A Sensitivity Analysis for Effective Use of CO2 for Heat Mining in Geothermal Reservoirs

2015 ◽  
Author(s):  
Ana Laura Soto-Sánchez ◽  
Carlos Rubio-Maya ◽  
Alicia Aguilar Corona ◽  
Oscar Chávez
Keyword(s):  
Carbon Dioxide ◽  
Sensitivity Analysis ◽  
Power Plants ◽  
Control Volume ◽  
Working Fluid ◽  
Unusual Behavior ◽  
Geothermal Heat ◽  
Geothermal Reservoirs ◽  
Linear Behavior ◽  
Better Than

Carbon dioxide (CO2) emitted from various sources, mainly fossil fuel power plants, is considered responsible of the global warming effect. Many processes and techniques are still under research for CO2 capture and sequestration. On the other hand, it is proposed that the geothermal heat be mined from geothermal reservoirs using captured CO2. In this sense, some theoretical studies show feasibility of using supercritical carbon dioxide (sCO2) as a heat mining media in such geothermal reservoirs. In this work, it is carried out a set of numerical simulations to determine the most effective distance between injection and production wells for extracting geothermal energy utilizing sCO2 (Water is used for comparison). In the study, the permeability is considered in the range of 0.5 mD to 3.5 mD, with the aim of determining also the critical point in which sCO2 works better than water (H2O) as a working fluid. The remaining properties such as volume, density and other thermal properties remain fixed. Afterwards, it is constructed a numerical model which is implemented in TOUGH2 and PETRASIM 5 software to simulate the cases established. In the model, it is considered a simplified control volume, i.e. only one well for injection and one for production, assuming a constant flow rate at the inlet and at the outlet, meaning that sequestration is not taken into account. A length of 300 meter is defined for reservoir thickness, considering also a pressure and temperature of 100 bar and 200 °C, respectively. The energy mined is estimated for a period of twenty-five years. As typically, the sensitivity analysis is performed by varying only one property and keeping the remaining properties constant, isolating in this way the effect of such variable. Results show that for small permeabilities H2O works better than sCO2, but it is possible to assure that for permeabilities greater than 1 mD, sCO2 presents more advantages as extracting heat media instead of water. Both, H2O and sCO2 show a linear behavior. A deep analysis is necessary to carry out, because results shows that sCO2 works better in an intermediate zone (greater than 200 meter length, but smaller than 800 meter length). An unusual behavior is presented when the distances between the wells are varied; water shows a linear behavior increasing monotonically, while sCO2 shows a nonlinear behavior for some distances sCO2 works better. As expected, the more the distance, the greater the amount of the energy mined due to the volume related with each one of the distances.

Enhanced Geothermal Systems Projects and its Potential for Carbon Storage

2013 ◽  
Vol 732-733 ◽  
pp. 109-115 ◽  
Author(s):  
Chao Yin Feng
Keyword(s):  
Carbon Dioxide ◽  
Power Plants ◽  
Subsurface Water ◽  
Working Fluid ◽  
Low Permeability ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Geothermal Fields ◽  
Geological Conditions ◽  
Geothermal Wells

Enhanced Geothermal Systems represent a series of technology, which use engineering methods to improve the performance of geothermal power plant. In some geothermal fields, the rocks are in high temperature but a low permeability, or the subsurface water is scarce. In these geological conditions, cool water was injected into the geothermal wells to fracture the tight rock and create man-made reservoir for thermal exploitation. Furthermore, these engineering methods can be utilized to improve the productivity of pre-existing hydrothermal power plants. To save water and treat the global warming, using carbon dioxide instead of water as working fluid was proposed. Numerical simulation reveals that the carbon dioxide has numerous advantages over water as working fluid in the heat mining process. The precipitation caused by carbon dioxide will restore part of carbon dioxide in the rock and reduce the micro-seismicity risk.

Application of Supercritical Fluids in Thermal- and Nuclear-Power Engineering

2021 ◽  
pp. 601-658
Author(s):  
Igor L. Pioro
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Supercritical Fluids ◽  
Nuclear Power ◽  
Power Plants ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Thermal Power Plants ◽  
Power Cycles

Supercritical Fluids (SCFs) have unique thermophyscial properties and heat-transfer characteristics, which make them very attractive for use in power industry. In this chapter, specifics of thermophysical properties and heat transfer of SCFs such as water, carbon dioxide, and helium are considered and discussed. Also, particularities of heat transfer at Supercritical Pressures (SCPs) are presented, and the most accurate heat-transfer correlations are listed. Supercritical Water (SCW) is widely used as the working fluid in the SCP Rankine “steam”-turbine cycle in fossil-fuel thermal power plants. This increase in thermal efficiency is possible by application of high-temperature reactors and power cycles. Currently, six concepts of Generation-IV reactors are being developed, with coolant outlet temperatures of 500°C~1000°C. SCFs will be used as coolants (helium in GFRs and VHTRs, and SCW in SCWRs) and/or working fluids in power cycles (helium, mixture of nitrogen (80%) and helium (20%), nitrogen and carbon dioxide in Brayton gas-turbine cycles, and SCW/“steam” in Rankine cycle).

Exergoeconomic comparison and optimization of organic Rankine cycle, trilateral Rankine cycle and transcritical carbon dioxide cycle for heat recovery of low-temperature geothermal water

2019 ◽  
Vol 233 (8) ◽  
pp. 1068-1084 ◽  
Author(s):  
Afsaneh Noroozian ◽  
Abbas Naeimi ◽  
Mokhtar Bidi ◽  
Mohammad Hossein Ahmadi
Keyword(s):  
Sensitivity Analysis ◽  
Low Temperature ◽  
Heat Source ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Cost Ratio ◽  
Exergetic Efficiency ◽  
Geothermal Heat ◽  
Product Cost

Depleting fossil fuel resources and the horrible environmental impacts due to burning fossil fuels emphasize the importance of using renewable energy resources such as geothermal and solar energies. This paper compares performance of CO2 transcritical cycle, organic Rankine cycle, and trilateral Rankine cycle using a low-temperature geothermal heat source. Thermodynamic analysis, exergetic analysis, economic analysis, and exergoeconomic analysis are applied for each of the aforementioned cycles. In addition, a sensitivity analysis is performed on the system, and the effects of geothermal heat source temperature, evaporator pinch point temperature, and turbine inlet pressure on the cycle's performance are evaluated. Finally, the systems are optimized in order to minimize product cost ratio and maximize exergetic efficiency by using the genetic algorithm. Results indicate that the maximum thermal efficiency is approximately 13.03% which belongs to organic Rankine cycle with R123 as working fluid. CO2 cycle has the maximum exergetic efficiency, equals to 46.13%. The minimum product cost ratio refers to the organic Rankine cycle with R245fa as working fluid. Moreover, sensitivity analysis shows that increasing geothermal heat source temperature results in higher output power, product cost ratio, and exergy destruction ratio in all cycles.

Application of Supercritical Pressures in Power Engineering

2017 ◽  
pp. 404-457
Author(s):  
Igor Pioro ◽  
Mohammed Mahdi ◽  
Roman Popov
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
High Temperature ◽  
Gas Turbine ◽  
Power Plants ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Thermal Power Plants ◽  
Power Cycles

SuperCritical Fluids (SCFs) have unique thermophyscial properties and heat-transfer characteristics, which make them very attractive for use in power industry. In this chapter, specifics of thermophysical properties and heat transfer of SCFs such as water, carbon dioxide and helium are considered and discussed. Also, particularities of heat transfer at SuperCritical Pressures (SCPs) are presented, and the most accurate heat-transfer correlations are listed. SuperCritical Water (SCW) is widely used as the working fluid in the SCP Rankine “steam”-turbine cycle in fossil-fuel thermal power plants. This increase in thermal efficiency is possible by application of high-temperature reactors and power cycles. Currently, six concepts of Generation-IV reactors are being developed, with coolant outlet temperatures of 500°C~1000°C. SCFs will be used as coolants (helium in GFRs and VHTRs; and SCW in SCWRs) and/or working fluids in power cycles (helium; mixture of nitrogen (80%) and helium [20%]; nitrogen, and carbon dioxide in Brayton gas-turbine cycles; and SCW “steam” in Rankine cycle).

scholarly journals HTR-Based Power Plants’ Performance Analysis Applied on Conventional Combined Cycles

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
José Carbia Carril ◽  
Álvaro Baaliña Insua ◽  
Javier Romero Gómez ◽  
Manuel Romero Gómez
Keyword(s):  
Carbon Dioxide ◽  
Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Safety Standards ◽  
Intermediate Heat Exchanger ◽  
Combined Cycles ◽  
Effective Cost ◽  
Cycle Structures

In high temperature reactors including gas cooled fast reactors and gas turbine modular helium reactors (GT-MHR) specifically designed to operate as power plant heat sources, efficiency enhancement at effective cost under safe conditions can be achieved. Mentioned improvements concern the implementation of two cycle structures: (a), a stand alone Brayton operating with helium and a stand alone Rankine cycle (RC) with regeneration, operating with carbon dioxide at ultrasupercritical pressure as working fluid (WF), where condensation is carried out at quasicritical conditions, and (b), a combined cycle (CC), in which the topping closed Brayton cycle (CBC) operates with helium as WF, while the bottoming RC is operated with one of the following WFs: carbon dioxide, xenon, ethane, ammonia, or water. In both cases, an intermediate heat exchanger (IHE) is proposed to provide thermal energy to the closed Brayton or to the Rankine cycles. The results of the case study show that the thermal efficiency, through the use of a CC, is slightly improved (from 45.79% for BC and from 50.17% for RC to 53.63 for the proposed CC with He-H2O operating under safety standards).

scholarly journals Process and Carbon Footprint Analyses of the Allam Cycle Power Plant Integrated with an Air Separation Unit

2019 ◽  
Vol 1 (1) ◽  
pp. 325-340 ◽  
Author(s):  
Dan Fernandes ◽  
Song Wang ◽  
Qiang Xu ◽  
Russel Buss ◽  
Daniel Chen
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Sensitivity Analysis ◽  
Power Plant ◽  
Carbon Footprint ◽  
Exergy Analysis ◽  
Air Separation ◽  
Working Fluid ◽  
Separation Unit ◽  
Air Separation Unit

The Allam cycle is the latest advancement in power generation technologies with a high cycle efficiency, zero NOx emission, and carbon dioxide available at pipeline specification for sequestration and utilization. The Allam cycle plant is a semi-closed, direct-fired, oxy-fuel Brayton cycle that uses high pressure supercritical carbon dioxide as a working fluid with sophisticated heat recuperation. This paper conducted process analyses including exergy analysis, sensitivity analysis, air separation unit (ASU) oxygen pump/compressor option analysis, and carbon footprint analysis for the integrated Allam power plant (natural gas)/ASU complex with a high degree of heat and work integration. Earlier works on exergy analysis were done on the Allam cycle and ASU independently. Exergy analysis on the integrated plants helps identify the equipment with the largest loss of thermodynamic efficiency. Sensitivity analysis investigated the effects of important ASU operational parameters along with equipment constraint limits on the downstream Allam cycle. Energy efficiency and carbon footprint are compared among the state-of-the-art fossil-fuel power generation cycles.

Performance of a Two-Phase Carbon Dioxide-Filled Thermosyphon

2008 ◽  
Vol 569 ◽  
pp. 345-348 ◽  
Author(s):  
S. J. Jeong ◽  
K. S. Lee
Keyword(s):  
Carbon Dioxide ◽  
Mass Flow ◽  
Temperature Difference ◽  
Common Ground ◽  
Environmental Safety ◽  
Coupled Systems ◽  
Working Fluid ◽  
Geothermal Heat ◽  
Two Phase ◽  
Condenser Section

In order to utilize low enthalpy geothermal heat sources, a thermosyphon is a good device which can extract heat without using electric power. The heat transfer in the thermosyphon occurs through the circulation of a working fluid through a sequence of evaporation, vapor transfer, condensation, and liquid return. A two-phase thermosyphon system using carbon dioxide (CO2) as a working fluid has been investigated both experimentally as well as theoretically. Carbon dioxide is the only non-flammable and non-toxic fluid that has the potential to offer environmental safety in a system. A copper tube thermosyphon of total length of 1,000 mm with inside and outside diameters of 9.9 mm and 12.7 mm was developed by consisting of evaporator and condenser sections. The temperature distribution along the thermosyphon was monitored and theninput heat to evaporator section and output heat from condenser were measured as well. The effects of temperature difference between evaporator and condenser section and coolant mass flow rates on the performance of the thermosyphon were determined. The results indicate that the heat flux transferred increased with increasing coolant mass flow rate and temperature difference between evaporation and condenser section. The experimental analysis of the thermosyphon system confirms that the proposed system must be a reliable and highly efficient as well as environmentally friendly alternative to common ground-coupled systems.

Effect of Mixtures on Compressor and Cooler in Supercritical Carbon Dioxide Cycles

2018 ◽  
Author(s):  
Ladislav Vesely ◽  
K. R. V. Manikantachari ◽  
Subith Vasu ◽  
Jayanta Kapat ◽  
Vaclav Dostal ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
Carbon Capture ◽  
Power Plants ◽  
High Efficiency ◽  
Waste Heat ◽  
Operating Conditions ◽  
Working Fluid ◽  
Supercritical Carbon

With the increasing demand for electric power, the development of new power generation technologies is gaining increased attention. The supercritical carbon dioxide (S-CO2) cycle is one such technology, which has relatively high efficiency, compactness, and potentially could provide complete carbon capture. The S-CO2 cycle technology is adaptable for almost all of the existing heat sources such as solar, geothermal, fossil, nuclear power plants, and waste heat recovery systems. However, it is known that, optimal combinations of: operating conditions, equipment, working fluid, and cycle layout determine the maximum achievable efficiency of a cycle. Within an S-CO2 cycle the compression device is of critical importance as it is operating near the critical point of CO2. However, near the critical point, the thermo-physical properties of CO2 are highly sensitive to changes of pressure and temperature. Therefore, the conditions of CO2 at the compressor inlet are critical in the design of such cycles. Also, the impurity species diluted within the S-CO2 will cause deviation from an ideal S-CO2 cycle as these impurities will change the thermodynamic properties of the working fluid. Accordingly the current work examines the effects of different impurity compositions, considering binary mixtures of CO2 and: He, CO, O2, N2, H2, CH4, or H2S; on various S-CO2 cycle components. The second part of the study focuses on the calculation of the basic cycles and component efficiencies. The results of this study will provide guidance and defines the optimal composition of mixtures for compressors and coolers.

scholarly journals Structural and Parametric Optimization of S–CO2 Nuclear Power Plants

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 1079
Author(s):  
Nikolay Rogalev ◽  
Andrey Rogalev ◽  
Vladimir Kindra ◽  
Ivan Komarov ◽  
Olga Zlyvko
Keyword(s):  
Carbon Dioxide ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Parametric Optimization ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Fluid Temperature

The transition to the use of supercritical carbon dioxide as a working fluid for power generation units will significantly reduce the equipment′s overall dimensions while increasing fuel efficiency and environmental safety. Structural and parametric optimization of S–CO2 nuclear power plants was carried out to ensure the maximum efficiency of electricity production. Based on the results of mathematical modeling, it was found that the transition to a carbon dioxide working fluid for the nuclear power plant with the BREST–OD–300 reactor leads to an increase of efficiency from 39.8 to 43.1%. Nuclear power plant transition from the Rankine water cycle to the carbon dioxide Brayton cycle with recompression is reasonable at a working fluid temperature above 455 °C due to the carbon dioxide cycle′s more effective regeneration system.

Thermal/electric energy generation and CO2 production for greenhouse facilities

2019 ◽  
Vol 2 (3) ◽  
pp. 141-151
Author(s):  
O. E. Gnezdova ◽  
E. S. Chugunkova
Keyword(s):  
Carbon Dioxide ◽  
Power Distribution ◽  
Power Plants ◽  
Electric Energy ◽  
Electricity Consumption ◽  
Vegetable Crops ◽  
Carbon Dioxide Injection ◽  
Electricity Rates ◽  
Traditional Patterns ◽  
Generation Power

Introduction: greenhouses need microclimate control systems to grow agricultural crops. The method of carbon dioxide injection, which is currently used by agricultural companies, causes particular problems. Co-generation power plants may boost the greenhouse efficiency, as they are capable of producing electric energy, heat and cold, as well as carbon dioxide designated for greenhouse plants.Methods: the co-authors provide their estimates of the future gas/electricity rates growth in the short term; they have made a breakdown of the costs of greenhouse products, and they have also compiled the diagrams describing electricity consumption in case of traditional and non-traditional patterns of power supply; they also provide a power distribution pattern typical for greenhouse businesses, as well as the structure and the principle of operation of a co-generation unit used by a greenhouse facility.Results and discussion: the co-authors highlight the strengths of co-generation units used by greenhouse facilities. They have also identified the biological features of carbon dioxide generation and consumption, and they have listed the consequences of using carbon dioxide to enrich vegetable crops.Conclusion: the co-authors have formulated the expediency of using co-generation power plants as part of power generation facilities that serve greenhouses.

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