Geothermal Research Articles

Cascade and effective utilization of medium and deep geothermal energy: A comprehensive review and application prospects

Cascade and effective utilization of medium and deep geothermal energy: A comprehensive review and application prospects

Thermo-Hydro-Mechanical–Chemical Modeling for Pressure Solution of Underground sCO2 Storage

Underground production and injection operations result in mechanical compaction and mineral chemical reactions that alter porosity and permeability. These changes impact the flow and, eventually, the long-term sustainability of reservoirs utilized for CO2 sequestration and geothermal energy. Even though mechanical and chemical deformations in rocks take place at the pore scale, it is important to investigate their impact at the continuum scale. Rock deformation can be examined using intergranular pressure solution (IPS) models, primarily for uniaxial compaction. Because the reaction rate parameters are estimated using empirical methods and the assumption of constant mineral saturation indices, these models frequently overestimate the rates of compaction and strain by several orders of magnitude. This study presents a new THMC algorithm by combining thermo-mechanical computation with a fractal approach and hydrochemical computations using PHREEQC to evaluate the pressure solution. Thermal stress and strain under axisymmetric conditions are calculated analytically by combining a derived hollow circle mechanical structure with a thermal resistance model. Based on the pore scale, porosity and its impact on the overall excessive stress and strain rate in a domain are estimated by applying the fractal scaling law. Relevant datasets from CO2 core flooding experiments are used to validate the proposed approach. The comparison is consistent with experimental findings, and the novel analytical method allows for faster inspection compared to numerical simulations.

Understanding Knowledge, Perception, and acceptance of geothermal energy among Indonesian Students: Implications for sustainable renewable energy initiatives

Understanding Knowledge, Perception, and acceptance of geothermal energy among Indonesian Students: Implications for sustainable renewable energy initiatives

Numerical simulation and thermal control factor analysis of deep high-temperature geothermal energy in the Zhenghe-Dapu fault zone and its adjacent areas, Southeast China

Numerical simulation and thermal control factor analysis of deep high-temperature geothermal energy in the Zhenghe-Dapu fault zone and its adjacent areas, Southeast China

A Comprehensive Review of Data Analytics and Storage Methods in Geothermal Energy Operations

A Comprehensive Review of Data Analytics and Storage Methods in Geothermal Energy Operations

Enhanced heat performances of penta-hybrid nanofluid flow across a stretching surface employing the homotopy perturbation method: An artificial neural network approach

This research investigates the heat and mass transfer properties and flow behavior of magnetohydrodynamic viscous non-Newtonian penta-hybrid nanofluid flow along a porous stretching surface. The present investigation considered the influence of thermal radiation, heat generation/absorption, Joule heating, chemical reaction, and first-order velocity slip at the wall. Similarity transformations are used to reduce the flow's nonlinear partial differential equations to ordinary differential equations and solved through the Homotopy Perturbation Method. Additionally, an artificial neural network is employed to validate and optimize the computational results, enhancing accuracy in predicting skin friction characteristics. A comparative analysis of various nanoparticles, such as metals and metal oxides, is conducted to examine their influence on heat and mass transfer, surface drag. The research identifies that penta-hybrid nanofluids have a significant influence on heat and mass transfer compared to tetra-hybrid and tri-hybrid nanofluids, with the highest contribution to skin friction from silver (Ag), the best heat transfer from zirconium dioxide (ZrO2), and the highest mass transfer from copper oxide (CuO). These results have extensive applications in thermal energy management, electronic cooling, aerospace thermal control, and biomedical systems. They also have applications in nuclear reactor cooling, microfluidic devices, and chemical process industries, where the regulation of heat and mass transfer is critical. The improved properties of penta-hybrid nanofluids also make them applicable to renewable energy systems, such as solar thermal collectors and geothermal energy systems. Since very few previous studies have taken into account penta-hybrid nanofluids, this research presents new knowledge of their potential for improved engineering and industrial applications.

Pore structure alteration in heated granite after LN2 treatment: An experimental study for the enhanced geothermal energy extraction

Pore structure alteration in heated granite after LN2 treatment: An experimental study for the enhanced geothermal energy extraction

Too hot to handle? Governance, markets, and the slow burn of geothermal energy in Taiwan

Too hot to handle? Governance, markets, and the slow burn of geothermal energy in Taiwan

Optimal utilization of geothermal energy through three organic cycles combined with a thermoelectric generator and an electrolysis unit

Optimal utilization of geothermal energy through three organic cycles combined with a thermoelectric generator and an electrolysis unit

Similarity criteria for advanced cooling of deep mines based on synergetic mining of mine geothermal energy

Similarity criteria for advanced cooling of deep mines based on synergetic mining of mine geothermal energy

Evaluation of Geothermal Potential in Eastern Africa: Insights from Multicriteria Analysis and Geospatial Techniques

Eastern Africa faces a significant energy deficit, with demand driven by transportation, domestic, and industrial needs. Despite the availability of substantial geothermal resources, their exploitation remains limited due to a lack of adequate information and technical capacity across many African countries. Geothermal energy, being a clean, reliable, and sustainable source, offers a promising alternative to conventional energy sources such as fossil fuels and hydropower, which often have high prices (oil and gas) and are environmentally unsustainable or seasonally constrained. This study addresses the knowledge and technological gaps by identifying and mapping geothermal potential zones across Eastern Africa using a Multi-Criteria Decision Analysis (MCDA) framework integrated with the Fuzzy Analytic Hierarchy Process (Fuzzy AHP) and ArcGIS. Five primary geothermal indicators were evaluated: proximity to hot springs and geysers, presence of active and young volcanic rocks, occurrence of major faults, regional heat flow, and land surface temperature. Each criterion was weighted using Fuzzy AHP, with hot springs and major faults receiving the highest significance in identifying geothermal prospects. The analysis revealed thirteen zones with extremely high geothermal potential: six in Ethiopia, two in Kenya, two in northern Tanzania, two in Uganda, and one between Rwanda and Burundi. Additional zones in northern Malawi, other regions of Kenya, Rwanda, and parts of Tanzania also demonstrated very high potential. The results were validated using known geothermal wells, confirming the effectiveness of the model. This research not only enhances the understanding of geothermal potential in the region but also provides a strategic tool for guiding future exploration and investment decisions.

Reliability control of mapping dataset on small subsurface geothermal gradient, a case study in the Zagreb geothermal field, Croatia

Purpose. The research aims to use interpolation methods for mapping, such as Inverse Distance Weighting (IDW), as well as normality tests on geothermal gradient data from the Zagreb geothermal field (ZGF) in the Croatian part of Pannonian Basin System (CPBS). Methods. The IDW method is applied to original small (8 values) and artificial added (45 values) datasets. The IDW method and a comparison of three geothermal gradient maps (8, 45 and 53 data, respectively) are applied for the ZGF breccia-fractured carbonate reservoir. The maps are compared visually and using mean square error / root mean square error (MSE / RMSE). Dataset is tested on normal distribution (Shapiro-Wilk and Kolmogorov-Smirnov tests, Q-Q plot). Findings. The insufficient amount of data is the main shortcoming for any subsurface reservoir characterisation. The IDW method has successfully outlined the main reservoir geothermal gradient zones. Increasing dataset with artificial values sampled onto original map (8 values) showed that starting dataset is enough reliable for basic reservoir characterisation. Further reservoir development should be based not on numerous new wells, but on the development of existing wells, including new trajectories and more precise determination of drainage radius, capacity and temperature decline over time. Originality. For the first time IDW, supplemented with normality tests and artificial sampling based on original small datasets, is applied as a development method in the geothermal reservoir of the CPBS area. Practical implications. This research is a necessary step in determining the future planning of geothermal reservoir development in the Zagreb urban area. This can be primary or additional approach for a similar reservoir with a small sample, while for a reservoir with a large sample it can show the meaningfulness of choosing an interpolation method.

Experimental Analysis of Flow Rates in Ground Source Heat Pumps for Heating: A Case Study Southeastern Anatolia, Turkey

Geothermal energy offers considerable potential for use in buildings and infrastructure. This research investigates the application of a Horizontal Type Ground Source Heat Pump system to reduce energy consumption in buildings. The study assesses the energy efficiency and operational characteristics of ground source heat pump systems under the specific climatic conditions of the Batman region. To conduct this analysis, a horizontal ground source heat pump and an underground circuit were installed in a container at Batman University’s West Raman Campus. Experimental data revealed that soil temperatures below two meters remained constant at 21°C. Tests were carried out in December 2020 at three flow rates: maximum (0.19 m³/h), medium (0.12 m³/h), and minimum (0.09 m³/h). During the experiments, measurements were taken for the internal and external temperatures of the heat pump, the inlet and outlet temperatures of the water-monoethylene glycol mixture, and the temperatures of the cooling liquid components. The highest coefficient of performance for the heat pump was recorded at 2.43, while the overall system coefficient of performance reached 2.23.

Technology Innovation in Mechanical Engineering Using Social Strategy for Sustainable Geothermal Business

To know the important role of technology innovation in a company achieving goals to support corporate, economic, social, & environment in geothermal business. Technology innovation could enhance resource assessment, resource development, & resource utilization & management. They could give a competitive advantage & sustainable business for the company that operates among communities. The geothermal field sometimes has different types of communities, the company should have a social strategy to make sure the operation will run as well as e xpectation. This research uses qualitative methods by undertaking social mapping, observation, interviews, analysis documents, & forum group discussion. Technology innovation in mechanical engineering that is applied by the company can give a competitive advantage & accelerate geothermal development. Social strategy is very important for geothermal developers so that communities can have a good impact to avoid issues of economic, social, & environmental. Technology innovation in the geothermal business is to choose the right power plant technology that use. By using the binary cycle power plant system, the company can sell the electricity power at a cheaper price because the grace period is shorter than others.

Imaging fault-controlled hydrothermal dolomite bodies in the subsurface: insights from 3D seismic modeling of the Hammam Faraun Fault system, Suez Rift, Egypt.

Understanding the geology of the subsurface has for centuries been a key success factor for example for mining and mineral exploitation, geohazard assessment and mitigation, hydrocarbon exploration and production, geothermal energy and groundwater management. Given the inaccessible nature of the subsurface, outcrop analogues have long been studied and used to understand and predict subsurface geology (e.g. Darwin and Sowerby, 1846; Newhouse, 1942; Virk and Singh, 1993; Bense and Person, 2006; Jahn et al., 2008; Bense et al., 2013; Beukes et al., 2013; Ebuna et al., 2013; Davidson et al., 2016; Yadav and Sircar, 2020). Over the last decades, increasingly high-quality seismic reflection data have also become one of our most important tools to image the subsurface, which in combination with data from wellbores allows for interpretation of subsurface geology. However, the variety and complexity of the subsurface, in combination with limitations and large variability in seismic imaging quality and resolution, make seismic-based geological interpretations inherently uncertain.

Application of the magnetotelluric method in geothermal exploration in Jianshi county, Hubei province, China

Geothermal resource is a kind of renewable green and clean energy stored in the earth’s interior. Under the impetus of the global energy revolution and the goal of “double-carbon”, the development and utilization of geothermal energy has become an important strategy for the energy development of all countries in the world. The Magnetotelluric (MT) sounding method, which is not shielded by high-resistance layers and provides high resolution for low-resistance layers, has unique advantages in revealing geothermal system structures, delineating hydrothermal geoelectric structures, and assessing the development potential of geothermal regions. Based on an MT profile in Maotian Township, Jianshi County, this paper processed data from 51 broadband MT measurement points using Fourier transform, Robust estimation, and impedance tensor decomposition techniques. After a detailed analysis of the dimensional characteristics and electrical axes, a 2D electrical structure model from the surface to a depth of 9 km was obtained via topography-based 2D inversion. The fault distribution was confirmed, and the potential geothermal resource areas were inferred based on geological information. The MT-sounding survey confirmed the favorable geothermal resource storage range in the study area and demonstrated the advantages of MT in geothermal exploration, with important practical value for investigating the underground electrical structure and geothermal resource distribution.

Seismic Strain Metrics for Tracking Fault Damage Evolution and Rupture Potential in Anthropogenic Seismicity

Abstract Human-induced earthquake is an important topic for its devastating damage impact. The laboratory experiments and observational studies indicate that strong earthquakes are often preceded by a sustained period of widespread volumetric deformation. This deformation may lead to progressive shear localization, resulting in major instabilities along rupture spanning the entire system. The significant challenge is to identify measurable indicators of seismic activity that can precisely determine the progression of deformation within a rockmass or fault system. Combining insights from fracture mechanics with observations from laboratory experiments and anthropogenic seismicity, we identify key parameters that track the evolution of seismic process, relating their values to a five-step rockmass damage model. These parameters, calculated for each stage of damage, enable assessment of the current damage stage, providing insight into the preparatory stages leading to major seismic events. Using the acoustic emission data, we identify proxies for stress and damage through seismic strain dynamics metric and clustering in patterns of rupture steps. We applied this model to analyze ten significant earthquakes associated with reservoir impoundment, mining, and geothermal energy production. Our results show that accelerated seismic deformation consistently precedes these events, highlighted by a distinct clustering pattern that suggests progressive localized damage. The duration of the final damage stage extends with increasing earthquake magnitude. We also discern two dynamic regimes in the patterns of earthquake parameters, distinguished by their fracture growth dynamics: a faster mode associated mainly with mining activities and a slower mode tied to fluid-related cases. This understanding enables targeted technological adjustments to mitigate earthquake risks in geo-energy projects.

Offshore Geothermal Energy Perspectives: Hotspots and Challenges

Geothermal energy is a low-carbon and reliable energy resource capable of generating both heat and electricity from the Earth’s internal thermal energy. While geothermal development has traditionally been focused on onshore sites, offshore geothermal resources are attracting growing interest due to advancements in technology, the search for alternative baseload power, and the opportunity to repurpose decommissioned petroleum infrastructure. Recent efforts include utilizing abandoned oil and gas fields to adapt existing infrastructure for geothermal use, as well as exploring high-temperature geothermal zones such as submarine volcanoes and hotspots. Despite these initiatives, research output, scientific publications and patents remain relatively limited, suggesting that offshore geothermal technology is still in its early stages. Countries like Italy, Indonesia and Turkey are actively investigating geothermal resources in volcanic marine areas, while North Sea countries and the USA are assessing the feasibility of converting mature oil and gas fields into geothermal energy sites. These diverse strategies underscore the regional geological and infrastructure conditions in shaping development approaches. Although expertise from the oil and gas industry can accelerate technological progress in marine geothermal energy, economic challenges remain. Therefore, improving cost competitiveness is crucial for offshore geothermal energy.

Improved Thermal Conductivity of High‐Density Polyethylene Pipes Used for Ground‐Source Heat Pump Systems

ABSTRACTImproving the through‐plane thermal conductivity of high‐density polyethylene (HDPE) pipe is essential to enhance geothermal energy utilization for ground‐source heat pump (GSHP) systems. In this work, highly thermally conductive flake‐like graphite (Gr) was employed to enhance the through‐plane thermal conductivity of HDPE pipe by controlling the alignment of the Gr sheet. The results revealed that multistage stretching extrusion (MSE) effectively dispersed Gr sheets and aligned them along the extrusion direction. Hot‐pressing‐cutting process (ST) reoriented the Gr sheets perpendicular to the extrusion direction while simultaneously reducing inter‐plate spacing along the extrusion axis. Consequently, the HDPE/Gr‐MSE composite exhibited significantly enhanced in‐plane thermal conductivity (8.7‐fold), whereas the HDPE/Gr‐MSE + ST sample showed dramatic improvement in through‐plane thermal conductivity (8.5‐fold). Meanwhile, HDPE/Gr‐MSE + ST exhibited a yield strength comparable to that of HDPE and a greatly improved creep resistance, which was beneficial for the long‐term resistance to internal fluid pressure. Furthermore, the conductivity resistance and breakdown strength of HDPE/Gr‐MSE + ST composite meet the requirements for HDPE pipes used for the GSHP system. This HDPE/Gr‐MSE + ST composite with excellent through‐plane thermal conductivity, mechanical, and electrical insulation properties has great application potential in GSHP systems.

The Gutenberg–Richter Relation May Not Hold for the Anthropogenic Seismicity

Abstract The empirical Gutenberg–Richter (GR) relation corresponds to an exponential model of magnitude distribution, the most widely used in the probabilistic assessments of seismic hazard and related risk. However, due to the complexity of seismic processes induced by technological activities, this model may not be applicable to anthropogenic seismicity (AS). Applying statistical hypotheses testing procedures, we investigate 63 AS catalogs resulting from various anthropogenic activities such as reservoir impoundment, underground mining, conventional and unconventional hydrocarbon extraction, geothermal energy production, and underground gas storage. In 30 cases (47.6%) the exponential model for magnitude is rejected. Furthermore, in 16 out of these cases, the magnitude probability density functions are complex, having either modes or bumps or both. We discuss possible reasons for the discovered statistically significant deviations of the actual magnitude distributions from the exponential distribution and hence from the GR relation. We demonstrate that using the exponential distribution may lead to unacceptable inaccuracy of seismic hazard estimates in AS. As a remedy, we recommend the use of kernel nonparametric estimators of magnitude distribution.