SCARABEUS: Supercritical carbon dioxide/alternative fluid blends for efficiency upgrade of solar power plants

This paper provides an assessment of the expected Levelised Cost of Electricity enabled by Concentrated Solar Power plants based on Supercritical Carbon Dioxide (sCO 2 ) technology. A global approach is presented, relying on previous results by the authors in order to ascertain whether these innovative power cycles have the potential to achieve the very low costs of electricity reported in the literature. From a previous thermodynamic analysis of sCO 2 cycles, three layouts are shortlisted and their installation costs are compared prior to assessing the corresponding cost of electricity. Amongst them, the Transcritical layout is then discarded due to the virtually impossible implementation in locations with high ambient temperature. The remaining layouts, Allam and Partial Cooling are then modelled and their Levelised Cost of Electricity is calculated for a number of cases and two different locations in North America. Each case is characterised by a different dispatch control scheme and set of financial assumptions. A Concentrated Solar Power plant based on steam turbine technology is also added to the assessment for the sake of comparison. The analysis yields electricity costs varying in the range from 8 to over 11 ¢/kWh, which is near but definitely not below the 6 ¢/kWh target set forth by different administrations. Nevertheless, in spite of the results, a review of the conservative assumptions adopted in the analysis suggests that attaining costs substantially lower than this is very likely. In other words, the results presented in this paper can be taken as an upper limit of the economic performance attainable by Supercritical Carbon Dioxide in Concentrated Solar Power applications.

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Influence of Working Fluid Composition on the Optimum Characteristics of Blended Supercritical Carbon Dioxide Cycles

10.1115/gt2021-60293 ◽

2021 ◽

Author(s):

F. Crespi ◽

G. S. Martínez ◽

P. Rodriguez de Arriba ◽

D. Sánchez ◽

F. Jiménez-Espadafor

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Power Plants ◽

Solar Power ◽

Operating Conditions ◽

Molar Content ◽

Concentrated Solar Power ◽

Solar Power Plants ◽

Concentrated Solar Power Plants ◽

Supercritical Carbon

Abstract The supercritical Carbon Dioxide power cycle technology has attracted growing interest from the scientific community, becoming one of the most important options currently considered for CSP applications. This is thanks to its high thermal efficiency, even at moderate turbine inlet temperatures, and small footprint. Nevertheless, sCO2 power cycles require a fairly low compressor inlet temperature to exploit their full thermodynamic potential. When this cannot be achieved, as it is usually the case for Concentrated Solar Power plants where ambient temperatures are high, the interest of the technology is compromised. To compensate for this effect, the SCARABEUS project is working on the development of certain chemical dopants that could be added to the raw CO2, obtaining new working fluids with the same or even better performance than pure CO2 even at higher minimum cycle temperatures. This paper studies the impact of using CO2 mixtures blended with Hexaflurorobenzene (C6F6) and Titanium Tetrachloride (TiCl4). It is found that these mixtures enable thermal efficiencies that are higher than if pure CO2 were used. The efficiency gain can be as high as 3 percentage points, depending on the dopant used and the operating conditions considered. In addition to this absolute performance gain, the paper reveals that there are additional degrees of freedom that enable more effective cycle optimisation. These are the dopant molar content, not only its composition, and the cycle layout used. When this is studied, it is found that the optimum molar content ranges from 10 to 20% and that the layouts of interest when using mixtures are simpler than if plain CO2 were used. These results open the way for a significant performance enhancement of Concentrated Solar Power plants.

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Preliminary design and assessment of concentrated solar power plant using supercritical carbon dioxide Brayton cycles

Energy Conversion and Management ◽

10.1016/j.enconman.2021.115066 ◽

2021 ◽

pp. 115066

Author(s):

Saboora Khatoon ◽

Man-Hoe Kim

Keyword(s):

Carbon Dioxide ◽

Power Plant ◽

Supercritical Carbon Dioxide ◽

Solar Power ◽

Preliminary Design ◽

Solar Power Plant ◽

Concentrated Solar Power ◽

Supercritical Carbon

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A Study of Supercritical Carbon Dioxide Power Cycle for Concentrating Solar Power Applications Using an Isothermal Compressor

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4038476 ◽

2018 ◽

Vol 140 (7) ◽

Cited By ~ 1

Author(s):

Jin Young Heo ◽

Jinsu Kwon ◽

Jeong Ik Lee

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Thermal Efficiency ◽

Solar Power ◽

Working Fluid ◽

Brayton Cycle ◽

Concentrating Solar Power ◽

Power Cycle ◽

Compressor Inlet ◽

Supercritical Carbon

For the concentrating solar power (CSP) applications, the supercritical carbon dioxide (s-CO2) power cycle is beneficial in many aspects, including high cycle efficiencies, reduced component sizing, and potential for the dry cooling option. More research is involved in improving this technology to realize the s-CO2 cycle as a candidate to replace the conventional power conversion systems for CSP applications. In this study, an isothermal compressor, a turbomachine which undergoes the compression process at constant temperature to minimize compression work, is applied to the s-CO2 power cycle layout. To investigate the cycle performance changes of adopting the novel technology, a framework for defining the efficiency of the isothermal compressor is revised and suggested. This study demonstrates how the compression work for the isothermal compressor is reduced, up to 50%, compared to that of the conventional compressor under varying compressor inlet conditions. Furthermore, the simple recuperated and recompression Brayton cycle layouts using s-CO2 as a working fluid are evaluated for the CSP applications. Results show that for compressor inlet temperatures (CIT) near the critical point, the recompression Brayton cycle using an isothermal compressor has 0.2–1.0% point higher cycle thermal efficiency compared to its reference cycle. For higher CIT values, the recompression cycle using an isothermal compressor can perform above 50% in thermal efficiency for a wider range of CIT than the reference cycle. Adopting an isothermal compressor in the s-CO2 layout can imply larger heat exchange area for the compressor which requires further development.

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Analysis of Advanced Supercritical Carbon Dioxide Power Cycles With a Bottoming Cycle for Concentrating Solar Power Applications

Journal of Solar Energy Engineering ◽

10.1115/1.4025700 ◽

2013 ◽

Vol 136 (1) ◽

Cited By ~ 62

Author(s):

Saeb M. Besarati ◽

D. Yogi Goswami

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Solar Power ◽

Waste Heat ◽

Operating Conditions ◽

Working Fluid ◽

Brayton Cycle ◽

Concentrating Solar Power ◽

Working Fluids ◽

Supercritical Carbon

A number of studies have been performed to assess the potential of using supercritical carbon dioxide (S-CO2) in closed-loop Brayton cycles for power generation. Different configurations have been examined among which recompression and partial cooling configurations have been found very promising, especially for concentrating solar power (CSP) applications. It has been demonstrated that the S-CO2 Brayton cycle using these configurations is capable of achieving more than 50% efficiency at operating conditions that could be achieved in central receiver tower type CSP systems. Although this efficiency is high, it might be further improved by considering an appropriate bottoming cycle utilizing waste heat from the top S-CO2 Brayton cycle. The organic Rankine cycle (ORC) is one alternative proposed for this purpose; however, its performance is substantially affected by the selection of the working fluid. In this paper, a simple S-CO2 Brayton cycle, a recompression S-CO2 Brayton cycle, and a partial cooling S-CO2 Brayton cycle are first simulated and compared with the available data in the literature. Then, an ORC is added to each configuration for utilizing the waste heat. Different working fluids are examined for the bottoming cycles and the operating conditions are optimized. The combined cycle efficiencies and turbine expansion ratios are compared to find the appropriate working fluids for each configuration. It is also shown that combined recompression-ORC cycle achieves higher efficiency compared with other configurations.

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Supercritical Carbon Dioxide Cycles for Concentrated Solar Power Plants: A Possible Alternative for Solar Desalination

Processes ◽

10.3390/pr10010072 ◽

2021 ◽

Vol 10 (1) ◽

pp. 72

Author(s):

Rafael González-Almenara ◽

Pablo Rodríguez de Arriba ◽

Francesco Crespi ◽

David Sánchez ◽

Antonio Muñoz ◽

...

Keyword(s):

Carbon Dioxide ◽

Energy Consumption ◽

Supercritical Carbon Dioxide ◽

Reverse Osmosis ◽

Solar Power ◽

Specific Energy Consumption ◽

Feed Water ◽

Concentrated Solar Power ◽

Solar Desalination ◽

Supercritical Carbon

This manuscript investigates the supercritical carbon dioxide (sCO2) power cycle employed in the power block of concentrated solar power (CSP) plants—solar tower—as an alternative for solar desalination, developed with either distillation or reverse osmosis. This concept is investigated as a possible up-scaling of the SOLMIDEFF project, originally based on a hot-air micro gas turbine combined with a solar dish collector. For the upscaled concept, five different sCO2 cycles are considered, chosen amongst the best-performing configurations proposed in the literature for CSP applications, and modelled with Thermoflex software. The influence of ambient conditions is studied, considering two minimum cycle temperatures (35 °C and 50 °C), corresponding to Santa Cruz de Tenerife and Abu Dhabi, respectively. The results show that the low temperatures at the inlet of the heat rejection unit compromise the viability of distillation technologies. On the other hand, the high thermal efficiency achieved by these cycles, especially with the recompression and partial cooling layouts, reduces the specific energy consumption when combined with reverse osmosis (RO), below that of photovoltaic (PV)+RO. Feed-water preheating is explored as a solution to further reduce energy consumption, concluding that its actual interest is not clear and strongly depends on the location considered and the corresponding water quality standards.

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Performance Analysis of Solar Tower Power Plants Driven Supercritical Carbon Dioxide Recompression Cycles for Six Different Locations in Saudi Arabia

Proceedings of the ISES Solar World Congress 2015 ◽

10.18086/swc.2015.04.16 ◽

2016 ◽

Author(s):

F. Al-Sulaiman ◽

Maimoon Atif ◽

Hafiz Abd-ur-rahman

Keyword(s):

Carbon Dioxide ◽

Saudi Arabia ◽

Performance Analysis ◽

Supercritical Carbon Dioxide ◽

Power Plants ◽

Supercritical Carbon

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Effect of Multicomponent Mixtures on Cycles With Supercritical Carbon Dioxide

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2017-64044 ◽

2017 ◽

Cited By ~ 1

Author(s):

Ladislav Vesely ◽

Vaclav Dostal

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Binary Mixtures ◽

Power Plants ◽

Waste Heat ◽

The Other ◽

Multicomponent Mixtures ◽

Other Hand ◽

Cycle Efficiency ◽

Supercritical Carbon

With the increasing interest in solar and geothermal power plants as well as waste heat recovery systems from many technologies, the whole world is more focused on gas power cycles. Especially, the supercritical carbon dioxide (S-CO2) cycles are very interesting for these applications. This is due to many advantages of the S-CO2 cycles over the other cycles such as a steam-water cycle or helium cycle. On the other hand, S-CO2 cycles have also disadvantages. One of the disadvantages is presence of impurities in the cycles. The big question is the effect of these impurities in the CO2, which can occur as impurities or can be suitably added to the pure CO2. From the previous research, it is obvious that binary mixtures affect the cycle as they influence cycle component design and thus the overall efficiency of the power cycle. The biggest effect of mixtures is on the heat exchangers and compressor, which operate close to the critical point. The positive effect of the binary mixtures is observed in the recuperative heat exchanger. On the other hand, negative effects occurs in the cooler. Therefore, the Czech Technical University in Prague (CTU) conducted research on supercritical carbon dioxide cycles, which is focused on the effect of the gaseous admixtures in S-CO2 on the different cycle components. The main goal of this paper is to describe the effect of gaseous admixtures on the efficiency of the cycles and their effect on each component. The first part of the study is focused on the calculation of the basic cycles for binary mixtures and description of the effect on the compressor and the cycle efficiency. The second part of the study is focused on the calculation of the basic cycles for multicomponent mixtures. In this part, the effect of the mixtures for different compositions and amounts of the individual mixture components will be presented. The calculations are performed for pure CO2 and then for selected multicomponent mixtures. A basic multicomponent mixture includes mixtures from technology of carbon capture and storage. Other multicomponent mixtures are combinations of previously investigated gaseous admixtures such as He, CO, O2, N2, H2, CH4 and H2S. The last part of the study is focused on the optimization of individual basic cycles for different amount of admixtures in CO2. The result of this study defines the optimum composition of multicomponent mixtures and describes their effect on the cycle efficiency for the particular utilization of S-CO2 cycle.

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