scholarly journals Subcritical organic ranking cycle based geothermal power plant thermodynamic and economic analysis

2018 ◽  
Vol 22 (5) ◽  
pp. 2137-2150 ◽  
Author(s):  
Nenad Mustapic ◽  
Vladislav Brkic ◽  
Matija Kerin
Keyword(s):  
Power Plant ◽  
Economic Analysis ◽  
Temperature Difference ◽  
Working Fluid ◽  
Pinch Point ◽  
Working Fluids ◽  
Point Temperature ◽  
Geothermal Power Plant ◽  
Geothermal Power ◽  
Net Power Output

This paper is focused both on the thermodynamic and economic analysis of an organic Rankine cycle (ORC) based geothermal power plant. The analysis is applied to a case study of the geothermal field Recica near the city of Karlovac. Simple cycle configuration of the ORC was applied. Thermodynamic and economic performance of an ORC geothermal system using 8 working fluids: R134a, isobutane, R245fa, R601, R601a, R290, R1234yf, and R1234ze(E)], with different critical temperatures are analyzed. The thermodynamic analysis is performed on the basis of the analysis of influence of the operation conditions, such as evaporation and condensation temperatures and pressures, and evaporator and con-denser pinch point temperature difference, on the cycle characteristics such as net power output, and plant irreversibility. The economic analysis is performed on the basis of relationship between the net power output and the total cost of equipment used in the ORC. Mathematical models are defined for proposed organic Rankine geothermal power plant, and the analysis is performed by using the software package engineering equation solver. The analysis reveals that the working fluids, n-pentane and isopentane, show the best economic performances, regardless the evaporation temperatures, while the working fluid R1234yf and R290 have the best thermodynamic performances. In addition, each analyzed working fluid has its corresponding economically optimal condensation temperature (and condensation pressure). Economically optimal pinch point temperature difference of evaporator has different values, depending on the working fluid, while pinch point temperature difference of condenser has similar values for all analyzed working fluids. Analysis results demonstrate that the subcritical ORC geothermal power plant represents a promising option for electricity production application.

scholarly journals Criteria for the Selection of Working Fluids for Geothermal Power Plants: A Case Study in Spain

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1424
Author(s):  
Antonio Luis Marqués Sierra ◽  
Noe Anes Garcia
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Working Fluid ◽  
Design Decision ◽  
Working Fluids ◽  
Geothermal Power Plant ◽  
Binary Geothermal Power Plant ◽  
Geothermal Power ◽  
Selection Of

An important key in binary geothermal power plant is the selection of working fluid. This design decision has great implications for the operation of this power plant. While there are many options available for working fluids, there are also many restrictions on the selection that relate to the thermodynamic properties of fluids, as well as considerations of salt, safety and environmental impact.

Performance Optimization and Economic Analysis of Geothermal Power Generation by Subcritical and Supercritical Organic Rankine Cycles

2016 ◽  
Author(s):  
Changwei Liu ◽  
Tieyu Gao ◽  
Jiangnan Zhu ◽  
Jiamin Xu
Keyword(s):  
Economic Analysis ◽  
Power Output ◽  
Performance Optimization ◽  
Supercritical Condition ◽  
Working Fluid ◽  
Outlet Temperature ◽  
Working Fluids ◽  
Turbine Inlet ◽  
Net Power Output ◽  
Subcritical Condition

In a sustainability context, using renewable energy sources to hedge against increasing consumption of fossil fuels and reduce greenhouse gas emissions becomes increasingly important. The geothermal resource has a great application prospect due to its rich reserves and convenient utilization, and Organic Rankine Cycle (ORC) is a effective method to convert the low-grade geothermal to electricity. To improve the performance of geothermal ORC system, working fluid selection, system parameter optimization and the cycle design are the main approaches. Zeotropic mixtures may show superiority as ORC working fluids due to the temperature glides during the phase transitions, which leads to better temperature matches between the working fluid and the heat source/sink. Moreover, owing to the changing temperature during the transition from liquid to vapor in the vapor generator, supercritical ORC provides a great potential in geothermal utilization and irreversibility reduction. This paper displays an investigation on the performance optimization and economic analysis of various working fluids under subcritical and supercritical conditions. To avoid the silica oversaturation, the geothermal water reinjection temperature should not be less than 70 °C. Turbine inlet temperature, condenser outlet temperature as well as turbine inlet pressure (for supercritical ORC) are optimized to maximize the net power output. Moreover, economic analysis is conducted by taking heat exchanger area per unit power output (APR) and the specific investment cost (SIC) as indicators under the optimal net power output condition. The results shows that working fluid with a medium critical temperature yields greater net power output in supercritical ORC and mixture produces larger net power output compared with its pure components in subcritical ORC. Compared with isobutane (R600a) under subcritical condition, isobutane/isopentane (R600a/R601a) and isobutane/pentane (R600a/R601) under subcritical condition, R134a and R1234ze(E) under supercritical condition yield 3.9%, 3.8%, 8.5% and 8.8% more net power outputs, respectively. In addition, R600a/R601a and R600a/R601 under subcritical condition own higher APR and SIC while R134a and R1234ze(E) under supercritical condition possess lower APR and SIC.

Thermo-economic analysis of a hybrid solar-binary geothermal power plant

Energy ◽  
2015 ◽  
Vol 87 ◽  
pp. 326-335 ◽  
Author(s):  
Mohammad Ayub ◽  
Alexander Mitsos ◽  
Hadi Ghasemi
Keyword(s):  
Power Plant ◽  
Economic Analysis ◽  
Geothermal Power Plant ◽  
Binary Geothermal Power Plant ◽  
Geothermal Power

Specified Maintenance of Steam Turbines in Geothermal Power Plants

2013 ◽  
Author(s):  
Almar Gunnarsson ◽  
Ari Elisson ◽  
Magnus Jonsson ◽  
Runar Unnthorsson
Keyword(s):  
Power Plant ◽  
Condition Monitoring ◽  
Power Plants ◽  
Maintenance Management ◽  
Working Fluid ◽  
Steam Turbines ◽  
Effect Analysis ◽  
Geothermal Power Plant ◽  
Management Procedures ◽  
Geothermal Power

In a geothermal power plant the working fluid used to produce electricity is often wet steam composed of corrosives chemicals. In this situation, more frequent maintenance of the equipment is required. By constructing an overview for maintenance in geothermal power plants and how it can be done with minimum power outages and cost, the geothermal energy can be made more competitive in comparison to other energy resources. This work is constructed as a part of a project, which has the aim of mapping the maintenance management system at the Hellisheiði geothermal power plant in Iceland. The object of the project is to establish Reliability Centered Maintenance (RCM) program for Hellisheiði power plant that can be utilized to establish efficient maintenance management procedures. The focus of this paper is to examine the steam turbines, which have been defined as one of the main subsystems of the power plant at Hellisheiði. A close look will be taken at the maintenance needed for the steam turbines by studying for example which parts break down and how frequently they fail. The local ability of the staff to repair or construct turbine parts on-site is explored. The paper explores how the maintenance and condition monitoring is carried out today and what can be improved in order to reduce cost. The data collected is analyzed using Failure Mode and Effect Analysis (FMEA) in order to get an overview of the system and to help organizing maintenance and condition monitoring of the power plant in the future. Furthermore, the paper presents an overview of currently employed maintenance methods at Hellisheiði power plant, the domestic ability for maintaining and repairing steam turbines and the power plant’s need for repairs. The results show that the need for maintenance of the geothermal steam turbines at Hellisheiði power plant is high and that on-site maintenance and repairs can decrease the cost.

Determination of an optimal pinch point temperature difference interval in ORC power plant using multi-objective approach

2019 ◽  
Vol 217 ◽  
pp. 798-807 ◽  
Author(s):  
Marcin Jankowski ◽  
Aleksandra Borsukiewicz ◽  
Katarzyna Szopik-Depczyńska ◽  
Giuseppe Ioppolo
Keyword(s):  
Power Plant ◽  
Temperature Difference ◽  
Pinch Point ◽  
Point Temperature ◽  
Multi Objective

Retrofitting a Geothermal Power Plant to Optimize Performance: A Case Study

1999 ◽  
Vol 121 (4) ◽  
pp. 295-301 ◽  
Author(s):  
M. Kanog˘lu ◽  
Y. A. C¸engel
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Geothermal Power Plant ◽  
Northern Nevada ◽  
Single Flash ◽  
Geothermal Power ◽  
Net Power Output ◽  
Double Flash

Performance evaluation of a 12.8-MW single-flash design geothermal power plant in Northern Nevada is conducted using actual plant operating data, and potential improvement sites are identified. The unused geothermal brine reinjected back to the ground is determined to represent about 50 percent of the energy and 40 percent of the exergy available in the reservoir. The first and second-law efficiencies of the plant are determined to be 6 percent and 22 percent, respectively. Optimizing the existing single-flash system is shown to increase the net power output by up to 4 percent. Some well-known geothermal power generation technologies including double-flash, binary, and combined flash/binary designs as alternative to the existing system are evaluated and their optimum operating conditions are determined. It is found that a double-flash design, a binary design, and a combined flash/binary design can increase the net power output by up to 31 percent, 35 percent, and 54 percent, respectively, at optimum operating conditions. An economic comparison of these designs appears to favor the combined flash/binary design, followed by the double-flash design.

Improving the Performance of an Existing Air-Cooled Binary Geothermal Power Plant: A Case Study

1999 ◽  
Vol 121 (3) ◽  
pp. 196-202 ◽  
Author(s):  
M. Kanog˘lu ◽  
Y. A. C¸engel
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Plant Performance ◽  
Working Fluid ◽  
Maximum Pressure ◽  
Geothermal Power Plant ◽  
Northern Nevada ◽  
Binary Geothermal Power Plant ◽  
Geothermal Power ◽  
Cooling Air

An existing air-cooled binary geothermal power plant in northern Nevada is studied. The current performance of the plant is analyzed with an emphasis on the effects of seasonal climate changes. Two potential sites have been identified to improve the performance of the plant. Northern Nevada has a dry climate, particularly in hot summer months, and the temperature of cooling air can be decreased considerably by evaporative cooling. When the air temperature is decreased to the wet-bulb temperature, the decrease in the condenser temperature is determined to increase the power output by up to 29 percent. The required amount of water for this case is calculated to be about 200,000 tons per yr. Several parametric studies are performed by simulating the operation of the plant with an equation solver with built-in thermophysical property functions. It is determined that the net power output of the plant can be increased by 2.8 percent by optimizing the maximum pressure in the cycle. Also, replacing the existing working fluid isobutane by other commonly used binary fluids such as butane, R-114, isopentane, and pentane do not produce as much of an improvement in the plant performance as operating with isobutane at the optimum maximum pressure. Therefore, isobutane appears to be the best choice for this power plant.

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