Parametric cost–benefit analysis for the installation of photovoltaic parks in the island of Cyprus

In this work a feasibility study is carried out in order to investigate whether the installation of large photovoltaic (PV) parks in Cyprus, in the absence of relevant feed-in tariff or other measures, is economically feasible. The study takes into account the available solar potential of the island of Cyprus as well as all available data concerning current renewable energy sources (RES) policy of the Cyprus Government and the current RES electricity purchasing tariff from Electricity Authority of Cyprus. In order to identify the least-cost feasible option for the installation of 1 MW PV park a parametric cost–benefit analysis is carried out by varying parameters such as PV park orientation, PV park capital investment, carbon dioxide emission trading system price, etc. For all above cases the electricity unit cost or benefit before tax, as well as after-tax cash flow, net present value, internal rate of return and payback period are calculated. The results indicate that capital expenditure of the PV park is a critical parameter for the viability of the project when no feed-in tariff is available.     

Parametric analysis for the installation of solar dish technologies in Mediterranean regions

In this work a feasibility study is carried out in order to investigate whether the installation of solar dish technologies for power generation in Mediterranean regions is economically feasible. The study takes into account the available solar potential for a typical Mediterranean country, such as Cyprus, as well as all available data concerning the current renewable energy sources policy of the island, including the relevant feed-in tariff of 0.26€/kWh. In order to identify the least cost feasible option for the installation of the solar dish plant a parametric cost–benefit analysis is carried out by varying the solar dish plant capacity, the solar dish plant capital investment and the CO₂ emissions trading scheme price. The results indicated that the installation of solar dish plants in Mediterranean regions is economically feasible only in some cases, when a feed-in tariff incentive scheme exists, and that the size and the capital cost of the solar dish power plant are critical parameters affecting the economic viability of the technology.     

Parametric assessment of concentrated photovoltaic parks for the Mediterranean region

Solar electricity produced by concentrated photovoltaic (CPV) solar cells is an alternative renewable energy technology for sustainably providing the world's future energy requirements. Although the technology is relatively recent, it could potentially become viable in regions with high direct irradiance levels, such as the Mediterranean region. The main objective of this feasibility study is to investigate whether the installation of CPV parks in the Mediterranean region is economically feasible. The study takes as an example the available solar potential of the island of Cyprus as well as all available data concerning the current renewable energy sources policy of the island. In order to identify the least cost-feasible option for the installation of 1 MW CPV park, a parametric cost–benefit analysis is carried out by varying the CPV park capital investment, the discount rate and the CO₂ emission trading scheme price. The results indicate that in the case where no feed-in tariff scheme is available, the capital expenditure of the CPV park is a critical parameter for the financial viability of the project.     

Utility scale hybrid wind–solar thermal electrical generation: A case study for Minnesota

The performance of a hybrid wind–solar power plant in southwestern Minnesota is modeled for a 2-yr period using hourly wind and solar insolation data. The wind portion of the plant consists of four interconnected wind farms within a radius of 90 km. The solar component of the plant is a parabolic trough solar thermal electric generating system using a heat transfer fluid that drives a steam turbine. The market value of energy produced, retail value of energy produced, and levelized cost of energy of the hybrid plant are compared to those of an energy equivalent wind-only plant. Results show that adding solar thermal electric generating capacity to a wind farm rather than expanding with additional wind capacity provides cost–benefit trade-offs that will continue to change as the two technologies evolve. At the present time, we find that capital cost and levelized cost of energy favor a wind-only plant while electric load matching favors a hybrid wind–solar plant. Regional differences in the solar resource in the US influence the economic viability of the hybrid plant, and a comparison using the present model is made with one location in the Southwest. The hourly data analysis presented here is a possible tool for evaluating the overall economic feasibility and generating characteristics for a hybrid wind–solar thermal electric power plant for any location with available wind, solar, electric load, and price data.     

Solar multiple optimization for a solar-only thermal power plant, using oil as heat transfer fluid in the parabolic trough collectors

Usual size of parabolic trough solar thermal plants being built at present is approximately 50 MW_e. Most of these plants do not have a thermal storage system for maintaining the power block performance at nominal conditions during long non-insolation periods. Because of that, a proper solar field size, with respect to the electric nominal power, is a fundamental choice. A too large field will be partially useless under high solar irradiance values whereas a small field will mainly make the power block to work at part-load conditions.This paper presents an economic optimization of the solar multiple for a solar-only parabolic trough plant, using neither hybridization nor thermal storage. Five parabolic trough plants have been considered, with the same parameters in the power block but different solar field sizes. Thermal performance for each solar power plant has been featured, both at nominal and part-load conditions. This characterization has been applied to perform a simulation in order to calculate the annual electricity produced by each of these plants. Once annual electric energy generation is known, levelized cost of energy (LCOE) for each plant is calculated, yielding a minimum LCOE value for a certain solar multiple value within the range considered.     

Performance of a direct steam generation solar thermal power plant for electricity production as a function of the solar multiple

This paper describes the influence of the solar multiple on the annual performance of parabolic trough solar thermal power plants with direct steam generation (DSG). The reference system selected is a 50 MW_e DSG power plant, with thermal storage and auxiliary natural gas-fired boiler. It is considered that both systems are necessary for an optimum coupling to the electricity grid. Although thermal storage is an opening issue for DSG technology, it gives an additional degree of freedom for plant performance optimization. Fossil hybridization is also a key element if a reliable electricity production must be guaranteed for a defined time span. Once the yearly parameters of the solar power plant are calculated, the economic analysis is performed, assessing the effect of the solar multiple in the levelized cost of electricity, as well as in the annual natural gas consumption.     

Assessment of solar electricity production in the United Arab Emirates

In this work the possible large-scale integration of photovoltaic (PV) systems and parabolic trough concentrated solar power (CSP) technologies in the United Arab Emirates (UAE) power system is investigated in technical, economic and environmental terms. The analysis takes into account the available solar potential for UAE and in particular for the Emirate of Sharjah. In order to identify the least-cost feasible option for each renewable energy source for power-generation (RES-E) technology, a parametric analysis is carried out by varying each RES-E candidate system capital cost. From the analysis it is evident that an alternative cost-effective technology to the installation of a 50 MWp PV system might be the utilisation of a 50 MWe parabolic trough CSP system with either a 14.5 h thermal storage system or a 24/7 operation. The advantages of the latter are the dispatchability and the increased electricity output due to the utilisation of a thermal storage system, which leads to higher amounts of annual CO₂ avoided emissions. However, the electricity selling prices are higher than the current UAE electricity tariffs; therefore, for the promotion of solar RES-E technologies in the UAE, relevant financial supporting mechanisms need to be developed such as feed-in tariffs or feed-in premiums.     

The application of parabolic trough technology under Jordanian climate

Parabolic trough solar thermal power plants are a proven technology in the utility scale since mid of the eighties. Between 1984 and 1991 nine power plants with an overall capacity of 354 MW have been installed in the Mojave Desert in California. Since, these power plants can be equipped with a thermal storage or a fossil back-up they offer a fully dispatchable electricity generation capacity. This technology will be a very interesting near term option for countries with high solar irradiation levels and small resources of fossil fuels like Jordan.This paper, discusses the use of parabolic trough solar thermal power plants for electricity production under Jordanian climate for two different sites (Amman, and Ma'an). An analysis of the daily power output, direct normal irradiation and the efficiency for the two sites has been carried out. The results showed that Ma'an site would be preferred than Amman site, so that it is recommended to erect the Parabolic Trough Concentrator (PTC) plant in the southern region of Jordan.Also this study aims to encourage the Jordanian government and the private sector to implement the solar thermal power plants for future expansion of power sector due to the increasing electricity demand and environmental degradation.     

Performance analysis of an Integrated Solar Combined Cycle using Direct Steam Generation in parabolic trough collectors

The contribution of solar thermal power to improve the performance of gas-fired combined cycles in very hot and dry environmental conditions is analyzed in this work, in order to assess the potential of this technique, and to feature Direct Steam Generation (DSG) as a well suited candidate for achieving very good results in this quest. The particular Integrated Solar Combined Cycle (ISCC) power plant proposed consists of a DSG parabolic trough field coupled to the bottoming steam cycle of a Combined Cycle Gas Turbine (CCGT) power plant. For this analysis, the solar thermal power plant performs in a solar dispatching mode: the gas turbine always operates at full load, only depending on ambient conditions, whereas the steam turbine is somewhat boosted to accommodate the thermal hybridization from the solar field.     

Screening of high melting point phase change materials (PCM) in solar thermal concentrating technology based on CLFR

We have investigated the suitability of high melting point phase change materials for use in new, large scale solar thermal electricity plants. Candidate materials for latent heat thermal energy storage are identified and their operating parameters modeled and analysed. The mathematical characteristics of charging and discharging these storage materials are discussed. Several high melting point, high conductivity materials are shown to be suitable and advantageous for use with solar thermal electricity plants, such as Sydney University’s novel, low cost CLFR and MTSA collector systems, as well as existing parabolic trough and tower technologies.     

Effect of using nanofluids on efficiency of parabolic trough collectors in solar thermal electric power plants

In this paper, forced convection heat transfer nanofluid flow inside the receiver tube of solar parabolic trough collector is numerically simulated. Computational Fluid Dynamics (CFD) simulations are carried out to study the influence of using nanofluid as heat transfer fluid on thermal efficiency of the solar system. The three-dimensional steady, turbulent flow and heat transfer governing equations are solved using Finite Volume Method (FVM) with the SIMPLEC algorithm. The results show that the numerical simulation are in good agreement with the experimental data. Also, the effect of various nanoparticle volume fraction on thermal and hydrodynamic characteristics of the solar parabolic collector is discussed in details. The results indicate that, using of nanofluid instead of base fluid as a working fluid leads to enhanced heat transfer performance. Furthermore, the results reveal that by increasing of the nanoparticle volume fraction, the average Nusselt number increases.     

Analytic modeling of a solar power plant with parabolic linear collectors

An analytic model for a solar thermal electric generating system with parabolic trough collectors was developed. The energy conversion of solar radiation into thermal power along the absorber tube of the parabolic collector is studied, taking into consideration the non-linearity of heat losses and its dependence on the local temperature. The coupling between the collector and the thermodynamic cycle is made up of three heat exchangers, yielding the characteristic temperatures of the cycle. The conventional Rankine cycle is treated as an endo-reversible Carnot cycle, whereby the mechanical and electric power is calculated. For comparison, we refer to the Solar Electric Generating System VI (SEGS VI), installed in the Mojave desert-CA, whose solar field is composed by LS2 parabolic trough collectors. We simulated the efficiency curves of collectors LS2 with evacuated and non-evacuated absorbers and compared with experimental results. A second simulation was carried out to estimate the optimum quantity of non-evacuated LS2 collectors in series in a collectors’ row, when friction losses along the absorber tubes are considered. Also, the performance of a 30 (MWe) power plant, composed of 50 rows with 16 LS2 collectors in series (total 800 collectors) was simulated. Three fields of different collectors were considered, the first field with evacuated absorbers, the second with non-evacuated absorbers and the third with bare absorbers. Finally, the output power of the plant is analyzed as a function of the evaporation temperature of the water-vapor fluid. A large maximum of the overall cycle efficiency is found for evaporation temperatures around 320 °C. Good agreement is obtained when comparing the results of this model with experimental data belonging to the Solar Electric Generating Systems (SEGS) installed in the Mojave desert. The analytic model developed combines simplicity, precision and flexibility, making it an attractive tool for simulation and design of solar power stations.     

Simulation study of a large scale line-focus trough collector solar power plant in Greece

This paper deals with the technical feasibility and economic viability of a solar thermal power plant using parabolic trough collectors in Greece. The power plant is to be installed in the island of Rhodes and its power output will be 8.55 MW. Power plant simulation is carried out using TRNSYS software (STEC library) and economic issues of the project such as initial cost of investment, operation and maintenance (O&M) and energy costs will be analyzed. It was found that for the particular investment, considering a 75% of initial investment cost loan (with a 10-year period), the payback period will be approximately 13 years.     

Organic Rankine Cycle coupling with a Parabolic Trough Solar Power Plant for cogeneration and industrial processes

Over the last 25 years solar power plants based on parabolic trough concentrators have been developed for the commercial power industry. On the other hand, in recent years, a way to harness the solar energy is to cogenerate through Concentrated Solar Power (CSP) technology coupled to an Organic Rankine Cycle (ORC) with potential applications to industrial processes. In this work we present a study of a small CSP plant coupled to an ORC with a novel configuration since useful energy is directly used to feed the power block and to charge the thermal storage. In order to analyze this novel configuration we consider a case study with cogeneration applied to textile industrial process at medium temperature. It turns out that this configuration reduces the size of the thermal storage disposal. The performance of the solar power plant was simulated with TRNSYS to emulate real operating conditions. We show the design, study and simulation results, including the production and efficiency curves for our load profile. Our results show that our system is a promising option for applications to medium temperature processes where electrical and heat generation is required.     

Numerical Investigation of Energy-Efficient Receiver for Solar Parabolic Trough Concentrator

In this paper, a thermal analysis of an energy-efficient receiver for solar parabolic trough concentrator is presented. Various porous receiver geometries are considered for the performance evaluation of a solar parabolic trough concentrator. Numerical models are proposed for a porous energy-efficient receiver for internal heat gain characteristics and heat loss due to natural convection. The internal flow and heat transfer analysis is carried out based on a RNG k-? turbulent model, whereas external heat losses are treated as a laminar natural convection model. The numerical models have been solved using the commercial engineering package, FLUENT. The thermal analysis of the receiver is carried out for various geometrical parameters, such as fin aspect ratio, thickness, and porosity, for different heat flux conditions. The inclusion of porous inserts in tubular receiver of solar trough concentrator enhanced the heat transfer about 17.5% with a pressure penalty of 2 kPa. The Nusselt number correlation is proposed based on the extensive numerical data for internal heat transfer inside the receiver. The proposed model is compared with more well-known natural convection models. A comparative study is carried out with different porous geometries to evolve an optimum configuration of energy-efficient receivers.     

Technical and economical analysis of a solar–geothermal hybrid plant based on an Organic Rankine Cycle

A combined concentrating solar power system and a geothermal binary plant based on an Organic Rankine Cycle (ORC) is analyzed. Given a supercritical ORC, designed for the optimal utilization of an intermediate enthalpy geothermal source, a solar parabolic trough field was included in the plant, introducing an additional high temperature heat source for the cycle and increasing power production. The off-design performance analysis of the power cycle was performed first. An hour-by-hour simulation was then carried out to estimate the yearly production using a detailed solar field model. Finally, a differential economic analysis was performed to determine the cost of the additional electricity generated with the solar source. On the basis of the current cost of solar collectors, levelized costs of electricity of 145-280 €/MWh were obtained depending on the location of the plant: a competitive value with respect to large, stand-alone concentrating solar power plants.     

Performance model for parabolic trough solar thermal power plants with thermal storage: Comparison to operating plant data

This paper describes a simulation model that reproduces the performance of parabolic trough solar thermal power plants with a thermal storage system. The aim of this model is to facilitate the prediction of the electricity output of these plants during the various stages of their planning, design, construction and operation. Model results for a 50 MW_e power plant are presented and compared to real data from an equivalent power plant currently operated by the ACS Industrial Group in Spain.     

The calculation and analysis of glass-to-metal sealing stress in solar absorber tube

The failure or degradation of solar absorber tubes is the single largest cost factor for current parabolic trough solar power plant. The main failure reason is that there are residual stresses in the glass-to-metal joint which are generated during the cooling process of sealing. According to the thin shell theory and thermal stress theory, this paper presents the analytic solution for the glass-to-metal sealing residual stress. It also analyses how the thickness of glass tube, thickness of metal ring, and thermal expansion coefficient affect the residual stress distribution. In order to verify the calculation results, the photoelastic technique is used to measure the residual stress and the tensile test is used to obtain the point of the most dangerous stress and the tensile strength for the sealed specimens. It can be concluded that the maximum tensile stress happens at some distance near the sealing interface on the outer surface of glass tube. The seal strength increases when the thickness of the glass tube is increased. The analytic solution is proved feasible to analyze the residual stress of glass-to-metal seals in solar absorber tubes.     

Control scheme for direct steam generation in parabolic troughs under recirculation operation mode

Electricity production using solar thermal energy is one of the main research areas at present in the field of renewable energies, these systems being characterised by the need of reliable control systems aimed at maintaining desired operating conditions in the face of changes in solar radiation, which is the main source of energy. A new prototype of solar system with parabolic trough collectors was implemented at the Plataforma Solar de Almería (PSA, South-East Spain) to investigate the direct steam generation process under real solar conditions in the parabolic solar collector field of a thermal power plant prototype. This paper presents details and some results of the application of a control scheme designed and tested for the recirculation operation mode, for which the main objective is to obtain steam at constant temperature and pressure at the outlet of the solar field, so that changes produced in the inlet water conditions and/or solar radiation will only affect the amount of steam produced by the solar field. The steam quality and consequently the nominal efficiency of the plant are thus maintained.     

太阳能热发电厂厂用电率计算方法分析

文章主要解决了太阳能热发电设计领域的厂用电计算思路及方法的问题。太阳能热发电已成为我国新能源发电的重要发展方向,太阳能热发电厂用电率的计算目前还没有相关的规程规范。在研究过程中,采用对太阳能热发电厂的运行模式与火力发电厂运行模式进行对比分析的方法,得出火力发电厂厂用电率的计算方法不适用于太阳能热发电厂的研究结果。通过对槽式太阳能热发电厂集热场系统、吸热传热系统、储热系统、常规岛系统分别进行分析,提出了槽式太阳能热发电厂厂用电量的计算方法,得出了太阳能热发电厂应采用长序列代表年辐照值,逐时计算代表年的发电量和厂用电量,以其比值来计算厂用电率的结论;提出了槽式太阳能热发电厂厂用电率的计算思路和方法,可供塔式太阳能热发电厂参考,对我国太阳能热发电厂的设计发展起到推动作用。