Techno-Economic Optimization of Molten Salt Concentrating Solar Power Parabolic Trough Plants With Packed-Bed Thermocline Tanks

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Freerk Klasing ◽  
Tobias Hirsch ◽  
Christian Odenthal ◽  
Thomas Bauer

Abstract This study focuses on the techno-economic optimization of direct molten salt parabolic trough solar thermal power plants (STPPs) equipped with thermocline filler (TCF) thermal energy storage (TES). On one hand, this technology allows for cost reductions compared with state of the art two-tank (2T) TES. On the other hand, however, it leads to a performance decrease of the power block (PB) due to partial part load operation. To evaluate the dominating effect, annual simulations on a system level are performed for the TCF direct molten salt storage concept and, as a reference, for the two-tank direct molten salt storage concept. The levelized cost of electricity (LCOE) serves as a global measure to compare the two systems and to optimally size the TCF storage and the solar field (SF). The result of this study is that LCOE can theoretically be reduced by up to 8% by using a TCF instead of 2T storage system. The influence of temperature deviations from the nominal value at the end of charge or discharge, porosity and particle diameter of the TCF on LCOE, and system behavior is investigated in detail. This study further presents alternative operation strategies with improved system behavior and reveals determining factors for the integration of TCF storage into a system.

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
A. Giostri ◽  
M. Binotti ◽  
P. Silva ◽  
E. Macchi ◽  
G. Manzolini

Parabolic trough (PT) technology can be considered the state of the art for solar thermal power plants thanks to the almost 30 yr of experience gained in SEGS and, recently, Nevada Solar One plants in the United States and Andasol plant in Spain. One of the major issues that limits the wide diffusion of this technology is the high investment cost of the solar field and, particularly, of the solar collector. For this reason, research has focused on developing new solutions that aim to reduce costs. This paper compares, at nominal conditions, commercial Fresnel technology for direct steam generation with conventional parabolic trough technology based on synthetic oil as heat-transfer. The comparison addresses nominal conditions as well as annual average performance. In both technologies, no thermal storage system is considered. Performance is calculated by Thermoflex®, a commercial code, with a dedicated component to evaluate solar plant. Results will show that, at nominal conditions, Fresnel technology has an optical efficiency of 67%, which is lower than the 75% efficiency of the parabolic trough. Calculated net electric efficiency is about 19.25%, whereas PT technology achieves 23.6% efficiency. In off-design conditions, the performance gap between Fresnel and parabolic trough increases because the former is significantly affected by high incident angles of solar radiation. The calculated sun-to-electric annual average efficiency for a Fresnel plant is 10.2%, which is a consequence of the average optical efficiency of 38.8%; a parabolic trough achieves an overall efficiency of 16%, with an optical efficiency of 52.7%. An additional case with a Fresnel collector and synthetic-oil outlines the differences among the cases investigated. Since part of the performance difference between Fresnel and PT technologies is simply due to different definitions, we introduce additional indexes to make a consistent comparison. Finally, a simplified economic assessment shows that Fresnel collectors must reduce investment costs of at least 45% than parabolic trough to achieve the same levelized cost of electricity.


Author(s):  
David Kearney ◽  
Henry Price

Parabolic trough power plant technology is one of the most demonstrated solar power options commercially available. While trough power plants are the least expensive solar option, cost of electricity still exceeds that needed to directly compete with conventional fossil-fired large-scale central power technologies. Several evaluations have been done that identify a series of mechanisms for significant cost reduction over the next decade. One of the opportunities for improving the economics of parabolic trough plants is the development of lower cost and more efficient thermal energy storage (TES) technologies. This paper focuses on several of the TES technologies currently under development, namely: the use of an indirect molten-salt storage system, the use of molten-salt as a heat transfer fluid in the solar field and thermal energy storage system, and the development of new types of storage fluids. The assessment compares the cost and performance of these candidate thermal energy storage technologies by evaluating their impact on the levelized cost of electricity from the plant. This analysis is updated based on work conducted on these technologies during the last year.


Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3973 ◽  
Author(s):  
Llamas ◽  
Bullejos ◽  
Ruiz de Adana

Parabolic-trough solar-thermal power-plant investments are subordinate to radiation availability, thermal-energy storage capacity, and dynamic behavior. Their integration into electricity markets is made by minimizing grid-connection costs, thus improving energy-availability and economic-efficiency levels. In this context, this work analyzes the sizing-investment adequacy of a 100 MWe parabolic-trough solar-thermal power plant regarding solar resources and thermal energy into power-block availability for both regulated and deregulated electricity markets. For this proposal, the design of a mathematical model for the optimal operation of parabolic-trough power plants with thermal storage by two tanks of molten salt is described. Model calibration is made by using a currently operated plant. Solar-resource availability is studied in three different radiation scenarios. The levelized cost of electricity and production profit relating to the investment cost are used to analyze plant sustainability. Thus, the levelized cost of electricity shows the best plant configuration for each radiation scenario within a regulated market. For deregulated markets, the optimal plant configuration tends to enhance the solar multiple and thermal-storage capacity thanks to an increment on selling profit. The gross average annual benefit for electricity generation of deregulated against regulated markets exceeds 21% in all radiation areas under study.


2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Scott M. Flueckiger ◽  
Brian D. Iverson ◽  
Suresh V. Garimella

System-level simulation of a molten-salt thermocline tank is undertaken in response to year-long historical weather data and corresponding plant control. Such a simulation is enabled by combining a finite-volume model of the tank that includes a sufficiently faithful representation at low computation cost with a system-level power tower plant model. Annual plant performance of a 100 MWe molten-salt power tower plant is optimized as a function of the thermocline tank size and the plant solar multiple (SM). The effectiveness of the thermocline tank in storing and supplying hot molten salt to the power plant is found to exceed 99% over a year of operation, independent of tank size. The electrical output of the plant is characterized by its capacity factor (CF) over the year, which increases with solar multiple and thermocline tank size albeit with diminishing returns. The economic performance of the plant is characterized with a levelized cost of electricity (LCOE) metric. A previous study conducted by the authors applied a simplified cost metric for plant performance. The current study applies a more comprehensive financial approach and observes a minimum cost of 12.2 ¢/kWhe with a solar multiple of 3 and a thermocline tank storage capacity of 16 h. While the thermocline tank concept is viable and economically feasible, additional plant improvements beyond those pertaining to storage are necessary to achieve grid parity with fossil fuels.


Author(s):  
Markus Eck ◽  
David Kretschmann ◽  
Jan Fabian Feldhoff ◽  
Michael Wittmann

Technical and economical evaluation of solar thermal power plants constantly gains more importance for industry and research. The reliability of the results highly depends on the assumptions made for the applied parameters. Reducing a power plant system to one single, deterministic number for evaluation, like the levelized cost of electricity (LCOE), might end in misleading results. Probabilistic approaches can help to better evaluate systems [1] and scenarios [2]. While industry looks for safety in investment and profitability, research is predominantly interested in the evaluation of concepts and the identification of promising new approaches. Especially for research, dealing with higher and hardly quantifiable uncertainties, it is desirable to get a detailed view of the system and its main influences. However, to get there, also a good knowledge on the stochastic interrelations and its interpretation is required. Therefore, this paper mainly assesses the influences of basic stochastic assumptions and suggests a methodology to consider suitable stochastic input, especially for parameters of systems still under research. As examples, the comparison between a parabolic trough plant with synthetic oil and direct steam generation is used.


Author(s):  
A. Giostri ◽  
M. Binotti ◽  
P. Silva ◽  
E. Macchi ◽  
G. Manzolini

Parabolic trough can be considered the state of the art for solar thermal power plants thanks to the almost 30 years experience gained in SEGS and, recently, Nevada Solar One plants in US and Andasol plants in Spain. One of the major issues that limits the wide diffusion of this technology is the high investment cost of the solar field and, particularly, of the solar collector. For this reason, since several years research activity has been trying to develop new solutions with the aim of cost reduction. This work compares commercial Fresnel technology with conventional parabolic trough plant based on synthetic oil as heat transfer fluid at nominal conditions and evaluates yearly average performances. In both technologies, no thermal storage system is considered. In addition, for Fresnel, a Direct Steam Generation (DSG) case is investigated. Performances are calculated by a commercial code, Thermoflex®, with dedicated component to evaluate solar plant. Results will show that, at nominal conditions, Fresnel technology have an optical efficiency of 67% which is lower than 75% of parabolic trough. Calculated net electric efficiency is about 19.25%, while parabolic trough technology achieves 23.6%. In off-design conditions, the gap between Fresnel and parabolic trough increases because the former is significantly affected by high radiation incident angles. The calculated sun-to-electric annual average efficiency for Fresnel plant is 10.2%, consequence of the average optical efficiency of 38.8%, while parabolic trough achieve an overall efficiency of 16%, with an optical one of 52.7%. An additional case with Fresnel collector and synthetic oil outlines differences among investigated cases. Finally, because part of performance difference between PT and Fresnel is simple due to different definitions, additional indexes are introduced in order to make a consistent comparison.


2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Doerte Laing ◽  
Wolf-Dieter Steinmann ◽  
Michael Fiß ◽  
Rainer Tamme ◽  
Thomas Brand ◽  
...  

Cost-effective integrated storage systems are important components for the accelerated market penetration of solarthermal power plants. Besides extended utilization of the power block, the main benefits of storage systems are improved efficiency of components, and facilitated integration into the electrical grids. For parabolic trough power plants using synthetic oil as the heat transfer medium, the application of solid media sensible heat storage is an attractive option in terms of investment and maintenance costs. For commercial oil trough technology, a solid media sensible heat storage system was developed and tested. One focus of the project was the cost reduction of the heat exchanger; the second focus lies in the energetic and exergetic analysis of modular storage operation concepts, including a cost assessment of these concepts. The results show that technically there are various interesting ways to improve storage performance. However, these efforts do not improve the economical aspect. Therefore, the tube register with straight parallel tubes without additional structures to enhance heat transfer has been identified as the best option concerning manufacturing aspects and investment costs. The results of the energetic and exergetic analysis of modular storage integration and operation concepts show a significant potential for economic optimization. An increase of more than 100% in storage capacity or a reduction of more than a factor of 2 in storage size and therefore investment cost for the storage system was calculated. A complete economical analysis, including the additional costs for this concept on the solar field piping and control, still has to be performed.


2017 ◽  
Vol 2 (2) ◽  
pp. 18
Author(s):  
Taqiy Eddine Boukelia

Most of Concentrating Solar Power (CSP) plants are usually installed in desert regions where water resource availability is a critical limitation due to the lack of water required for the exploitation of these systems in these regions. Therefore, the aim of this study is to investigate the techno-economic competitiveness of deploying both modes of cooling (wet and dry) in two different parabolic trough solar thermal power plants integrated with thermal energy storage and fuel backup system; the first one is using thermic oil, while the other is working using molten salt. The obtained results show that the dry cooling mode can decrease the yields of the two power plants down to 8.7 % and 9.3 % for oil and salt configurations respectively. On the other hand, the levelized cost of electricity can increase by using this cooling option up to 9.3 % for oil plant, and 10.0 % for salt one. However, the main advantage of using dry cooling option is reducing water consumption which has been decreased by more than 94 % for both plants. The application of our methodology to other two sites worldwide, confirms the viability of the obtained results. The importance of this results is to show the effect of working fluids on the cooling system of solar power plants.


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