Qapqal Xibe Autonomous County is located in the central Yili Basin of Xinjiang. It possesses significant potential for geothermal resource development, but the lack of in-depth research on deep geothermal genetic mechanisms and refined resource evaluation restricts its large-scale utilization. Therefore, this paper integrates regional geological surveys, borehole thermometry, geophysical exploration, and hydrochemical and isotopic tracing to reveal the formation mechanism of the geothermal field. Furthermore, it quantitatively evaluates the resource potential and analyzes uncertainties by combining the volumetric method, analytical method, and Monte Carlo simulations. The results indicate that the shallow geothermal gradient is 2.2 °C/100 m, while the deep gradient increases to 3.8 °C/100 m. The Gagestai Fault and its secondary faults serve as dominant channels for deep thermal fluid migration. The Cretaceous Donggou Formation and the Jurassic Badaowan Formation constitute a dual-layer high-quality reservoir, with measured reservoir temperatures of 42.50 °C and 91.25 °C, respectively. Isotopic and hydrochemical analyses infer that the geothermal water mainly originates from atmospheric precipitation and snowmelt in mountainous areas. After long-distance deep circulation, cation exchange, and heating by the basement heat source, the fluid upwells along the faults to accumulate, forming a typical layered confined fault-controlled geothermal system. Resource evaluation, verified by Monte Carlo simulations, demonstrates that the volumetric method exhibits higher robustness at the current exploration stage. The total recoverable heat in the study area is 8.19 × 1016 J, classifying it as a medium-sized geothermal field. Rational development of these resources could save approximately 2.75 × 106 tons of standard coal and reduce CO2 emissions by about 7.315 × 106 tons. This study provides key parameters and a scientific basis for geothermal resource development in the Yili Basin, holding significant practical value for promoting the clean energy industry in Xinjiang and achieving the "dual carbon" goals.
Against the backdrop of the energy transition and to support the sustainable development of karst geothermal resources in the Laiyuan area, this study addresses the insufficient understanding of its formation mechanisms and thermal accumulation patterns. By innovatively integrating hydrogeochemical analysis, hydrogen-oxygen isotope tracing, and coupled water-heat numerical modeling, we systematically reveal the origin, evolution, and thermal controlling factors of geothermal fluids in this region. The results indicate that the geothermal water in Laiyuan is of the HCO3-Ca-Mg type with low mineralization, which is controlled by carbonate rock weathering. The average temperature of the thermal reservoir estimated by the quartz geothermometer is 48.5 °C with a circulation depth of approximately 1363 m. Hydrogen and oxygen isotope data indicate that geothermal water originates from atmospheric precipitation, which undergoes deep circulation after vertical infiltration through karst fissures. Upon heating at depth, it ascends along compressional-torsional fault zones, thereby forming a regional thermal anomaly. Hydrothermal coupling modeling further confirms that groundwater flow in karst aquifers significantly controls the distribution of the geothermal field, while conductive faults serve as the main thermal pathways and demarcate the temperature field boundaries. The thermal reservoir volume method estimates the geothermal resources in the study area to be approximately 5.50 × 1015 kJ, indicating considerable exploitation potential. However, extraction schemes must be optimized based on geological conditions to delay thermal breakthrough. This study elucidates the genetic mechanism and heat accumulation model of the Laiyuan karst geothermal system, providing a scientific basis for the exploration and sustainable development of geothermal resources.
To be fair and inclusive, the transition to net zero must combine technological rollout with enabling communities to participate in energy decision making. Participation in the energy system can take many forms, and one area with great potential for improving fairness and inclusivity is the siting and implementation of renewable energy infrastructure. In the UK, one emerging renewable energy technology is geothermal energy. Our study aims to understand how the geothermal industry is approaching engagement in a country with limited geothermal development and research into engagement practices. Using qualitative interviews conducted at three geothermal energy sites in the UK, we reveal that the operators interviewed appear to share an ethos characterised by honesty, trust and relationship-building. This ethos underpins good community engagement practices, such as approachability, accessibility, flexibility and two-way communication. We also observe that the operators are proactive in their engagement activities and responsive to queries from local communities. Our results provide an initial analysis of engagement practices in the UK geothermal industry and offer a model of good community engagement practice around geothermal energy. Guided by an ethics of care towards communities, operators can routinely go beyond the minimal engagement requirements of planning. This enables them to address communities' concerns, act on them, and maintain a dialogue between different stakeholders. There is a need for policy instruments to support this approach and establish higher engagement requirements for energy projects. The online version contains supplementary material available at 10.1186/s13705-026-00566-y.
Deep coal mining operations are subject to elevated geothermal gradients that fundamentally alter coal oxidation behavior, yet the coupling mechanisms between the ground temperature and coal metamorphic grade remain poorly understood. In this study, we establish a comprehensive framework integrating multiscale structural characterization, functional group reaction network analysis, and stage-resolved kinetics to elucidate geothermal-induced spontaneous combustion mechanisms. Four coals spanning a wide range of metamorphic grades (Ro,max = 0.58%-1.12%) were subjected to simulated geothermal conditions (30, 40, and 50 °C) and characterized by using TG-DTG and in situ FTIR techniques. We propose a novel "Geothermal Activation-Oxidation Acceleration" (GAOA) mechanism wherein ground temperature pretreatment activates oxygen-containing functional groups, creating reactive sites that substantially lower oxidation barriers. A functional group reaction network model was developed, revealing a hierarchical reactivity sequence: -OH > CO > C-O-C > aliphatic C-H > aromatic CC. Multimethod kinetic analysis (Coats-Redfern, FWO, KAS, and Starink) demonstrated that activation energy decreased by 15.3%-28.7% under 50 °C pretreatment, with lower-rank coals exhibiting greater sensitivity (ΔEa = 28.7 kJ/mol for long-flame coal vs 18.2 kJ/mol for coking coal). Based on these findings, we developed a Spontaneous Combustion Risk Index incorporating metamorphic grade, geothermal gradient, and functional group reactivity, providing a quantitative tool for fire hazard assessment in deep mining operations. This work advances the mechanistic understanding of geothermal effects on Coal Spontaneous Combustion and offers practical guidance for risk management in China's increasingly deeper mines.
Geothermal heating is a sustainable technique used for heating and cooling of buildings using geothermal heat pumps (GHPs). In this study, a novel idea is proposed to use the excess heat injected into the subsurface during geothermal heating as a temperature source to enhance the bioremediation of pollutants. Since in-situ bioremediation in the subsurface can be slow due to the low subsurface temperatures (10-15 °C), that limit microbial degradation activity, geothermal heating can provide optimum growth temperatures, proliferating microbial growth and enhancing bioremediation sustainably. In this paper, the effect of cyclic temperature fluctuations on a small scale has been studied in BTEX-contaminated soil using B. infantis, M. esteraromaticum and the microbial consortium. To understand the influence of the soil matrix, three different soil types- silty loam, fine sand, and coarse sand were studied in continuous soil column experiments. The results revealed that cyclic temperature of 5 °C to 40 °C (shallow low enthalpy geothermal temperature range) enhanced BTEX biodegradation in all soils but showed more promising results for silty loam soil (> 80%) in comparison to constant aquifer temperature (12 °C). Higher Kbio for all four compounds was observed above 25 °C in cyclic treatment for the three soil types compared to the isothermal 12 °C treatment. The study demonstrated that increased and cyclic temperatures facilitated enhanced microbial metabolism and simultaneous BTEX biodegradation, thereby promoting a cleaner approach to subsurface remediation.
The global shift toward low-carbon and sustainable energy marks a critical step in advancing decarbonization and resilient energy systems. This study presents a process-to-system modeling of a geothermal energy integrated with direct air capture (DAC) and district heating systems. The designed geothermal-DAC-district heating configuration demonstrates a technically robust and thermodynamically synergistic pathway toward carbon-negative energy systems. By effectively integrating geothermal power generation with an all-electric DAC and heat recovery system, this designed configuration advances deep decarbonization goals and aligns directly with the United Nations Sustainable Development Goals (SGDs) on affordable clean energy, sustainable cities, and climate action. The analysis indicates that the turbine output and DAC performance are highly sensitive to geothermal operating parameters, suggesting that maximizing CO2 capture efficiency requires operation at low flashing pressures and elevated reservoir pressures to ensure stable turbine performance and uninterrupted DAC operation. Employing the operational results obtained from the sensitivity analyses and parametric studies, the designed configuration captures 666.6 tCO2 per year employing 8 DAC units and provides district heating to 124 households. The findings reveal that geothermal-DAC integration enables continuous, zero-emission CO2 removal using renewable baseload energy while supporting community-scale heating demands, positioning the system as a viable technological pathway toward carbon neutrality and a sustainable energy infrastructure.
Belowground carbon transfer from non-equilibrium sources can alter isotopic signatures in terrestrial ecosystems, yet the transfer of such carbon into vegetation under natural field conditions remains poorly constrained. Understanding these processes is essential for improving radiocarbon (14C) transfer models used in environmental risk assessments. Geothermal fields offer natural analogue systems where isotopically enriched 13CO2 emitted from the subsurface can be used as a proxy for potential belowground 14C releases. This study determined the contribution of geogenic versus biogenic carbon to soil gas, near-surface air, and plant functional groups along a geothermal warming gradient in a forested volcanic field in Iceland. Stable isotope analyses (δ13C) with two-endmember mixing models revealed that geogenic CO2 dominated soil gas in all warmed plots (≥98%). Near-surface air (5 cm aboveground) showed geothermal influence, with geogenic CO2 contributing up to 45% in the warmest plots. Despite this pronounced subsurface signal, only lichens assimilated geogenic carbon (10-25%), while bryophytes and all vascular plants assimilated their carbon from biogenic sources. These results highlight physiological and microclimatic differences in carbon acquisition pathways among plant groups, while identifying lichens as sensitive integrators of subsurface CO2 due to their thallus structure, boundary layer positioning, and hydration dynamics. Overall, these findings provide field-based evidence of non-equilibrium carbon pools in geothermal soils and highlight the limitations of assuming homogeneous isotopic signatures across environmental compartments in most current 14C biosphere assessment models. Incorporating such species-specific and spatially explicit carbon transfer dynamics will improve the accuracy of radiological impact assessments from subsurface 14C releases.
The accurate identification of water sources and tracing of inrush pathways in deep coal mines remain challenging, as elevated geothermal temperatures can alter the molecular fingerprints of coal-derived dissolved organic matter (Coal-DOM), a potential organic tracer. To address this, we investigated the evolution of Coal-DOM from coals of different ranks (long flame coal, lean coal, anthracite) under simulated geothermal conditions (25 and 50°C). By integrating ultrahigh-resolution mass spectrometry (FT-ICR MS) with an interpretable machine learning framework (XGBoost-SHAP and reactomics), we decoded the rank-specific molecular transformation pathways. Results showed that warming diversified the DOM pool from low-rank coals via fragmentation and oxidation, while it selectively enriched condensed aromatic and sulfur-containing structures in high-rank anthracite DOM, forming a stable and distinct fingerprint. Key molecular descriptors (O/C, NOSC, AImod, sulfur content) were identified as robust predictors of thermal reactivity. Overall, this integrated framework enables molecular-scale prediction of DOM reactivity in coal-bearing aquifers under geothermal perturbation. In addition, it yields quantifiable organic fingerprints that complement conventional indicators for mine-water source identification and water-inrush tracing. These capabilities can support environmental risk assessment and guide management of deep mine water systems.
Microbial communities in geothermal environments constitute an underexplored reservoir of biosynthetic gene clusters with significant biotechnological potential. Here, we investigate the secondary metabolite potential of 219 microbial communities across marine and continental geothermal field sites, encompassing broad environmental gradients in temperature (4.7 °C to 93.5 °C), pH (0.85 to 10.3), and tectonic setting, including convergent margins, divergent margins at mid-ocean ridges, and paleo-convergent intraplate plume systems. We identified 9,019 putative biosynthetic gene cluster families, mostly lacking similarity to known biosynthetic gene clusters. Volcanic arc systems consistently exhibited the highest diversity of biosynthetic repertoires, whereas intraplate plume systems showed a greater representation of terpene-associated gene cluster families. In contrast, divergent margin systems were primarily characterized by nonribosomal peptide synthetase and ribosomally synthesized and post-translationally modified peptide pathways, together accounting for a large fraction of their predicted biosynthetic diversity. These findings suggest that tectonic context could be associated with large-scale patterns in microbial biosynthetic potential and provide a geobiological framework for guiding future natural product discovery in geothermal environments.
This paper describes a simple method for the simultaneous determination of the isotopic composition (δ13CCO2) and concentration of CO2 in volcanic and geothermal gases using a continuous flow mass spectrometry system (CF-IRMS). The instrumental configuration includes a Thermo Fisher Scientific Delta Q mass spectrometer, connected through a Conflo IV to a Thermo Trace 1610 gas chromatograph (GC) physically connected at the module Isolink II. The performance of the developed GC-IRMS method was evaluated through a comprehensive series of tests assessing the precision and accuracy of the δ13C values and the simultaneous determination of CO2 concentrations. Specifically, we evaluated instrumental precision and isotopic data reproducibility (δ13CCO2) under various gas chromatographic operating conditions (split ratio) using gas mixture and certified isotopic standards; concentration calibration curves were specifically developed at different split ratios (3, 20, 35, and 45) using certified gas mixtures to quantitative CO2 determination with a wide concentration range (from 0.06-100 % vol.). The concentration data were compared with those obtained with traditional analytical techniques (GC and IR). Subsequently, the entire system performance, for both isotopic composition and CO2 concentration, was validated on volcanic and geothermal gases. These samples, including fumaroles, bubbling pools, and soil gas emissions, were selected to test the simultaneous determination capability under real-world conditions. The results confirm that the achieved operating configuration ensures optimal performance for the simultaneous determination of δ13CCO2 and CO2 concentrations, guaranteeing a precision of ± 0.08 ‰ and an accuracy within ± 0.1 ‰ for isotopic data and a quantitative accuracy typically within ± 5 % for concentration data.
This study utilizes a model to investigate the thermal performance and determine the optimal design parameters for the low-enthalpy geothermal energy system earth-air heat exchanger in two climatically distinct regions: the arid, high-extreme environment of the Upper Egypt region and the milder conditions of the Egyptian Mediterranean region. First, a parametric analysis was conducted, focusing on the influence of pipe length, installation depth, air velocity, and pipe diameter, using Typical Meteorological Year data. The analysis identifies an optimal design configuration, recommending a pipe length of 40-50 m, an air velocity of 2 m/s, and a practical installation depth of 3-5 m to maximize heat exchange efficiency without incurring unnecessary costs. Using optimal design conditions, performance comparison reveals that earth-air heat exchanger effectiveness is directly proportional to the magnitude of the ambient-to-soil temperature difference. At peak hours, the temperature drop in the Aswan arid region was found to be 45% higher than in the Alexandria semi-arid region, highlighting the system's enhanced effectiveness in arid environments. Furthermore, the earth-air heat exchanger demonstrates year-round potential by providing effective heating during winter months when the soil is warmer than the ambient air at both regions. It is demonstrated that the low-enthalpy geothermal system hold a higher energy-saving potential in arid regions with extreme temperature conditions.
Fresh water aquifers adjoining the geothermal resources are often vulnerable to trace metal contamination and associated risks to human health. Realistic assessment of health hazard as well as source apportionment play a vital role in designing suitable remedial actions, which can be better achieved through application of probabilistic methods using Monte Carlo Simulations (MCS) and multivariate based Absolute Principal Component Score-Multiple Linear Regression (APCS-MLR) methods. In this study, a comprehensive analysis of groundwater quality was performed using multiple pollution indices (HPI, HEI, Cd, IWPI), MCS and APCS-MLR methods. Chemical results indicate that TDS, F- and NO3- showed exceedances in 19%, 38% and 23% of the samples respectively while trace metals (Fe, Mn, Pb, and As) showed higher exceedances compared to WHO limits. Pollution indices suggest that 73% of the samples fall under low contamination and the rest (27%) in high risk category. MCS infers both non-carcinogenic and carcinogenic health risks to different age groups mainly due to arsenic and lead. Sensitivity analysis indicates body weight, ingestion rate as most influential followed by arsenic concentration. High geochemical mobility is noticed for Zn and Co while Al and Ni are largely immobile. Both relative mobility index and APCS-MLR model output point to rock weathering and geothermal sources as the key contributors accounting for 19.8% of the trace metal load in this region. This integrative approach underscores the need for regular monitoring and implementation of policies for safeguarding public health in this region.
Enhanced Geothermal Systems (EGSs), developed to extract heat from hot dry rock (HDR) formations, are promising renewable heat resources; however, their long-term performance is governed by coupled thermo-hydro-mechanical (THM) processes. This study introduces a novel L-shaped injection-production wellbore configuration designed to enhance reservoir contact while reducing drilling complexity compared to conventional vertical, multilateral, and closed-loop systems. A fully coupled three-dimensional THM numerical model is developed to evaluate its performance, accounting for conductive-convective heat transfer, pore-pressure evolution, and thermally induced deformation. A sensitivity analysis investigates the effects of horizontal wellbore length, injection pressure, injection temperature, rock thermal expansion coefficient, and fluid compressibility. Extending the horizontal section increases the stable production period from 2.6 to 6 years and doubles reservoir lifetime from 6.3 to 12.4 years compared to a quintuplet vertical system, while delivering more than twice the thermal power output. Reducing injection pressure from 10 to 5 MPa suppresses cold-front migration and extends sustainability beyond 20 years. Increasing injection temperature from 323.15 to 343.15 K raises lifetime from 11 to 12.4 years but reduces power by 20%. The results demonstrate that the proposed configuration provides a balanced solution between thermal efficiency, mechanical response, and operational simplicity for HDR development.
Thousands of cubic kilometers of magma lie in the upper crust below supervolcanoes such as Yellowstone (USA), Toba (Indonesia), and Taupo (New Zealand). Most of these systems are identified because of surface geomorphology and eruptive deposits. Recognizing such volcanoes without surface evidence is challenging, causing large magmatic reservoirs to go unnoticed. The Tuscan Magmatic Province, Italy, features only sparse Quaternary volcanic activity, but subsurface data indicate the presence of supercritical fluids at shallow depths. Here we show that more than 5'000 km3 of magma and partial melt are stored in the middle crust of the Tuscan Magmatic Province, Italy. This fuels the high-enthalpy geothermal systems of the region. Such volumes are comparable to those of mid-crust reservoirs beneath recognized supervolcanoes. The discovery of large volumes of magma is critical to explain the long-term evolution of mature magmatic systems and to understand the behavior of large magmatic provinces.
A novel bacterial strain, designated HK31-PT, was isolated from a deep subsurface geothermal aquifer in southwestern Iceland. Phylogenetic analyses, based on 16S rRNA gene sequences, revealed that the strain was affiliated to the genus Phreatobacter. Cells of the strain were Gram-negative, rod-shaped, motile by means of a polar flagellum and granule-containing. Colonies were small, circular, convex, smooth and white in colour. Growth under chemoorganoheterotrophic and aerobic conditions was observed at the following ranges: 20-35 °C (optimum, 30-35 °C), pH 7-9 (optimum, 8) and 0-0.5% salinity (optimum, 0%). The strain was also capable of growing under chemolithoautotrophic and (micro)aerobic conditions with Fe(II) as an electron donor. The major respiratory quinone identified was ubiquinone Q-10 (97.0%), and the predominant fatty acid was C18:1  ω7c. The dominant polar lipids consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and an unidentified aminophospholipid, along with several unidentified glycolipids, phospholipids and lipids. The G+C content of the genomic DNA of strain HK31-PT was 67.66 mol%, and its complete genome was 4.34 Mbp in size. The values of the digital DNA-DNA hybridization and average nucleotide identity indices between strain HK31-PT and the type species of the genus Phreatobacter ranged, respectively, from 21.30 to 27% and from 78.25 to 86.32%. These values are well below the accepted species delineation thresholds, thereby clearly indicating that strain HK31-PT represents a distinct genomic species within the genus Phreatobacter, strongly supporting that the former represents a new species belonging to the genus Phreatobacter. Therefore, based on this polyphasic approach, strain HK31-PT represents a new species within the genus Phreatobacter, for which the name Phreatobacter aquiterrae sp. nov. is proposed. The type strain is HK31-PT (DSM 116433T=UBOCC-M-3430T).
暂无摘要（点击查看详情）
暂无摘要（点击查看详情）
暂无摘要（点击查看详情）
This paper presents the findings of a comprehensive non-invasive monitoring survey of the reservoir in the Beppu hot spring area, which has the largest discharge and the highest average temperature among hot springs in Japan. Interferometric synthetic aperture radar (InSAR) indicates a settlement of 15 mm over the past decade, even in areas with active geothermal use, demonstrating negligible subsidence compared to that in other geothermal areas reported globally. Gravimeters and seismometers were installed at the surface in two locations: one where geothermal manifestations and usage were particularly active and another where there were no discernible geothermal signs. Comparative observations over two and a half years revealed irregular variations in gravity and velocity at the high-geothermal activity site. Seasonal changes in gravity and velocity were observed at another site. The results of each non-invasive monitoring are interpreted as follows: although InSAR detected no significant subsidence, short‑term changes in density and elastic properties capable of producing gravity and velocity variations may have occurred in the subsurface. Based on rock‑physics considerations, we show that, as one possible mechanism, if several percent of gas‑saturation change had occurred in association with production activities, the resulting changes in density and elastic properties could have given rise to the observed changes in gravity and seismic velocity. In hot‑spring regions, production rate and reservoir water‑level data are often unavailable, and in this study too, the lack of such data made it difficult to fully separate the multiple factors that could contribute to gravity and velocity variations. Meanwhile, attempts to capture short‑term subsurface variations through gravity and velocity monitoring may contribute to assessing the risk of overextraction, similarly to long‑term InSAR deformation time‑series analyses.
In low-temperature geothermal development (typically <150 °C), significant heat loss through the wellboreespecially across the cement sheathreduces produced fluid temperature and system efficiency. Conventional oil well cement, with high thermal conductivity (0.8-1.5 W/(m·K)), offers poor insulation, undermining geothermal project economics. To address this, we investigate prediction and control strategies for the thermal conductivity of concrete under subsurface conditions. Systematic experiments reveal that, within practical ranges, thermal conductivity positively correlates with moisture content, curing temperature, and age but negatively with porosity, permeability, and water-to-cement ratio. A regression model for Jiahua G-grade cement accurately predicts thermal conductivity based on these parameters, identifying moisture content as the dominant factor. Crucially, incorporating impermeable insulating additives to maintain low internal moistureby preserving air-filled, uninvaded poresemerges as the most effective approach to enhance insulation. This strategy enables tailored cement formulations with thermal conductivity below 0.4 W/(m·K) while ensuring mechanical integrity. The findings provide a robust technical foundation for designing high-performance insulating cement systems that minimize wellbore heat loss, improve geothermal efficiency, and support sustainable utilization of low-temperature geothermal resources.