Conceptual design and techno-economic assessment of integrated solar combined cycle system with DSG technology

Direct steam generation (DSG) in parabolic trough collectors causes an increase to competitiveness of solar thermal power plants (STPP) by substitution of oil with direct steam generation that results in lower investment and operating costs. In this study the integrated solar combined cycle system with DSG technology is introduced and techno-economic assessment of this plant is reported compared with two conventional cases. Three considered cases are: an integrated solar combined cycle system with DSG technology (ISCCS-DSG), a solar electric generating system (SEGS), and an integrated solar combined cycle system with HTF (heat transfer fluid) technology (ISCCS-HTF).This study shows that levelized energy cost (LEC) for the ISCCS-DSG is lower than the two other cases due to reducing O&M costs and also due to increasing the heat to electricity net efficiency of the power plant. Among the three STPPs, SEGS has the lowest CO₂ emissions, but it will operate during daytime only.     

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.     

Steam temperature stability in a direct steam generation solar power plant

Direct steam generation (DSG) is one alternative to the current oil-based parabolic trough solar thermal power plants. Within the German research project ITES, the dynamic behavior of a DSG collector field and the interactions with the conventional power block are assessed in detail. A transient solar field model developed by DLR is used to simulate the steam temperature behavior. Artificial irradiance disturbances as well as real irradiance data are used as input to the system. The resulting main steam temperature gradients are then analyzed by Siemens considering the standards for steam turbines.This paper presents the transient simulation results of the steam temperature as well as the corresponding results of the steam turbine analysis. It is found that the occurring temperature gradients are challenging for a safe turbine operation, if a conservative control system is used. Therefore, the use of an additional thermal inertia to stabilize the steam temperature is suggested. Its impact is also analyzed and discussed in this paper.     

Optimum power from a solar thermal power plant using solar concentrators

In this paper, the optimum temperature of operation of a solar concentrator and thus the maximum power obtained from a solar thermal power plant has been calculated. Results are plotted graphically and discussed.     

Critical evaluation of solar chimney power plant performance

This paper evaluates the influence of a recently developed convective heat transfer equation, more accurate turbine inlet loss coefficient, quality collector roof glass and various types of soil on the performance of a large scale solar chimney power plant. Results indicate that the new heat transfer equation reduces plant power output considerably. The effect of a more accurate turbine inlet loss coefficient is insignificant, while utilizing better quality glass enhances plant power production. Models employing Limestone and Sandstone soil produce virtually similar results to a Granite-based model. The plant collector height is found to differ from previously obtained optimal values.     

Performance of low temperature solar rankine power generation system

The overall performance of a solar thermal electrical power generation system is governed by the performance of the energy collection system and the power conversion unit. Any system operating under given meteorological and solar radiation conditions has a unique energy collection temperature for which the electrical output of the system will be a maximum. An engineering analysis of the system was carried out to obtain general correlations which can be used for determining such an optimum temperature. Factual experience on the design and operation of a Rankine system, using flat plate collectors and the climatological data, was used to obtain numerical estimates for the net energy conversion capability of such systems operating in Kuwait.     

Economic analysis of power generation from parabolic trough solar thermal plants for the Mediterranean region—A case study for the island of Cyprus

In this work a feasibility study is carried out in order to investigate whether the installation of a parabolic trough solar thermal technology for power generation in the Mediterranean region is economically feasible. The case study takes into account the available solar potential for Cyprus, as well as all available data concerning current renewable energy sources policy of the Cyprus Government, including the relevant feed-in tariff. In order to identify the least cost feasible option for the installation of the parabolic trough solar thermal plant a parametric cost–benefit analysis is carried out by varying parameters, such as, parabolic trough solar thermal plant capacity, parabolic trough solar thermal capital investment, operating hours, 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 under certain conditions such projects can be profitable.     

Saturated steam process with direct steam generating parabolic troughs

The direct steam generation (DSG) in parabolic trough collectors is an attractive option regarding the economic improvement of parabolic trough technology for solar thermal electricity generation in the multi Megawatt range. The European DISS project has proven the feasibility of the direct steam generation under real solar conditions in more than 4000 operation hours. Within the European R&D project INDITEP the detailed engineering for a pre-commercial DSG solar thermal power plant with an electrical power of 5 MW is being performed. This small capacity was chosen to minimise the risk for potential investors.In regards to DSG solar thermal power plants, only steam cycles using superheated steam have been investigated so far. The paper will investigate the advantages, disadvantages, and design considerations of a steam cycle operated with saturated steam for the first time. For near term applications, saturated steam operated DSG plants might be an interesting alternative for power generation in the small capacity range due to some specific advantages:

• Simple set up of the collector field.

• Proven safe collector field operation.

• Higher thermal efficiency in the collector field.

A model for optimal sizing of solar thermal hydroelectric power plant

This paper presents the model for optimal sizing of a Solar Thermal (ST) power plant with parabolic collectors, which operates with Pump Storage Hydroelectric (PSH), all for the purpose of providing full energy independence of an isolated consumer. The sustainability of such system is based exclusively on solar energy input (without hybridization with any fossil fuel), as a renewable and pure energy resource, and the use of hydro energy, due to the possibility of its continuous production of energy. The feasibility and characteristics of the ST-PSH power plant were tested on power supply of the Island of Vis in Croatia, and the results show that the proposed model describes the operation of the power plant very well. For average solar irradiation of about 1500 kW h/m²/a, precipitation 644 mm/a, evaporation 1444 mm/a, volume of PSH upper reservoir of 20 h m³, electric energy consumption of 18 GV A h/a and reserve in the system for 3-4 months, the obtained power of the ST power plant is 22 MW, which can produce unit value of the annual thermal energy of 459 kW h/m²/a and electric energy of 160 kW h/m²/a, while the total collector aperture in the observed case is about 16 ha. These results show that ST-PSH plants can be successfully applied on locations with relatively low irradiation, wherein the key element that ensures continuous production of energy is precisely the PSH technology that can in the best way, in economic-technical, and especially in ecological sense, balance the relatively large summer surpluses and winter energy shortages.     

Condenser Optimization in Steam Power Plant

In this paper the effects of the condenser design parameters (such as turbine inlet condition, turbine power and condenser pressure) on heat transfer area, cooling water flow-rate, condenser cost and specific energy generation cost are studied for surface type condenser. The results are given in the text and also shown as diagrams.     

Techno-economic evaluation of concentrating solar power generation in India

The Jawaharlal Nehru National Solar Mission (JNNSM) of the recently announced National Action Plan on Climate Change (NAPCC) by the Government of India aims to promote the development and use of solar energy for power generation and other uses with the ultimate objective of making solar competitive with fossil-based energy options. The plan includes specific goals to (a) create an enabling policy framework for the deployment of 20,000 MW of solar power by 2022; (b) create favourable conditions for solar manufacturing capability, particularly solar thermal for indigenous production and market leadership; (c) promote programmes for off grid applications, reaching 1000 MW by 2017 and 2000 MW by 2022, (d) achieve 15 million m² solar thermal collector area by 2017 and 20 million by 2022, and (e) deploy 20 million solar lighting systems for rural areas by 2022. The installed capacity of grid interactive solar power projects were 6 MW until October 2009 that is far below from their respective potential.     

Techno-economic appraisal of a dish/stirling solar power plant in Greece based on an innovative solar concentrator formed by elastic film

As the environmental problems caused by the use of conventional fuels have risen significantly and due to the increase in fossil fuel prices, the importance of reducing society dependence on non-renewable energy sources becomes more and more urgent. It is clear that this could only happen by switching to extensive use of clean energy sources such as renewable energy sources. In this paper a technical feasibility and economic viability study of a dish/Stirling solar power plant in Greece is presented. The proposed power plant uses Dish/Stirling technology and has nominal power 10 MW. The proposed solar concentrator system consists of a primary mirror, formed by elastic film, used to focus the sun's rays onto a secondary mirror which then deviates this radiation into the receiver (Stirling engine). TRNSYS program was developed to simulate Dish/Stirling power plant operation in order to investigate its performance in Greece. The simulation predicted that the proposed power plant could produce 11.19 GWh annually. Project investment cost is approximately 27,000,000 €, while payback is achieved after 16 years of operation. The total profit at the end of the analysis period of 25 years is estimated to be 25,500,000 €.     

Partial geometric similarity for solar chimney power plant modeling

A solar chimney power plant derives its mechanical power from the kinetic power of the hot air which rises through a tall chimney, the air being heated by solar energy through a transparent roof surrounding the chimney. In our previous studies, the achievement of complete dynamic similarity between a prototype and its models imposed the use of different solar heat fluxes between them. It is difficult to conduct an experiment by using dissimilar heat fluxes with different physical models. Therefore, this study aimed to maintain dynamic similarity for a prototype and its models while using the same solar heat flux. The study showed that, to achieve the same-heat-flux condition, the roof radius between the prototype and its scaled models must be dissimilar, while all other remaining dimensions of the models are still similar to those of the prototype. In other words, the models are ‘partially’ geometrically similar to the prototype. The functional relationship that provides the condition for this partial similarity is proposed and its validity is proved by scaling the primitive numerical solutions of the flow. Engineering interpretations of the similarity variables are also presented.     

Estimation of the energy output of a photovoltaic power plant in the Austrian Alps

An output simulation is one of the first steps in planning a photovoltaic power plant (PVP) at a certain location. Various computer codes already exist to assess the energy output of a PVP, when fed with the relevant meteorological data. For the alpine area, however, there is no appropriate data considering the altitude of the site available. A computer code has been written to check the available raw data for plausibility and to fill in missing data synthetically. On the basis of 6 yr of measured data a test reference year (TRY) has been developed for the town of Leonding and the summit Loser. They are located just 80 km apart but have a 1250 m difference in their altitudes. For comparison, these new TRYs, together with other already existing TRYs from different places in a surrounding area of about 300 km, are used for calculation of the expected energy output of a PVP. A clear increase of energy yield with higher altitude can be observed. The summit Loser (1550 m), with the highest altitude investigated in this study, proved to be the most productive location. Besides the clearer sky and snow reflection, the lower temperature as well as better cooling of the panels by the wind in the Alps contribute to the higher amount of energy output.     

The first pilot demonstration: solar updraft tower power plant in Jordan

The high cost of importing heavy fuel oil from neighbouring countries of Jordan stimulated the need to consider renewable energy as an alternative to imported power. The paper describes a systematic experimental study on the pilot solar updraft tower power plant model system. Particular attention is given to measurements of air velocity, temperature, solar radiation and voltage difference. This is the first pilot solar updraft power plant that has been built in Jordan to evaluate such technology in Mutah Area. In this paper, all the experimental data were taken from a very small pilot project (compared with other prototypes that we constructed which were placed in the backyard of our faculty). For the experimental part, the solar updraft power plant was a pilot project with an updraft power plant height H=4(m), updraft power plant radius R _c=0.29(m), plastic solar collector area A _coll=36(m²), collector roof height=1(m), wind turbine that was a compensation of the suction fan with a diameter D _fan=0.5(m), and a small generator (6 V) The experimental results in this paper show that the maximum height (H _max) gradually increases with the solar irradiation (G). Also, in the same way, with the pressure difference (Δ p) increases with solar irradiation.     

Improved solutions for temperature and thermal power delivery profiles in linear solar collectors

For the conversion of absorbed sunlight into useful thermal power, we demonstrate that the profiles of absorber temperature, fluid temperature and thermal power delivery along linear solar collectors can be solved in closed form even when the collector heat-loss coefficient is far from constant over the collector operating range. This analytic solution eliminates the errors inherent in earlier approximate solutions, and makes the dependence of collector performance on component properties transparent. An example for a realistic solar concentrator illustrates the improvement in prediction accuracy.     

Technical and economical evaluation of solar thermal power generation

This article presents a feasibilty on a solar power system based on the Stirling dish (SD) technology, reviews and compares the available Stirling engines in the perspective of a solar Stirling system.The system is evaluated, as a parameter to alleviate the energy system of the Cretan island while taking care of the CO₂ emissions. In the results a sensitivity analysis was implemented, as well as a comparison with conventional power systems.In the long-term, solar thermal power stations based on a SD can become a competitive option on the electricity market, if a concerted programme capable of building the forces of industry, finance, insurance and other decision makers will support the market extension for this promising technology.     

Dynamic simulation of thermal energy storage system of Badaling 1 MW solar power tower plant

In this paper, the thermal energy storage system of Badaling 1 MW solar power tower plant is modelled from mathematical models for whole of the working conditions using the modular modelling method. This model can accurately simulate the recharge and discharge processes of thermal energy storage system. The dynamic and static characteristics of the thermal energy storage system are analyzed based on the model response curves of the system state parameters that are obtained from different steam flow disturbances. Conclusions of this paper are good references for the design, operating, and control strategy of solar thermal power plant.     

GA-based fuzzy logic control of a solar power plant using distributed collector fields

A novel genetic algorithm (GA) based fuzzy logic control (FLC) system has been developed for the solar power plant, Plataforma Solar de Almería (PSA) at Tabernas, in Almería, Spain. The rule base encompasses an empirical set of 49 “if-then” rules. Chromosomes consisting of 49 genes of 5-bit data are created to link to the rule base. The 5-bit data of each gene represents the stength of the corresponding ‘If-Then’ rule. The GA performs the basic operations of reproduction, crossover and mutation on a pool of chromosomes to search for the best rule base which optimises the response time of the plant to input temperature or power demand by controlling the distributed collector field of the plant. The collect field is essentially an array of parabolic mirrors and oil pipes in which the transversal of solar energy takes place. Simulation results on the plant with an optimised rule-base using the 100th generation of the chromosome show that the proposed GA-FLC scheme gives a better and more robust performance of the plant than other schemes previously implemented.     

Development of a feasibility prediction tool for solar power plant installation analyses

The solar energy becomes a challenging area among other renewable sources since the solar energy sources have the advantages of not causing pollution, having low maintenance cost, and not producing noise due to the absence of the moving parts. Although these advantages, the installation cost of a solar power plant is considerably high. However, feasibility analyses have a great role before installation in order to determine the most appropriate power plant site. Despite there are many methods used in feasibility analysis, this paper is focused on a new intelligent method based on an agglomerative hierarchical clustering approach. The solar irradiation and insolation parameters of Central Anatolian Region of Turkey are evaluated utilizing the intelligent feasibility analysis tool developed in this study. The clustering operation in the tool is performed by using the nearest neighbor algorithm. At the stage of determining the optimum hierarchical clustering results, Euclidean, Manhattan and Minkowski distance metrics are adapted to the tool. The achieved clustering results based on Minkowski distance metric provide the most feasible inferences to knowledge domain expert according to other distance metrics.