Solar Trough Integration Into Combined Cycle Systems

Parabolic trough power plants have several concepts for production energy, these concepts are developed by Solar Electric Generating System (SEGS) and Direct Solar Steam (DISS) project for research and development, the SEGS is developed the integrated solar combined cycle system (ISCCS), however in recent years the DISS project with direct steam generation (DSG) technology proves the evaluation from the cost, the process control and the easy erection in construction. There are many studies developed in the solar hybrid power plants system for ISCCS and DSG, in this paper will be evaluated these models of solar hybrid system compound a natural gas combined-cycle backup for solar thermal energy, taken into account the thermodynamic analyses and techno-economic assessment for each concept of the ISCCS and DSG plants. These models evaluated in this work will be simulated with TRNSYS program and SAM System Advisor Model. This analysis was conducted to get the performance in these concepts and shows the lower levelized energy cost (LEC), so to increase to the electricity net efficiency in solar contribution of the power plants.

The integrated solar combined cycle (ISCC) system is a proven solution for grid-connected power generation from solar energy. How to further improve the ISCC system efficiency and propose a more efficient system solution has become a research focus. A novel gas turbine combined cycle (GTCC) benchmark system is proposed by replacing the conventional steam Rankine bottom cycle with a supercritical CO2 Brayton cycle, whose output power and efficiency are increased by 9.07 MW and 1.3%, respectively, compared to those of the conventional GTCC system. Furthermore, the novel ISCC systems are established with the parabolic trough solar collector (PTC) and the solar tower (ST) collector coupled to the novel GTCC system. Thermal performance analysis, exergy performance analysis, and the sensitivity analysis of the ISCC systems have been performed, and the results show that the system efficiencies of both ISCC systems are lower than that of the GTCC system, at 57.1% and 57.5%, respectively, but the power generation of the ISCC system with PTC is greater than that of the benchmark system, while that of the ISCC system with ST is less than that of the benchmark system. The photoelectric efficiency of the ISCC system with PTC is 27.6%, which is 2.1% greater than that of ISCC system with ST. In the ISCC system with PTC, the components with the highest exergy destruction and the lowest exergy efficiency are the combustion chamber, and PTC, respectively. ST is the component with the highest exergy destruction and the lowest exergy efficiency in the ISCC system with ST. With the increase in direct normal irradiance (DNI), the total output power, solar energy output power, and photoelectric efficiency of the ISCC system with PTC increase, while the system efficiency decreases; the solar energy output power and photoelectric efficiency of the ISCC system with ST increase, while the total output power and system efficiency decrease. The photoelectric efficiency of the ISCC system with PTC is greater when the DNI is greater than 600 W/m2; conversely, the photoelectric efficiency of the ISCC system with ST is greater. After sensitivity analysis, the optimal intercooler pressure for the ISCC system is 11.3 MPa.

Parabolic trough solar technology is the most proven and lowest cost large-scale solar power technology available today, primarily because of the nine large commercial-scale solar power plants that are operating in the California Mojave Desert. These plants, developed by Luz International Limited and referred to as Solar Electric Generating Systems (SEGS), range in size from 14–80 MW and represent 354 MW of installed electric generating capacity. More than 2,000,000m2 of parabolic trough collector technology has been operating daily for up to 18 years, and as the year 2001 ended, these plants had accumulated 127 years of operational experience. The Luz collector technology has demonstrated its ability to operate in a commercial power plant environment like no other solar technology in the world. Although no new plants have been built since 1990, significant advancements in collector and plant design have been made possible by the efforts of the SEGS plants operators, the parabolic trough industry, and solar research laboratories around the world. This paper reviews the current state of the art of parabolic trough solar power technology and describes the R&D efforts that are in progress to enhance this technology. The paper also shows how the economics of future parabolic trough solar power plants are expected to improve.

General performance evaluation method of integrated solar combined cycle (ISCC) system

In this research, a malfunction diagnosis method based on the enhanced exergy concept is applied to quantify the anomalies' sources in a real integrated solar combined cycle system (ISCCS). A comprehensive parametric study is performed to evaluate the malfunction indicators and the overall performance of the power plant by varying the substantial operating parameters under single and multi-malfunction conditions. Then, the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) is applied to maximise the net power and minimise the total exergy destruction rate of the system under a multi-malfunction condition.

Modeling and numerical simulation of an Integrated Solar Combined Cycle System in Algeria

Comprehensive evaluation of integrated solar combined cycle system regarding fuel-savability under unified framework

Recently, it is more necessary to maintain or improve the thermal efficiency of actual thermal power plants to reduce CO2 emission and energy consumption in the world, and it is also important to reduce the maintenance cost of commercial thermal power plants. Thus, it is crucial to investigate power plant performance deterioration factors and solve problems related to these factors promptly when the thermal efficiency decreases. However, it is difficult to understand the internal state of power plants sufficiently and to determine power plant performance deterioration factors only from operation data because actual thermal plants are composed of many components and are very complex systems. In particular, it is more difficult to understand performance deterioration in gas turbine combined cycle (GTCC) power plants than in steam power plants because the performance changes markedly in GTCC power plants depending on atmospheric conditions (temperature, pressure, humidity). In other words, when thermal efficiency changes, it is difficult to determine whether the cause is the change in external factors or that in the performance of the component. Therefore, we develop a method based on heat balance analysis to calculate the immeasurable quantity of state and the efficiency of each component in GTCC power plants, and to correct the performance of each component in a plant to a standard state using the performance function obtained from long-term operation data. Through the method, the analysis of the effects of deterioration factors on thermal efficiency becomes possible, and the performance of a plant can be simulated when the operation conditions are changed. Thus, we can determine the main factor that affects thermal efficiency using our method.

Major problems with using solar energy are the intermittently and the instability, which are influenced by the weather. Storage of thermal energy is very important in solar energy system. Among various methods of thermal energy storage, latent heat storage is one of the most efficient ways of storing thermal energy. Unlike the sensible heat storage, the latent heat storage provides much higher energy storage density, with a smaller temperature difference between storing and releasing heat. So the use of phase change materials(PCMS) especially high temperature PCMS for thermal energy storage in Solar Electric Generating Systems(SEGS) has received considerable attention. This paper reviewed middle and high temperature PCMS that could be used for SEGS. At last, an innovative idea of solar electric generating system was proposed in this study.

A three stage combined power cycle with a Brayton cycle as the topping cycle, a Rankine cycle as the middling cycle and an Organic Rankine Cycle (ORC) as the bottoming cycle is proposed in the present investigation. A two-stage Gas Turbine Power Plant (GTPP) with inter-cooling, reheating and regeneration based on the Brayton cycle, a single-stage Steam Turbine Power Plant (STPP) based on the Rankine cycle, and a two-stage ORC power plant with reheating based on ORC with atmospheric air as the coolant is considered in the present study. This arrangement enables the proposed plant to utilize the waste heat to the maximum extent possible and convert it into electric power. As the plant can now operate at low sink temperatures depending on atmospheric air, the efficiency of the combined cycle power plant increases dramatically. Further, Steam Turbine Exhaust Pressure (STEP) is positive resulting in smaller size units and a lower installation cost. A simulation code is developed in MATLAB to investigate the performance of a three stage combined power cycle at different source and sink temperatures with varying pressure in heat recovery steam boiler and condenser-boiler. Performance results are plotted with Gas Turbine Inlet Temperature (GTIT) of 1200 to 1500 °C, Coolant Air Temperature (CAT) of −15 to +25 °C, and pressure ratio of GTPP as 6.25, 9.0 and 12.25 for different organic substances and NH3 as working fluids in the bottoming ORC. Simulation results show that the efficiency of the three stage combined power cycle will go up to 64 to 69% depending on the pressure ratio of GTPP, GTIT, and CAT. It is also observed that the variation in the efficiency of the three stage combined power cycle is small with respect to the type of working fluid used in the ORC. Among the organic working fluids R134a, R12, R22, and R123, R134a gives a higher combined cycle efficiency.

Renewable energy is a core issue when it comes to energy resources today. However, the use of tidal energy has received less attention compared to solar and wind energy. This study investigates the technical‐economic evaluation of tidal power plants in three areas of Bushehr, Pol, and Khowr‐e Musa, all located along the southern coast of Iran. Four economic indices including net present value (NPV), benefit–cost ratio, capital return time, and internal rate of return are used. The study compares a tidal power plant with a solar and a Combined Cycle Gas Turbine power plant bearing a capacity of 10 MW. The results show that the total initial cost of a tidal power plant is 1.92 times higher compared to a PV and 7.16 times higher compared to a CCGT power plant. Due to the potential of solar and tidal energy, the three studied regions are economically different. The results show the NPV of a tidal power plant in Khowr‐e Mousa region is 4.90 times higher than a PV power plant and 9.93 times higher than a CCGT power plant. In addition, the cost of energy production per kilowatt depends on the region and the type of power plant technology. The lowest cost of energy production is related to tidal energy in Khowr‐e Musa region. The results of sensitivity analysis also show that the highest sensitivity is related to the initial cost and electricity sales rate.

This paper presents the results from an evaluation of the performance and cost of Italian power plants (a steam cycle power plants — 500 MW — fed by coal and a combined cycle power plant — 300 MW — fed by natural gas) with CO2 emissions control equipment to achieve a fixed reduction in atmospheric discharge of carbon dioxide (CO2) and so to accomplish the CO2 emission targets established by the Kyoto Protocol. The reduction of the CO2 content in the flue gas is achieved by amine scrubbing (CO2 removal), removal of water from CO2 (drying), compression to pipeline pressure; transport and storage are not considered. The paper presents an economic evaluation of the CO2 abatement cost and compares it with the cost of allowances in the Emission Trading System and with the payment of the penalty for the emissions in excess when there is no CO2 quota available on the market.

In chemical engineering design, process plants are often capable of turndown and flexible operation to maximise profitability depending on demand and price signals, and the optimisation of these processes needs to take into account the variability in the plant operation. By performing the optimisation with flexible operating conditions the overall plant performance can be improved. The optimisation process makes use of two computational modelling techniques: multi-objective optimisation (MOO) and surrogate modelling. Multi-objective optimisation allows for the optimisation of two or more competing variables simultaneously. In the cases studied here, the long individual simulation time coupled with the large number of individual simulations required meant that the total simulation time was prohibitive for dynamic MOO. In order to reduce computation time surrogate models of the processes are developed using artificial neural networks. A statistical dynamic modelling framework within a multi-objective optimisation methodology is developed to optimise a process plant’s performance. Here the dynamic modelling is used to optimise the economic and environmental performance of natural gas combined cycle power plant systems fitted with carbon capture and storage (CCS) and solar thermal energy (STE) in a time-integrated MOO framework. This framework allows for variable process inputs and flexible operation based on external signals, such as product price. By introducing a probabilistic approach to the modelling of flexible operation allows for more data to be included in the analysis. The methodology for dynamic modelling of flexible operation could be applied to other industrial processes that face similar dynamic economic and/or environmental conditions. From a CCS standpoint dynamic MOO was used to show that variable capture can be used to make the CCS plant more profitable over steady state operation. At a capture rate of 80 % the NPV of a gas turbine combined cycle with CCS improved by 38 m$AU by utilising flexible operation of the capture process. This also allows for various economic scenarios to incentivise the reduction of CO₂ emissions from natural gas based power plants, with the use of CCS and STE used to reduce the greenhouse emissions. The economic strategies of a carbon price and governmental grants are investigated to determine the levels of policy help to incentivise implementing CO₂ reduction technologies. In order to achieve a financial incentive for limiting CO₂ emissions from a combined cycle power plants equipped with CCS a government co-investment grant of 50 % of the capital costs and a carbon price of 83 $AU/tCO₂ is required.

The paper deals with problems of power and heating plants optimal operation. There is described present state of operated plants performance of older concept (usually used steps to increase plant power and to achieve required environmental emission limits) and boundaries which can limit the plant management effort to achieve a higher plant performance level. The attention is paid mainly to conventional power plants, which are in Europe mostly more than twenty years old and their unit power is mostly in power range 100 - 300 MW. There is described impact of the plant automatic control system level enhancement comparing with higher qualified manual operator implementation on plant performance, on decrease operational costs and achievement lower limits on the plant emissions. The topic of the paper is to demonstrate a possible way how to improve the plant performance and to achieve these requirements by using an advanced computerized support system for the operator. Such a computerized system called DECISION SUITE was developed in the Czech company I&C Energo under collaboration with the Czech Technical University and other Czech companies and is described in the paper. The system works with validated measured data and provides concentrated information about achievable plant performance, real loss, degradation of important systems, etc and recommendation for the plant operators. It presents results from the system application at an older Czech power plant. There is demonstrated how utilization of concentrated information provided by the support system can help to the plant performance increase (plant efficiency, emissions and plant reliability) comparing with utilization of the operator experience by manual inputs only.

High performance integrated solar combined cycles with minimum modifications to the combined cycle power plant design