Daniele Tardani ● Profesor Asociado

As the world explores alternatives to fossil fuels, hydrogen (H₂) has emerged as a critical element in accelerating the transition to clean and renewable energy sources (Gaucher et al., 2023; Le et al., 2023; Blay-Roger et al., 2024). Unlike gasoline, which emits CO2 when burned, H₂ combustion produces only water vapor, making it a high-quality and environmentally friendly fuel alternative. Hydrogen is primarily produced for industry processes, including “green hydrogen”, “blue hydrogen”, and “gray hydrogen” (IEA, 2019). On the other hand, the so-called “natural” or “white hydrogen” is potentially a more cost-effective and environmentally friendly alternative because it is ready to be used for energy production, without the need for polluting processes to obtain it (Smith et al., 2005; Lapi et al., 2022; Gaucher et al., 2023; Blay-Roger et al., 2024). However, H₂ accumulation in the subsurface has been largely overlooked due to assumptions of its rarity or nonexistence, attributed to the hydrogen's inheritance characteristics (small and reactive molecule). The first fortuitous discoveries in the USA or Mali (West Africa) proved that it was a mistake (Zgonnik, 2020). Currently, the geological processes that generate natural hydrogen have started to be better understood, but the conditions for its accumulation remain poorly constrained (Lévy et al., 2023). The potential for global extraction of natural hydrogen is significant, so it is critical that we understand how it is generated, transported, and ultimately trapped. Recent discoveries of natural hydrogen in various geological settings, including mid-ocean ridges, ophiolitic nappes, transform faults, convergent subduction margins, and intraplate settings (Zgonnik et al., 2020; Jackson et al., 2024) highlight the increasing interest in this resource. As a result, exploration projects are currently active in several countries such as Australia, the USA, France, Spain, and South America (e.g., Zgonnik et al., 2020, Jackson et al., 2024). Experience in managing H₂ reservoirs is obviously still missing, but the analogies should perhaps rather be sought in the field of geothermal energy (Moretti et al., 2023). In terms of geotectonic settings of natural hydrogen formation, subduction zones represent the primary geological environment for the large-scale interaction between water and mantle peridotite, i.e., serpentinization processes (Zgonnik et al., 2020). Serpentinization is the most effective and hence important subsurface process for producing and focusing natural hydrogen in potentially commercial volumes (Jackson et al., 2024). Particularly, in the Central Andean Volcanic Zone (CAVZ; 18-28°S; Fig. 1a) only a limited number of investigations have focused on natural hydrogen data. Moretti et al. (2023) confirmed the presence of natural hydrogen in the Bolivian Altiplano (e.g., Pampa Lirima and Sol de Mañana; Fig. 1a) by using geochemical measurements of gasses from hot springs and in-situ analysis of soil gas. Moreover, the 3He/4He ratios in the Altiplano-Puna plateau indicate that the amount of He uprising from the mantle (i.e., 3He content) is very large (Fig. 1b). This indicates that deep gasses are migrating toward the overriding plate surface above subduction (Fig. 1c). Based on the findings of Moretti et al. (2023), it is highly probable to find natural hydrogen in the Chilean portion of the Altiplano. In this context, the proposed research plans to unlock the geological origin and assess the potential of natural hydrogen in northern Chile. Moreover, this project goes one step further than the study of Moretti et al. (2023) and proposes to investigate the potential occurrences of natural hydrogen associated with specific structural arrangements related to volcanic and geothermal systems (Veloso et al., 2019). For that reason, the acquisition of new geological, structural, geochemical, seismological, and geophysical data is crucial to better understand natural hydrogen systems and to determine the prospectivity of new areas in Chile.

We propose to undertake a 3-year long project, devoted to achieving a detailed comprehension of the Li dynamics and impacts, from source to sink, in the Andean salars (including Preandean and high Andean salars) of the Antofagasta Region of Chile (Fig. 1). The methodological approach is multidisciplinary and includes geological, hydrological, mineralogical, geochemical, microbiological and social techniques. The specific study cases are given by the Salar de Atacama (SDA), recognized as the most important Li brine reservoir in Chile (Cabello, 2022), and 3 salt flats domains located eastwards; these latter domains are, from south to north: Northern domain. Pujsa, Tara, and Quisquiro salt lakes. Southern domain. Capur, Talar, and Tuyajto salt lakes. Central domain. Aguas Calientes Sur and Laguna Lejia salt lakes.

Implementación de una microrred de energías renovables (solar, eólica y geotérmica) en el distrito salinero artesanal Barranca-La Villa de Cáhuil. Implementación de una planta piloto geotérmica de producción de sal y electrificación de bombas y planta de yodación comunitaria mediante energías renovables no convencionales.

Ensuring a secure and sustainable water supply is a major challenge for the 21th century. The population growth, urbanization, and industrial/agriculture expansion need an increasing water provision, delivered at a constant rate. Furthermore, under the current climate change and droughts scenarios, with the depletion of surface water storage and quality, groundwater resources are fulfilling the growing water requirement for food and energy production. Estimated data indicate that in the 2010 ́s, groundwater supplies 36% of potable water, 43% of irrigated agriculture (considering the baseflow feeding rivers, this percentage is higher), and 24% of direct industrial water supply. The groundwater use is growing at a rate of 5% per year, and by 2050, the food and water demand will increase by 50%. However, the misconceiving and oversimplification of conceptual models about groundwater recharge points out that around 25% of its use is unsustainable. These considerations highlight how identifying innovative and integrated solutions to tackle the intertwined challenges of water and climate change as well as the complex interlink between water, energy, and food supply systems under current climate variability is an increasingly major imperative for the near future. The study of the water–energy–food nexus has received increasing attention from the global scientific community, focusing on how these three elements can interact sustainably. The interdependence of water resources, energy generation, and food production depends on reliable data and information on these resources. In this context, groundwater can serve to supply water and energy demand, strengthening food security and reducing fossil fuel energy dependence. Aquifers can provide water and geothermal energy, a clean baseload resource independent from weather conditions, which could significantly contribute to energy needs, improved air quality and food production as well as to reach the decarbonization targets. This combined aquifer’s use improvement could be especially relevant in urban areas where more than 50% of the world’s population lives and which is forecast to increase to 68% by 2050 with associated greenhouse gas emissions growth up to 80%. Aquifers are important heat reservoirs because groundwater flow is a powerful heat carrier, which can help achieve a more sustainable water-energy-food management, representing a major challenge to improving water, energy, and food security. In fact, by 2050, the demand for water and food is expected to increase by 60%, and the energy demand will be practically doubled. In this proposal, the WEF nexus will be specially addressed from the point of view of resources to generate the necessary knowledge to understand its complexity in Central Chile, and that will provide a timely transfer of the existing connections to decision makers and society. The aim of this study will be to comprehend the recharge and connection of surface and ground water in Central Chile and unravel their relationship with energy and food production. In this sense, the focus is on evaluating the hydrological cycle from mountain areas to the lowlands and evaluating the possibility that water resources can generate enough heat for direct geothermal projects. These results, calculated based on real and current water data, will provide valuable information for the energy transition in Central Chile and will be an instrument to evaluate the real possibility of greenhouse gas reduction. Food production not only needs water but also to increase its resilience to extreme events (frost, heavy rains, etc.), so the relationship between water availability, production per hectare, and geothermal energy (direct use) to stabilize crop conditions will be explored.

Ensure a secure and sustainable energy and mineral supply is a major challenge for the 21th century. Understanding the nature and evolution of hydrothermal systems can contribute to that aim by improving the effectiveness of exploration strategies for geothermal energy and precious metal epithermal deposits. Studies bridging together geochemistry and structural geology have shown that fault activity plays a critical role on fluid circulation and fluid chemical composition in hydrothermal systems. Despite the relevance of processes affecting the chemical and physical dimensions in such dynamic systems, little is known about the residence times of fluids and its metal budget in different structural contexts. Into this framework, fundamental questions arise regarding the optimal conditions leading to the development of high enthalpy geothermal resources and the formation of epithermal deposits: What is the structural control on the sources and concentration of base metals in hydrothermal fluids? How does the structural context affect the water residence times in hydrothermal systems? How does the meteoric recharge affect the geothermal systems in different structural domains? An ideal natural laboratory to address these questions is the Andean Cordillera of Central-Southern Chile, where hydrothermal systems occur in close spatial relationship with active volcanism as well as major seismically-active fault systems. Recent studies based on fluid geochemistry and noble gases isotopic composition have shown that the intersection of structural features promotes both the accumulation formation of magmatic/hydrothermal reservoir in the upper crust exerting a first-order control on hydrothermal fluid composition by conditioning residence times of magmas, promoting magma differentiation and separation of magmatic vapors. However, how similar processes are involved on residence times and metal budget of hydrothermal fluids remains unconstrained. We propose a geochemical and multi-isotopic study that integrates state-of-the-art analytical techniques to unravel the circulation times and base metals contribution from magma degassing and water- rock interaction in two volcano-tectonic settings in Southern Andes, i) the arc parallel strike-slip Liquiñe- Ofqui Fault System (LOFS) and ii) the intersection between the LOFS structures and the Andean Transverse Fault (ATF). I will integrate major and trace elements (e.g., Cu, Pb, Zn, among others) geochemistry of hot springs with water dating systems (3H-3He, 14C, U-Th/4He), noble gas (3He/4He; 40Ar/36Ar, 4He/20Ne), strontium (87Sr/86Sr) and water stable (𝛿!"𝑂, 𝛿 #𝐻) isotopes to identify the circulation times, recharge condition and metal budget of hydrothermal systems. This study will be the first to directly measure the residence times and metals contents of hydrothermal fluids in the Southern Andes of Chile. The results from the study will contribute to a better understanding of the fundamental geological and environmental controls on the evolution of hydrothermal systems. The data will directly impact the community exploring for geothermal energy in the Andes because it will help them to better constrain the formation and recharge times of geothermal reservoirs. In addition, this will be an original contribution that will impact the general geochemical science community, as no data exists on the links between residence times of hydrothermal fluids and the structural context.

The main aim of the present proposal is to assess, in the Western Andean Front, the magnitude and the spatiotemporal variability of deep groundwater flows and derived mountain block recharge using an original and direct collection of hydrogeological, lithological, and geophysical data. Specific objectives are: - Obj. 1: Assess the spatial variation at depth of the Abanico Formation hydraulic properties to improve the understanding of Western Andean Front fault systems and their impacts on the water transference to alluvial aquifers. - Obj. 2: Unravel the aquifer capacity of fractured rocks (i.e. Abanico Formation) and the critical zone extinction depth for groundwater flows and mountain block recharge mechanisms in the Western Andean Front of Central Chile. - Obj. 3: Estimate the mountain block recharge mechanisms regarding their quantitative (flow) and qualitative (hydrogeochemistry) aspects and assess the vulnerability of deep groundwater flows to shallow water-store variations caused by current and future hydroclimatic changes in the Western Andean Front. The study of borehole core lithological and hydraulic properties, groundwater geochemical composition, flow rates, together with spring hydraulic and hydrogeochemistry behaviors will help to fill a gap of knowledge about deep groundwater flows originating from the Principal Cordillera. This deep borehole and derived original information will therefore be used as an “eye” inside the deep Chilean Andes groundwater resources. Finally, it will be a useful observation point for multidisciplinary research due to the interest of national and international researchers to collect samples at depth and therefore will expand shared knowledge and national frontier research