Hybrid Solar Gas Turbine Research Articles

Energy losses study in solar hybrid gas turbine in Colombia

Energy losses study in solar hybrid gas turbine in Colombia

Thermodynamics performance optimization of a hybrid solar gas turbine power plant in Colombia

A thermodynamic model is presented for evaluation of a solar hybrid gas-turbine power plant. The model uses variable ambient temperature and estimates direct solar radiation at different day times. The plant is evaluated in Barranquilla, Colombia, with a solar concentration system and a combustion chamber that burns natural gas. The hybrid system enables to maintain almost constant the power output throughout day. The model allows optimizing the different plant parameters and evaluating maximum performance point. This work presents pressure ratio ranges where the maximum values of overall efficiency, power output, thermal engine efficiency and fuel conversion rate are found. The study is based on the environmental conditions of Barranquilla, Colombia. The results obtained shows that optimum pressure ratio range for power output and overall efficiency is between 6.4 and 8.3, when direct solar radiation its maximum at noon. This thermodynamic analysis is necessary to design new generations of solar thermal power plants.

Effect of a regenerator on hybrid solar gas turbine performance in Barranquilla, Colombia

A thermodynamic analysis of a hybrid gas turbine solar plant, represented in three basic subsystems related to the power cycle, the combustion chamber subsystem, and the solar concentrator subsystem, allows evaluating the performance of a hybrid cycle from a reduced number of parameters, which include energy losses in each of its components. The solar radiation values are estimated with an evaluated and validated theoretical model, the combustion chamber uses natural gas as fuel and the numerical values of the system are taken from the Solugas experimental plant in Spain. This work presents an integrated model that allows to estimate the operation of a hybrid solar Brayton power plant in any place and day of the year. The evaluation of the plant in Barranquilla, Colombia is shown from the influence of the regenerator has on the plant performance and solar concentrating system. The results show that the regenerator can increase the overall efficiency of the plant by 29% and allows reaching a maximum temperature of the central receiver of the concentrator of 1044 K at noon, when solar radiation is maximum.

Daily performance of a solar hybrid regenerative gas turbine in Colombia

This work presents the evolution of the operation of a regenerative hybrid solar gas turbine in an average day of the year. The system is evaluated by means of a thermodynamic model that includes a solar concentrated heliostat field solar concentrator with central receiver, a combustion chamber, and the thermal engine. The model is applied in Barranquilla, Colombia using local temperature and the solar radiation estimated with a theoretical model. Power output, the global efficiency and thermal engine efficiency are estimated. Additionally, to estimate the temperatures in different states of the cycle with and without regenerator. Finally, the impact of the regenerator is evaluated, which can increase the temperature of the solar receiver by up to 13.6%, and the inlet temperature to the combustion chamber increases by 17.3% at noon, when solar radiation is maximum.

Influence of the geographical parameters on the performance of hybrid solar gas turbine

This study aims to investigate the influence of the geographical and climate parameters on the performance of the hybrid solar gas turbine with a pressurized air receiver. A number of sites located in South America (Chile, Bolivia, and Peru) and North Africa (Algeria and Libya) are considered. The geometric design parameters of the solar receiver and the tower are calculated using an in-house code. The layout and the optical performance of the heliostat field are carried out using SolarPILOT software. The simulation of the complete hybrid solar gas turbine is carried out using TRNSYS software. A 50 MWe hybrid solar gas turbine is chosen in this study. Results show that a hybrid solar gas turbine installed in North Africa performs better than that installed in South America. This is mainly due to the optical performance of the heliostat field, which are better in North Africa are than in South America. The highest annual optical efficiency of a solar field is observed at Bechar (Algeria) 56.8% while the lowest annual efficiency is observed at Antofagasta (Chile) 48.1%. The solar-to-electric efficiency at Atacama Desert is lower than in the Sahara Desert. Indeed, in Atacama region, the solar-to-electric efficiency varies from 17% at Antofagasta to about 18% in Arequipa while it is above 19% at Sabha and Bechar.

Thermodynamic Characteristics of Hybrid Solar Microgas Turbine Plants under Tropical Climate

The article presents the results obtained during the study of the characteristics of hybrid solar micro-gas turbine units with an integrated parabolocylindrical solar collector. The efficiency of a hybrid solar gas turbine plant depends both on the efficiency of the solar collector and the location of its integration, and on the efficiency of the gas turbine engine. (Research purpose) The research purpose is in studying hybrid solar gas turbine installations based on a parabolocylindrical focusing solar collector in combination with micro-gas turbine engines of various configurations to determine the most suitable match. (Materials and methods) The article considers four basic schemes of gas turbine engines running on organic fuel, their parameters and optimization results. The article presents the main climatic parameters for the study of the focusing solar collector, as well as the parameters of the collector itself and the main dependencies that determine its efficiency and losses. The place of integration of the focusing solar collector into the gas turbine plant was described and justified. (Results and discussion) Hybrid solar micro-gas turbine installations based on micro-gas turbine engines of a simple cycle, a simple cycle with heat recovery, a simple cycle with a turbocharger utilizer, a simple cycle with a turbocharger utilizer and heat recovery for tropical climate conditions were studied on the example of Abu Dhabi. (Conclusions) The most suitable configuration of micro-gas turbine engines for integrating a focusing solar collector is a combination of a simple cycle with a turbocharger utilizer and regeneration. The combination of micro-gas turbine engines of a simple cycle with a turbocharger heat recovery and heat recovery with an integrated focusing solar collector can relatively increase the average annual efficiency of fuel consumption of such installations in a tropical climate by 10-35 percent or more, while maintaining cogeneration capabilities.

Analysing the benefits of hybridisation and storage in a hybrid solar gas turbine plant

ABSTRACTA dynamic model of a tower-driven, hybrid solar gas turbine power plant is presented to highlight the benefits of hybrid operation as well as the development a novel plant configuration to improve solar fraction by leveraging a packed-bed thermal energy storage (TES). Relative to solar-only plant, hybridisation increases solar-to-electric efficiency (STE) by 30%. Introduction of a passive packed-bed TES only leads to slight improvement in solar energy utilisation and displacement of solar load. A novel plant configuration, which utilises a recycle stream to charge TES, is presented to improve solar energy utilisation. The recycle stream gives freedom to manipulate the thermal capacity of flow in the tower collector to control collector exit temperature and direct excess solar energy to TES. Employment of the proposed plant configuration leads to a 10.8% and 11.3% improvement in yearly STE and solar fraction, respectively, relative to a plant not utilising such a control scheme.

Predicting the performance of a micro gas turbine under solar-hybrid operation

There are currently no commercial solar-hybrid gas turbine systems readily available off-the-shelf. Several operation and control challenges still exist, and significant development effort is still required to provide technically proven units. To address this gap, this study modeled the performance of a solar-hybrid micro gas turbine (MGT) system, considering both steady-state and transient operation. Based on the component matching, the equilibrium running point shifted on the compressor characteristic, to counter the additional system pressure losses, and ensure a useful work output, albeit with a reduced surge margin. Solar-hybrid operation was only possible for solar share of at least 20%, while the work output and cycle thermal efficiency drop below standard operation levels beyond certain solar share. In contrast to standard operation, a higher nominal work output of 20 kW, at a lower SFC of 0.0004 kg/kWh and a higher cycle thermal efficiency of 8% was predicted, the latter potentially increasing to 20% with recuperation. Solar-hybrid equilibrium running could eliminate the risk of running into compressor surge. The findings from this study should guide operation and control strategies for the proposed, and future solar-hybrid MGT systems, which should in turn contribute to their development and commercialization.

Simulation models for supporting the solar thermal power plant operator

The benefits that may accrue for the operators of Solar Thermal Power Plants by integrating simulators to everyday operation and maintenance management is demonstrated by using a simulation environment allowing steady state and transient modelling. Two representative STPPs are used as test cases, namely a hybrid solar gas turbine plant and a solar steam turbine plant. The plants operation is simulated for different operating modes utilizing annual meteorological data. Component faults that may occur during operation, such as mirror soiling and misalignment are studied. The effects of different operating modes on performance and operability are established and evaluated. The effect of components degradation on performance is assessed, the overall plant performance deterioration is quantified, and the possibility for selecting optimal maintenance planning is discussed.

Thermal energy storage for CSP hybrid gas turbine systems: Dynamic modelling and experimental validation

Integration of Thermal Energy Storage (TES) is one of the promising features of Concentrated Solar Power (CSP) technology which allows the Renewable Energy Sources (RES) to provide uninterrupted and dispatchable power supply, and thus facilitates the RES grid integration. Hybrid Solar Gas Turbine (HSGT) systems along with TES integration have gained great attention for the last decades. Numerical modelling and simulation tools are essential for the TES design optimization and analysis of its thermal behaviour during charging and discharging phases. This paper deals with the dynamic modelling and experimental validation of a TES at laboratory scale, which is part of the HSGT system. The TES is modelled with two different approaches: the CFD model using a commercial tool and a reduced-order model using the in-house transient simulation tool TRANSEO, which has been developed by Thermochemical Power Group (TPG) for the energy system dynamic analysis. The validation of both model results against the data obtained by the Authors through experimental investigation has highlighted that 2D discretization of the TES through the CFD model gives accurate representation of the thermal behaviour of the system, but it causes a significant computational expense. On the other side, 1D dynamic model reasonably predicts the time dependent thermal behaviour of TES, except some deviations from the experiments which are related to the simplified discretization scheme. However, due to its fast approach, the TRANSEO model can be effectively used to perform both TES initial design and sensitivity analysis, and also to develop or verify the control system at a later stage of HSGT system development.

Thermodynamic model of a hybrid Brayton thermosolar plant

Abstract We present a thermodynamic model for the prediction of the performance records of a solar hybrid gas turbine power plant. Variable irradiance and ambient temperature conditions are considered. A serial hybridization is modeled with the aim to get an approximately constant turbine inlet temperature, and thus to deliver to the grid a stable power output. The overall thermal efficiency depends on the efficiencies of the involved subsystems and the required heat exchangers in a straightforward analytical way. Numerical values for input parameters are taken from a central tower heliostat field recently developed near Seville, Spain. Real data for irradiance and external temperature are taken in hourly terms. Curves for the evolution of plant efficiencies (solar, gas turbine, fuel conversion efficiency, overall efficiency, etc.) and solar share are presented for representative days of each season. The cases of non-recuperative and recuperative plant configurations are shown. Estimations of the hourly evolution of fuel consumption are simulated as well as savings between the hybrid solar operation model and the pure combustion mode. During summer, fuel saving can reach about 11.5% for a recuperative plant layout. In addition, plant emissions for several configurations are presented.

Impact of thermal energy storage integration on the performance of a hybrid solar gas-turbine power plant

The interest for hybrid solar gas-turbine systems (HSGT) in solar power tower plant technologies is growing. This is due to the high conversion efficiency and to the low water consumption that are achieved when a combined cycle is implemented. This paper presents a simulation tool which is dedicated to the performance analysis a hybrid solar gas turbine solar plant featuring a thermal energy storage (TES) unit. This study is conducted within the framework of the French PEGASE project (Production of Electricity from Gas and Solar Energy) which aims at setting up and testing at THEMIS site (France) a demonstration plant based on HSGT technology. The TES unit called packed bed consists in a cylindrical tank filled with spherical rocks. For a given gas-turbine, the designs of the storage and the heliostat field are carried out. Depending on the operating strategy, this work establishes that the integration of a TES unit offers a higher and more stable electrical generation. The TES unit increases, in some case drastically, the daily average solar share of the power plant. Finally it leads to a higher electrical production per unit of fuel consumed.

Seasonal thermodynamic prediction of the performance of a hybrid solar gas-turbine power plant

An entirely thermodynamic model is developed for predicting the performance records of a solar hybrid gas turbine power plant with variable irradiance and ambient temperature conditions. The model considers a serial solar hybridization in those periods when solar irradiance is high enough. A combustion chamber allows to maintain an approximately constant inlet temperature in the turbine ensuring a stable power output. The overall plant thermal efficiency is written as a combination of the thermal efficiencies of the involved subsystems and the required heat exchangers. Numerical values of model input parameters are taken from a central tower installation recently developed near Seville, Spain. Real data for irradiance and external temperature are taken in hourly terms. The curves of several variables are obtained for representative days of all seasons: overall plant efficiency, solar subsystem efficiency, solar share, fuel conversion rate, and power output. The fuel consumption assuming natural gas fueling is calculated and the reduction in greenhouse emissions is discussed. The model can be applied to predict the daily and seasonal evolution of the performance of real installations in terms of a reduced set of parameters.

Hybrid High Solar Share Gas Turbine Systems with Innovative Gas Turbine Cycles

In this paper results from an ongoing research project (HYGATE) are presented, which is performed to reduce the levelized cost of electricity (LCOE) and to increase the CO2 reduction potential of the solar-hybrid gas turbine plant concept (SHGT). Key improvements are the integration of thermal energy storage and the reduction of the operating temperature of the gas turbine to 950°C. As a result the solar receiver can provide the necessary temperature for solar-only operation of the plant at design point - without using the auxiliary burner. Annual performance calculations and an economic analysis of four different plant concepts were performed. Those concepts were analyzed using innovative power block processes. In general, such systems offer reliable and dispatchable power with low specific CO2 emissions. A substantial decrease of CO2 emissions has been achieved all along the four variants compared to results of a previous project [1]. Compared to the defined reference molten salt solar tower the solar-hybrid gas turbine plants as of now yield higher plant efficiencies, but have a slightly lower potential for CO2 reduction. Among the SHGT plants the variants including a bottoming Organic Rankine Cycle (SHORCC and SHORCC-R) achieve the highest efficiencies but have significantly higher LCOE, caused by the high costs of the ORC components which are not yet commercially available in the required dimensions. The solar-hybrid combined cycle plant (SHCC) and solar-hybrid gas turbine plant with quasi isothermal compression and recuperation (SHGT-ICR) perform best among the SHGT plants in terms of LCOE, and can be considered an interesting alternative to molten salt tower plants. Taking into account other factors, such as plant complexity and water consumption, an isothermal solar gas turbine plant shows the most potential advantages. However, the SHCC has the highest technological maturity and is a likely candidate for a future demonstration plant.

Solar Gas Turbine Systems with Centrifugal Particle Receivers, for Remote Power Generation

There is a growing demand from remote communities in Australia to increase the amount of decentralised renewable energy in their energy supply mix in order to decrease their fuel costs. In contrast to large scale concentrated solar power (CSP) plants, small solar-hybrid gasturbine systems promise a way to decentralise electricity generation at power levels in the range of 0.1-10MWe, and reduce to cost of energy production for off-grid, isolated communities. Thermal storage provides such CSP systems with an advantage over photovoltaic (PV) technology as this would be potentially cheaper than adding batteries to PV systems or providing stand-by back-up systems such as diesel fuelled generators. Hybrid operation withconventional fuels and solar thermal collection and storage ensures the availability of power even if short term solar radiation is not sufficient or the thermal storage is empty. This paper presents initial modellingresults of a centrifugal receiver (CentRec)system, using hourly weather data of regional Australia for a 100 kWemicroturbine as well as a more efficient and cost effective 4.6MWe unit. The simulations involve calculation and optimisation of the heliostat field, by calculating heliostat by heliostat annual performance. This is combinedwith a model of the receiver efficiency based on experimental figures and a model of the particle storage system and turbine performance data. The optimized design for 15 hours of thermal storage capacity results in a tower height of 35m and a solar field size of 2100m2 for the 100 kWe turbine, and a tower height of 115m and solar field size of 50 000m2 for the 4.6MWe turbine. The solar field provides a greater portion of the operational energy requirement for the 100kWe turbine, as the TIT of the 4.6MWe turbine (1150°C) is greater than what the solar system can provide. System evaluations of the two particle receiver systems, with a selection of cost assumptions, are then compared to the current conventional means of supplying energy in such remote locations.

Development and assessment of integrating parabolic trough collectors with steam generation side of gas turbine cogeneration systems in Saudi Arabia

Integrating solar thermal technologies with gas turbine cogeneration plants reduces fuel consumption and consequently results in a considerable reduction in gas emissions. These technologies are expected to play an important role in solving the global environmental and energy problems. The present work provides a detailed investigation of the technical and economic feasibility of integrating a Parabolic Trough Collector (PTC) system with gas turbine cogeneration system. In this regard, different generating capacities of gas turbine and areas of solar collectors have been examined and presented for a hybrid solar gas turbine cogeneration system that produces electricity and process steam at a rate of 81.44kg/s at 394°C and 45.88bar. Thermoflex with PEACE simulation software has been used to assess the performance of each proposed integration design option. Optimum solar field size for each considered gas turbine generating capacity (size) has been identified. Also, the reduction in CO2 emissions due to the integration of PTC systems has been calculated as percentage of the CO2 emissions from the conventional system for each gas turbine generating capacity size. The results indicated that hybrid solar gas turbine cogeneration systems with gas turbine generating capacities less than 90MWe demonstrate a negligible increase in the levelized electricity cost (LEC), which was between 5US¢ and 10US¢/kWh. It was demonstrated also that integrating a PTC system with a gas turbine cogeneration system of less than 110MWe generating capacity has more economic feasibility compared to CO2 capturing technologies.

A Thermo-Economic Study of Storage Integration in Hybrid Solar Gas-Turbine Power Plants

A thermo-economic simulation model of a hybrid solar gas-turbine (HSGT) power plant with an integrated storage unit has been developed, allowing determination of the thermodynamic and economic performance. Designs were based around two representative industrial gas-turbines: a high efficiency machine and a low temperature machine. In order to examine the trade-offs that must be made, multi-objective thermo-economic analysis was performed, with two conflicting objectives: minimum investment costs and minimum specific carbon dioxide (CO2) emissions. It was shown that with the integration of storage, annual solar shares above 85% can be achieved by HSGT systems. The levelized electricity cost (LEC) for the gas-turbine system as this level of solar integration was similar to that of parabolic trough plants, allowing them to compete directly in the solar power market. At the same time, the water consumption of the gas-turbine system is significantly lower than contemporary steam-cycle based solar thermal power plants.

Experimentation of a High Temperature Thermal Energy Storage Prototype Using Phase Change Materials for the Thermal Protection of a Pressurized Air Solar Receiver

The work addresses the issue of fast variations of temperature of a central solar receiver under cloud covering. A specific attention is paid to the situation of Hybrid Solar Gas Turbine (HSGT) systems using pressurized air as Heat Transfer Fluid (HTF), as it is considered in the Pegase project (France). A Thermal Energy Storage (TES) unit integrated in the receiver is proposed for smoothing the variation of temperature. The technology is based on the utilization of both Phase Change Material (PCM) and metallic fins in order to enhance charge and discharge capability of the storage unit. A test-bench is designed with copper fins and is experienced with paraffin wax and with Li2CO3 successively as PCMs. In the same time, the test unit is modeled and the charging and discharging modes are simulated. The results show that the full charging is achieved in about 4hours starting from 700°C when the receiver is maintained at 900°C, whereas the discharge from 900°C to 700°C is achieved in 2.5hours.

Solugas – Operation Experience of the First Solar Hybrid Gas Turbine System at MW Scale

CSP hybridisation is one of the most promising concepts for cost reduction and dispatchability, and also one of the most competitive with conventional electricity generation systems. The Solugas project, first solar hybrid system topped with a gas turbine at megawatt scale, was commissioned in May 2012 in Abengoa's Solúcar Platform near Seville.Numerous operation objectives of the project have been tackled since the operation started and the project is running for several hundred solar operation hours already, yet for the technology assessment the stable operation and evaluation of long time behaviour are crucial. In 2012 the maximum receiver outlet temperature objective was achieved: the temperature of the heat transfer medium -pressurised air- has been heated up to 800°C in one receiver, reaching a temperature gradient of almost 500K.Current objectives include obtaining the tubular receiver efficiency accurately and optimisation of plant operation and control, in order to be able to characterise the behaviour of the plant and the production of the future plants.

Simulation of a Hybrid Solar Gas-turbine Cycle with Storage Integration

The interest for hybrid solar gas-turbine systems (HSGT) in solar tower plant technologies is growing This is due to the high conversion efficiency and to the low water consumption that are achieved when a combined cycle is implemented. This paper presents a simulation tool which is dedicated to the performance analysis of the top cycle featuring a thermal energy storage unit (TES). The influence of the TES operating conditions on the power plant production is highlighted. A major advantage of the storage is to stabilize the air temperature at the combustion chamber inlet in order to keep the operating conditions of the combustion chamber close to the design point. This work establishes that a higher and more stable electrical generation is achieved through this concept. According to the storage capacity, the TES unit increases the daily average solar share of the power plant. This study is conducted within the framework of the French PEGASE project (Production of Electricity from Gas and Solar Energy) which aims at setting up and testing at THEMIS site (France) a demonstration plant based on HSGT technology.