Organic Rankine cycle(ORC)is widely used for the low grade geothermal power generation.However,a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between th...Organic Rankine cycle(ORC)is widely used for the low grade geothermal power generation.However,a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between the heat source/sink and the working medium in the condenser and the evaporator.The condensing temperature,cooling water temperature difference and pinch point temperature difference are often fixed according to engineering experience.In order to optimize the ORC system comprehensively,the coupling effect of evaporation and condensation process was proposed in this paper.Based on the laws of thermodynamics,the energy analysis,exergy analysis and entropy analysis were adopted to investigate the ORC performance including net output power,thermal efficiency,exergy efficiency,thermal conductivity,irreversible loss,etc.,using geothermal water at a temperature of 120℃as the heat source and isobutane as the working fluid.The results show that there exists a pair of optimal evaporating temperature and condensing temperatures to maximize the system performance.The net power output and the system comprehensive performance achieve their highest values at the same evaporating temperature,but the system comprehensive performance corresponds to a lower condensing temperature than the net power output.展开更多
At present,industrial development is heavily dependent on traditional fossil energy,which has had an increasingly serious impact on the environment.Clean and renewable energy has received extensive attention and its p...At present,industrial development is heavily dependent on traditional fossil energy,which has had an increasingly serious impact on the environment.Clean and renewable energy has received extensive attention and its proportion in daily life has gradually increased.As a clean and renewable energy source that is not affected by changes in weather and seasons,geothermal energy has developed rapidly in recent years and has received increasing attention.According to reports,the total installed capacity of geothermal power generation in the world in 2020 was 15950 MW-an increase of~27%over 2015.At the end of 2019,the total installed capacity for global geothermal direct use was 107727 MW-an increase of 52.0%compared with 2015;the total annual energy use was 1020887 TJ(283580 GWh)-an increase of 72.3%over 2015.Through the investigation of geothermal power generation technology in recent years,the characteristics and shortcomings of various power generation methods are analysed.At the same time,this review analyzes the characteristics of geothermal energy and other renewable-energy(solar energy,water energy)coupling power generation,and analyzes the principles and characteristics of geothermal energy and various new-energy coupling power generation methods.Through investigation and analysis,this review provides a complete understanding of various geothermal power generation technologies and provides insights into the future development direction.展开更多
In order to improve the efficiency of a geothermal power plant, oil wells in the high water cut stage were used as geothermal wells, thereby improving the recovery ratio and economic benefit. A new function that refle...In order to improve the efficiency of a geothermal power plant, oil wells in the high water cut stage were used as geothermal wells, thereby improving the recovery ratio and economic benefit. A new function that reflects both the technical and economic performances was put forward and used as the objective function. An organic Rankine cycle (ORC) was analyzed through the energetic and exergetic analyses, and the reasons for low efficiency were pinpointed. Results indicate that geothermal water directly transferring heat to the working fluid reduces energy dissipation and increases cycle efficiencies. The net power output with an internal heat exchanger (IHE) is averagely 5.3% higher than that without an IHE. R601a and R601 can be used to replace R123 for geothermal water below 110℃. Moreover, the modified ORC dramatically outperforms the actual one.展开更多
Under the national"Dual Carbon"strategy,the development and utilization of stable and efficient renewable energy has become pivotal for energy structure transformation.Shandong Province hosts abundant geothe...Under the national"Dual Carbon"strategy,the development and utilization of stable and efficient renewable energy has become pivotal for energy structure transformation.Shandong Province hosts abundant geothermal resources with significant potential for large-scale exploitation.This paper systematically reviews the technological framework and application prospects of geothermal energy development in Shandong.First,the geological model of the geothermal system,centered on the"source-reservoir-caprock-conduit"framework,is elucidated.The characteristics of major thermal reservoirs,including the Neogene Guantao Formation,Paleogene Dongying Formation,and Cambrian-Ordovician strata,are analyzed in the context of Shandong’s geologic setting.Subsequently,advanced geophysical exploration methodologies—such as Magnetotelluric(MT),Controlled-Source Audio-Frequency Magnetotellurics(CSAMT),and Wide-Field Electromagnetic Method(WFEM)—are highlighted for their critical roles in precisely delineating thermal reservoirs and identifying heat-controlling structures,significantly improving exploration efficiency.In terms of utilization,this study examines diversified application models guided by the"cascade utilization"principle,emphasizing high-efficiency geothermal heating technologies(e.g.,geothermal heat pump systems)and power generation technologies(dry steam,fl ash steam,and binary cycle systems)tailored to resources of varying temperatures.The review demonstrates that technological innovations and mature application frameworks are driving the geothermal industry in Shandong toward high-quality development,providing robust support for regional energy security and low-carbon transition.展开更多
Enhanced geothermal system(EGS)is a primary method to develop geothermal resources stored in hot dry rock(HDR),but it faces several key problems,such as unreasonable hydraulic fracture networks at high reservoir tempe...Enhanced geothermal system(EGS)is a primary method to develop geothermal resources stored in hot dry rock(HDR),but it faces several key problems,such as unreasonable hydraulic fracture networks at high reservoir temperature,unclear multi-scale and multi-field coupling regularity,low heat extraction efficiency caused by the flashing flow in geothermal wells,and low thermoelectric conversion efficiency of geothermal fluid,which restricts the large-scale commercial development of geothermal resources.To resolve these major bottleneck problems,systematically reviews and analysis of the research progress and development trend of EGS are conducted in this paper.Particular attentions are devoted to four key technologies involved in the development of HDR geothermal resource by EGS:(1)the hydraulic fracturing technology for HDR reservoirs,including reservoir reconstruction methods,hydraulic fracturing network forming mechanisms and fracture propagation prediction models is illustrated in detail;(2)the fracture characterization methods,mathematical models and solution methods are described from three aspects including pore-scale multi-field coupled models,reservoir-scale multi-field coupled models and upscaling methods;(3)the efficient extraction technology of wellbore thermal fluid,involving the mechanism of flashing flows in geothermal wells and the experimental and numerical methods for investigating the characteristics offlashing flows are discussed;(4)the HDR geothermal power generation technologies,considering the principles of geothermal power generation,the types of power generation systems and the main application markets are introduced.In conclusion,EGS is a technology-intensive system,however,due to the complex working conditions of the underground reservoirs and the instability of the ground equipment,theoretical research tends to be separated from the practice.For the purpose of promoting the applicability of EGS,intimate combination and mutual guidance with the pilot tests are necessary to develop a production-research combined mode,and to raise the awareness and break through the key points in a constant back-and-forth.展开更多
基金Project(2018YFB1501805)supported by the National Key Research and Development Program of ChinaProject(51406130)supported by the National Natural Science Foundation of ChinaProject(201604-504)supported by the Key Laboratory of Efficient Utilization of Low and Medium Grade Energy(Tianjin University),China
文摘Organic Rankine cycle(ORC)is widely used for the low grade geothermal power generation.However,a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between the heat source/sink and the working medium in the condenser and the evaporator.The condensing temperature,cooling water temperature difference and pinch point temperature difference are often fixed according to engineering experience.In order to optimize the ORC system comprehensively,the coupling effect of evaporation and condensation process was proposed in this paper.Based on the laws of thermodynamics,the energy analysis,exergy analysis and entropy analysis were adopted to investigate the ORC performance including net output power,thermal efficiency,exergy efficiency,thermal conductivity,irreversible loss,etc.,using geothermal water at a temperature of 120℃as the heat source and isobutane as the working fluid.The results show that there exists a pair of optimal evaporating temperature and condensing temperatures to maximize the system performance.The net power output and the system comprehensive performance achieve their highest values at the same evaporating temperature,but the system comprehensive performance corresponds to a lower condensing temperature than the net power output.
基金support of the Science and Technology Support Program of Sichuan Province(2022JDRC0025)the National Natural Science Foundation of China(NFSC,Grant No.52007025).
文摘At present,industrial development is heavily dependent on traditional fossil energy,which has had an increasingly serious impact on the environment.Clean and renewable energy has received extensive attention and its proportion in daily life has gradually increased.As a clean and renewable energy source that is not affected by changes in weather and seasons,geothermal energy has developed rapidly in recent years and has received increasing attention.According to reports,the total installed capacity of geothermal power generation in the world in 2020 was 15950 MW-an increase of~27%over 2015.At the end of 2019,the total installed capacity for global geothermal direct use was 107727 MW-an increase of 52.0%compared with 2015;the total annual energy use was 1020887 TJ(283580 GWh)-an increase of 72.3%over 2015.Through the investigation of geothermal power generation technology in recent years,the characteristics and shortcomings of various power generation methods are analysed.At the same time,this review analyzes the characteristics of geothermal energy and other renewable-energy(solar energy,water energy)coupling power generation,and analyzes the principles and characteristics of geothermal energy and various new-energy coupling power generation methods.Through investigation and analysis,this review provides a complete understanding of various geothermal power generation technologies and provides insights into the future development direction.
基金Project(2012AA052804) supported by the National High Technology Research and Development Program of China
文摘In order to improve the efficiency of a geothermal power plant, oil wells in the high water cut stage were used as geothermal wells, thereby improving the recovery ratio and economic benefit. A new function that reflects both the technical and economic performances was put forward and used as the objective function. An organic Rankine cycle (ORC) was analyzed through the energetic and exergetic analyses, and the reasons for low efficiency were pinpointed. Results indicate that geothermal water directly transferring heat to the working fluid reduces energy dissipation and increases cycle efficiencies. The net power output with an internal heat exchanger (IHE) is averagely 5.3% higher than that without an IHE. R601a and R601 can be used to replace R123 for geothermal water below 110℃. Moreover, the modified ORC dramatically outperforms the actual one.
基金support from the foundation"Research on Key Technologies for Multi-source Energy Integration and Full-scenario Utilization of Zero-carbon Expressways under the Dual-Carbon Strategy"(NO.JS2024B004).
文摘Under the national"Dual Carbon"strategy,the development and utilization of stable and efficient renewable energy has become pivotal for energy structure transformation.Shandong Province hosts abundant geothermal resources with significant potential for large-scale exploitation.This paper systematically reviews the technological framework and application prospects of geothermal energy development in Shandong.First,the geological model of the geothermal system,centered on the"source-reservoir-caprock-conduit"framework,is elucidated.The characteristics of major thermal reservoirs,including the Neogene Guantao Formation,Paleogene Dongying Formation,and Cambrian-Ordovician strata,are analyzed in the context of Shandong’s geologic setting.Subsequently,advanced geophysical exploration methodologies—such as Magnetotelluric(MT),Controlled-Source Audio-Frequency Magnetotellurics(CSAMT),and Wide-Field Electromagnetic Method(WFEM)—are highlighted for their critical roles in precisely delineating thermal reservoirs and identifying heat-controlling structures,significantly improving exploration efficiency.In terms of utilization,this study examines diversified application models guided by the"cascade utilization"principle,emphasizing high-efficiency geothermal heating technologies(e.g.,geothermal heat pump systems)and power generation technologies(dry steam,fl ash steam,and binary cycle systems)tailored to resources of varying temperatures.The review demonstrates that technological innovations and mature application frameworks are driving the geothermal industry in Shandong toward high-quality development,providing robust support for regional energy security and low-carbon transition.
基金supported by the Key Program of National Natural Science Foundation of China“Thermo-fluid-mechanical-chemical coupling research on heat-mass transport mechanism of enhanced geothermal system”(No.51936001).
文摘Enhanced geothermal system(EGS)is a primary method to develop geothermal resources stored in hot dry rock(HDR),but it faces several key problems,such as unreasonable hydraulic fracture networks at high reservoir temperature,unclear multi-scale and multi-field coupling regularity,low heat extraction efficiency caused by the flashing flow in geothermal wells,and low thermoelectric conversion efficiency of geothermal fluid,which restricts the large-scale commercial development of geothermal resources.To resolve these major bottleneck problems,systematically reviews and analysis of the research progress and development trend of EGS are conducted in this paper.Particular attentions are devoted to four key technologies involved in the development of HDR geothermal resource by EGS:(1)the hydraulic fracturing technology for HDR reservoirs,including reservoir reconstruction methods,hydraulic fracturing network forming mechanisms and fracture propagation prediction models is illustrated in detail;(2)the fracture characterization methods,mathematical models and solution methods are described from three aspects including pore-scale multi-field coupled models,reservoir-scale multi-field coupled models and upscaling methods;(3)the efficient extraction technology of wellbore thermal fluid,involving the mechanism of flashing flows in geothermal wells and the experimental and numerical methods for investigating the characteristics offlashing flows are discussed;(4)the HDR geothermal power generation technologies,considering the principles of geothermal power generation,the types of power generation systems and the main application markets are introduced.In conclusion,EGS is a technology-intensive system,however,due to the complex working conditions of the underground reservoirs and the instability of the ground equipment,theoretical research tends to be separated from the practice.For the purpose of promoting the applicability of EGS,intimate combination and mutual guidance with the pilot tests are necessary to develop a production-research combined mode,and to raise the awareness and break through the key points in a constant back-and-forth.
