The project work started with the formulation of the conceptual framework. The objective of this work phase was to synthesise our knowledge about ultra-deep (> 4 km) metallic mineralisation that could be suitable for the CHPM technology, and to reveal data gaps.
The results from laboratory experiments showed evidence that relatively ‘mild’ leaching agents are capable of liberating metals into the recirculating fluid within an EGS. Surface modification of carbon-based nano-particles allowed metals to be adsorbed, both in acid and alkaline pH regions.
High-pressure, high-temperature metal recovery experiments proved that metals can be successfully electrodeposited at pressures up to 5 MPa and temperatures up to 150 °C. At lower temperatures (20-60 °C), gas-diffusion electroprecipitation and electrocrystallisation experiments (GDEx) resulted in different metallic products at different temperatures, with a broader variety of compounds at higher temperatures. Experiments investigating salinity-gradient power generation by reverse electrodialysis (SGP-RE) using pre-treated geothermal brines, proved that the presence of multivalent ions in geothermal fluids does not eliminate the potential for SGP-RE. Furthermore, the extraction of electrical energy was enhanced by increasing brine temperature.
Seven main technological components were identified as important in a CHPPM system. Based on a conceptual framework, a mathematical model was developed that linked the different components into a single overall system. The model was applied to several scenarios and it can be used to simulate and optimise a CHPM plant. The potential application of the technology included assessing environmental, economic, social, policy and ethical aspects.
Within the framework of the project, the future implementation of CHPM plants was also examined. Two time horizons were considered: 2030 for pilot-scale operation and 2050 for full-scale operation. Efforts were undertaken looking forward in three interlinked areas: mapping convergent technologies, studying pilot areas, and developing research roadmaps for the two identified time horizons.
Due to the extensive dissemination activities by the partners and the linked third parties of the European Federation of Geologists, the project concepts and results have reached about 50 000 scientists and professionals in Europe.
Reports on the research work and outcomes of the project are available on the project website:
http://www.chpm2030.eu/outreach(öffnet in neuem Fenster).
