The Experts below are selected from a list of 88455 Experts worldwide ranked by ideXlab platform
Martin O Saar - One of the best experts on this subject based on the ideXlab platform.
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combining brine or co2 Geothermal preheating with low temperature waste heat a higher efficiency hybrid Geothermal power system
2020Co-Authors: Nagasree Garapati, Benjamin M. Adams, Martin O Saar, Thomas H. Kuehn, Mark R FlemingAbstract:Abstract Hybrid Geothermal power plants operate by using Geothermal fluid to preheat the working fluid of a higher-temperature power cycle for electricity generation. This has been shown to yield higher electricity generation than the combination of a stand-alone Geothermal power plant and the higher-temperature power cycle. Here, we test both a direct CO2 hybrid Geothermal system and an indirect brine hybrid Geothermal system. The direct CO2 hybrid Geothermal system is a CO2 Plume Geothermal (CPG) system, which uses CO2 as the subsurface working fluid, but with auxiliary heat addition to the geologically produced CO2 at the surface. The indirect brine Geothermal system uses the hot geologically produced brine to preheat the secondary working fluid (CO2) within a secondary power cycle. We find that the direct CPG-hybrid system and the indirect brine-hybrid system both can generate 20 % more electric power than the summed power of individual Geothermal and auxiliary systems in some cases. Each hybrid system has an optimum turbine inlet temperature which maximizes the electric power generated, and is typically between 100 °C and 200 °C in the systems examined. The optimum turbine inlet temperature tends to occur where the Geothermal heat contribution is between 50 % and 70 % of the total heat addition to the hybrid system. Lastly, the CO2 direct system has lower wellhead temperatures than indirect brine and therefore can utilize lower temperature resources.
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A Hybrid Geothermal Energy Conversion Technology - A Potential Solution for Production of Electricity from Shallow Geothermal Resources
2017Co-Authors: Nagasree Garapati, Philipp Schaedle, Benjamin M. Adams, Jeffrey M. Bielicki, Jimmy B Randolph, Thomas H. Kuehn, Martin O SaarAbstract:Geothermal energy has been successfully employed in Switzerland for more than a century for direct use but presently there is no electricity being produced from Geothermal sources. After the nuclear power plant catastrophe in Fukushima, Japan, the Swiss Federal Assembly decided to gradually phase out the Swiss nuclear energy program. Deep Geothermal energy is a potential resource for clean and nearly CO2-free electricity production that can supplant nuclear power in Switzerland and worldwide. Deep Geothermal resources often require enhancement of the permeability of hot-dry rock at significant depths (4-6 km), which can induce seismicity. The Geothermal power projects in the Cities of Basel and St. Gallen, Switzerland, were suspended due to earthquakes that occurred during hydraulic stimulation and drilling, respectively. Here we present an alternative unconventional Geothermal energy utilization approach that uses shallower, lower-temperature, naturally permeable regions, that drastically reduce drilling costs and induced seismicity. This approach uses Geothermal heat to supplement a secondary energy source. Thus this hybrid approach may enable utilization of Geothermal energy in many regions in Switzerland and elsewhere, that otherwise could not be used for Geothermal electricity generation. In this work, we determine the net power output, energy conversion efficiencies, and economics of these hybrid power plants, where the Geothermal power plant is actually a CO2-based plant. Parameters varied include Geothermal reservoir depth (2.5-4.5 km) and turbine inlet temperature (100-220 °C) after auxiliary heating. We find that hybrid power plants outperform two individual, i.e., stand-alone Geothermal and waste-heat power plants, where moderate Geothermal energy is available. Furthermore, such hybrid power plants are more economical than separate power plants.
Wen-long Cheng - One of the best experts on this subject based on the ideXlab platform.
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Insights into Geothermal utilization of abandoned oil and gas wells
2018Co-Authors: Yong-le Nian, Wen-long ChengAbstract:Abandoned oil and gas wells (AOGW) with high bottom-hole temperature contain abundant Geothermal energy, which can be retrofitted to a novel Geothermal system for different utilizations without high-cost drilling. Thus, at recently, some researchers concentrate on evaluation of the performance of thermal energy extraction from AOGW and Geothermal power generation using AOGW with Organic Rankine cycle (ORC) systems. The aim of this paper is not only to review advanced Geothermal utilizations for AOGW, but also make insights into the thermal simulation methods and power generation as well as working fluids selection for AOGW Geothermal system. Due to heat extraction from AOGW dominating the Geothermal utilizations; firstly, this paper performed to summarize and discuss the heat transfer models of AOGW Geothermal system, which involve wellbore heat transfer and transient heat conduction in surrounding formation. Then, for evaluating the performance of power generation systems using AOGW, three different power plants were compared and the influence factors were examined. In addition, the optimum selection criteria of working fluids were also summarized, and the optimal fluids for different wells were determined. At last, the summary of key problems of the AOGW Geothermal utilizations were proposed, and the future development and applications of AOGW were suggested for improving the Geothermal utilizations.
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evaluation of working fluids for Geothermal power generation from abandoned oil wells
2014Co-Authors: Wen-long Cheng, Yongle Nia, Ku XieAbstract:Geothermal power generation from abandoned oil wells is a new way to utilize Geothermal energy. The organic Rankine cycle is used for exploiting Geothermal energy from abandoned oil wells efficiently. The investigation on influences of working fluids on the power generation efficiency is significant. An analysis model for Geothermal power generation based on the transient formation heat conduction of abandoned oil wells is presented in this paper. For abandoned oil wells with different kinds of well depths and Geothermal gradients, the power generation performances using various organic fluids are analyzed. Direct power generation system (DPGS) is compared with flashing power generation system (FPGS). The results show that the Geothermal energy from the abandoned oil wells with well depth less than 3000m is worthless to be exploited due to low power generation efficiency. For the abandoned oil wells with well depths larger than 3000m and Geothermal gradients higher than 0.04K/m, DPGS efficiency of supercritical working fluids leaving the recovery well is higher than FPGS efficiency of subcooled working fluids. R134a and R245fa are more suitable than R600a, R600, propylene, R290 and R143a for the Geothermal power generation using abandoned oil wells.
Prasad Kaparaju - One of the best experts on this subject based on the ideXlab platform.
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Geothermal energy: Power plant technology and direct heat applications
2018Co-Authors: Diego Moya, Clay Aldás, Prasad KaparajuAbstract:The transition from current fossil-fuel energy system towards a sustainable one-based requires renewable energy technology. Although Geothermal energy presents its own particular challenges in comparison with other renewable energy technologies, Geothermal energy has showed significant potential to reduce environmental impact and greenhouse gas emissions from electricity production. Advantages of Geothermal energy are not only the generation of electricity in different plant configurations but also the direct application of heat in industry and household uses regardless of meteorological conditions. In this study, a research review is carried out on the aspect of Geothermal energy development, assessing power plant technology and direct heat applications. Five power plant configurations are studied: single-flash, double-flash, dry-steam, binary and advanced. The thermodynamic aspects are addressed in order to consider them for future Geothermal power plant analysis. Furthermore, the most common direct uses of Geothermal heat are discussed. Results illustrate that Binary – Organic Ranking Cycle Power Plants might play a vital role in the exploitation of low temperature Geothermal resources. Furthermore, it is identified a need for research in hybrid Geothermal-solar-biomass configurations for poly-generation purposes. These configurations increase the energy output, increasing the thermal efficiency and increasing the life of the Geothermal reservoir. Similarly, direct applications of Geothermal heat present good opportunities for increasing the revenue of a Geothermal project. Depending of the geographic zone, cascade configurations contributes to maximise the use of Geothermal resources. Future research reviews should consider the financial, economic and policy aspects of Geothermal developments along with the geology, geophysics, geochemistry, drilling, reservoir engineering and environmental aspects. The main goal of addressing these topics is to provide the state-of-the-art of Geothermal development for developers, policy makers, researchers and communities interested in Geothermal energy.
Yangsheng Zhao - One of the best experts on this subject based on the ideXlab platform.
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forecast and evaluation of hot dry rock Geothermal resource in china
2005Co-Authors: Yangsheng Zhao, Jianrong KangAbstract:Utilizing information from plate tectonics characteristics, volcanic activities, and Geothermal anomaly, this paper identifies areas where hot dry rock (HDR) may exist as potential Geothermal resource in China. Further investigations are also carried out in the paper based on results from regional tectonics, volcanic geology and lithology, as well as data from Geothermal displays, geochemistry, geophysics, and shallow borehole temperature measurements. The study reveals several promising areas of HDR Geothermal resource in China, including Tengchong of Yunnan province, Qiongbei of Hainan province, Changbaishan of Jilin province, Wudalianchi of Heilongjiang province, and the Southern Tibet area. A 3D static heat conduction model was developed to study the underground temperature gradient characteristics of the Rehai Geothermal field in Tengchong and the Yangbajing Geothermal field in Tibet. The model adopted is a geological block 10km deep from the ground surface and 50km wide in each of the horizontal directions (2500km2 area). The numerical simulation results in evaluations on the quantities of the HDR Geothermal resource in Rehai and Yangbajing Geothermal fields. The paper shows that there is abundant HDR Geothermal resource with large exploitation value in China. If developed with a power capacity of 1×108kW, the Rehai and Yangbajing fields along would be able to generate electricity for 1560 years.
Nagasree Garapati - One of the best experts on this subject based on the ideXlab platform.
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combining brine or co2 Geothermal preheating with low temperature waste heat a higher efficiency hybrid Geothermal power system
2020Co-Authors: Nagasree Garapati, Benjamin M. Adams, Martin O Saar, Thomas H. Kuehn, Mark R FlemingAbstract:Abstract Hybrid Geothermal power plants operate by using Geothermal fluid to preheat the working fluid of a higher-temperature power cycle for electricity generation. This has been shown to yield higher electricity generation than the combination of a stand-alone Geothermal power plant and the higher-temperature power cycle. Here, we test both a direct CO2 hybrid Geothermal system and an indirect brine hybrid Geothermal system. The direct CO2 hybrid Geothermal system is a CO2 Plume Geothermal (CPG) system, which uses CO2 as the subsurface working fluid, but with auxiliary heat addition to the geologically produced CO2 at the surface. The indirect brine Geothermal system uses the hot geologically produced brine to preheat the secondary working fluid (CO2) within a secondary power cycle. We find that the direct CPG-hybrid system and the indirect brine-hybrid system both can generate 20 % more electric power than the summed power of individual Geothermal and auxiliary systems in some cases. Each hybrid system has an optimum turbine inlet temperature which maximizes the electric power generated, and is typically between 100 °C and 200 °C in the systems examined. The optimum turbine inlet temperature tends to occur where the Geothermal heat contribution is between 50 % and 70 % of the total heat addition to the hybrid system. Lastly, the CO2 direct system has lower wellhead temperatures than indirect brine and therefore can utilize lower temperature resources.
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A Hybrid Geothermal Energy Conversion Technology - A Potential Solution for Production of Electricity from Shallow Geothermal Resources
2017Co-Authors: Nagasree Garapati, Philipp Schaedle, Benjamin M. Adams, Jeffrey M. Bielicki, Jimmy B Randolph, Thomas H. Kuehn, Martin O SaarAbstract:Geothermal energy has been successfully employed in Switzerland for more than a century for direct use but presently there is no electricity being produced from Geothermal sources. After the nuclear power plant catastrophe in Fukushima, Japan, the Swiss Federal Assembly decided to gradually phase out the Swiss nuclear energy program. Deep Geothermal energy is a potential resource for clean and nearly CO2-free electricity production that can supplant nuclear power in Switzerland and worldwide. Deep Geothermal resources often require enhancement of the permeability of hot-dry rock at significant depths (4-6 km), which can induce seismicity. The Geothermal power projects in the Cities of Basel and St. Gallen, Switzerland, were suspended due to earthquakes that occurred during hydraulic stimulation and drilling, respectively. Here we present an alternative unconventional Geothermal energy utilization approach that uses shallower, lower-temperature, naturally permeable regions, that drastically reduce drilling costs and induced seismicity. This approach uses Geothermal heat to supplement a secondary energy source. Thus this hybrid approach may enable utilization of Geothermal energy in many regions in Switzerland and elsewhere, that otherwise could not be used for Geothermal electricity generation. In this work, we determine the net power output, energy conversion efficiencies, and economics of these hybrid power plants, where the Geothermal power plant is actually a CO2-based plant. Parameters varied include Geothermal reservoir depth (2.5-4.5 km) and turbine inlet temperature (100-220 °C) after auxiliary heating. We find that hybrid power plants outperform two individual, i.e., stand-alone Geothermal and waste-heat power plants, where moderate Geothermal energy is available. Furthermore, such hybrid power plants are more economical than separate power plants.
