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

[EN] 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.MINECO of Spai

Thermodynamic model of a hybrid Brayton thermosolar plant

[EN]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

On- and off-design thermodynamic analysis of a hybrid polar solar thermal tower power plant

[EN]Concentrated solar power (CSP) is one challenging renewable technology for the production of electricity. Within this concept central receiver solar plants combined with gas turbines are being investigated because of their promising efficiencies and reduced water consumption. Hybrid plants incorporate a combustion chamber in such a way that in periods of low solar irradiance power output can be kept approximately constant and so, electricity production is predictable. An integrated, non-complex solar thermodynamic model of a hybrid gas turbine solar plant is developed employing a reduced number of parameters with a clear physical meaning. The solar subsystem is modeled in detail, taking into account the main heliostats field losses factors as cosine effect, blocking and shadowing, or attenuation. An heliostat field with polar symmetry together with a cavity receiver are considered. The model is implemented in our own software, developed in Mathematica language, considering as reference SOLUGAS solar field (Seville, Spain). Heliostats field configuration is determined for the design point and its associated efficiency is computed. First, an on-design analysis is performed for two different working fluids (dry air and carbon dioxide), for recuperative and non-recuperative modes. A pre-optimization process is carried out regarding the pressure ratio of the gas turbine for different configurations. Some significant efficiency and power rises can be obtained when pressure ratio is adapted for each specific configuration and working fluid. Maximum achievable plant overall efficiency is 0.302 for both fluids in the recuperative mode, taking a pressure ratio of 7 for dry air and 16 for carbon dioxide. In non-recuperative configurations maximum overall efficiency is obtained for dry air, about 0.246. Moreover, a dynamic study is performed for four representative days of each season. Then, efficiencies and solar share are plotted against time. In addition, fuel consumption and greenhouse emissions are computed for all seasons

On-design and off-design thermodynamic analysis of a hybrid multi-stage solar thermal tower power plant

[ENConcentrated solar power (CSP) is one challenging renewable technology for the future production of electricity. Within this concept central receiver solar plants combined with gas turbines are being investigated because of their promising efficiencies and reduced water consumption. Hybrid plants incorporate a combustion chamber in such a way that in periods of low solar irradiance power output can be kept approximately constant and so, electricity production is predictable. An integrated, non-complex solar thermodynamic model of a hybrid multi-stage gas turbine solar plant is developed employing a reduced number of parameters with a clear physical meaning. The solar subsystem is modelled in detail, taking into account the main heliostats field losses factors as cosine effect, blocking, or attenuation. The model is implemented in our own software, developed in Mathematica® language, considering as reference Gemasolar solar field (Seville, Spain). First, an on-design analysis is performed for four different working fluids (dry air, nitrogen, carbon dioxide, and helium), for different number of expansion and compression stages, and for recuperative and non-recuperative modes. Moreover, heliostats field configuration is determined for the design point and its associated efficiency is computed. A pre-optimization process is carried out regarding the pressure ratio of the gas turbine for different configurations. Some significant efficiency and power rises can be obtained when pressure ratio is adapted for each specific configuration and working fluid. Three particular plant configurations are chosen for the off-design analysis due to their interesting behaviours. For these configurations, a dynamic study is performed for four representative of each season. Then, efficiencies and solar share are plotted against time. In addition, fuel consumption and greenhouse emissions are computed for all seasons. Heliostats efficiency varying with the season and the solar time is also forecasted. Keywords: Dynamic analysis, On-design pre-optimization, Multi-stage gasJunta de Castilla y León of Spain (project SA017P17

Thermo-economic and sensitivity analysis of a central tower hybrid Brayton solar power plant

[EN]A hybrid central tower thermo-solar plant working with a gas turbine is simulated by means of an in-house developed model and software. The model considers the integration of all plant subsystems. The calculation of the heliostat solar field efficiency includes the main losses factors as blocking, shadowing, attenuation, interception, and cosine effect. The simulation considers a Brayton cycle for the power unit with irreversibilities in the compressor and turbine, and pressure drops in the heat absorption and extraction processes. A combustion chamber burning natural gas ensures an approximately constant power output. The model is flexible and precise. At the same time it is fast enough to perform sensitivity studies on the efficiency of any subsystem and the overall plant. Thus, it allows for performing a thermo-economic analysis of the plant checking the influence of the main plant design parameters. The focal objective is to analyze the importance on the levelized cost of electricity (LCoE) of the key plant design parameters. The direct influence of parameters from the heliostat field and receiver (as tower height, distance to the first row of heliostats, heliostats size, receiver size and heat losses, etc.) on final LCoE is surveyed. Similarly, parameters from the turbine as pressure ratio, turbine inlet temperature, influence of recuperation and others, are also analyzed. The dimensions of the plant are taken from SOLUGAS prototype near Seville, Spain, although another location with quite different solar conditions in Spain is also considered. LCoE values predicted are about 158 USD/MWh. The analysis concludes that among several parameters surveyed, two of them are key in LCoE predicted values: turbine inlet temperature and solar receiver aperture size.Junta de Castilla y León of Spain (project SA017P17

Towards a Sustainable Future through Renewable Energies at Secondary School: An Educational Proposal

[EN]A compilation of innovative educational activities to work on concepts related to the production of electrical energy is presented. To approach the real-life secondary education curriculum, they are grouped to be performed during a week denominated Renewable Energy Week: an educational proposal aimed to promote the respect for the environment through the insight on Sustainable Development Goals (SDG) and renewable energy sources. The students would build and perform low-cost experiments so as to deeply understand the essence of energetic transformations, as well as electricity generation. Learning by discovery, collaborative learning and experimentation, are the methodological pillars that characterize Renewable Energy Week, since they have been proven to be efficient methodologies to promote students’ learning. Innovative techniques for pupils evaluation are employed, including a rubric, Socrative application and a set of sheets regarding experiments. Through this educational proposal, the students are expected to achieve a deep understanding of some key concepts related to electricity and awaken their interest in scientific subjects, making them conscious of the transition to sustainable development that our planet urgently requires. At the same time, this project offers to teachers a series of experiments and innovative activities to work on the SDG in Physics, Chemistry and Technology subjects.University of Salamanca through Innovation and teaching improvement project ID 2019/16

Thermodynamic and Cost Analysis of a Solar Dish Power Plant in Spain Hybridized with a Micro-Gas Turbine

[EN]Small-scale hybrid parabolic dish concentrated solar power systems are a promising option to obtain distributed electricity. During the day, solar energy is used to produce electricity, and the absence of sunlight can be overwhelmed with fuel combustion. This study presents a thermo-economic survey for a hybridized power plant in different regions of Spain, considering the local climatic conditions. The developed model considers the instant solar irradiance and ambient temperature dynamically, providing an estimation of the power output, the associated fuel consumption, and the most relevant pollutant emissions linked to combustion. Hybrid and combustion-only operating modes at selected geographical locations in Spain (with different latitudes, mean solar irradiances, and meteorological conditions) are analyzed. The levelized cost of electricity indicator is estimated as a function of investment, interest rate, maintenance, and fuel consumption actual costs in Spain. Values of about 124 e/MWhe are feasible. Fuel consumption and emissions in hybrid operation can be reduced above 30% with respect to those of the same turbine working in a pure combustion mode. This model shows the potential of hybrid solar dishes to become cost-competitive against non-renewable technologies from the point of view of costs and reduction in gas emission levels in regions with high solar radiation and low water resources.University of Salamanca Grant Number PC-TCUE18-20-002, Junta de Castilla y León of Spain Grant Number SA017P17

Expression Patterns of Irx Genes in the Developing Chick Inner Ear

© 2016 Springer-Verlag Berlin Heidelberg.This document is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This document is the Accepted version of a Published Work that appeared in final form in Brain Structure and Function. To access the final edited and published work see https://doi.org/10.1007/s00429-016-1326-6The vertebrate inner ear is a complex three-dimensional sensorial structure with auditory and vestibular functions. The molecular patterning of the developing otic epithelium creates various positional identities, consequently leading to the stereotyped specification of each neurosensory and non-sensory element of the membranous labyrinth. The Iroquois (Iro/Irx) genes, clustered in two groups (A: Irx1, Irx2, and Irx4; and B: Irx3, Irx5, and Irx6), encode for transcriptional factors involved directly in numerous patterning processes of embryonic tissues in many phyla. This work presents a detailed study of the expression patterns of these six Irx genes during chick inner ear development, paying particular attention to the axial specification of the otic anlagen. The Irx genes seem to play different roles at different embryonic periods. At the otic vesicle stage (HH18), all the genes of each cluster are expressed identically. Both clusters A and B seem involved in the specification of the lateral and posterior portions of the otic anlagen. Cluster B seems to regulate a larger area than cluster A, including the presumptive territory of the endolymphatic apparatus. Both clusters seem also to be involved in neurogenic events. At stages HH24/25-HH27, combinations of IrxA and IrxB genes participate in the specification of most sensory patches and some non-sensory components of the otic epithelium. At stage HH34, the six Irx genes show divergent patterns of expression, leading to the final specification of the membranous labyrinth, as well as to cell differentiation

Thermo-economic study of hybrid parabolic dish solar power plants in different regions of Spain

[EN]Small-scale hybrid parabolic dish Concentrated Solar Power (CSP) systems coupled to a micro-gas turbine are a promising option to obtain electrical energy in a distributed manner. During the day, solar energy is used to produce electricity and the absence of sunlight can be overcome with the combustion of a fossil or renewable fuel. This study presents the technical feasibility and thermo-economic model of a hybridized power plant in different regions of Spain, considering the local climatic conditions. The implemented model aims to provide a realistic view of the behaviour of the system, using a reduced number of selected parameters with a clear physical meaning. The irreversibilities taking place in all subsystems (solar part, combustion chamber, micro-gas turbine, and the corresponding heat exchangers) have been considered in the model, developed in Mathematica® language. The model considers the instant solar irradiance and ambient temperature dynamically, providing an estimation of the power output, the associated fuel consumption, and the most relevant pollutant emissions (CO2, CH4 and NO2) linked to combustion, for hybrid and combustion only operating modes at selected geographical locations in Spain. The considered power output ranges between 7 to 30 kWe which is achieved by varying the design specifications. The levelized cost of electricity (LCoE) indicator is estimated as a function of investment, interest rate, maintenance and fuel consumption actual costs in Spain. The electricity costs from hybrid parabolic dish are between 22% and 27% lower compared to pure combustion power plant, while specific fuel consumption and therefore CO2 emissions can be reduced up to 33%. This model shows the potential of hybrid solar dishes to become cost-competitive against non-renewable ones from the point of view of electricity costs and significant reduction in gas emission levels in regions with high solar radiation and low water resources.Junta de Castilla y Leó

Micro Gas Turbine and Solar Parabolic Dish for distributed generation

[EN]A thermodynamic model for a Brayton-like microturbine in combination with a solar parabolic dish is analyzed in order to evaluate its efficiency under any ambient condition. The thermodynamic cycle is a recuperative Brayton cycle with internal irreversibilities in the recuperator, compressor and turbine and external losses associated to the heat transfers in the solar receiver, the combustion chamber, and the environment. All the irreversibilities have been taken into account in the model with home-software elaborated using Mathematicaâ. The model validation is done by comparison with results provided by Semprini et al. [1]. An analysis of hybrid and sunless performance is carried out for four different microturbine power outlets (30, 23, 15 and 7 kWe) and for four days of the year (corresponding to each season). The greenhouse emissions are also calculated for both off-design performance and for the four power output levels