The GEMex project: Developing Los Humeros (Mexico) as a Superhot Geothermal Site

The GEMex project is a Mexican-European research cooperation on developing concepts for the use of superhot and engineered geothermal systems (i.e., Los Humeros and Acoculco) for power generation. Key focus in the first stage of the project is the confirmation and characterization of a superhot geothermal reservoir, which is expected in the deeper structural level of the Los Humeros volcanic complex. Los Humeros is located at the eastern tip of the Mexican Volcanic Belt within a Quaternary volcanic complex. The conventional hydrothermal reservoir in Los Humeros has been harnessed by the governmental utility CFE (Comisión Federal de Electricidad) since 1990 with a current operating capacity of 94 MWe. Reservoir temperatures around 380°C were found at depths below 2,000 m, indicating the presence of a superhot geothermal reservoir. However, geothermal fluids at such high temperatures could only be used to some extent for energy production, due to their aggressive physicochemical characteristics. For that reason, research is also required on the development of novel technological concepts. The complexity of the available data and the heterogeneity of the geothermal system requires sophisticated solutions for a meaningful integration of information. The paper will give an overview of the exploration strategy, selected results and interpretation.