• Energy Research

The growth of the geothermal industry demands the constant search of techniques with the aim of reducing exploration efforts whilst minimizing subsurface uncertainty. The exploration of geothermal resources is fundamental from the exploitation point of view, especially in those regions where this energy is not as widespread as the rest of renewable sources. This research shows how geoelectrical methods can contribute to the investigation and characterization of medium–low enthalpy geothermal resources until about 800 m of depth. A 2000 m long electrical-resistivity tomography profile was performed in a region of Southern Spain with previous evidence of moderate geothermal potential. Results of this geophysical campaign (together with a preliminary geological characterization) allowed for the obtainment of a 2D profile and a pseudo-3D model with extensive information about the subsoil in terms of geological composition and formations. The interpretation of geophysical results denotes the existence of a potential formation constituted by carbonate materials with thickness greater than 300 m, crossing different fractures. Once the ideal location for the geothermal exploitation is defined, the research evaluates the contribution of the possible energy source, deducing that the energy extraction in the potential fracturing area would be double that of the one in the vicinity of the site.

Geothermal energy is becoming essential to deal with the catastrophic effect of climate change. Although the totality of the Earth’s crust allows the exploitation of shallow geothermal resources, it is important to identify those areas with higher thermal possibilities. In this sense, geophysical prospecting plays a vital role in the recognition and estimation of potential geothermal resources. This research evaluates the geothermal conditions of a certain area located in the center of Spain. The evaluation is mainly based on geological and geophysical studies and, in particular, the Time Domain Electromagnetic Method and the Electrical Resistivity Tomography. Once we analyzed the geology and the historical thermal evidence near the study area, our geophysical results were used to define the geothermal possibilities from a double perspective. In relation to anomalous heat gradient, the identification of a fault and the contact with impermeable granitic materials at the depth of 180 m denotes a potential location for the extraction of groundwater. Regarding the common ground-source heat-pump uses, the analysis has allowed the determination of the most appropriate area for the location of the geothermal well field. Finally, the importance of accurately defining the position of the drillings was confirmed by using software GES-CAL.

Exploring and exploiting a geothermal resource has become one of the most prolific tasks for contributing to the global sustainable development. Despite this fact, several countries, such as Spain, are still far from achieving a generalized use of these renewable systems. The reason for this underuse often derives from the lack of information and characterization of the geothermal energy source. Considering this, the present research aims to provide relevant data about the geothermal potential of the Spanish region of Ávila. The geological context of this province lays the foundations for considering the region as a promising site for different geothermal uses. In order to estimate the geothermal energy potential of the region, the existing geological information has been complemented with thermal surveys carried out in the study area. The experimental measuring has consisted of the register of the underground temperature in piezometers of variable depth and natural springs distributed throughout the province. The processing of these records has allowed knowing the thermal evolution of the subsoil at the different levels evaluated in the research. Results show that there are two main potential areas in the province that could be successfully used for heating purposes (maybe as part of district heating systems) and for future deeper evaluations in the sense of Hot Dry Rock (HDR) techniques. Final conclusions have also been included in an interactive and open-source tool that allows visualizing the thermal findings with the aim of planning future geothermal uses in the region.

The pig farm sector has been developing rapidly over recent decades, leading to an increase in the production of slurry and associated environmental impacts. Breeding farms require the maintenance of adequate indoor thermal environments, resulting in high energy demands that are frequently met by fossil fuels and electricity. Farm heating systems and the storage of slurry constitute considerable sources of polluting gases. There is thus a need to highlight the advantages that new green heating solutions can offer to reduce the global environmental impact of pig farming. This research presents an overview of alternative pig farm slurry technology, using geothermal heat pumps, which reduces the harmful effects of slurry and improves the energy behavior of farms. The results reflect the environmental benefits of this solution in terms of reducing carbon and hydric footprints. Reducing the temperature of slurry with the geothermal heat pump of the system also reduces the annual amount of greenhouse gases and ammonia emissions, and, via the heat pump, slurry heat is used for installation heating. Annual emissions of CO2e could be reduced by more than half, and ammonia emissions could also experience a significant reduction if the slurry technology is installed. Additional advantages confirm the positive impact that the expansion of this renewable technology could have on the global pig farm sector.

The present research presents a novel methodology that using geospatial tools is intended to facilitate the inclusion of geothermal energy in the urban sector by selecting viable zones for geothermal district heating's The methodology is a three-step screening process based in Castilla y León (Spain), whose starting point is taking the information needed from the spatial data infrastructure about its geology, provinces and buildings and further adding selected criteria to narrow the results such as thermal conductivity, population density, energy consumption, etc. This process is intended to help with site selection of district heating's as a tool that can be applied everywhere as long as the base material is available and its key point is its agility to study multiple sites and display the information in a visual representation. As a result, the methodology provides a range of suitable sites that can be studied in detail in the future, based on the needs that the user seeks to cover.

Sustainable energy development in the farming sector is an essential strategy to respond the combined challenge of achieving a reliable and affordable solution but including mitigation and adaptation to climate change. Intensive breeding farms require maintaining an adequate indoor thermal environment that results in high energy demands, usually covered by fossil fuels and electricity. This paper addresses the application of the combined slurry technology for a particular pig farm that currently uses a diesel boiler to supply the piglet heating energy needs. The study also considers different options based on closed ground source heat pump systems. After the design of the slurry alternative and the geothermal ones, notable advantages are detected compared to the existing diesel system. Results show that the implementation of the slurry technology implies an important reduction of the operational costs, which, in turn, involves short amortization periods for this system in relation to the diesel one. Greenhouse gases emissions are also highly reduced in the slurry alternative based on the low electricity use of the heat pump. The environmental side is reinforced by the reduction of polluting substances such as methane of ammonia derived from the descent of temperature of the slurry.

The present research shows a novel approach for the acquisition of specific competences related to energy efficiency in the Bachelor’s Degree in Electrical Engineering by the use of Geographic Information Systems (GIS) when designing shallow geothermal installations. In particular, the article is focused on defining the thermal behaviour of the subsoil, a critical issue when performing a geothermal energy project. The approach is aimed at improving the comprehension and interpretation of thermal parameters and its role within the operation of a shallow geothermal system. The contribution is originated from a depth research process of the authors in the field that has resulted in the creation of a rigorous but at the same time simple systematic methodology for use at an educational level. In this way, the presented geothermal procedure (currently implemented in the Electrical Engineering Degree) will help university students to contextualize the theoretical knowledge and to better understand and manage the challenges they will have to face in their future professional career.

District heating systems play a pivotal role in providing efficient and sustainable heating solutions for urban areas. In this sense, district heating systems that use geothermal resources have been gaining prominence in recent years, due to the non-intermittent nature of their application, among many other reasons. The present study investigates the thermal performance of novel coaxial pipes in comparison to conventional pipes within district heating distribution networks supplied by geothermal energy. Through experimental simulation and analysis, key thermal parameters such as heat transfer efficiency, thermal losses, and overall system effectiveness are evaluated through laboratory tests developed on a scale model. Experimental analysis concludes that, at a laboratory scale, heat energy efficiency can be improved by around 37% regarding the traditional geothermal distribution network. This improvement translates into a significant economic and environmental impact that has a direct influence on the viability of this type of system in different application scenarios. The results highlight the potential benefits of coaxial pipe designs in enhancing heat transfer efficiency and minimizing thermal losses, thus offering insights for optimizing geothermal district heating infrastructure for improved energy efficiency and sustainability. The novelty of this study lies in the innovative design and experimental validation of coaxial pipes, which demonstrate a 37% improvement in heat energy efficiency over conventional pipe designs in geothermal district heating systems, offering a breakthrough in optimizing heat transfer and minimizing thermal losses.