Rosa María Prol-Ledesma

This study presents the discovery of four hot springs, located across an area of 65 181 km2, on the eastern flank of the Sierra Madre Oriental in Mexico. These springs emerge from sedimentary formations dating back to the Cretaceous period, displaying surface temperatures that range from 26.3° to 38 °C with electrical conductivity measurements varying between 1049 and 2421 µS/cm. The altitudinal range of these springs is documented from 55 to 1229 meters above sea level. The results from this research indicate that these springs are likely fed by rainwater infiltrating into the mountainous regions, where carbonate-evaporite rocks exist at probable depths of 3.5 km. The equilibrium temperatures at depth calculated using a multicomponent geothermometric model and isotopic geothermometers based on the chemical-isotopic composition of the four springs, fall within the range from 34° to 120 °C. These temperature values indicate the presence of geothermal groundwater flow systems. This geothermal resource has significant potential for utilization in electricity generation using binary plants and for various direct applications. This potential is especially relevant in regions where fossil fuels constitute the predominant source of energy.

Burgos Basin is an important hydrocarbon province in Mexico, as it has high gas production and some wells also produce condensed oil. The Burgos Basin has favorable geological conditions to store fluids, like dry gas, gas condensate and formation water and has a geothermal gradient between 40 and 70°C/km, which makes the Burgos Basin a possible geothermal prospect with numerous deep wells that can be used to produce geothermal energy. Here, we present the evaluation of electric power production potential using a binary power plant. Comitas field has wells with depths between 2,000 and 3,000 meters, and bottomhole temperatures in the range from 120°C to 180°C. The geological characterization of the area and the existing temperatures could be used to assess the geothermal potential with the volumetric method using the method that Garg and Combs (2015) reformulated to use a binary plant to produce electric power and the Montecarlo approach to define the probability of the estimated production. The results of the evaluation indicate a probability of P90 for 0.8 MW (Mega Watt) production, P50 for 4 MW and P10 for 12 MW. The results demonstrate that electric power production is feasible using the active or the abandoned wells in this gas field, which may provide renewable energy to the nearby towns.

Deep-sea vents microorganisms have been well characterized with defined typical taxonomic groups, principally composed of archaea, while shallow hydrothermal vents are considered to host a different community with bacteria as predominant prokaryotes. This work focuses on two shallow basins in the northern Gulf of California: Wagner and Consag basins which show evidence of early stages of rifting processes and host numerous submarine vents with intense gas discharge. The exploratory study of archaea and bacteria in six sediment samples from the shallow vents in those basins (average depths of 100 m), demonstrate that similar archaea phyla inhabit these vents. The phylum Thermoproteota with Nitrosopumilus as the most abundant genera in five sites. However, in the sample with the highest temperature, the phylum Asgardarchaeota was predominant, and also the occurrence of archaeal lineages typical of deep sea vents like Nanoarchaeota, Thermoproteota, Euryarchaeota, and members from phylum Asgardarchaeota, were identified. This work is the first report of the presence of a typically deep vent community of archaea in this shallow vent environment.

Geophysical surveys discovered low resistivity values that, in combination with geochemical and structural data, indicate the presence of a previously unrecognized geothermal system with a possible maximum size potential similar to that of the presently installed capacity of the Cerro Prieto geothermal field. The only evidence of a hydrothermal system in the San Felipe Valley are warm groundwater wells and four intertidal hot springs. Exploration at San Felipe was part of a research project that included geological, geochemical and geophysical studies, which indicated the presence of low resistivity anomalies and high temperature at depth; the geological survey provided evidence of active fault systems that may act as channels for convective heat transport. Estimation of the energy potential of the San Felipe prospect using the heat in place method yielded a 50% probability of more than 300 MW that would add to the 570 MW of the Cerro Prieto geothermal field and can supply almost 40% of the state of Baja California electricity demand. The Baja California Peninsula is not connected with the national grid and has one of the highest electricity prices in Mexico, which should be an incentive to develop this clean energy source. The results of this work support the recommendation to pursue further advanced exploration of this prospect.

During the geothermal prospecting and exploration stages, different interests may arise that motivate a socio-environmental conflict over the use of the resource. To prevent this, it is important to have a social management plan and consider cultural values within the exploration stages. The objective of this project is to evaluate the social impacts of the implementation of direct use in the Los Baños geothermal zone, in the intraplate volcanism province of eastern Mexico; as well as to identify the main actors of the territory and their perception of the geothermal resource. To do this, semi-structured field surveys were implemented, and the evaluation format required for larger energy projects (in Mexico) was adapted to identify local aspects of the social dimension.The main results are identification of actors with greater cultural weight and influence in local decision-making, identification of the existence of a socio-environmental conflict linked to mining in the area, identification of the type of direct geothermal use that can be implemented with greater feasibility (social and technical) in the area, a constant dialogue with the managers of the territory and the joint approach of later stages for the social acceptance of the project.AcknowledgementProject PAPIIT-UNAM IA100921 Exploración geotérmica en el Oriente de la Faja Volcánica Transmexicana. Project PAPIIT-UNAM IA102123 Exploración avanzada en Los Baños, Veracruz para usos directos de la energía geotérmica.