operations and project economics. Currently, there are no standard solutions for operators to deal with these challenges. The aim of REFLECT is to avoid the problems related to fluid chemistry rather than treat them. This requires accurate predictions and thus a thorough knowledge of the physical and chemical properties of the fluids throughout the geothermal loop. These properties are often only poorly defined, as in situ sampling as well as measurements at extreme conditions are hardly possible to date. As a consequence, large uncertainties in current model predictions prevail, which will be tackled in REFLECT by collecting new, high quality data in critical areas. The proposed approach includes advanced fluid sampling techniques, the measurement of fluid properties at in situ conditions, and the exact determination of key parameters controlling precipitation and corrosion processes. The sampled fluids and measured fluid properties cover a large range of salinity and temperature, including those from enhanced and super-hot geothermal systems. The data obtained will be implemented in a European geothermal fluid atlas and in predictive models that both ultimately allow to adjust operational conditions and power plant layout to prevent unwanted reactions before they occur. That way, recommendations can be derived on how to best operate geothermal systems for sustainable and reliable electricity generation, advancing from an experience-based to a knowledge-based approach.