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  • 1. Benmakhlouf, Y.
    et al.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Wallmander, J.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A methodology to assess the market potential and identify most promising business cases for small scale CSP plants with thermal energy storage2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2126, article id 130001Conference paper (Refereed)
    Abstract [en]

    This study presents a methodology to quantify the market potential for a novel distributed CSP technology with thermal energy technology. The system in question relies on the Stirling engine for power production, which is fed by heat collected from a heliostat field and stored in an integrated latent heat storage unit. Selected countries in the MENA region are investigated to identify best prospective business cases for such a technology. With a global market potential above 40 GW in the whole MENA, industrial sectors such as mining and cement hold the best prospects in terms of market share. The achievable costs of generation vary depending on the DNI of the sites considered but prove to be lower compared with conventional distributed generation (diesel gensets or PV-BEES). However, several countries in the MENA, although having high DNI resource, still offer low electricity utility prices to industrial customers for distributed CSP to become competitive with on-grid electricity procurement. A scenario analysis coupled with a multi criteria selection of the optimal business case quantifies the amount of subsidies necessary to reach competitiveness.

  • 2. Christoph, Richter
    et al.
    Ferruzza, Davide
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dinter, Frank
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Haglind, Fredrik
    Identification of optimum molten salts for use as heat transfer fluids in parabolic trough CSP plants. A techno-economic comparative optimization2017In: AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616Article in journal (Refereed)
    Abstract [en]

    Parabolic trough power plants using thermal oil as heat transfer fluid are the most mature concentrating solar power technology and state of the art. To further increase their efficiency and lower costs, molten salts can be used as heat transfer fluid. This results in higher operating temperature differences for improved cycle efficiencies and enables direct thermal energy storage at lower costs due to omission of the oil-to-salt heat exchanger and the need for smaller storage sizes. As a variety of salts are available to choose from, this study uses a multi-objective optimization to identify the most suitable heat transfer fluid for three locations in South Africa, Spain and Chile. The lowest values for the levelized costs of electricity (LCOE) can be found in Chile using Solar Salt as heat transfer fluid (75.0 $/MWhe). Generally, Solar Salt offers the lowest LCOE values followed by thermal oil and Hitec. The results also suggest that the choice of the heat transfer fluid is dependent on the direct normal irradiance (DNI) at each location. Thermal oil is competitive with Solar Salt in small systems at locations with low DNI values, whereas Hitec can be cheaper than thermal oil in large systems at locations with high DNI. Furthermore, it is also investigated at which freeze alert temperature set point the activation of the freeze protection system is optimal. The results indicate that this temperature should be chosen close to the solar field inlet temperature for small systems, while it can be lowered significantly for large systems to reduce electricity consumption from the freeze protection system.

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  • 3.
    Gan, Philipe Gunawan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Deutsches Zentrum für Luft- und Raumfahrt (DLR), Linder Höhe, Cologne, 51147, Germany.
    Monnerie, N.
    Brendelberger, S.
    Roeb, M.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sattler, C.
    Modeling, simulation and economic analysis of CSP-driven solar fuel plant for diesel and gasoline production2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, article id 180009Conference paper (Refereed)
    Abstract [en]

    The present research focuses on modeling of solar thermal driven fuel production plant with CO2 and H2O as raw materials to produce synthetic gas (syngas) which is converted into hydrocarbons through Fischer-Tropsch process either with Fe and Co catalyst to produce diesel, gasoline and kerosene. The solar reactor uses cerium oxide (CeO2) as a metal-redox and operates at 1773 K and 1300 K for reduction and oxidation step respectively under non-stoichiometric condition. The plant is analyzed by performing a quasi-steady state simulation under boundary condition that the Fischer-Tropsch reactor should operate with the capacity factor of 0.95 or 8350 hours annually. A storage tank is used to store and regulate the flow of syngas going into the Fischer-Tropsch reactor. Sensitivity analysis is carried out, particularly on solar reactor conversion and solid-to-solid heat exchanger efficiency. Another sensitivity analysis is to combine PV and CSP as the external electricity source. The production cost is finally calculated using annuity method with constant discount rate.

  • 4.
    García, José
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Smet, Vincent
    KTH, School of Industrial Engineering and Management (ITM).
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Alessandro, Sorce
    Univ Genoa.
    Techno-Economic Optimization of a Combined Cycle Combined Heat and Power Plant With Integrated Heat Pump and Low-Temperature Thermal Energy Storage2020In: Proceedings of the ASME Turbo Expo: Turbomachinery Technical Conference and Exposition, September 21-25, 2020, ASME Press, 2020, Vol. 5Conference paper (Refereed)
    Abstract [en]

    The present study presents a techno-economic analysis of a novel power plant layout developed to increase the dispatch flexibility of a Combined Cycle Gas Turbine (CCGT) coupled to a District Heating Network (DHN). The layout includes the incorporation of high temperature heat pumps (HP) and thermal energy storage (TES). A model for optimizing the short-term dispatch strategy of such system has been developed to maximize its operational profit. The constraints and boundary conditions considered in the study include hourly demand and price of electricity and heat, ambient conditions and CO2 emission allowances. To assess the techno-economic benefit of the new layout, a year of operation was simulated for a power plant in Turin, Italy. Furthermore, different layout configurations and critical size-related parameters were considered. Finally, a sensitivity analysis was made to assess the performance under different market scenarios.

    The results show that it is indeed beneficial, under the assumed market conditions, to integrate a HP in a CCGT plant coupled to a DHN, and that it remains profitable to do so under a variety of market scenarios. The best results for the assumed market conditions were found when integrating a 15 MWth capacity HP in the 400 MWel CCGT-CHP. For this case study, the investment in the HP would yield a net present value (NPV) of 1.22 M€ and an internal rate of return (IRR) of 3.04% for a lifetime of 20 years. An increase was shown also in operational flexibility with 0.14% of the electricity production shifted while meeting the same heating demand. Additionally, it was found that the TES makes the system even more flexible, but does not make up for the extra investment.

  • 5. Gini, L.
    et al.
    Maccarini, S.
    Traverso, A.
    Pesatori, E.
    Milani, A.
    Bisio, V.
    Valente, R.
    Barberis, S.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Part-Load Behaviour And Control Philosophy Of A Recuperated Supercritical Co2Cycle2022In: Proceedings of the ASME Turbo Expo, American Society of Mechanical Engineers (ASME) , 2022Conference paper (Refereed)
    Abstract [en]

    High efficiency, flexibility and competitive capital costs make supercritical CO2 (sCO2) systems a promising technology for renewable power generation in a low carbon energy scenario. Recently, innovative supercritical systems have been studied in the literature and proposed by DOE-NETL (STEP project) and a few projects in the EU Horizon 2020 program aiming to demonstrate supercritical CO2 Brayton power plants, promising superior techno-economic features than steam cycles particularly at high temperatures. The H2020 SOLARSCO2OL project1, which started in 2020, is building the first European MW-scale sCO2 demonstration plant and has been specifically tailored for Concentrating Solar Power (CSP) applications. This paper presents the first offdesign analysis of such a demonstrator, which is based on a simply recuperated sCO2 cycle. The part-load analysis ranged from 50% of nominal up to a 105% peak load, discussing the impact on compressor and turbine operating conditions. The whole system dynamic model has been developed in TRANSEO MATLAB® environment. Full operational envelop has been determined considering cycle main constraints, such as maximum turbine inlet temperature and minimum pressure at compressor inlet. The off-design performance analysis highlights the most relevant relationships among the main part-load regulating parameters, namely mass flow rate, total mass in the loop, and available heat source. The results show specific features of different control approaches, discussing the pros and cons of each solution, considering also its upscale towards commercial applications. In particular, the analysis shows that at 51% of load an efficiency decrease of 20% is expected. 

  • 6.
    Gini, Lorenzo
    et al.
    Univ Genoa, Thermochem Power Grp, Genoa, Italy..
    Maccarini, Simone
    Univ Genoa, Thermochem Power Grp, Genoa, Italy..
    Traverso, Alberto
    Univ Genoa, Thermochem Power Grp, Genoa, Italy..
    Barberis, Stefano
    Univ Genoa, Thermochem Power Grp, Genoa, Italy..
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pesatori, Emanuel
    Franco Tosi Meccan, Legnano, Italy..
    Bisio, Valentina
    Nuovo Pignone Baker Hughes, Florence, Italy..
    A prototype recuperated supercritical CO2 cycle: Part-load and dynamic assessment2023In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 225, p. 120152-, article id 120152Article in journal (Refereed)
    Abstract [en]

    High efficiency, flexibility and competitive capital costs make supercritical CO2 (sCO2) systems a promising technology for renewable power generation in a low carbon energy scenario. Recently, innovative supercritical systems have been studied in the literature and proposed by DOE-NETL (STEP project) and by a few projects in the EU Horizon 2020 (H2020) program aiming to demonstrate supercritical CO2 Brayton power plants, promising superior techno-economic features than steam cycles particularly at high temperatures. The H2020 SOLARSCO2OL project, which started in 2020, is building the first European MW-scale sCO2 demonstration plant and has been specifically tailored for Concentrating Solar Power (CSP) applications. After a detailed explanation of the modelling approach for steady and unsteady cycle simulations, this paper presents the off-design and dynamic analysis of such plant layout, which is based on a simply recuperated sCO2 cycle. The entire system model has been developed in TRANSEO environment. The part-load analysis ranged from 50% of nominal up to a 105% peak load, discussing the impact on compressor and turbine operating conditions. Full operational envelop has been determined considering cycle main constraints, such as maximum turbine inlet temperature and minimum pressure at compressor inlet. The off-design performance analysis highlights the most relevant relationships among the main part-load regulating parameters, namely molten salt mass flow rate, CO2 mass flow rate, total CO2 mass in the loop, and shaft line speed. The results show specific features of different control approaches, discussing the pros and cons of each solution, considering also its upscale towards commercial applications. In particular, the analysis shows that at 51% of load an efficiency decrease of 20% is expected. Finally, the dynamic characterization of the closed loop shows the relatively fast responsiveness of the plant to compressor speed variations, causing quick changes in CO2 mass flow rate, together with longer time scale phenomena related to the plant heat exchangers. In this respect, sCO2 plants demonstrate to have the potential to provide primary reserve for the electrical grid, as far as thermal stresses on main plant components are kept under acceptable limits.

  • 7.
    Guccione, Salvatore
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fontalvo, Armando
    Australian Natl Univ, Sch Engn, Canberra, ACT 2600, Australia..
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Pye, John
    Australian Natl Univ, Sch Engn, Canberra, ACT 2600, Australia..
    Savoldi, Laura
    Politecn Torino, Dept Energia Galileo Ferraris, I-10129 Turin, Italy..
    Zanino, Roberto
    Politecn Torino, Dept Energia Galileo Ferraris, I-10129 Turin, Italy..
    Techno-economic optimisation of a sodium-chloride salt heat exchanger for concentrating solar power applications2022In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 239, p. 252-267Article in journal (Refereed)
    Abstract [en]

    To enhance the economic viability of Concentrating solar power (CSP) plant, recent efforts have been directed towards employing high-temperature working fluid in the receiver and incorporating higher-efficiency power cycles. This work presents a techno-economic analysis of a sodium-chloride salt heat exchanger included in a sodium-driven CSP system with a supercritical CO2 power block. A quasi-steady state heat exchanger model was developed based on the TEMA guidelines, with the possibility of being customised in terms of media adopted, constraints, boundary conditions, and heat transfer correlations. The sodium-salt heat exchanger has been designed aiming at minimising the Levelized Cost of Electricity (LCOE) of the plant. The performance and the design of the proposed heat exchanger have been evaluated via multi-objective optimisation and sensitivity analyses. Results show that advanced CSP systems employing sodium and an indirect chloride salt storage can represent an economically viable solution and can drive towards the future goal of 5 USD/MWh. For a base-case 100 MWe plant with 12 h of storage, a LCOE of 72.7 USD/MWh and a capacity factor (CF) higher than 60% were reached. The techno-economic investigations showed the potential LCOE reduction of 6% as well as the flexibility and robustness of the heat exchanger model. The developed tool lays the groundwork to explore potential improvements of this new generation of CSP systems.

  • 8.
    Guccione, Salvatore
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic optimization of molten salt based CSP plants through integration of supercritical CO2 cycles and hybridization with PV and electric heaters2023In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 283, article id 128528Article in journal (Refereed)
    Abstract [en]

    The present study explores the integration of supercritical CO2 (sCO2) power cycles into Concentrating Solar Power (CSP) plants using molten salt, and the hybridization of these plants with solar photovoltaic (PV) systems through electric heaters. Techno-economic evaluations determined the optimal power cycle configuration and subsystem designs for two different scales and locations and then compared them with state-of-the-art solar power plants. The results show that hybridizing PV with state-of-the-art CSP can lead up to a 22% reduction in the Levelized Cost of Electricity (LCOE) compared to standalone CSP systems. This hybridization and the use of electric heaters are particularly beneficial for small-scale installations and locations with low DNI/GHI ratios. By replacing the steam Rankine cycle with a sCO2 power block, a further 42% reduction in LCOE can be achieved at small scales, even with a simple recuperated cycle. In conclusion, the hybridization with PV and the integration of sCO2 power blocks provide cost benefits despite the temperature limitations imposed by the molten salt. Hybrid PV-CSP plants with sCO2 power blocks prove to be a cost-effective solution for capacity factors exceeding 60%. For lower capacity factors, configurations combining PV with battery energy storage or PV with electric heaters, thermal energy storage, and sCO2 power blocks are preferable options.

  • 9.
    Guccione, Salvatore
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Trevisan, Silvia
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Optimum Coupling of Thermal Energy Storage and Power Cycles2023In: Proceedings of ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition, GT 2023, American Society of Mechanical Engineers (ASME) , 2023, article id v006t09a010Conference paper (Refereed)
    Abstract [en]

    The present work proposes a methodology that enables decision-making in selecting the adequate power cycle and Thermal Energy Storage (TES) type for a wide range of operating temperatures between 380 and 1200 °C. A broad spectrum of power block configurations has been explored including steam Rankine, gas turbine, supercritical CO2, (sCO2) combined gas turbine with Rankine, and combined gas turbine with sCO2. The study also evaluated molten salt, particle, and air packed bed TES to identify the most cost-effective power cycle and TES combination. A techno-economic optimization has been conducted aimed at minimizing the Levelized Cost of Storage (LCOS) for different plant capacities and charging costs. Results show that coupling of a sCO2 power block with recompression and intercooling with a particle TES is the most cost-effective solution for a 100 MWe plant with 12 hours of storage and a charging cost of 50 EUR/MWh. This achieved an LCOS value of 154.7 EUR/MWh at 750 °C with a 200 °C temperature difference. Particle-based energy storage is the most cost-effective option for a wide range of temperature combinations, while an intercooled sCO2 power block with an air-packed bed TES should be preferred when electricity is free, and storage represents a significant portion of the capital cost. Molten salt TES is the optimal choice provided that the design temperatures align with the limitations of the salts.

  • 10.
    Guccione, Salvatore
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Trevisan, Silvia
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermodynamic Analysis of a Hybrid PV-Particle Based sCO2 Concentrating Solar Power Plant2023In: AIP Conference Proceedings, AIP Publishing , 2023, article id 030007Conference paper (Refereed)
    Abstract [en]

    The present work performs a thermodynamic analysis of a hybrid CSP – PV plant characterized by a particle tower CSP running a supercritical CO2 power unit and a PV field. The two plants are hybridized by employing a particle electrical heater that allows to store the electricity produced in excess by the PV field as thermal energy in the CSP storage. The PV production is compensated by the CSP plant to achieve the maximum power that can be injected into the grid (25 MW). The main key performance indicators considered in this analysis are the capacity factor, the share of energy wasted, the annual energy yield, the electric heater utilization factor, and the share of TES charged by the electric heater. The influence of the plant solar multiple, storage size, PV nominal size, electric heater efficiency, and electric heater capacity has been assessed through different sensitivity analyses. The results show that it is worth hybridizing the system, indeed the solar power plant operates during summer continuously day and night, exploiting the advantages of the two technologies, while limiting their drawbacks. Plant configurations leading to a capacity factor higher than 81% with a share of energy wasted limited to 5% can be identified. The electric heater capacity and efficiency are shown to be highly important parameters, highlighting the need for further component development.

  • 11.
    Guccione, Salvatore
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Trevisan, Silvia
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    MacCarini, S.
    Traverso, A.
    Techno-Economic Optimization of a Hybrid PV-CSP Plant With Molten Salt Thermal Energy Storage and Supercritical CO2 Brayton Power Cycle2022In: Proceedings of the ASME Turbo Expo, ASME International , 2022Conference paper (Refereed)
    Abstract [en]

    High-efficient supercritical CO2 (sCO2) power blocks and the hybridization with solar photovoltaic (PV) plants have been identified as two viable solutions to enhance the economic competitiveness of Concentrating Solar Power (CSP) plants. This work introduces an innovative hybrid PV-CSP system layout with molten salt thermal energy storage and a sCO2 power block. An active hybridization has been proposed employing a molten salt electric heater that allows storing the excess PV production as thermal energy. The scalability of the plant has been investigated using size-dependent cost functions and introducing a novel methodology for scaling the sCO2 turbomachinery efficiencies. The conducted techno-economic optimizations show that the proposed hybrid PV-CSP plants can be cost-competitive. For a European solar resource location - 1900 kWh/(m2yr) - Levelized Cost of Electricity (LCOE) values lower than 66 EUR/MWh and capacity factors higher than 70 % can be achieved at 100 MWe. For a high-irradiance location - 3400 kWh/(m2yr) - a capacity factor of 85 % and a LCOE of 46 EUR/MWh have been found for the same scale. The selection of the sCO2 power cycle has a marginal impact on these results so that a simple recuperated cycle can yield similar LCOEs as the recompressed, reheated, and intercooled layouts. For smaller scales, systems with large gaps between the PV and CSP capacities are preferred, laying the optimal conditions for the electric heater integration with utilization factors up to 21 %. 

  • 12.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Arnaudo, Monica
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zanino, R.
    Hassar, Z.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic Performance Evaluation of Direct Steam Generation Solar Tower Plants with Thermal Energy Storage Systems Based on High-temperature Concrete and Encapsulated Phase Change Materials2016In: SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, 2016, article id UNSP 070011Conference paper (Refereed)
    Abstract [en]

    Nowadays, direct steam generation concentrated solar tower plants suffer from the absence of a cost-effective thermal energy storage integration. In this study, the prefeasibility of a combined sensible and latent thermal energy storage configuration has been performed from thermodynamic and economic standpoints as a potential storage option. The main advantage of such concept with respect to only sensible or only latent choices is related to the possibility to minimize the thermal losses during system charge and discharge processes by reducing the temperature and pressure drops occurring all along the heat transfer process. Thermodynamic models, heat transfer models, plant integration and control strategies for both a pressurized tank filled with sphere-encapsulated salts and high temperature concrete storage blocks were developed within KTH in-house tool DYESOPT for power plant performance modeling. Once implemented, cross-validated and integrated the new storage model in an existing DYESOPT power plant layout, a sensitivity analysis with regards of storage, solar field and power block sizes was performed to determine the potential impact of integrating the proposed concept. Even for a storage cost figure of 50 USD/kWh, it was found that the integration of the proposed storage configuration can enhance the performance of the power plants by augmenting its availability and reducing its levelized cost of electricity. As expected, it was also found that the benefits are greater for the cases of smaller power block sizes. Specifically, for a power block of 80 MWe a reduction in levelized electricity costs of 8% was estimated together with an increase in capacity factor by 30%, whereas for a power block of 126 MWe the benefits found were a 1.5% cost reduction and 16% availability increase.

  • 13.
    Guedez, Rafael Eduardo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, J.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Enhancing the profitability of solar tower power plants through thermoeconomic analysis based on multi-objective optimization2015In: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 2014, 2015, Vol. 69, p. 1277-1286Conference paper (Refereed)
    Abstract [en]

    Solar tower power plants with integrated thermal energy storage units represent one of the most promising technologies for enhancing the economic viability of concentrating solar power in the short term. Tower systems allow higher concentration ratios to be achieved, which in turn means higher fluid operating temperatures and thus higher power cycle efficiencies. Moreover, the integration of storage allows power production to be shifted from times where there is low demand to periods where electricity prices are higher, potentially enhancing the profitability of the plant despite representing an additional upfront cost. The variable nature of the solar resource and the myriad potential roles that storage can assume, together with the complexity of enhancing the synergies between the three blocks: the solar field, the storage block and power block, make the design of these power plants a challenging process. This paper introduces a comprehensive methodology for designing solar tower power plants based on a thermoeconomic approach that allows the true optimum trade-off curves between cost, profitability and investment to be identified while simultaneously considering several operating strategies as well as varying critical design parameters in each of the aforementioned blocks. The methodology is presented by means of analyzing the design of a power plant for the region of Seville. For this location, results show that similar profits, measured in terms of the internal rate of return, can be achieved from different power plant configurations in terms of sizing and operating strategy, each associated to different investments. In particular, optimum configurations found corresponded to larger power blocks with medium-to-large solar field and storage blocks that allow the plants to operate continuously throughout the day and be shut down during midnight. Moreover, it is shown that for a fixed power block size it can also be economically interesting to consider smaller storage units and adopt instead a peaking strategy, as this can still be profitable whilst representing a lower investment, thus lower risk.

  • 14.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ferruzza, Davide
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Arnaudo, Monica
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Rodriguez, Ivette
    Perez-Segarra, Carlos D.
    Hassar, Zhor
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic Performance Evaluation of Solar Tower Plants with Integrated Multi-layered PCM Thermocline Thermal Energy Storage - A Comparative Study to Conventional Two-tank Storage Systems2016In: SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, American Institute of Physics (AIP), 2016, article id UNSP 070012Conference paper (Refereed)
    Abstract [en]

    Solar Tower Power Plants with thermal energy storage are a promising technology for dispatchable renewable energy in the near future. Storage integration makes possible to shift the electricity production to more profitable peak hours. Usually two tanks are used to store cold and hot fluids, but this means both higher investment costs and difficulties during the operation of the variable volume tanks. Instead, another solution can be a single tank thermocline storage in a multi-layered configuration. In such tank both latent and sensible fillers are employed to decrease the related cost up to 30% and maintain high efficiencies. This paper analyses a multi-layered solid PCM storage tank concept for solar tower applications, and describes a comprehensive methodology to determine under which market structures such devices can outperform the more conventional two tank storage systems. A detail model of the tank has been developed and introduced in an existing techno-economic tool developed by the authors (DYESOPT). The results show that under current cost estimates and technical limitations the multi-layered solid PCM storage concept is a better solution when peaking operating strategies are desired, as it is the case for the two-tier South African tariff scheme.

  • 15.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    García, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nuutinen, Antti
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Graziano, Giovanni
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Chiu, Justin NingWei
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Sorce, Alessandro
    Univ Genoa, Mech Engn, I-16145 Genoa, Italy..
    Piantelli, Luca
    IREN SpA, Innovat Dept, I-10143 Turin, Italy..
    Traverso, Alberto
    Univ Genoa, Mech Engn, I-16145 Genoa, Italy..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Techno-economic comparative analysis of innovative combined cycle power plant layouts integrated with heat pumps and thermal energy storage2019In: Proceedings of the ASME Turbo Expo: Turbomachinery Technical Conference and Exposition, 2019, Vol 3, ASME Press, 2019, Vol. 3Conference paper (Refereed)
    Abstract [en]

    In the pursuit of increasing their profitability, the design and operation of combined cycle power plants needs to be optimized for new liberalized markets with large penetration of renewables. A clear consequence of such renewable integration is the need for these plants for being more flexible in terms of ramping-up periods and higher part-load efficiencies. Flexibility becomes an even clearer need for combined heat and power plants to be more competitive, particularly when simultaneously following the market hourly price dynamics and varying demands for both the heat and the electricity markets. In this paper, three new plant layouts have been investigated by integrating different storage concepts and heat-pump units in key sections of a traditional plant layout. The study analyses the influence that market has on determining the optimum layouts for maximizing profits in energy-only markets (in terms of plant configuration, sizing and operation strategies). The study is performed for a given location nearby Turin, Italy, for which hourly electricity and heat prices, as well as meteorological data, have been gathered. A multi parameter modeling approach was followed using KTH's in house teclmo-economic modeling tool, which uses time dependent market data, e.g. price and weather, to determine the trade-off curves between minimizing investment and maximizing profits when varying critical size-related power plant parameters e.g. installed power capacities and storage size, for pre-defined layouts and operating strategies. A comparative analysis between the best configurations found for each of the proposed layouts and the reference plant is presented in the discussion section of the results. For the specific case study set in northern Italy, it is shown that the integration of a pre-cooling loop into baseload-like power-oriented combined cycle plants is not justified, calling for investigating new markets and different operating strategies. Only the integration of a heat pump alone was shown to improve the profitability, but within the margin of error of the study. Alternatively, a layout where district heating supply water is preheated with a combination of a heat pump with hot thermal tank was able to increase the internal rate of return of the plant by up to 0.5%, absolute, yet within the error margin and thus not justifying the added complexity in operation and in investment costs. All in all, the analysis shows that even when considering energy-only market revenue streams (i.e. heat and electricity sells) the integration of heat pump and storage units could increase the profitability of plants by making them more flexible in terms of power output levels and load variations. The latter is shown true even when excluding other flexibilityrelated revenue streams. It is therefore conclusively suggested to further investigate the proposed layouts in markets with larger heat and power price variations, as well as to investigate the impact of additional control logics and dispatch strategies.

  • 16.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Larchet, Kevin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Dent, Jolyon
    Green, Adam
    Hassar, Zhor
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Techno-Economic Analysis Of Hybrid Concentrating Solar Power And Solar Photovoltaic Power Plants For Firm Power In Morocco2016In: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986Article in journal (Refereed)
    Abstract [en]

    The present study evaluates the optimum configurations and operating strategies of hybrid concentrating solar power and solar photovoltaic power plants for minimizing levelized costs of electricity. These configurations were also required to meet specific design objectives as provided by competitive bid tenders, such as power plant size and operating hours, for a suitable location near Midelt, Morocco. A detailed techno-economic model of the hybrid plant was developed at KTH’s in-house optimization tool DYESOPT, which allows power plant evaluation by means of technical and economic performance indicators. Results show that hybrid plants are able to achieve higher capacity factors. It is also confirmed that, under current cost estimates, hybridization enables a lower cost solution for a given high capacity factor objective than what is achievable either with stand-alone concentrating solar power or solar photovoltaic power plants, respectively. The analysis highlights synergies among the technologies and shows the relation and influence between sizing and operation of their critical components. Main challenges for successful hybridization are also raised together with recommendations for addressing them. Lastly, optimum configurations found for different tender conditions are compared and a brief discussion section at the end is introduced to highlight the relevance of adequate policy design and its impact on the work of project developers for proposing the most competitive solutions

  • 17.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Enhancing the Economic Competitiveness of Concentrating Solar Power Plants through an Innovative Integrated Solar Combined-Cycle with Thermal Energy Storage2014In: Proceedings of the ASME TurboExpo 2014, 2014, Vol. 3AConference paper (Refereed)
    Abstract [en]

    The present work deals with the thermoeconomic analysis of an innovative combined power cycle consisting of a molten- salt solar tower power plant with storage supported by additional heat provided from the exhaust of a topping gas- turbine unit. A detailed dynamic model has been elaborated using an in house simulation tool that simultaneously encompasses meteorological, demand and price data. A wide range of possible designs are evaluated in order to show the trade-offs between the objectives of achieving sustainable and economically competitive designs. Results show that optimal designs of the novel concept are a promising cost-effective hybrid option that can successfully fulfill both the roles of a gas peaker plant and a baseload solar power plant in a more effective manner. Moreover, designs are also compared against conventional combined cycle gas turbine power plants and it is shown that, under specific peaking operating strategies, the innovative concept can not only perform better from an environmental standpoint but also economically.

  • 18.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Reducing the Number of Turbine Starts in Concentrating Solar Power Plants through the Integration of Thermal Energy Storage2015In: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 137, no 2Article in journal (Refereed)
    Abstract [en]

    The operation of steam turbine units in solar thermal power plants is very different than in conventional base-load plants. Due to the variability of the solar resource, much higher frequencies of plant start-ups are encountered. This study provides an insight to the influence of thermal energy storage (TES) integration on the typical cycling operation of solar thermal power plants. It is demonstrated that the integration of storage leads to significant reductions in the annual number of turbine starts and is thus beneficial to the turbine lifetime. At the same time, the effects of storage integration on the electricity costs are analyzed to ensure that the designs remain economically competitive. Large storage capacities, can allow the plant to be shifted from a daily starting regime to one where less than 20 plant starts occur annually. Additionally, the concept of equivalent operating hours (EOHs) is used to further analyze the direct impact of storage integration on the maintenance planning of the turbine units.

  • 19.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Optimization of Thermal Energy Storage Integration Strategies for Peak Power Production by Concentrating Solar Power Plants2014In: PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE, 2014, Vol. 49, p. 1642-1651Conference paper (Refereed)
    Abstract [en]

    The integration of thermal energy storage systems in concentrating solar thermal power plants allows power production to be shifted from times where there is low demand to periods where electricity prices are higher. Although increasing the total investment, thermal energy storage can therefore enhance profitability of the solar power plant. The present study presents optimum power plant configurations for a given location considering different price-based grid integration strategies. Such optimum plant configurations were determined using a thermo-economic optimization approach where the operating strategy was set such that electricity was generated once the market price exceeds a given price level, defined as the minimum price selling indicator. Plants were optimized for different indicator values to cover designs from base load and peak power production. For each of these price-operating strategies, optimum plant configurations were found by varying two solar-related design parameters, namely the solar multiple and the storage size, whilst simultaneously evaluating the economic performance of each design. Finally, an economic analysis was performed for each of the optimum power plants, assuming financial conditions throughout the lifetime of the power plant. Results show that the optimum plant configurations vary with respect to the chosen operating strategy. Optimum configurations for peak power production yielded relatively smaller storage units than that of the optimum baseload plants. Furthermore, the study demonstrates that under current cost estimations, and for the specified location, concentrating solar thermal power is not an attractive option for utility-grid investors. However, it is shown that when considering a reduction in investment costs or the possibility of having renewable electricity incentives such as the investment tax credit treasury cash grant, concentrating solar thermal power plants can become an economically viable technology.

  • 20.
    Guedez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Conde, Inés
    Gas Natural Fenosa Engineering.
    Ferragut, Francisco
    Gas Natural Fenosa Engineering.
    Callaba, Irene
    Gas Natural Fenosa Engineering.
    Spelling, James
    IMDEA .
    Hassar, Zhor
    Total New Energies.
    Perez-Segarra, Carlos David
    UPC.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Methodology for Determining Optimum Solar Tower Plant Configurations and Operating Strategies to Maximize Profits Based on Hourly Electricity Market Prices and Tariffs2016In: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 138, no 2, article id 021006Article in journal (Refereed)
    Abstract [en]

    The present study analyzes the influence that market conditions have on determining optimum molten salt solar tower plants with storage that maximizes profits (in terms of plant configuration, sizing, and operation) for a location in South Africa. Three different scenarios based on incentive programs and local wholesale electricity prices are considered. A multi-objective optimization modeling approach was followed, showing the tradeoff curves between minimizing investment and maximizing profits when varying critical size-related parameters (such as nameplate capacity, solar multiple (SM), and storage capacity) together with power-cycle design and operating specifications including dynamic startup curves and different storage dispatchability strategies. Results are shown by means of a comparative analysis between optimal plants found for each scenario, highlighting the value that storage has under the current two-tier tariff scheme and the relevance of designing a suitable policy for technology development. Finally, a final analysis is performed with regard to the indicators used for economic evaluation of power plants, by comparing the differences between optimum designs found when using the levelized cost of electricity (LCoE) solely as performance indicator instead of cash-flows and profit-based indicators, such as the internal rate of return (IRR).

  • 21.
    Gupta, Sunay
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Market potential of solar thermal enhanced oil recovery-a techno-economic model for Issaran oil field in Egypt2017In: SOLARPACES 2016: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2017, article id 190001Conference paper (Refereed)
    Abstract [en]

    Solar thermal enhanced oil recovery (S-EOR) is an advanced technique of using concentrated solar power (CSP) technology to generate steam and recover oil from maturing oil reservoirs. The generated steam is injected at high pressure and temperature into the reservoir wells to facilitate oil production. There are three common methods of steam injection in enhanced oil recovery - continuous steam injection, cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD). Conventionally, this steam is generated through natural gas (NG) fired boilers with associated greenhouse gas emissions. However, pilot projects in the USA (Coalinga, California) and Oman (Miraah, Amal) demonstrated the use of S-EOR to meet their steam requirements despite the intermittent nature of solar irradiation. Hence, conventional steam based EOR projects under the Sunbelt region can benefit from S-EOR with reduced operational expenditure (OPEX) and increased profitability in the long term, even with the initial investment required for solar equipment. S-EOR can be realized as an opportunity for countries not owning any natural gas resources to make them less energy dependent and less sensible to gas price fluctuations, and for countries owning natural gas resources to reduce their gas consumption and export it for a higher margin. In this study, firstly, the market potential of S-EOR was investigated worldwide by covering some of the major ongoing steam based EOR projects as well as future projects in pipeline. A multi-criteria analysis was performed to compare local conditions and requirements of all the oil fields based on a defined set of parameters. Secondly, a modelling approach for S-EOR was designed to identify cost reduction opportunities and optimum solar integration techniques, and the Issaran oil field in Egypt was selected for a case study to substantiate the approach. This modelling approach can be consulted to develop S-EOR projects for any steam flooding based oil fields. The model was developed for steam flooding requirements in Issaran oil field using DYESOPT, KTH's in-house tool for techno-economic modelling in CSP.

  • 22.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Techno-Economic Framework for the Analysis of Concentrating Solar Power Plants with Storage2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Concentrating solar power plants can integrate cost-effective thermal energy storage systems and thereby supply controllable power on demand, an advantage against other renewable technologies. Storage integration allows a solar thermal power plant to increase its load factor and to shift production to periods of peak demand. It also enables output firmness, providing stability to the power block and to the grid. Thus, despite the additional investment, storage can enhance the performance and economic viability of the plants.

    However, the levelized cost of electricity of these plants yet remains higher than for other technologies, so projects today are only viable through the provision of incentives or technology-specific competitive bid tenders. It is the variability of the solar resource, the myriad roles that storage can assume, and the complexity of enhancing the synergies between the solar field, the storage and the power block, what makes the development of adequate policy instruments, design and operation of these plants a challenging process.

    In this thesis a comprehensive methodology for the pre-design and analysis of concentrating solar power plants is presented. The methodology is based on a techno-economic modeling approach that allows identifying optimum trade-off curves between technical, environmental, and financial performance indicators. A number of contemporary plant layouts and novel storage and hybridization concepts are assessed to identify optimum plant configurations, in terms of component size and storage dispatch strategies.

    Conclusions highlight the relevance between the sizing of key plant components, the operation strategy and the boundaries set by the location. The interrelation between critical performance indicators, and their use as decisive parameters, is also discussed. Results are used as a basis to provide recommendations aimed to support the decision making process of key actors along the project development value chain of the plants. This research work and conclusions are primarily meant to set a stepping stone in the research of concentrating solar power plant design and optimization, but also to support the research towards understanding the value of storage in concentrating solar power plants and in the grid.

    Download full text (pdf)
    PhD Thesis - Rafael Guedez
  • 23.
    Guédez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Barberis, S.
    MacCarini, S.
    López-Román, A.
    Milani, A.
    Pesatori, E.
    Oyarzábal, U.
    Sánchez, A.
    Design Of A 2 Mw Molten Salt Driven Supercritical Co2 Cycle And Turbomachinery For The Solarsco2Ol Demonstration Project2022In: Proceedings of the ASME Turbo Expo, ASME International , 2022Conference paper (Refereed)
    Abstract [en]

    Supercritical CO2 (sCO2) power cycles have been identified as technology enablers for increasing the cost-competitiveness of Concentrating Solar Power (CSP) plants. Compared to steam cycles, sCO2 cycles have the advantage of allowing higher inlet turbine temperatures, while also deploying turbomachinery that can be a ten-fold more compact. Ongoing research in CSP focuses mainly in developing new receiver and storage concepts able to withstand such required higher temperatures, alongside new heat exchangers that enable coupling to a sCO2 cycle. Meanwhile, advancements in sCO2 turbomachinery have taken place in research projects aimed at investigating the technical feasibility of the cycle, including the optimized design of its individual components and new cycle configurations. Among these, only few focus in demonstrating a full-integrated system, including cycle control and dynamics, and only two worldwide have started plans for MW-scale pilots, none of them in Europe. The EU-funded SOLARSCO2OL project aims at demonstrating a first-of-a-k ind 2 MW gross simple-recuperated sCO2 Brayton cycle driven by heat provided by molten salt s similar to those deployed in commercial CSP plants, which are able to operate at temperatures of up to 580°C. This paper introduces the project objectives and implementation plan, to then focus primarily on the results derived from the first year in specific relation to the conceptual design of each of 2 MW scale power cycle and its k ey components, including also the proposed integration and operational regimes, expected thermod ynamic performance at nominal point, and up-scaling considerations. 

  • 24.
    Guédez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ferragut, F.
    Hassar, Z.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Callaba, I.
    Pérez-Segarra, C. D.
    Buezas, I. C.
    Spelling, J.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A methodology for determining optimum solar tower plant configurations and operating strategies to maximize profits based on hourly electricity market prices and tariffs2015In: ASME 2015 9th International Conference on Energy Sustainability, ES 2015, collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum, ASME Press, 2015Conference paper (Refereed)
    Abstract [en]

    The present study analyses the influence that market conditions have on determining optimum molten salt solar tower plants with storage that maximize profits (in terms of plant configuration, sizing and operation) for a location in South Africa. Three different scenarios based on incentive programs and local wholesale electricity prices are considered. A multi-objective optimization modeling approach was followed, showing the trade-off curves between minimizing investment and maximizing profits when varying critical sizerelated parameters (such as nameplate capacity, solar multiple and storage capacity) together with power-cycle design and operating specifications including dynamic start-up curves and different storage dispatchability strategies. Results are shown by means of a comparative analysis between optimal plants found for each scenario, highlighting the value that storage has under the current two-tier tariff scheme, and the relevance of designing a suitable policy for technology development. Lastly, a final analysis is performed with regards of the indicators used for economic evaluation of power plants, by comparing the differences between optimum designs found when using the levelized cost of electricity solely as performance indicator instead of cash-flows and profit-based indicators, such as the internal rate of return.

  • 25.
    Guédez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Garcia, Jose Angel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Martin, Fernando
    AF Aries Energia, Paseo Castellana 130,3th Floor, Madrid 28046, Spain..
    Wiesenberg, Ralf
    AF Aries Energia, Paseo Castellana 130,3th Floor, Madrid 28046, Spain..
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Integrated Solar Combined Cycles vs Combined Gas Turbine to Bottoming Molten Salt Tower Plants - A Techno-economic Analysis2018In: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2017) / [ed] Mancilla, R Richter, C, AMER INST PHYSICS , 2018, article id 180006-1Conference paper (Refereed)
    Abstract [en]

    The present work deals with the techno-economic analysis of a novel combined power cycle consisting of a molten-salt solar tower power plant with storage supported by additional heat provided from the exhaust of a topping gas-turbine unit. A detailed model has been elaborated using in house simulation tools that simultaneously encompass meteorological, demand and required dispatch data. A range of possible designs are evaluated for a suitable location with both good solar resource and vast natural gas resources in order to show the trade-offs between the objectives of achieving low carbon-intensive and economically competitive designs. These were compared against more conventional integrated solar combined cycles of equivalent capacity factors. It is shown that the novel concept is worth further investigating as it is able to outperform the more conventional cycle while simultaneously offering additional flexibility to grid-operators.

    Download full text (pdf)
    fulltext
  • 26.
    Guédez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Enhancing the Economic Competitiveness of Concentrating Solar Power Plants Through an Innovative Integrated Solar-Combined Cycle With Thermal Energy Storage2015In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, no 4, article id 041701Article in journal (Refereed)
    Abstract [en]

    The present work deals with the thermo-economic analysis of an innovative combined power cycle consisting of a molten-salt solar tower power plant with storage supported by additional heat provided from the exhaust of a topping gas-turbine unit. A detailed dynamic model has been elaborated using an in house simulation tool that simultaneously encompasses meteorological, demand and price data. A wide range of possible designs are evaluated in order to show the trade-offs between the objectives of achieving sustainable and economically competitive designs. Results show that optimal designs of the novel concept are a promising cost-effective hybrid option that can successfully fulfill both the roles of a gas peaker plant and a baseload solar power plant in a more effective manner. Moreover, designs are also compared against conventional combined cycle gas turbine (CCGT) power plants and it is shown that, under specific peaking operating strategies (P-OSs), the innovative concept cannot only perform better from an environmental standpoint but also economically.

  • 27.
    Guédez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermoeconomic Optimization of Solar Thermal Power Plants with Storage in High-Penetration Renewable Electricity Markets2013In: Energy Procedia, 2013, Vol. 57Conference paper (Refereed)
    Abstract [en]

    Unlike most of renewable energy technologies, solar thermal power plants with integrated thermal energy storage are able to store heat from the sun and thereby supply electricity whenever it is needed to meet the demand. This attribute makes concentrating solar power ideally suited to compensate for fluctuations in other renewable energy sources. In order to analyze this market role, three scenarios were modeled, with low, medium and high penetrations of non- dispatchable renewables (i.e. wind and solar photovoltaics). The demand that cannot be met by these variable sources is met by a solar thermal power plant with heat provided either by a solar field and storage system or a back-up gas burner. For each scenario, the size of the solar field and storage were varied in order to show the trade-off between the levelized generation costs of the system, the annual specific CO2 emissions and the share of renewable electricity generation. The results show that, regardless of the scenario, there exist optimum plant configurations with viable costs whilst simultaneously ensuring a considerable reduction in CO2 emissions. Furthermore, it is shown that the limited flexibility of the power block prevents the system from reaching higher levels of sustainability. Lastly, the results were compared with an equivalent combined cycle power plant, showing that solutions involving solar thermal power can be justified in environmental terms only if large storage units are integrated into the plants.

  • 28.
    Guédez, Rafael
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Reducing the Number of Turbine Starts in Concentrating Solar Power Plants through the Integration of Thermal Energy Storage2013In: Proceedings of the ASME TurboExpo 2013, 2013Conference paper (Refereed)
    Abstract [en]

    The operation of steam turbine units in solar thermal power plants is very different than in conventional base-load plants. Due to the variability of the solar resource, much higher frequencies of plant start-ups are encountered. This study provides an insight to the influence of thermal energy storage integration on the typical cycling operation of solar thermal power plants. It is demonstrated that the integration of storage leads to significant reductions in the annual number of turbine starts and is thus beneficial to the turbine lifetime. At the same time, the effects of storage integration on the electricity costs are analyzed to ensure that the designs remain economically competitive. Large storage capacities, can allow the plant to be shifted from a daily starting regime to one where less than 20 plant starts occur annually. Additionally, the concept of equivalent operating hours is used to further analyze the direct impact of storage integration on the maintenance planning of the turbine units.

  • 29.
    Hansson, Linus
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Larchet, Kevin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Development and implementation of a dynamic TES dispatch control component in a PV-CSP techno-economic performance modelling tool2017In: AIP Conference Proceedings, American Institute of Physics (AIP), 2017, Vol. 1850, article id 160013Conference paper (Refereed)
    Abstract [en]

    The dispatchability offered by thermal energy storage (TES) in concentrated solar power (CSP) and solar hybrid plants based on such technology presents the most important difference compared to power generation based only on photovoltaics (PV). This has also been one reason for recent hybridization efforts of the two technologies and the creation of Power Purchase Agreement (PPA) payment schemes based on offering higher payment multiples during daily hours of higher (peak or priority) demand. Recent studies involving plant-level thermal energy storage control strategies are however to a large extent based on pre-determined approaches, thereby not taking into account the actual dynamics of thermal energy storage system operation. In this study, the implementation of a dynamic dispatch strategy in the form of a TRNSYS controller for hybrid PV-CSP plants in the power-plant modelling tool DYESOPT is presented. In doing this it was attempted to gauge the benefits of incorporating a day-ahead approach to dispatch control compared to a fully pre-determined approach determining hourly dispatch only once prior to annual simulation. By implementing a dynamic strategy, it was found possible to enhance technical and economic performance for CSP-only plants designed for peaking operation and featuring low values of the solar multiple. This was achieved by enhancing dispatch control, primarily by taking storage levels at the beginning of every simulation day into account. The sequential prediction of the TES level could therefore be improved, notably for evaluated plants without integrated PV, for which the predicted storage levels deviated less than when PV was present in the design. While also featuring dispatch performance gains, optimal plant configurations for hybrid PV-CSP was found to present a trade-off in economic performance in the form of an increase in break-even electricity price when using the dynamic strategy which was offset to some extent by a reduction in upfront investment cost. An increase in turbine starts for the implemented strategy however highlights that this is where further improvements can be made.

  • 30. Kesseli, D.
    et al.
    Wagner, M.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Turchi, C. S.
    CSP-plant modeling guidelines and compliance of the system advisor model (SAM)2019In: SolarPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2019, article id 170006Conference paper (Refereed)
    Abstract [en]

    Accurately modeling risks, costs, and electricity output is essential to the financing and advancement of concentrating solar power projects. To address this need, a group of CSP experts created a guideline document, titled SolarPACES Guideline for Bankable STE Yield Assessment [1]. To make this information more accessible and allow stakeholders to test specific models against the recommendations, the guidelines have been condensed into a spreadsheet-based checklist. The checklist was applied to NREL's System Advisor Model (SAM) software, providing useful feedback to both the checklist group and the SAM development team. This study showed strong agreement between SAM and the guidelines, demonstrated the use of the guidelines in model validation, and resulted in several recommended improvements to SAM.

  • 31.
    Larchet, Kevin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Topel, Monika
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gustavsson, L.
    Machirant, A.
    Hedlund, M. -L
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Enhancing economic competiveness of dish Stirling technology through production volume and localization: Case study for Morocco2017In: SOLARPACES 2016: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2017, Vol. 1850, article id 050002Conference paper (Refereed)
    Abstract [en]

    The present study quantifies the reduction in the levelized cost of electricity (LCoE) and capital expenditure (CAPEX) of a dish Stirling power plant (DSPP) through an increase in localization and unit production volume. Furthermore, the localization value of the plant is examined to determine how much investment is brought into the local economy. Ouarzazate, Morocco, was chosen as the location of the study due to the country's favorable regulatory framework with regards to solar power technologies and its established industry in the concentrating solar power (CSP) field. A detailed techno-economic model of a DSPP was developed using KTH's in-house modelling tool DYESOPT, which allows power plant evaluation by means of technical and economic performance indicators. Results on the basis of LCoE and CAPEX were compared between two different cases of production volume, examining both a minimum and maximum level of localization. Thereafter, the DSPP LCoE and localization value were compared against competing solar technologies to evaluate its competitiveness. In addition, a sensitivity analysis was conducted around key design parameters. The study confirms that the LCoE of a DSPP can be reduced to values similar to solar photovoltaic (PV) and lower than other CSP technologies. Furthermore, the investment in the local economy is far greater when compared to PV and of the same magnitude to other CSP technologies. The competiveness of a DSPP has the potential to increase further when coupled with thermal energy storage (TES), which is currently under development.

  • 32. Lindquist, T.
    et al.
    Karlsson, J.
    Wallmander, J.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Hedlund, M. -L
    Jamot, J.
    Gloss, D.
    Lindh, J.
    Hertin, A.
    Nilsson, M.
    Abou-Taouk, A.
    Kjellin, K.
    Bouzekri, H.
    A novel modular and dispatchable CSP Stirling system: Design, validation, and demonstration plans2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2126, article id 060005Conference paper (Refereed)
    Abstract [en]

    This paper summarizes the preliminary results from the on-going development of a novel modular dispatchable solar power plant concept. The work encompasses techno-economic feasibility assessment, concept design, full scale sub-system tests and validation work, and ultimately plans for a fully integrated demonstration of the system. The proposed solar power plant concept consists of a heliostat field that powers a latent heat thermal energy storage (TES), fitted on a small tower. The solar receiver located underneath the TES tank, is an optical cavity with a small aperture that enables the concentrated sunlight to be emitted directly on the solar absorber surface while ensuring low convective and radiative losses. The stored thermal energy is provided to the engine, in proximity to the latent heat storage, with a pumped heat transfer fluid (HTF). The Stirling engine with a rated power of 13 kW has been modified and optimised for the operational conditions that the eutectic aluminum-silicon latent heat storage provides. For example, a new engine tubular gas heater has been developed for the HTF (i.e. sodium) and the expansion cylinder has been enlarged to improve both efficiency and power output as the temperature of the working gas is somewhat lower than in previous dish Stirling application. The choice of eutectic aluminum-silicon as TES media resulted from a thorough assessment of several phase change materials throughout the design phase of the project. Indeed, such a TES media selected would benefit from a suitable melting temperature of around 580°C, high energy density, high thermal conductivity, and low cost.

  • 33.
    Mantilla, Weimar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    García Frediani, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Sorce, Alessandro
    University of Genoa.
    Short-Term Optimization of a Combined Cycle Power Plant Integrated With an Inlet Conditioning Unit2021In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 143, no 9, article id 091013Article in journal (Refereed)
    Abstract [en]

    Under new scenarios with high shares of renewable electricity, combined cycle gas turbines (CCGTs) are required to improve their flexibility to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. An inlet conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine (GT) inlet temperature using cold thermal energy storage (TES) and a heat pump (HP). Consequently, an evaluation of a CCGT integrated with this unit including a day-ahead optimized operation strategy was developed in this study. To establish the hourly dispatch of the power plant and the operation mode of the ICU, a mixed-integer linear programing (MILP) optimization was formulated, aiming to maximize the operational profit of the plant within a 24 h horizon. To assess the impact of the unit operating under this dispatch strategy, historical data have been used to perform annual simulations of a reference power plant located in Turin, Italy. Results indicate that the power plant's operational profit increases by achieving a wider operational range during peak and off-peak periods. For the specific case study, it is estimated that the net present value (NPV) of the CCGT integrated with the ICU is 0.5% higher than the CCGT without it. Results also show that the unit reduces the MEL by approximately 1.34% and can increase the net power output by 0.17% annually.

  • 34.
    Mantilla, Weimar
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    García, José
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Sorce, A.
    Short-term optimization of a combined cycle power plant integrated with an inlet air conditioning unit2020In: Proceedings of the ASME Turbo Expo, American Society of Mechanical Engineers (ASME) , 2020Conference paper (Refereed)
    Abstract [en]

    Under new scenarios with high shares of variable renewable electricity, combined cycle gas turbines (CCGT) are required to improve their flexibility, in terms of ramping capabilities and part-load efficiency, to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. Among the different possibilities to enhance the power plant performance, an inlet air conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine inlet temperature using cold thermal energy storage and a heat pump. Consequently, an evaluation of a CCGT integrated with this inlet conditioning unit including a day-ahead optimized operation strategy was developed in this study. 

  • 35.
    Montes, M. J.
    et al.
    E.T.S. Ingenieros Industriales - UNED, C/Juan del Rosal 12, 28040 Madrid, Spain, C/Juan Del Rosal 12; High Temperature Processes Unit, IMDEA Energy, Avda. Ramon de la Sagra 3, 28935, Mostoles, Spain.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    D'Souza, D.
    E.T.S. Ingenieros Industriales - UNED, C/Juan del Rosal 12, 28040 Madrid, Spain, C/Juan Del Rosal 12; High Temperature Processes Unit, IMDEA Energy, Avda. Ramon de la Sagra 3, 28935, Mostoles, Spain.
    Linares, J. I.
    Comillas Pontifical University, Alberto Aguilera, 25, 28015 Madrid, Spain.
    González-Aguilar, J.
    High Temperature Processes Unit, IMDEA Energy, Avda. Ramon de la Sagra 3, 28935, Mostoles, Spain.
    Romero, M.
    High Temperature Processes Unit, IMDEA Energy, Avda. Ramon de la Sagra 3, 28935, Mostoles, Spain.
    Proposal of a new design of central solar receiver for pressurised gases and supercritical fluids2023In: International journal of thermal sciences, ISSN 1290-0729, E-ISSN 1778-4166, Vol. 194, article id 108586Article in journal (Refereed)
    Abstract [en]

    This work presents a novel design of microchannel central receiver for pressurised gases and supercritical fluids in solar tower plants. It consists of a radial arrangement of vertical absorber panels that converge on the central axis of the tower. The absorber panels comprise compact structures, whose compactness is increased in one flow pass compared to the previous one, as the fluid is heated. This concept reduces radiation heat losses due to its light-trapping geometry and increases heat transfer to the thermal fluid without over penalising its pressure drop. For the receiver assessment, it has been developed a thermal resistance model characterising the fluid heating along the panel height and the temperature gradient between parallel channel rows of the compact structure across the panel thickness. Once the thermal and optical boundary conditions are defined, an optimisation analysis of the main geometrical parameters of the receiver has been accomplished. The receiver performance is evaluated by means of a global exergy efficiency referred to the solar subsystem, which computes the receiver heat losses, the fluid pressure drop and the optical efficiency of the heliostat field in which the receiver is integrated. For each parametric optimisation, the configuration that maximises this efficiency is identified.

  • 36.
    Montes, M. J.
    et al.
    E.T.S. Ingenieros Industriales - UNED, C/Juan del Rosal 12, 28040 Madrid, Spain, C/Juan del Rosal 12.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Linares, J. I.
    ICAI School of Engineering, Comillas Pontifical University, Alberto Aguilera, 25, 28015 Madrid, Spain, Alberto Aguilera, 25.
    Reyes-Belmonte, M. A.
    Department of Chemical and Energy Technology, School of Experimental Sciences and Technology (ESCET), Rey Juan Carlos University, 28933 Móstoles, Madrid, Spain, 28933 Móstoles.
    Advances in solar thermal power plants based on pressurised central receivers and supercritical power cycles2023In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 293, article id 117454Article in journal (Refereed)
    Abstract [en]

    This work addresses the comparative thermo-economic study of different configurations of solar thermal power plants, based on supercritical power cycles and pressurised central receiver systems. For all the cases examined, two innovations are introduced in the solar subsystem, compared to other similar studies. Firstly, the heat transfer fluid in the receiver is either a pressurised gas or a supercritical fluid. Secondly, the receiver is composed of compact structures performing as absorber panels, arranged in a radial configuration. The investigation considers different supercritical CO2 recompression cycles of 50 MWe, including a novel proposal of a directly coupled cycle with heat input downstream of the turbine. Furthermore, the study evaluates different heat transfer fluids in the receiver, specifically CO2, N2, and He, concluding that the former is preferred due to its better thermal performance. The main results show that an increase in the receiver inlet pressure yields to a reduction in its size, favouring the thermal efficiency but penalising the optical efficiency of the solar field. Therefore, optimal working pressures may exist for each configuration, depending on the operating temperature. When comparing the optimal configurations, it is observed that the plant based on the intercooling cycle demonstrates the highest overall efficiency, reaching 32.05%. At last, an economic analysis is conducted to assess the viability of the identified optimal configurations. In this regard, the plant based on the partial-cooling cycle exhibits the lowest levelised cost of electricity at 0.15 $/kWh. This is primarily due to its lower investment cost. The innovative directly coupled cycle follows closely with a cost of 0.17 $/kWh, driven by its high electricity production resulting from its low self-consumption.

  • 37.
    Montes, Maria Jose
    et al.
    Univ Nacl Educ Distancia UNED, ETS Ingn Ind, C-Juan Rosal 12, Madrid 28040, Spain..
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    D'Souza, David
    Univ Nacl Educ Distancia UNED, ETS Ingn Ind, C-Juan Rosal 12, Madrid 28040, Spain..
    Linares, Jose Ignacio
    Comillas Pontif Univ, Rafael Marino Chair New Energy Technol, Alberto Aguilera 25, Madrid 28015, Spain..
    Thermoeconomic Analysis of Concentrated Solar Power Plants Based on Supercritical Power Cycles2023In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 13, article id 7836Article in journal (Refereed)
    Abstract [en]

    Featured Application This work is intended as a guide for the design of solar thermal tower plants based on a microchannel radial receiver refrigerated by a pressurised gas, and coupled to a supercritical CO2 power cycle. The work demonstrates the influence of the receiver configuration on the plant performance and investment costs. Solar thermal power plants are an alternative for the future energy context, allowing for a progressive decarbonisation of electricity production. One way to improve the performance of such plants is the use of supercritical CO2 power cycles. This article focuses on a solar thermal plant with a central solar receiver coupled to a partial cooling cycle, and it conducts a comparative study from both a thermal and economic perspective with the aim of optimising the configuration of the receiver. The design of the solar receiver is based on a radial configuration, with absorber panels converging on the tower axis; the absorber panels are compact structures through which a pressurised gas circulates. The different configurations analysed keep a constant thermal power provided by the receiver while varying the number of panels and their dimensions. The results demonstrate the existence of an optimal configuration that maximises the exergy efficiency of the solar subsystem, taking into account both the receiver exergy efficiency and the heliostat field optical efficiency. The evolution of electricity generation cost follows a similar trend to that of the exergy efficiency, exhibiting minimum values when this efficiency is at its maximum.

  • 38. Musi, R.
    et al.
    Grange, B.
    Sgouridis, S.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Armstrong, P.
    Slocum, A.
    Calvet, N.
    Techno-economic analysis of concentrated solar power plants in terms of levelized cost of electricity2017In: SOLARPACES 2016: International Conference on Concentrating Solar Power and Chemical Energy Systems, American Institute of Physics (AIP), 2017, article id 160018Conference paper (Refereed)
    Abstract [en]

    Levelized Cost of Electricity (LCOE) is an important metric which provides one way to compare the economic competitiveness of different electricity generation systems, calculated simply by dividing lifetime costs by lifetime production. Hidden behind the simplicity of this formula are various assumptions which may significantly alter results. Different LCOE studies exist in the literature, although their assumptions are rarely explicitly stated. This analysis gives all formulas and assumptions which allow for inter-study comparisons. The results of this analysis indicate that CSP LCOE is reducing markedly over time and that given the right location and market conditions, the SunShot 6¢/kWh 2020 target can be reached. Increased industrial cooperation is needed to advance the CSP market and continue to drive down LCOE. The results also indicate that there exist a country and technology level learning effect, either when installing an existing CSP technology in a new country or when using a new technology in an existing CSP country, which seems to impact market progress.

  • 39. Pan, C. A.
    et al.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dinter, F.
    Harms, T. M.
    A techno-economic comparative analysis of thermal oil and molten salt parabolic trough power plants with molten salt solar towers2019In: AIP Conference Proceedings, American Institute of Physics (AIP), 2019, Vol. 2126, article id 120014Conference paper (Refereed)
    Abstract [en]

    This study presents a comparison between thermal oil and molten salt parabolic trough power plants as well as molten salt solar towers. Although higher temperature differences in solar towers enable higher power cycle efficiencies, the necessity of large solar fields for increasing turbine capacities and capacity factors pose a limitation through increased attenuation losses. This effect is amplified when unfavourable atmospheric conditions with visibilities of e.g. 15km are present to the extent where 200 MW parabolic trough power plants with molten salt as heat transfer fluid can achieve lower levelised costs of electricity and higher capacity factors than solar towers. Additionally, solar towers require a significantly larger solar field and thus land area as compared to molten salt parabolic through power plants. Moreover, both molten salt parabolic troughs and solar towers outperform thermal oil parabolic trough systems in terms of LCOE and capacity factors.

  • 40.
    Payaro, Albert
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Naik, Ankit Anurag
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Identification of Required Cost Reductions for CSP to Retain Its Competitive Advantage as Most Economically Viable Solar-Dispatchable Technology2018In: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2017) / [ed] Mancilla, R Richter, C, AMER INST PHYSICS , 2018, article id 040028-1Conference paper (Refereed)
    Abstract [en]

    The present study evaluates and compares the optimum configurations for both PV-batteries and molten salt tower concentrating solar power plants that minimize the levelized cost of electricity for a suitable location for deployment of both solar technologies nearby Ouarzazate, Morocco, when considering two capacity factor objectives, namely 50% and 85%, and cost-projections for 2020 and 2030. Required target cost reduction rates for each of the main blocks in the tower plant (i.e. the solar field, the storage and the power block) are identified for guaranteeing its competitive advantage as the most economically viable solar-only technology at both capacity factor objectives investigated. It is shown that the larger the capacity factor requirement is, the more competitive the solar thermal technology would be. Specifically, the case-study shows that for an 85% capacity factor objective, tower plants would be more competitive even when considering the most pessimistic and optimistic cost projections for the solar thermal and PV-batteries sub-components, respectively. Nevertheless, it was also determined that in order to ensure being the most competitive solar-only technology at a 50% capacity factor objective by 2030, the costs of the solar field of the solar tower plants should reach values as low as 20-50 (sic)/m(2), depending on the scenario, which means approximately a three to seven fold decrease of the costs as of 2017. At last, recommendations to solar thermal technology owners and developers are provided, and a short discussion regarding the viability and limitations of using battery electric storage systems for utility-scale solar plants is presented.

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  • 41. Reboli, T.
    et al.
    Ferrando, M.
    Mantelli, L.
    Gini, L.
    Sorce, A.
    Garcia, Jose
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Gas Turbine Combined Cycle Range Enhancer - Part 1: Cyber-Physical Setup2022In: Proceedings of the ASME Turbo Expo, ASME International , 2022Conference paper (Refereed)
    Abstract [en]

    Natural gas turbine combined cycles (GTCCs) are playing a fundamental role in the current energy transition phase towards sustainable power generation. The competitiveness of a GTCC in future electrical networks will thus be firmly related to its capability of successfully compensating the discontinuous power demands. This can be made possible by enhancing power generation flexibility and extending the operative range of the plant. To achieve this goal, a test rig to investigate gas turbine inlet conditioning techniques was developed at the TPG laboratory of the University of Genoa, Italy. The plant is composed of three key hardware components: a micro gas turbine, a butane-based heat pump, and a phase-change material cold thermal energy storage system. The physical test-rig is virtually scaled up through a cyber-physical approach, to emulate a full scale integrated system. The day-ahead schedule of the plant is determined by a high-level controller referring to the Italian energy market, considering fluctuations in power demands. By using HP and TES, it is possible to control the mGT inlet air temperature and thus enhance the operational range of the plant optimizing the management of energy flows. This article (Part 1) introduces the new experimental facility, the real-time bottoming cycle dynamic model, and the four-level control system that regulates the operation of the whole cyber-physical plant. The experimental campaign and the analysis of the system performance are presented in the Part 2. 

  • 42.
    Reyes-Belmonte, Miguel Angel
    et al.
    Rey Juan Carlos University.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Montes, María José
    UNED.
    Bibliometric Analysis on Supercritical CO2 Power Cycles for Concentrating Solar Power Applications2021In: Entropy, E-ISSN 1099-4300, Vol. 23, no 10, article id 1289Article in journal (Refereed)
    Abstract [en]

    In recent years, supercritical CO2 power cycles have received a large amount of interest due to their exceptional theoretical conversion efficiency above 50%, which is leading a revolution in power cycle research. Furthermore; this high efficiency can be achieved at a moderate temperature level; thus suiting concentrating solar power (CSP) applications; which are seen as a core business within supercritical technologies. In this context; numerous studies have been published; creating the need for a thorough analysis to identify research areas of interest and the main researchers in the field. In this work; a bibliometric analysis of supercritical CO2 for CSP applications was undertaken considering all indexed publications within the Web of Science between 1990 and 2020. The main researchers and areas of interest were identified through network mapping and text mining techniques; thus providing the reader with an unbiased overview of sCO2 research activities. The results of the review were compared with the most recent research projects and programs on sCO2 for CSP applications. It was found that popular research areas in this topic are related to optimization and thermodynamics analysis; which reflects the significance of power cycle configuration and working conditions. Growing interest in medium temperature applications and the design of sCO2 heat exchangers was also identified through density visualization maps and confirmed by a review of research projects.

  • 43.
    Shamsi, Syed Safeer Mehdi
    et al.
    Univ Genoa, Genoa, Italy..
    Maccarini, Simone
    Univ Genoa, Genoa, Italy..
    Trevisan, Silvia
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Barberis, Stefano
    Univ Genoa, Genoa, Italy..
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Sco2 Based Pumped Heat Thermal Energy Storage Systems Valorizing Industrial Waste Heat Recovery: A Techno-Economic Analysis Of The Role Of High Temperature Tes2023In: Proceedings Of Asme Turbo Expo 2023: Turbomachinery Technical Conference And Exposition, Gt2023, Vol 6, ASME International , 2023Conference paper (Refereed)
    Abstract [en]

    In the current renewable energy dominated power system, as power production is becoming more and more unpredictable, it would be important to act at two levels: integrating relevant power/energy capacity of energy storage and making demand more controllable. At this purpose, acting on industrial energy demand via integration of energy storage and electrification of local processes, could provide a significant contribution. At the same time, waste heat recovery (WHR) is quite a consolidated industrial practise. Nevertheless, WH valorisation is usually performed via bottoming cycles, such as steam, ORC or supercritical CO2 (sCO(2)) power cycles. The development of thermo-mechanical storages to be installed at industrial level, can contribute in this direction through the use of traditional technologies (rotating machinery) employed in power plants as well as in Waste-heat-to-power (WH2P) plants. This paper presents a thermo-economic analysis of Pumped Thermal Energy Storages (PTES) for sCO(2) cycles, comparing market available thermal energy storage materials for different temperature range of operation. The proposed system is purposefully designed to exploit the waste heat sources for the temperature ranges of 150-400 degrees C, difficult to exploit for WH2P solutions and rarely addressed in literature so far. The use of sCO(2) enhances the techno-economic features of these systems, the independent charging and discharging system proposed in this study can also provide a keen sense of flexibility especially for the upscaling of a PTES plant to reach an equal grid flexibility power for charging and discharging. At the same time, the valorisation of low temperature waste heat enables industries to enhance their energy efficiency, limit their operational costs and environmental impact, whilst becoming an active part in the regulation of the grid. At this purpose optimal system configurations and dispatch strategies are identified based on typical load curves of specific EU markets. Starting from an identified reference case (a cement production plant with WH temperature to be valorized around 330 degrees C), different PTES cycle layouts and TES technological solutions are compared on a techno-economic basis. The waste heat integration to the PTES system has been found to add satisfactory value in terms of RTE. On the other hand, it proves to be an optimal use case of waste heat valorisation than traditional waste heat to power cycles when compared in terms of exergy, capital cost and dispatchability in ever increasing RES penetration scenarios. The identification of the most optimal TES however is driven by economic factors too as presented in CAPEX and dispatchability analysis.

  • 44.
    Soliman, Hady R.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Þórsson, Björn J.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Trevisan, Silvia
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Utilizing Industrial Waste Heat for Power Generation Using sCO2 Cycles2021In: Proceedings of the 4th European sCO2 Conference 2021, sCO2 2021, DuEPublico - Duisburg-Essen Publications Online , 2021, p. 322-332Conference paper (Refereed)
    Abstract [en]

    The industrial sector accounts for approximately 30% of the global total energy consumption and 50% of that is lost as waste heat. Recovering waste heat from industries and utilizing it as an energy source is a sustainable way of generating electricity. Supercritical CO2 (sCO2) cycles can be used with various heat sources including waste heat. Current literature primarily focuses on the cycle’s thermodynamic performance without investigating the economics of the system. This is mainly due to the lack of reliable cost estimates for the cycle components. Recently developed cost scaling makes it possible to perform more accurate techno-economic studies on these systems. This work aims to model waste-heat-to-power systems and by performing sensitivity analysis on various system components, attempts to determine which factors require the most attention to bring this technology into commercialization. The industries with the largest unutilized waste heat are cement, iron and steel, aluminum and gas compressor stations. In this work, models of different sCO2 cycle configurations were developed and simulated for these industries. The techno-economic model optimizes for the highest Net Present Value (NPV) using an Artificial Bee Colony algorithm. The optimization variables are the pressure levels, split ratios, recuperator effectiveness, condenser temperature and the turbine inlet temperature limited by the heat source. The results show industries can cut down costs by 8-34M using this system. Furthermore, the system can achieve an LCOE between 2.5-4.5 c/kWh which is competitive with ORC (3.2-18 c/kWh) and steam cycles (3-9 c/kWh). Out of the modeled industries, waste heat recovery in the steel industry yields the highest NPV of 34.6M.

  • 45.
    Sorce, Alessandro
    et al.
    Univ Genoa, TPG, Genoa, Italy..
    Giugno, Andrea
    Univ Genoa, TPG, Genoa, Italy..
    Marino, Daniela
    Ansaldo Energia, Genoa, Italy..
    Piola, Stefano
    Ansaldo Energia, Genoa, Italy..
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Analysis of a combined cycle exploiting inlet conditioning technologies for power modulation2019In: Proceedings of the ASME Turbo Expo: Turbomachinery Technical Conference and Exposition, 2019, Vol 3, ASME Press, 2019Conference paper (Refereed)
    Abstract [en]

    The high share of non-dispatchable renewable energy source generators in the electrical grid has increased the need for flexibility of Gas Turbine Combined Cycles (GTCC) already installed. To maximize not only the maximum power produced, via Power Augmentation Technologies (PATs), but also to reduce the Minimum Environmental Load (MEL), both OEMs and GTCC owners have adopted several technical solutions. This kind of flexibility has become, year-by-year, ever more crucial to guarantee GTCC economical sustainability. Amongst the solutions which can be adapted to guarantee GTCC flexibility, the Inlet Conditioning System is a particularly interesting technical solution, which can be installed without restrictions related to the different GT design. In this paper, an evaluation of the compressor inlet temperature effect over the Combined Cycle performance is presented, with a focus on the bottoming Cycle impact. Different Inlet Conditioning Strategies are then compared considering the energy, and the environmental impact on GTCC behavior. The performance of a layout including a Thermal Energy Storage (TES) and a Heat Pump (HP) is then evaluated and compared to other technical solutions.

  • 46.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    A Thermo-Economic Study of Storage Integration in Hybrid Solar Gas-Turbine Power Plants2015In: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 137, no 1Article in journal (Refereed)
    Abstract [en]

    A thermo-economic simulation model of a hybrid solar gas-turbine (HSGT) power plant with an integrated storage unit has been developed, allowing determination of the thermodynamic and economic performance. Designs were based around two representative industrial gas-turbines: a high efficiency machine and a low temperature machine. In order to examine the trade-offs that must be made, multi-objective thermo-economic analysis was performed, with two conflicting objectives: minimum investment costs and minimum specific carbon dioxide (CO2) emissions. It was shown that with the integration of storage, annual solar shares above 85% can be achieved by HSGT systems. The levelized electricity cost (LEC) for the gas-turbine system as this level of solar integration was similar to that of parabolic trough plants, allowing them to compete directly in the solar power market. At the same time, the water consumption of the gas-turbine system is significantly lower than contemporary steam-cycle based solar thermal power plants.

  • 47.
    Spelling, James
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    The Value of Storage in Hybrid Solar Gas-Turbine Power Plants2012In: Proceedings of the International SolarPACES Conference 2012, Marrakesh, 2012Conference paper (Refereed)
    Abstract [en]

    A thermoeconomic simulation model of a hybrid solar gas-turbine power plant with an integrated storage unit has been developed, allowing determination of the thermodynamic and economic performance. Designs were based around two representative industrial gas-turbines: a high efficiency machine and a low temperature machine. In order to examine the trade-offs that must be made, multi-objective thermo-economic analysis was performed, with two conflicting objectives: minimum investment costs and minimum specific CO2 emissions. It was shown that with the integration of storage, annual solar shares above 85% can be achieved by hybrid solar gas-turbine systems. The levelised electricity cost for the gas-turbine system as this level of solar integration was similar to that of parabolic trough plants, allowing them to compete directly in the solar power market. At the same time, the water consumption of the gas-turbine system is significantly lower than contemporary steam-cycle based solar thermal power plants.

  • 48.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ellakany, Farid
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Genrup, Magnus
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-Economic Study on the Implementation of Steam Turbine Concepts for Flexible Operation on a Direct Steam Generation Solar Tower Power Plant2016In: SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, American Institute of Physics (AIP), 2016, article id 060005Conference paper (Refereed)
    Abstract [en]

    Among concentrating solar power technologies, direct steam generation solar tower power plants represent a promising option. These systems eliminate the usage of heat transfer fluids allowing for the power block to be run at greater operating temperatures and therefore further increasing the thermal efficiency of the power cycle. On the other hand, the current state of the art of these systems does not comprise thermal energy storage as there are no currently available and techno-economically feasible storage integration options. This situation makes direct steam generation configurations even more susceptible to the already existing variability of operating conditions due to the fluctuation of the solar supply. In the interest of improving the annual performance and competitiveness of direct steam generation solar tower systems, the present study examines the influence of implementing two flexibility enhancing concepts which control the steam flow to the turbine as a function of the incoming solar irradiation. The proposed concepts were implemented in a reference plant model previously developed by the authors. Then, a multi-objective optimization was carried out in order to understand which configurations of the steam turbine concepts yield reductions of the levelized cost of electricity at a lower investment costs when compared to the reference model. Results show that the implementation of the proposed strategies can enhance the thermo-economic performance of direct steam generation systems by yielding a reduction of up to 9.2% on the levelized cost of electricity, mainly due to allowing 20% increase in the capacity factor, while increasing the investment costs by 7.8%.

  • 49.
    Topel, Monika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Guedez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Impact of Increasing Steam Turbine Flexibility on the Annual Performance of a Direct Steam Generation Tower Power Plant2014In: Energi Procedia, Beijing, 2014, Vol. 69, p. 1171-1180Conference paper (Refereed)
    Abstract [en]

    Among concentrating solar power technologies, solar tower power plants currently represent one of the most promising ones. Compared to parabolic trough configurations, tower systems enable considerable efficiency gains as higher concentration ratios can be achieved. Direct steam generation systems, in particular, eliminate the usage of heat transfer fluids allowing for the power block to be run at greater operating temperatures and therefore further increasing the thermal efficiency of the power cycle. On the other hand, the current state of the art of these systems does not comprise thermal energy storage. Although it has been shown that the integration of storage potentially enhances the economic viability and profitability of the plants, there are no currently available and techno-economically feasible storage integration options for the case of direct steam generation towers.

    The lack of storage adds to the already existing variability of operating conditions that all concentrating power plants endure due to the fluctuating nature of the solar supply. This situation is more prominent for the case of direct steam generation systems; leading up to multiple start-ups during a 24h period if the weather conditions are not optimal. In the interest of improving the annual performance and competitiveness of direct steam generation concentrating solar power plants, it is desirable for the plant to achieve fast start-up times to harness the solar energy as soon as possible. The start-up speed of the whole plant is limited by the thermal inertia of certain key components, one of which is the steam turbine.

    This paper studies the potential for power plant performance improvement through the increase of steam turbine flexibility at the time of start-up. The methodology consisted of performing sensitivity studies on the annual operation of a power plant while considering different scenarios of turbine operational modifications. For each study, the corresponding power plant performance indicators were evaluated and compared to the base case without modifications. It is shown that gains of up to 7% in total power plant electric output and reductions in turbine maintenance periods can be achieved as a result of the implemented operational improvements. 

  • 50.
    Trevisan, Silvia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Europe Power Solutions AB, 182 65 Djursholm, Stockholm, Sweden.
    Buchbjerg, Bjarke
    KYOTO Group AS, 1366 Lysaker, Norway.
    Guédez, Rafael
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Europe Power Solutions AB, 182 65 Djursholm, Stockholm, Sweden.
    Power-to-heat for the industrial sector: Techno-economic assessment of a molten salt-based solution2022In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 272, article id 116362Article in journal (Refereed)
    Abstract [en]

    The industrial sector is a major source of wealth, producing about one-quarter of the global gross product. However, industry is also a major emitter of CO2 and it represents a key challenge towards achieving the worldwide CO2 emission reduction targets. Nowadays, about 22 % of the overall energy demand is heating for the industrial sector, generating about 40 % of the global CO2 emissions. Solutions to decarbonize the industrial sector are needed. This work presents the techno-economic assessment of molten salt based power-to-heat solution aiming at decarbonizing the industrial sector, requiring medium temperature heat (150–450 ◦C). The system is studied under different electric markets considering electricity prices of 2021, future electricity market price modifications are assessed via sensitivity analyses. Dispatch strategies and system sizing are identified to ensure optimal techno-economic performance. The main performance indicators investigated are the Levelized cost of heat, the operational expenditure, and the attainable savings with respect to traditional solutions. The system scalability and sizing criteria are investigated accounting for different typical industrial load profile curves and nominal thermal power demands. The results highlight that nominal levelized cost of heat as low as55 €/MWhth are attainable in cheap electricity markets (i.e. Denmark) and 80 €/MWhth in more expensive scenarios (i.e. United Kingdom). The proposed system can provide operational cost savings between 0.5 and 3M€/y against traditional non-flexible electric boilers and even wider benefits if fossil fuels-based boilers are considered. Future electricity markets, subjected to higher renewable penetration causing cheaper average electricity prices and higher price volatility, could lead to further reductions of the levelized cost of heat of more than 20 % achieving values below 45 €/MWhth in markets such as Denmark. This study sets the ground for further power-to-heat techno-economic investigations addressing different industrial sectors and identifies main system design strategies.

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