Geothermal water can have a wide range of direct applications,including drinking,domestic use,irrigation and industrial use.This study analyses geothermal water from Dholera,Diu,Gandhar,Kutch,Porbandar,Tulsishyam,and ...Geothermal water can have a wide range of direct applications,including drinking,domestic use,irrigation and industrial use.This study analyses geothermal water from Dholera,Diu,Gandhar,Kutch,Porbandar,Tulsishyam,and Unai regions located in Gujarat,India,to determine the hydrochemistry for establishing the water's suitability for drinking and irrigation purposes.From each region,three different water samples were collected.For drinking purpose,total eleven water quality parameters such as pH,electrical conductivity,total dissolved solids,calcium,magnesium,sodium,potassium,chloride,sulphate,carbonate and bicarbonate were evaluated.Piper and Durov plots were used to understand the ionic composition and evolution of water.Whereas for irrigation,the parameters such as total dissolved solids,sodium absorption ration,electrical conductivity,and potential salinity were used for water quality check.Wilcox Plot was plotted to understand the sodium and salinity hazard of water.Water quality index and irrigation water quality index were used to assess the water quality for making the analytical procedure easy.The findings indicate that the water samples from the Dholera and Diu areas had extremely high values for both the water quality index and total dissolved solids content.Water in these places may be appropriate for making salt.All the other samples show adequacy for utilization in irrigation purpose.展开更多
Longling is characterized by a wide distribution of hydrothermal areas, among which the Banglazhang hydrothermal system is the most geothermally active. Banglazhang is marked by intensive hydrothermal activities inclu...Longling is characterized by a wide distribution of hydrothermal areas, among which the Banglazhang hydrothermal system is the most geothermally active. Banglazhang is marked by intensive hydrothermal activities including hot springs, geysers, fumaroles and hydrothermal explosions. The geothermal waters from the Longling region are mainly HCO3-Na type with low but comparable SO4 and Cl concentrations. Calculations based on a variety of chemical geothermometers and a K-Ca geobarometer indicate that the Banglazhang hydrothermal system has much higher subsurface temperature and CO2 pressure compared to the other systems such as Daheba, Dazhulin and Huangcaoba. However, geothermal water samples collected from all these alternative hydrothermal areas are either partially equilibrated with reservoir minerals or are immature. The silica-enthalpy relationships of Banglazhang geothermal waters indicate the presence of a deep geothermal fluid with an enthalpy value and silica concentration of 945 J/g（up to around 220 °C） and 339 mg/L. Our work indicates the Banglazhang area is a promising source in terms of long-term utilization of hydrothermal resources.展开更多
To study the mechanism of bio-clogging in a porous medium during the reinjection of geothermal water and to improve reinjection efficiency, an indoor one-dimensional reinjection experiment was conducted based on the g...To study the mechanism of bio-clogging in a porous medium during the reinjection of geothermal water and to improve reinjection efficiency, an indoor one-dimensional reinjection experiment was conducted based on the geological model of the geothermal reinjection demonstration project in Dezhou City. The biological process of porous media clogging was investigated by analyzing the variation of permeability within the medium, the main indexes of nutrient salts, and the content of extracellular polymeric substances (EPS). High-throughput sequencing, based on 16S rRNA, was used to analyze the characteristics and succession of microbial communities during the reinjection of geothermal water. The results of the study show that significant bio-clogging occurs during the reinjection of geothermal water, with an increase in the heterogeneity of the thermal reservoir medium, and a decrease in permeability. The extent of clogging gradually reduces with an increase in seepage path. Thus, thermal reservoir clogging is more serious closer to the water inlet. With an increase in the duration of reinjection, the permeability of the porous medium undergoes three stages: “rapid”, “decline-slow”, and “decrease-stable”. The results show that the richness and diversity of the bacterial community increase and decrease, respectively, during the reinjection process. Bacterial community succession occurs, and the bacterial communities mainly include the Proteobacteria and Bacteroidetes phyla. <em>Pseudomonas</em> and <em>Devosia</em> are respectively the dominant bacteria in the early and late stages of geothermal water reinjection.展开更多
The studies of water, gas and isotope chemistry indicate that the formation of geothermal water in the Henjing area is not related to the magmatic and volcanic sources. The geothermal water mainly derives from the met...The studies of water, gas and isotope chemistry indicate that the formation of geothermal water in the Henjing area is not related to the magmatic and volcanic sources. The geothermal water mainly derives from the meteoric source, and the gas components originate from the mixing of meteoric, crustal and mantle sources. Moreover, the geothermal water is in a low to moderate temperature geothermal reservoir. The results calculated by the quartz geothermometer and the silicaenthalpy diagram demonstrate that the lowest temperature of geothermal reservoir is in the range 78℃ to 134 ℃ and the highest temperature is in the range 95℃C to 155℃. Based on isotopic data, the possible elevation of recharge water is about 337. 5 m to 743. 6 m, which corresponds to the Wunizhang area.展开更多
Based on comparative analysis on hydrochemical characteristics of geothermal water in the north part of Liaokao fault,this research focuses on studying the indicative significance of hydrochemical characteristics for ...Based on comparative analysis on hydrochemical characteristics of geothermal water in the north part of Liaokao fault,this research focuses on studying the indicative significance of hydrochemical characteristics for the formation of geothermal water.The result shows that:(1)There is no obvious hydraulic connection between the karst geothermal water(occurred in the east part of the Liaokao fault)and the sandstone geothermal water(occurred in the west part of Liaokao fault).(2)In a close hydrological environment,caused by tectonic activities,geothermal water remains longer time in reservoir,hence the water-rock interaction is more complete,with high degree of concentrations,whereas the renewable capacity of the water is weaker.(3)There is no high temperature mantle source fluid mixed in the geothermal water.Karst geothermal water occurred deep circulatory convection along Liaokao fault and its secondary fault,therefore there is deep crust source fluid added into the geothermal water,closer to the Liaokao fault,the greater affected by the deep crust fluid.However,sandstone geothermal water has weak deep circulatory convection.展开更多
In the process of geothermal exploitation and utilization, the reinjection amount of used geothermal water in super-deep and porous reservoir is small and significantly decreases over time. This has been a worldwide p...In the process of geothermal exploitation and utilization, the reinjection amount of used geothermal water in super-deep and porous reservoir is small and significantly decreases over time. This has been a worldwide problem, which greatly restricts the exploitation and utilization of geothermal resources. Based on a large amount of experiments and researches, the reinjection research on the tail water of Xianyang No.2 well, which is carried out by combining the application of hydrogeochemical simulation, clogging mechanism research and the reinjection experiment, has achieved breakthrough results. The clogging mechanism and indoor simulation experiment results show: Factors affecting the tail water reinjection of Xianyang No.2 well mainly include chemical clogging, suspended solids clogging, gas clogging, microbial clogging and composite clogging, yet the effect of particle migration on clogging has not been found; in the process of reinjection, chemical clogging was mainly caused by carbonates(mainly calcite), silicates(mainly chalcedony), and a small amount of iron minerals, and the clogging aggravated when the temperature rose; suspended solids clogging also aggravated when the temperature rose, which showed that particles formed by chemical reaction had a certain proportion in suspended solids.展开更多
Fault has an important influence on the storage and movement of geothermal water. The Zhangzhou Basin is wholly located in a granodiorite rock mass. Due to the low permeability of granodiorite, faulted structure has a...Fault has an important influence on the storage and movement of geothermal water. The Zhangzhou Basin is wholly located in a granodiorite rock mass. Due to the low permeability of granodiorite, faulted structure has an evident control action on the hydrothermal activity of geothermal fields. Hot springs in Zhangzhou Basin crack along Pingtan-Dongshan Fault to the northeastern direction and emerge along Fu'an-Nanjing Fault. Through measurement of the temperature of several hot springs in the Basin, we found the temperature along the northwestern direction of Zhangzhou-Tianbao Fault is high and the temperature gap between the two sides of Yangxi-Yuanshan Fault is huge; the estimation of geothermal reservoir temperature of geothermal water through quartz geothermometer indicates that the geothermal reservoir temperature of the northern area of Nanjing-Xiamen Fault is obviously higher than that of southern area. Such result indicates that Fault obviously obstructs underground heat source. Under the condition that the average geothermal gradient of the Zhangzhou Basin is set, the circulation depth of the geothermal water of the Zhangzhou Basin measured by geothermal reservoir temperature is 3 550-5 200 m and the circulation depth of the geothermal water of the north of Nanjing-Xiamen Fault is deeper than that of the South.展开更多
There exists abundant thermal water recourses in Guanzhong basin, Shaanxi province (northwestern China). With the deepening of exploitation for thermal aquifer nowadays, the information about the origin and movement o...There exists abundant thermal water recourses in Guanzhong basin, Shaanxi province (northwestern China). With the deepening of exploitation for thermal aquifer nowadays, the information about the origin and movement of thermal water is limited by using traditional methods. This paper applies environmental isotope techniques to offer direct constraints on the recharge and movement of thermal water and improve the geological and hydrogeological data- base in Guanzhong Basin. The research on the environmental isotopes shows that the geothermal water of the area is mainly recharged by meteoric water. The temperature of meteoric water which replenishes geothermal water in the study area is -16 ℃. The estimated age of recharging the geothermal water is 13.3-28.2 ka based on the isotope analysis, belonging to the last glacial period in Late Quaternary. The source of replenishment of the geothermal water is thought to have been derived from glacial snow-melt water with an elevation higher than 1 500 m (ASL) in the north side of Qinling Mountain. The isotopic analysis denotes that the geothermal water in the southern Guanzhong basin is the mixture of net thermal water and normal temperature groundwater. Based on calculating the percentage of the mixture, nearly half of cold groundwater had participated the circulating of the geothermal water. However, in the center part of the basin, some artificial factors such as mismanage of pumping are probably the reason for the mixturing. The temperature range of the geothermal reservoirs in the basin is estimated at about 80-121 ℃ based on calculation of both SiO2 geothermometer and thermal water saturation index, which are basically in accordance with the measured temperature of thermal water. Based on the replenishment time and mixture extent with cold water, the thermal water in the studied area can be classified into three parts: mixed thermal water replenished by modern meteoric water; mixed thermal water replenished by both modern and ancient meteoric water, and deep circulating thermal water replenished by ancient meteoric water without mixture.展开更多
Nyemo-Nagqu, Tibet, is rich in high-temperature geothermal resources. The geothermal fields in Yangbajain and Yangyi as well as 11 unexplored geothermal fields along the geothermal belt from Nyemo to Nagqu were system...Nyemo-Nagqu, Tibet, is rich in high-temperature geothermal resources. The geothermal fields in Yangbajain and Yangyi as well as 11 unexplored geothermal fields along the geothermal belt from Nyemo to Nagqu were systematically investigated and the hydrochemistry data were collected from the whole field. Meanwhile, H-O-C-S isotope data were obtained for the new fields, and H-O isotope data for the Yangbajain and Yangyi fields. A comparison of the Nyemo-Nagqu geothermal fields with those in the Yangbajain area shows that the types of high-temperature geothermal water are dominated by Cl-Na and Cl·HCO_3-Na, while the types of medium-high-temperature geothermal water are dominated by HCO_3-Na. The concentrations of Li, F, SiO_2, and HBO_2 in the geothermal water are positively correlated with Cl content, indicating possible mixing with magma water. The reservoir temperatures range from 90 to 270°C by geothermometers. Slight drifting of ^(18)O was recorded at the Dongweng and Nyingzhong high-temperature geothermal fields, while more significant drifting was recorded at Gulu. The geothermal water is mainly replenished by atmospheric precipitation. The low tritium contents(<1 TU) of the geothermal water from Nyingzhong, Gulu, and Luoma indicate that it is mainly replenished by sub-modern(prior to 1952) water, while the high tritium content(8.4 TU) in Yuela implies modern water replenishment. Other geothermal fields are replenished by a mix of sub-modern fresher water. The isotopic data in this study show that the carbon and sulfur in the geothermal water originates mainly from sediment leaching, with some of the carbon and sulfur having a deep origin.展开更多
This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal ?eld, located in north-central Algeria. The aquifer that...This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal ?eld, located in north-central Algeria. The aquifer that feeds these springs is mainly situated in the deeply fractured Jurassic limestone and dolomite of the Zaccar Mount. Measured discharge temperatures of the cold waters range from 16.0 to 26.5 °C and the hot waters from 32.1 to 68.2 °C. All waters exhibited a near-neutral p H of 6.0–7.6. The thermal waters had a high total dissolved solids(TDS) content of up to 2527 mg/l, while the TDS for cold waters was 659.0–852.0 mg/l. Chemical analyses suggest that two main types of water exist: hot waters in the up?ow area of the Ca–Na–SO_4type(Hammam Righa) and cold waters in the recharge zone of the Ca–Na–HCO_3type(Zaccar Mount). Reservoir temperatures were estimated using silica geothermometers and?uid/mineral equilibria at 78, 92, and 95 °C for HR4, HR2,and HR1, respectively. Stable isotopic analyses of the δ^(18)O and δD composition of the waters suggest that the thermal waters of Hammam Righa are of meteoric origin. We conclude that meteoric recharge in?ltrates through the fractured dolomitic limestones of the Zaccar Mount and is conductively heated at a depth of 2.1–2.2 km. The hot waters then interact at depth with Triassic evaporites located in the hydrothermal conduit(fault), giving rise to the Ca–Na–SO_4water type. As they ascend to the surface,the thermal waters mix with shallower Mg-rich groundwater, resulting in waters that plot in the immature water?eld in the Na–K–Mg diagram. The mixing trend between cold groundwaters from the recharge zone area(Zaccar Mount) and hot waters in the up?ow area(Hammam Righa) is apparent via a chloride-enthalpy diagram that shows a mixing ratio of 22.6 \ R \ 29.2 %. We summarize these results with a geothermal conceptual model of the Hammam Righa geothermal ?eld.展开更多
In this study, the Ag/Ag Cl/WO3 plasmonic Z-scheme photocatalysts with different contents of Ag/Ag Cl nanoparticles(NPs) were prepared through a facile ultrasonic precipitation method in geothermal water,wherein the g...In this study, the Ag/Ag Cl/WO3 plasmonic Z-scheme photocatalysts with different contents of Ag/Ag Cl nanoparticles(NPs) were prepared through a facile ultrasonic precipitation method in geothermal water,wherein the geothermal water served as the chlorine source. Then the photocatalytic activity was investigated by degradation of 4-Aminobenzoic acid(4-ABA) under visible-light irradiation. It was found that the as-prepared 50 wt% Ag/Ag Cl/WO3 photocatalyst showed the highest photocatalytic efficiency with 25.12 and 3.53 times higher than those of pure WO3 and Ag/Ag Cl, respectively. The active species trapping experiments indicated that h+and ·O2-were key factors in 4-ABA photodegradation process. The possible plasmonic Z-scheme photocatalytic mechanism of photocatalytic reaction for 4-ABA degradation was proposed based on systematical characterizations. We hope this paper could give new ideas for further exploiting geothermal energy to design and fabricate highly efficient visible-light-driven photocatalysts for environmental remediation.展开更多
According to the chemical composition of thermal water from Geothermal Well DR2010 located in the Weiyuan Geothermal Field of Huzhu County in Qinghai Province, the groundwater recharge, age and geothermal resource pot...According to the chemical composition of thermal water from Geothermal Well DR2010 located in the Weiyuan Geothermal Field of Huzhu County in Qinghai Province, the groundwater recharge, age and geothermal resource potential of the thermal water are discussed by using the methods of Langelier-Ludwig Diagram, isotopic hydrology and geochemical thermometric scale. The analysis results indicate that the Weiyuan Geothermal Field is located in the northern fringe of Xining Basin, where the geothermal water, compared with that located in the central area of Xining Basin, is characterized by greater water yield, shallower buried depth of thermal reservoir and easier exploitation. Due to its active exchange with the modern cold water, the thermal water here shows relatively younger age. These findings provide a hydro-geochemical evidence for the exploitation of Weiyuan Geothermal Field.展开更多
Geothermal with features of large reserves and non-pollution has been one of the most important energy. China has significant geothermal resources. There are rich hydrothermal resources in Xinji, which has been in dev...Geothermal with features of large reserves and non-pollution has been one of the most important energy. China has significant geothermal resources. There are rich hydrothermal resources in Xinji, which has been in development for 5 years. However, hot water continues to decrease because of extensive exploitation and utilization. We selected exploration area as study area, build a set of numerical models of Guantao formation on the basis of actual geological conditions. We get the distribution of hydraulic conductivity from 1.7 m/d to 1.9 m/d by parameter inversion using historical water level monitoring data, and simulation effect is good. We calculate the maximum permissible exploitation under the limitation of 200 m in depth in 50 years which is about 2.2 million m3/a. The results will provide theoretic support for plan making of geothermal exploitation.展开更多
The geothermal waters of south hot spring, small hot spring and Qiaokouba in Chongqing, are all part of the south hot spring geothermal water system. Exploitation has caused a decline in the water levels of the south ...The geothermal waters of south hot spring, small hot spring and Qiaokouba in Chongqing, are all part of the south hot spring geothermal water system. Exploitation has caused a decline in the water levels of the south and small hot springs, which have not flowed naturally for 15 years. Now, bores pump geothermal water to the springs. If the water level drops below the elevation of the rivers, river-water will replenish the geothermal water, destroying this resource. It is therefore an urgent task to model the geothermal water system, to enable sustainable development and continued use of the geothermal water in Qiaokouba. A numerical simulation of the geothermal water system was adoptedand a quantitative study on the planning scheme was carried out. A mathematical model was set up to simulate the whole geothermal water system, based on data from the research sites. The model determined the maximum sustainable water yield in Qiaokouba and the two hot springs, and the south hot spring and small hot spring sustainable yields are 1 100 m3/d and 700 m3/d from 2006 to 2010, 1 300 m3/d and 1 000 m3/dfrom 2011 to 2015, and 1 500 m3/d and 1 200 m3/d from 2016 to 2036. The maximum exploitable yield is 3 300 m3/d from 2006 to 2036 in Qiaokouba. The model supplies a basis to adequately exploit and effectively protect the geothermal water resources, and to continue to develop the geothermal water as a tourist attraction in Chongqing.展开更多
On the basis of discussion about hydro-geologic condition of geothermal water in Xiaoquan area, Chongqing, a three-dimensional mathematical model was established. The Modflow(a modular three-dimensional finite-differe...On the basis of discussion about hydro-geologic condition of geothermal water in Xiaoquan area, Chongqing, a three-dimensional mathematical model was established. The Modflow(a modular three-dimensional finite-difference groundwater model) software was adopted to simulate the geothermal water, and quantificational study on sustainable exploration of the geothermal water in Xiaoquan area was carried out. Firstly, a mathe- matical model was set up. Then, the geothermal water was simulated by Modflow software, and the mathematical model was identified. The simulative water level was compared with the actual water level and the mathematical model was calibrated. The feasibility of appli- cation of this mathematical model to studying underground geothermal water was proved that the simulative water level is approximated to actual one, and a right mathematical model was obtained. This mathematical model was used to simulate geothermal water under different exploitation conditions, at last the yields of sustainable exploitation includ- ing the maximum yield and the optimal yield were determined.展开更多
Study on the Nuanquanzi geothermal field in the Yanshan uplift is of great significance for understanding the origin of geothermal fluid in the intracontinental orogenic belt of the fault depression basin margin in No...Study on the Nuanquanzi geothermal field in the Yanshan uplift is of great significance for understanding the origin of geothermal fluid in the intracontinental orogenic belt of the fault depression basin margin in North China.The geochemical characteristics and formation mechanism of the Nuanquanzi geothermal system were elucidated by classical hydrogeochemical analysis,multi-isotopes approach(δD,δ^(18)O,δ^(13)C,δ^(87)Sr/^(86)Sr),14CAMSdating,and integrated geophysical prospecting of surface-soil radon gas measurement and CSAMT inversion.The results show that the Nuanquanzi geothermal field is a medium-low temperature convection-fault semi-enclosed geothermal system.The hydrochemical type of thermal water is primarily HCO_(3)-Na,and rich in soluble SiO_(2),F^(-)and Cl^(-).The geothermal water primarily originated from the recharging meteoric water with a maximum circulation depth of 2400-3200 m,but affected by the mixing of endogenous sedimentary water.The reservoir temperature calculated by Na-K and quartz geothermometer of the Nuanquanzi geothermal system was determined to be 73.39-92.87℃.The conduction-cooling and shallow cold-water mixing processes occurred during the parent geothermal fluid ascent to surface,and the proportion of cold-water mixing during circulation was approximately 88.3%to 92.2%.The high-anomaly radon zones matched well to the low apparentresistance areas and hiding faults,indicating that the Nuanquanzi geothermal field was dominated by a graben basin restricted by multiple faults.展开更多
High residual concentration of arsenic and fluoride is a tricky problem to be solved in the process of reinjection after geothermal water utilization.We develop a method to simultaneously remove As(V)and F-from geothe...High residual concentration of arsenic and fluoride is a tricky problem to be solved in the process of reinjection after geothermal water utilization.We develop a method to simultaneously remove As(V)and F-from geothermal water using magnetic Fe_(3)O_(4)@MgO adsorbent,fabricated via a one-step method.The effects of pH,contact time,adsorbent dose and temperature on the removal efficiency were investigated systematically.The results show that the Fe_(3)O_(4)@MgO composite has a wide range of pH(2-11),ultrafast removal dynamics(As(V):2 min;F-:30 min),and high removal efficiency(As(V):99.9%;F-:96.6%).The adsorption kinetics follows the pseudo-secondorder kinetics model,and the adsorption isotherm model fits Freundlich.The adsorption capacity of As(V)and F-can reach 123 and 98.4 mg/g,respectively.The exchange of As(V)and F-with Mg-hydroxyl groups hydrolysis by MgO was determined the adsorption mechanism.The Fe_(3)O_(4)@MgO adsorbent was capable of achieving the adsorption efficiency as high as 99.9%for As(V)and 97.3%for F-in real geothermal water,respectively.Hence,the proposed Fe_(3)O_(4)@MgO composite exhibited as an excellent adsorbent for the remediation of As-and F-contaminated geothermal water.展开更多
The Xi'an Depression in the Guanzhong Basin of western China has been suggested to contain geothermal resources that could aid China in achieving carbon neutrality and optimizing energy structure.However,the high ...The Xi'an Depression in the Guanzhong Basin of western China has been suggested to contain geothermal resources that could aid China in achieving carbon neutrality and optimizing energy structure.However,the high concentration of total dissolved solids(TDS)and scale-forming ions in geothermal water from the depression causes severe scaling problems in harvesting geothermal energy.To reduce scale-related problems,accurate identification of scale types and prediction of scaling during geothermal energy utilization are crucial.This study starts with identifying the types and trends of scaling in the study area,using index-based discriminant methods and hydrogeochemical simulation to calculate and analyze the mineral saturation index of water samples from some wellheads and of reconstructed fluid samples of geothermal reservoirs.The results indicate that the scales are mostly calcium carbonate scales rather than sulfate scales as a result of temperature changes.Several portions of the geothermal water systems are found to have distinct mineral scaling components.Quartz and chalcedony are formed in low temperature areas,while carbonate minerals are in high temperature areas.Despite the low iron content of geothermal water samples from the study area,scaling is very common due to scaling-prone iron minerals.The findings can be used to evaluate geothermal drainage systems and guide anti-scaling during geothermal energy utilization in similar settings.展开更多
This paper provides an overview of conventional geothermal systems and unconventional geothermal developments as a common reference is needed for discussions between energy professionals. Conventional geothermal syste...This paper provides an overview of conventional geothermal systems and unconventional geothermal developments as a common reference is needed for discussions between energy professionals. Conventional geothermal systems have the heat, permeability and fluid, requiring only drilling down to °C, normal heat flow or decaying radiogenic granite as heat sources, and used in district heating. Medium-temperature (MT) 100°C - 190°C, and high-temperature (HT) 190°C - 374°C resources are mostly at plate boundaries, with volcanic intrusive heat source, used mostly for electricity generation. Single well capacities are °C - 500°C) and a range of depths (1 m to 20 Km), but lack permeability or fluid, thus requiring stimulations for heat extraction by conduction. HVAC is 1 - 2 m deep and shallow geothermal down to 500 m in wells, both capturing °C, with °C are either advanced by geothermal developers at <7 Km depth (Enhanced Geothermal Systems (EGS), drilling below brittle-ductile transition zones and under geothermal fields), or by the Oil & Gas industry (Advanced Geothermal Systems, heat recovery from hydrocarbon wells or reservoirs, Superhot Rock Geothermal, and millimeter-wave drilling down to 20 Km). Their primary aim is electricity generation, relying on closed-loops, but EGS uses fractures for heat exchange with earthquake risks during fracking. Unconventional approaches could be everywhere, with shallow geothermal already functional. The deeper and hotter unconventional alternatives are still experimental, overcoming costs and technological challenges to become fully commercial. Meanwhile, the conventional geothermal resources remain the most proven opportunities for investments and development.展开更多
A multi-faceted Case Area Targeted Intervention (CATI) approach emphasizing the integration of Water, Sanitation and Hygiene (WASH) interventions and Oral Cholera Vaccine (OCV) campaign was employed to respond to the ...A multi-faceted Case Area Targeted Intervention (CATI) approach emphasizing the integration of Water, Sanitation and Hygiene (WASH) interventions and Oral Cholera Vaccine (OCV) campaign was employed to respond to the outbreak of cholera in Garissa County. Drinking water sources in areas heavily impacted by cholera were systematically mapped and tested for microbiological quality. The quality assessment was carried out in April 2023 during an ongoing cholera outbreak in the county. A total of 109 samples were collected and tested for thermotolerant coliforms and other in situ parameters. The finding revealed that more than 87% of the samples did not meet the World Health Organization (WHO) standard for thermotolerant coliforms;and 30% had turbidity values above the recommended threshold values. None of the 109 samples had any traceable residual chlorine. Following these findings, the county government implemented the targeted interventions which resulted in a positive impact in the fight against cholera. The WHO supported key interventions which included capacity building in water quality monitoring and prepositioning of critical WASH commodities to the cholera affected areas.展开更多
文摘Geothermal water can have a wide range of direct applications,including drinking,domestic use,irrigation and industrial use.This study analyses geothermal water from Dholera,Diu,Gandhar,Kutch,Porbandar,Tulsishyam,and Unai regions located in Gujarat,India,to determine the hydrochemistry for establishing the water's suitability for drinking and irrigation purposes.From each region,three different water samples were collected.For drinking purpose,total eleven water quality parameters such as pH,electrical conductivity,total dissolved solids,calcium,magnesium,sodium,potassium,chloride,sulphate,carbonate and bicarbonate were evaluated.Piper and Durov plots were used to understand the ionic composition and evolution of water.Whereas for irrigation,the parameters such as total dissolved solids,sodium absorption ration,electrical conductivity,and potential salinity were used for water quality check.Wilcox Plot was plotted to understand the sodium and salinity hazard of water.Water quality index and irrigation water quality index were used to assess the water quality for making the analytical procedure easy.The findings indicate that the water samples from the Dholera and Diu areas had extremely high values for both the water quality index and total dissolved solids content.Water in these places may be appropriate for making salt.All the other samples show adequacy for utilization in irrigation purpose.
基金financially supported by the National Natural Science Foundation of China (No. 41120124003, 41572335 and 41521001)the research program of China Power Investment Corporation (2015-138-HHS-KJ-X)the research program of State Key Laboratory of Biogeology and Environmental Geology of China
文摘Longling is characterized by a wide distribution of hydrothermal areas, among which the Banglazhang hydrothermal system is the most geothermally active. Banglazhang is marked by intensive hydrothermal activities including hot springs, geysers, fumaroles and hydrothermal explosions. The geothermal waters from the Longling region are mainly HCO3-Na type with low but comparable SO4 and Cl concentrations. Calculations based on a variety of chemical geothermometers and a K-Ca geobarometer indicate that the Banglazhang hydrothermal system has much higher subsurface temperature and CO2 pressure compared to the other systems such as Daheba, Dazhulin and Huangcaoba. However, geothermal water samples collected from all these alternative hydrothermal areas are either partially equilibrated with reservoir minerals or are immature. The silica-enthalpy relationships of Banglazhang geothermal waters indicate the presence of a deep geothermal fluid with an enthalpy value and silica concentration of 945 J/g（up to around 220 °C） and 339 mg/L. Our work indicates the Banglazhang area is a promising source in terms of long-term utilization of hydrothermal resources.
文摘To study the mechanism of bio-clogging in a porous medium during the reinjection of geothermal water and to improve reinjection efficiency, an indoor one-dimensional reinjection experiment was conducted based on the geological model of the geothermal reinjection demonstration project in Dezhou City. The biological process of porous media clogging was investigated by analyzing the variation of permeability within the medium, the main indexes of nutrient salts, and the content of extracellular polymeric substances (EPS). High-throughput sequencing, based on 16S rRNA, was used to analyze the characteristics and succession of microbial communities during the reinjection of geothermal water. The results of the study show that significant bio-clogging occurs during the reinjection of geothermal water, with an increase in the heterogeneity of the thermal reservoir medium, and a decrease in permeability. The extent of clogging gradually reduces with an increase in seepage path. Thus, thermal reservoir clogging is more serious closer to the water inlet. With an increase in the duration of reinjection, the permeability of the porous medium undergoes three stages: “rapid”, “decline-slow”, and “decrease-stable”. The results show that the richness and diversity of the bacterial community increase and decrease, respectively, during the reinjection process. Bacterial community succession occurs, and the bacterial communities mainly include the Proteobacteria and Bacteroidetes phyla. <em>Pseudomonas</em> and <em>Devosia</em> are respectively the dominant bacteria in the early and late stages of geothermal water reinjection.
文摘The studies of water, gas and isotope chemistry indicate that the formation of geothermal water in the Henjing area is not related to the magmatic and volcanic sources. The geothermal water mainly derives from the meteoric source, and the gas components originate from the mixing of meteoric, crustal and mantle sources. Moreover, the geothermal water is in a low to moderate temperature geothermal reservoir. The results calculated by the quartz geothermometer and the silicaenthalpy diagram demonstrate that the lowest temperature of geothermal reservoir is in the range 78℃ to 134 ℃ and the highest temperature is in the range 95℃C to 155℃. Based on isotopic data, the possible elevation of recharge water is about 337. 5 m to 743. 6 m, which corresponds to the Wunizhang area.
基金This research was financially supported by China Geological Survey Project(DD20189114,DD20190129)the Basic Scientific Research Project of the Chinese Academy of Geological Sciences(JKY1722,YWF201903-01 and JYYWF20180501).
文摘Based on comparative analysis on hydrochemical characteristics of geothermal water in the north part of Liaokao fault,this research focuses on studying the indicative significance of hydrochemical characteristics for the formation of geothermal water.The result shows that:(1)There is no obvious hydraulic connection between the karst geothermal water(occurred in the east part of the Liaokao fault)and the sandstone geothermal water(occurred in the west part of Liaokao fault).(2)In a close hydrological environment,caused by tectonic activities,geothermal water remains longer time in reservoir,hence the water-rock interaction is more complete,with high degree of concentrations,whereas the renewable capacity of the water is weaker.(3)There is no high temperature mantle source fluid mixed in the geothermal water.Karst geothermal water occurred deep circulatory convection along Liaokao fault and its secondary fault,therefore there is deep crust source fluid added into the geothermal water,closer to the Liaokao fault,the greater affected by the deep crust fluid.However,sandstone geothermal water has weak deep circulatory convection.
基金funded by National Science Foundation Project in 2015 (No.41472221)
文摘In the process of geothermal exploitation and utilization, the reinjection amount of used geothermal water in super-deep and porous reservoir is small and significantly decreases over time. This has been a worldwide problem, which greatly restricts the exploitation and utilization of geothermal resources. Based on a large amount of experiments and researches, the reinjection research on the tail water of Xianyang No.2 well, which is carried out by combining the application of hydrogeochemical simulation, clogging mechanism research and the reinjection experiment, has achieved breakthrough results. The clogging mechanism and indoor simulation experiment results show: Factors affecting the tail water reinjection of Xianyang No.2 well mainly include chemical clogging, suspended solids clogging, gas clogging, microbial clogging and composite clogging, yet the effect of particle migration on clogging has not been found; in the process of reinjection, chemical clogging was mainly caused by carbonates(mainly calcite), silicates(mainly chalcedony), and a small amount of iron minerals, and the clogging aggravated when the temperature rose; suspended solids clogging also aggravated when the temperature rose, which showed that particles formed by chemical reaction had a certain proportion in suspended solids.
基金supported by Basal Science Research Fund from Institute of Hydrogeology and Environmental Geology(Grant No.SK201606 and SK201501)China Geological Survey Project(No.DD20160191 and DD20160190)
文摘Fault has an important influence on the storage and movement of geothermal water. The Zhangzhou Basin is wholly located in a granodiorite rock mass. Due to the low permeability of granodiorite, faulted structure has an evident control action on the hydrothermal activity of geothermal fields. Hot springs in Zhangzhou Basin crack along Pingtan-Dongshan Fault to the northeastern direction and emerge along Fu'an-Nanjing Fault. Through measurement of the temperature of several hot springs in the Basin, we found the temperature along the northwestern direction of Zhangzhou-Tianbao Fault is high and the temperature gap between the two sides of Yangxi-Yuanshan Fault is huge; the estimation of geothermal reservoir temperature of geothermal water through quartz geothermometer indicates that the geothermal reservoir temperature of the northern area of Nanjing-Xiamen Fault is obviously higher than that of southern area. Such result indicates that Fault obviously obstructs underground heat source. Under the condition that the average geothermal gradient of the Zhangzhou Basin is set, the circulation depth of the geothermal water of the Zhangzhou Basin measured by geothermal reservoir temperature is 3 550-5 200 m and the circulation depth of the geothermal water of the north of Nanjing-Xiamen Fault is deeper than that of the South.
基金Project 2005003 supported by the Natural Science Foundation of Shaanxi Province
文摘There exists abundant thermal water recourses in Guanzhong basin, Shaanxi province (northwestern China). With the deepening of exploitation for thermal aquifer nowadays, the information about the origin and movement of thermal water is limited by using traditional methods. This paper applies environmental isotope techniques to offer direct constraints on the recharge and movement of thermal water and improve the geological and hydrogeological data- base in Guanzhong Basin. The research on the environmental isotopes shows that the geothermal water of the area is mainly recharged by meteoric water. The temperature of meteoric water which replenishes geothermal water in the study area is -16 ℃. The estimated age of recharging the geothermal water is 13.3-28.2 ka based on the isotope analysis, belonging to the last glacial period in Late Quaternary. The source of replenishment of the geothermal water is thought to have been derived from glacial snow-melt water with an elevation higher than 1 500 m (ASL) in the north side of Qinling Mountain. The isotopic analysis denotes that the geothermal water in the southern Guanzhong basin is the mixture of net thermal water and normal temperature groundwater. Based on calculating the percentage of the mixture, nearly half of cold groundwater had participated the circulating of the geothermal water. However, in the center part of the basin, some artificial factors such as mismanage of pumping are probably the reason for the mixturing. The temperature range of the geothermal reservoirs in the basin is estimated at about 80-121 ℃ based on calculation of both SiO2 geothermometer and thermal water saturation index, which are basically in accordance with the measured temperature of thermal water. Based on the replenishment time and mixture extent with cold water, the thermal water in the studied area can be classified into three parts: mixed thermal water replenished by modern meteoric water; mixed thermal water replenished by both modern and ancient meteoric water, and deep circulating thermal water replenished by ancient meteoric water without mixture.
基金funded by the Natural Science Foundation of China(Grant Nos.41502220)the Chinese Academy of Geological Sciences Fund(No.YK201611)
文摘Nyemo-Nagqu, Tibet, is rich in high-temperature geothermal resources. The geothermal fields in Yangbajain and Yangyi as well as 11 unexplored geothermal fields along the geothermal belt from Nyemo to Nagqu were systematically investigated and the hydrochemistry data were collected from the whole field. Meanwhile, H-O-C-S isotope data were obtained for the new fields, and H-O isotope data for the Yangbajain and Yangyi fields. A comparison of the Nyemo-Nagqu geothermal fields with those in the Yangbajain area shows that the types of high-temperature geothermal water are dominated by Cl-Na and Cl·HCO_3-Na, while the types of medium-high-temperature geothermal water are dominated by HCO_3-Na. The concentrations of Li, F, SiO_2, and HBO_2 in the geothermal water are positively correlated with Cl content, indicating possible mixing with magma water. The reservoir temperatures range from 90 to 270°C by geothermometers. Slight drifting of ^(18)O was recorded at the Dongweng and Nyingzhong high-temperature geothermal fields, while more significant drifting was recorded at Gulu. The geothermal water is mainly replenished by atmospheric precipitation. The low tritium contents(<1 TU) of the geothermal water from Nyingzhong, Gulu, and Luoma indicate that it is mainly replenished by sub-modern(prior to 1952) water, while the high tritium content(8.4 TU) in Yuela implies modern water replenishment. Other geothermal fields are replenished by a mix of sub-modern fresher water. The isotopic data in this study show that the carbon and sulfur in the geothermal water originates mainly from sediment leaching, with some of the carbon and sulfur having a deep origin.
基金the MEXT(Ministry of Education,Culture,Sports,Science and Techn ology,Japan)Ph.D.scholarship providing support for the first author during this studythe G-COE of Kyushu University for funding this research
文摘This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal ?eld, located in north-central Algeria. The aquifer that feeds these springs is mainly situated in the deeply fractured Jurassic limestone and dolomite of the Zaccar Mount. Measured discharge temperatures of the cold waters range from 16.0 to 26.5 °C and the hot waters from 32.1 to 68.2 °C. All waters exhibited a near-neutral p H of 6.0–7.6. The thermal waters had a high total dissolved solids(TDS) content of up to 2527 mg/l, while the TDS for cold waters was 659.0–852.0 mg/l. Chemical analyses suggest that two main types of water exist: hot waters in the up?ow area of the Ca–Na–SO_4type(Hammam Righa) and cold waters in the recharge zone of the Ca–Na–HCO_3type(Zaccar Mount). Reservoir temperatures were estimated using silica geothermometers and?uid/mineral equilibria at 78, 92, and 95 °C for HR4, HR2,and HR1, respectively. Stable isotopic analyses of the δ^(18)O and δD composition of the waters suggest that the thermal waters of Hammam Righa are of meteoric origin. We conclude that meteoric recharge in?ltrates through the fractured dolomitic limestones of the Zaccar Mount and is conductively heated at a depth of 2.1–2.2 km. The hot waters then interact at depth with Triassic evaporites located in the hydrothermal conduit(fault), giving rise to the Ca–Na–SO_4water type. As they ascend to the surface,the thermal waters mix with shallower Mg-rich groundwater, resulting in waters that plot in the immature water?eld in the Na–K–Mg diagram. The mixing trend between cold groundwaters from the recharge zone area(Zaccar Mount) and hot waters in the up?ow area(Hammam Righa) is apparent via a chloride-enthalpy diagram that shows a mixing ratio of 22.6 \ R \ 29.2 %. We summarize these results with a geothermal conceptual model of the Hammam Righa geothermal ?eld.
基金the financial support by the National Natural Science Foundation of China (grant no. 51272107 and 51372118)the Doctor Discipline Special Research Foundation of Chinese Ministry of Education (grant no. 20133219110015)
文摘In this study, the Ag/Ag Cl/WO3 plasmonic Z-scheme photocatalysts with different contents of Ag/Ag Cl nanoparticles(NPs) were prepared through a facile ultrasonic precipitation method in geothermal water,wherein the geothermal water served as the chlorine source. Then the photocatalytic activity was investigated by degradation of 4-Aminobenzoic acid(4-ABA) under visible-light irradiation. It was found that the as-prepared 50 wt% Ag/Ag Cl/WO3 photocatalyst showed the highest photocatalytic efficiency with 25.12 and 3.53 times higher than those of pure WO3 and Ag/Ag Cl, respectively. The active species trapping experiments indicated that h+and ·O2-were key factors in 4-ABA photodegradation process. The possible plasmonic Z-scheme photocatalytic mechanism of photocatalytic reaction for 4-ABA degradation was proposed based on systematical characterizations. We hope this paper could give new ideas for further exploiting geothermal energy to design and fabricate highly efficient visible-light-driven photocatalysts for environmental remediation.
基金funded by Science and Technology Project Subsidized by Central Budget (2009-840)
文摘According to the chemical composition of thermal water from Geothermal Well DR2010 located in the Weiyuan Geothermal Field of Huzhu County in Qinghai Province, the groundwater recharge, age and geothermal resource potential of the thermal water are discussed by using the methods of Langelier-Ludwig Diagram, isotopic hydrology and geochemical thermometric scale. The analysis results indicate that the Weiyuan Geothermal Field is located in the northern fringe of Xining Basin, where the geothermal water, compared with that located in the central area of Xining Basin, is characterized by greater water yield, shallower buried depth of thermal reservoir and easier exploitation. Due to its active exchange with the modern cold water, the thermal water here shows relatively younger age. These findings provide a hydro-geochemical evidence for the exploitation of Weiyuan Geothermal Field.
基金supported by thermal response test(TRT)and numerical modeling with vertical ground heat exchanger in media sand(41302189)the research on the behavior characteristic of As and REE in high temperature geothermal fluid(1415042249)geothermal survey of Xiamen-Qiongbei region in Southeast coastal(12120115045901)
文摘Geothermal with features of large reserves and non-pollution has been one of the most important energy. China has significant geothermal resources. There are rich hydrothermal resources in Xinji, which has been in development for 5 years. However, hot water continues to decrease because of extensive exploitation and utilization. We selected exploration area as study area, build a set of numerical models of Guantao formation on the basis of actual geological conditions. We get the distribution of hydraulic conductivity from 1.7 m/d to 1.9 m/d by parameter inversion using historical water level monitoring data, and simulation effect is good. We calculate the maximum permissible exploitation under the limitation of 200 m in depth in 50 years which is about 2.2 million m3/a. The results will provide theoretic support for plan making of geothermal exploitation.
文摘The geothermal waters of south hot spring, small hot spring and Qiaokouba in Chongqing, are all part of the south hot spring geothermal water system. Exploitation has caused a decline in the water levels of the south and small hot springs, which have not flowed naturally for 15 years. Now, bores pump geothermal water to the springs. If the water level drops below the elevation of the rivers, river-water will replenish the geothermal water, destroying this resource. It is therefore an urgent task to model the geothermal water system, to enable sustainable development and continued use of the geothermal water in Qiaokouba. A numerical simulation of the geothermal water system was adoptedand a quantitative study on the planning scheme was carried out. A mathematical model was set up to simulate the whole geothermal water system, based on data from the research sites. The model determined the maximum sustainable water yield in Qiaokouba and the two hot springs, and the south hot spring and small hot spring sustainable yields are 1 100 m3/d and 700 m3/d from 2006 to 2010, 1 300 m3/d and 1 000 m3/dfrom 2011 to 2015, and 1 500 m3/d and 1 200 m3/d from 2016 to 2036. The maximum exploitable yield is 3 300 m3/d from 2006 to 2036 in Qiaokouba. The model supplies a basis to adequately exploit and effectively protect the geothermal water resources, and to continue to develop the geothermal water as a tourist attraction in Chongqing.
文摘On the basis of discussion about hydro-geologic condition of geothermal water in Xiaoquan area, Chongqing, a three-dimensional mathematical model was established. The Modflow(a modular three-dimensional finite-difference groundwater model) software was adopted to simulate the geothermal water, and quantificational study on sustainable exploration of the geothermal water in Xiaoquan area was carried out. Firstly, a mathe- matical model was set up. Then, the geothermal water was simulated by Modflow software, and the mathematical model was identified. The simulative water level was compared with the actual water level and the mathematical model was calibrated. The feasibility of appli- cation of this mathematical model to studying underground geothermal water was proved that the simulative water level is approximated to actual one, and a right mathematical model was obtained. This mathematical model was used to simulate geothermal water under different exploitation conditions, at last the yields of sustainable exploitation includ- ing the maximum yield and the optimal yield were determined.
基金financially supported by the China Geological Survey(Nos.DD20190822 and DD20190536)the Key Research Program of Hebei Science and Technology Department(No.19224205D)。
文摘Study on the Nuanquanzi geothermal field in the Yanshan uplift is of great significance for understanding the origin of geothermal fluid in the intracontinental orogenic belt of the fault depression basin margin in North China.The geochemical characteristics and formation mechanism of the Nuanquanzi geothermal system were elucidated by classical hydrogeochemical analysis,multi-isotopes approach(δD,δ^(18)O,δ^(13)C,δ^(87)Sr/^(86)Sr),14CAMSdating,and integrated geophysical prospecting of surface-soil radon gas measurement and CSAMT inversion.The results show that the Nuanquanzi geothermal field is a medium-low temperature convection-fault semi-enclosed geothermal system.The hydrochemical type of thermal water is primarily HCO_(3)-Na,and rich in soluble SiO_(2),F^(-)and Cl^(-).The geothermal water primarily originated from the recharging meteoric water with a maximum circulation depth of 2400-3200 m,but affected by the mixing of endogenous sedimentary water.The reservoir temperature calculated by Na-K and quartz geothermometer of the Nuanquanzi geothermal system was determined to be 73.39-92.87℃.The conduction-cooling and shallow cold-water mixing processes occurred during the parent geothermal fluid ascent to surface,and the proportion of cold-water mixing during circulation was approximately 88.3%to 92.2%.The high-anomaly radon zones matched well to the low apparentresistance areas and hiding faults,indicating that the Nuanquanzi geothermal field was dominated by a graben basin restricted by multiple faults.
基金funded by the Second Comprehensive Scientific Investigation Project of Qinghai-Tibet Plateau(No.2019QZKK0603)the National Natural Science Foundation of China(No.22066022)+2 种基金Science and Technology Plan Projects of Tibet Autonomous Region(No.ZYYD2022000255)Key Projects of“Science and Technology Help Economy 2020”(No.SQ2020YFF0423891)Key Projects of Solid Waste Recycling(No.2019YFC1904103-04)。
文摘High residual concentration of arsenic and fluoride is a tricky problem to be solved in the process of reinjection after geothermal water utilization.We develop a method to simultaneously remove As(V)and F-from geothermal water using magnetic Fe_(3)O_(4)@MgO adsorbent,fabricated via a one-step method.The effects of pH,contact time,adsorbent dose and temperature on the removal efficiency were investigated systematically.The results show that the Fe_(3)O_(4)@MgO composite has a wide range of pH(2-11),ultrafast removal dynamics(As(V):2 min;F-:30 min),and high removal efficiency(As(V):99.9%;F-:96.6%).The adsorption kinetics follows the pseudo-secondorder kinetics model,and the adsorption isotherm model fits Freundlich.The adsorption capacity of As(V)and F-can reach 123 and 98.4 mg/g,respectively.The exchange of As(V)and F-with Mg-hydroxyl groups hydrolysis by MgO was determined the adsorption mechanism.The Fe_(3)O_(4)@MgO adsorbent was capable of achieving the adsorption efficiency as high as 99.9%for As(V)and 97.3%for F-in real geothermal water,respectively.Hence,the proposed Fe_(3)O_(4)@MgO composite exhibited as an excellent adsorbent for the remediation of As-and F-contaminated geothermal water.
基金supported by the Research Project on Middle and Deep Geothermal Energy Utilization in Guanzhong Area of Shaanxi ProvincedSpecial Study on Sandstone Thermal Storage Recharge(No.21152920349)the Special Fund for Basic Scientific Research Operating Expenses of Central Universities of Chang'an University(Grant No.300102292903)+1 种基金the Basic Research Plan of Natural Sciences of Shaanxi Province General Project“Study on Loess Landslide Chronology Based on OSL Dating Technology”(Grant No.2017JM4018)the Open Fund of State Key Laboratory of Loess and Quaternary Geology(Grant No.SKLLQG1933).
文摘The Xi'an Depression in the Guanzhong Basin of western China has been suggested to contain geothermal resources that could aid China in achieving carbon neutrality and optimizing energy structure.However,the high concentration of total dissolved solids(TDS)and scale-forming ions in geothermal water from the depression causes severe scaling problems in harvesting geothermal energy.To reduce scale-related problems,accurate identification of scale types and prediction of scaling during geothermal energy utilization are crucial.This study starts with identifying the types and trends of scaling in the study area,using index-based discriminant methods and hydrogeochemical simulation to calculate and analyze the mineral saturation index of water samples from some wellheads and of reconstructed fluid samples of geothermal reservoirs.The results indicate that the scales are mostly calcium carbonate scales rather than sulfate scales as a result of temperature changes.Several portions of the geothermal water systems are found to have distinct mineral scaling components.Quartz and chalcedony are formed in low temperature areas,while carbonate minerals are in high temperature areas.Despite the low iron content of geothermal water samples from the study area,scaling is very common due to scaling-prone iron minerals.The findings can be used to evaluate geothermal drainage systems and guide anti-scaling during geothermal energy utilization in similar settings.
文摘This paper provides an overview of conventional geothermal systems and unconventional geothermal developments as a common reference is needed for discussions between energy professionals. Conventional geothermal systems have the heat, permeability and fluid, requiring only drilling down to °C, normal heat flow or decaying radiogenic granite as heat sources, and used in district heating. Medium-temperature (MT) 100°C - 190°C, and high-temperature (HT) 190°C - 374°C resources are mostly at plate boundaries, with volcanic intrusive heat source, used mostly for electricity generation. Single well capacities are °C - 500°C) and a range of depths (1 m to 20 Km), but lack permeability or fluid, thus requiring stimulations for heat extraction by conduction. HVAC is 1 - 2 m deep and shallow geothermal down to 500 m in wells, both capturing °C, with °C are either advanced by geothermal developers at <7 Km depth (Enhanced Geothermal Systems (EGS), drilling below brittle-ductile transition zones and under geothermal fields), or by the Oil & Gas industry (Advanced Geothermal Systems, heat recovery from hydrocarbon wells or reservoirs, Superhot Rock Geothermal, and millimeter-wave drilling down to 20 Km). Their primary aim is electricity generation, relying on closed-loops, but EGS uses fractures for heat exchange with earthquake risks during fracking. Unconventional approaches could be everywhere, with shallow geothermal already functional. The deeper and hotter unconventional alternatives are still experimental, overcoming costs and technological challenges to become fully commercial. Meanwhile, the conventional geothermal resources remain the most proven opportunities for investments and development.
文摘A multi-faceted Case Area Targeted Intervention (CATI) approach emphasizing the integration of Water, Sanitation and Hygiene (WASH) interventions and Oral Cholera Vaccine (OCV) campaign was employed to respond to the outbreak of cholera in Garissa County. Drinking water sources in areas heavily impacted by cholera were systematically mapped and tested for microbiological quality. The quality assessment was carried out in April 2023 during an ongoing cholera outbreak in the county. A total of 109 samples were collected and tested for thermotolerant coliforms and other in situ parameters. The finding revealed that more than 87% of the samples did not meet the World Health Organization (WHO) standard for thermotolerant coliforms;and 30% had turbidity values above the recommended threshold values. None of the 109 samples had any traceable residual chlorine. Following these findings, the county government implemented the targeted interventions which resulted in a positive impact in the fight against cholera. The WHO supported key interventions which included capacity building in water quality monitoring and prepositioning of critical WASH commodities to the cholera affected areas.
