Artículos (Ingeniería Energética)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11362

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Dynamic modeling and transient simulation of supercritical CO2 power cycles: A review of approaches, assumptions and research gaps
(Elsevier, 2026-10) Muke, Leonard; Rodríguez de Arriba, Pablo Enrique; González Almenara, Rafael; Sánchez Martínez, David Tomás; Ingeniería Energética; European Union (UE)
Supercritical CO2 (sCO2) cycles have gained significant interest in the scientific community in recent years as a promising alternative for power generation systems, thanks to their high thermal efficiency, compact design, and adaptability to a wide range of heat sources and application fields. The operation of sCO2 systems as a power generation cycle under highly variable operating conditions and fluctuating boundary conditions is highly demanding on the stability and mechanical integrity of the components. With this in mind, the transient cycle operation has to be studied extensively, to ensure a safe, stable and efficient operation. This has been studied widely in the past, ranging from different fidelities of models, scopes of research and boundary conditions. In this context, the present paper provides a review of all relevant studies on dynamic sCO2 cycle simulations with details on simulation approaches and modeling strategies. To this aim, an extensive literature review on dynamic modeling approaches as well as component formulations is conducted. The foregoing studies are then grouped and analyzed according to their scope and modeling fidelity. From this, a critical analysis of the studies is made and possible gaps in the literature on system and component level are identified, providing a comprehensive overview and pathway for future research on this topic.
Evaluation of the corrosion of metal-based containers in contact with molten salts at high temperature under inert atmosphere
(Elsevier, 2026-10) Cabeza, Luisa F.; Martínez, Rodrigo; Borri, Emiliano; Mani Kala, Saranprabhu; Escribà-Gelonch, M.; Prieto Ríos, Cristina; Ingeniería Energética; European Union (UE); Ministerio de Ciencia e Innovación (MICIN). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Institución Catalana de Investigación y Estudios Avanzados
The reliable deployment of high-temperature thermal energy storage (TES) systems in concentrated solar power (CSP) plants requires an accurate assessment of material compatibility under realistic operating conditions. However, conventional corrosion testing in air atmosphere does not adequately represent the inert environments typically used in TES tanks, potentially leading to overly conservative material selection. This study experimentally evaluates the corrosion behaviour of PCM–metal wool composite materials under inert atmosphere conditions representative of CSP operation. Sixteen molten salt formulations, including nitrate-, carbonate-, chloride-, and sulphate-based systems, were tested in contact with metallic fibres and structural alloys (SS 314, SS 434, and Alloy 20) over a wide temperature range. The results demonstrate that inert atmosphere significantly alters material compatibility. Several PCM formulations that previously failed under air conditions exhibit acceptable behaviour under inert atmosphere, highlighting the limitations of conventional testing approaches. Nitrate- and carbonate-based systems operating between 300 and 500 °C show good compatibility with conventional alloys, whereas chloride-rich systems above 500 °C remain highly corrosive regardless of the atmosphere. These findings define a clear operational window for safe material selection. Importantly, the incorporation of metallic wool as a conductive matrix does not introduce additional corrosion penalties within this window, supporting the feasibility of PCM–metal wool composites for enhanced TES performance. This work provides experimental validation of TES materials under representative conditions and demonstrates that inert atmosphere is a critical factor for realistic material qualification in CSP applications.
Evaluating a compressed air energy storage (CAES) system with high-temperature concentrated solar power (CSP): techno-economic and sensitivity analysis
(Elsevier, 2026-12) Baigorri, Javier; Rodríguez de Arriba, Pablo Enrique; Kubikova, Tereza; Du Toit, Theunis; Romani, Jacopo; Ávila-Marín, Antonio L.; Sánchez Martínez, David Tomás; Ingeniería Energética; European Union (UE)
This study assesses the novel integration of Compressed Air Energy Storage (CAES) with high-temperature air-based Concentrated Solar Power (CSP), enabling both electricity storage and generation, as well as supplying medium-temperature waste heat to nearby industrial processes. The proposed system is analyzed for a Chilean case study using detailed annual simulations and an updated techno-economic framework. A parametric analysis is conducted for plant sizes ranging from 1 to 400 MWe, including optimization of key design and operational variables. Results reveal a pronounced dependence of economic performance on plant scale, identifying that a 100 MWe plant achieves the most attractive economics under base-case assumptions, with an Internal Rate of Return (IRR) of 5.6% and a Levelized Cost of Electricity (LCOE) of 125 USD/MWhe. Sensitivity analyses further examine the influence of electricity price fluctuations and cost-reduction pathways, highlighting the critical importance of waste heat recovery. Comparative benchmarking against alternative storage solutions — adiabatic CAES (A-CAES), CSP with an electric heater, and Battery Energy Storage Systems (BESS) — demonstrates that the competitiveness of energy storage is highly context-dependent: no single technology consistently outperforms others across all scales and market conditions. While the IRR of CAES-CSP is slightly below the assumed discount rate under base-case assumptions, the proposed configuration shows particular promise for large-scale deployment in regions with high solar irradiance, significant electricity price variability, and nearby industrial heat demand. These results provide quantitative guidance for the design and deployment of CAES-CSP systems, positioning the technology as a potential solution for supporting the energy transition in specific use cases.
Double-skin roof as a passive cooling system: Modelling and smart control performance assessment through a field experiment
(Elsevier, 2026-10) Monge Palma, Rafael; Guerrero Delgado, María del Carmen; Erba, Silvia; Castro Medina, Daniel; Sánchez Ramos, José; Pagliano, Lorenzo; Álvarez Domínguez, Servando; Ingeniería Energética; European Union (UE); TEP143: Termotecnia
Improving passive cooling performance in naturally conditioned buildings requires not only effective design solutions but also control frameworks that adapt to dynamic environmental and indoor conditions. This study develops and experimentally validates a model-based predictive control strategy for a novel double-skin roof system integrating night ventilation and evaporative cooling. The key novelty lies in coupling a lightweight physically based model with a predictive control algorithm designed for real-world implementation. A comprehensive monitoring campaign during summer 2024 captured the thermal behaviour of the roof and indoor environment across multiple operating modes for calibration and validation of the passive-cooling roof model. The smart control was implemented and assessed during the summer of 2025. This new control architecture was embedded into the existing KNX communication framework of the double-skin roof system, with the control optimiser deployed in a server service. Unlike conventional rule-based approaches, the proposed controller anticipates future conditions to optimise operation, enabling proactive night-time heat dissipation and improved cooling storage. Indoor conditions remained within the restrictive ASHRAE adaptive comfort limits for 96.6% of the time, with a maximum daily discomfort of 13%. Compared to rule-based control, overheating was reduced by an average of 11.5 percentage points, exceeding 20 points during peak summer periods. The results indicated that this new smart passive cooling roof solution can mitigate energy poverty in vulnerable contexts without requiring additional subsidies for the public administration or imposing an economic burden on householders, as its operating costs are equivalent to less than 3% of household monthly income.
Week-ahead electricity price forecasting for battery arbitrage: benchmarking ML/DL models and interpreting feature importance through merit-order pricing in Spain
(Multidisciplinary Digital Publishing Institute (MDPI), 2026-07) Khamis, Amgad; Crespi, Francesco Maria; Sánchez Martínez, David Tomás; Ingeniería Energética; European Union (UE)
Accurate electricity price forecasting is essential for market participants seeking to optimise bidding and arbitrage strategies. This paper presents a week-ahead (168 h) hourly electricity price forecasting study for the Spanish day-ahead market. Nine competing models—two naïve baselines (a Seasonal Naïve and a Day-of-Week persistence), a Lasso-estimated auto-regressive (LEAR) statistical benchmark, and six machine- and deep-learning models (CatBoost, Random Forest, LSTM, GRU, CNN, and a hybrid CNN–LSTM)—are benchmarked; the two leading models, CNN–LSTM and CatBoost, are then compared under exogenous-feature configurations. The analysis is complemented by an ex-post Add-One-In and Leave-One-Out feature-importance analysis, a controlled comparison of weather-input scenarios, and a rolling battery-arbitrage backtest that translates forecast quality into economic value. Under an endogenous benchmark of weekly rolling origins across 2024 (with a rotating start weekday) and Diebold–Mariano testing, a recursive CatBoost and the hybrid CNN–LSTM are statistically indistinguishable and both significantly outperform a direct multi-horizon CatBoost; once an operational (forecasted) weather input is added, recursive CatBoost becomes significantly the most accurate while remaining simpler and more stable to train, a ranking confirmed on a fully out-of-sample 2025 year. Operational weather forecasts are found to be the best weather input, recovering about 84% of the perfect-foresight weather improvement over a no-weather baseline, with the advantage concentrated at longer lead times. Natural-gas-fired generation emerged as the dominant explanatory feature, consistent with the marginal-pricing mechanism governing the Spanish market. In a rolling battery-arbitrage backtest on the out-of-sample 2025 year, a deployable forecast-driven 4-h grid-scale unit (200 MW/800 MWh) captured about 89% of perfect-foresight value at a 168 h optimisation horizon and about 87% at 24 h; extending the horizon from 24 h to 168 h added about 2.4% of profit, an optimisation-horizon (look-ahead) effect bounded at +4.5% under perfect foresight.
Power systems based on directly-fired oxy-combustion: A review
(Elsevier, 2026-09) López Muñoz, Giovanny Andrés; Crespi, Francesco Maria; Sánchez Martínez, David Tomás; Ingeniería Energética; European Union (UE)
Directly-fired oxy-combustion power cycles have been proposed as a promising route for high-efficiency power generation with inherent CO2 capture. However, the configurations reported in the literature have often been developed under different assumptions, nomenclatures, boundary conditions, and system boundaries, making direct comparison difficult. This work presents a systematic review of 41 directly-fired oxy-combustion power cycles and proposes a classification framework based on five defining characteristics: oxygen production method, recirculation fluid composition, reheat stages, recuperator presence, and dense-phase CO2 pressurization strategy. In addition, eight oxygen production technologies are reviewed and compared in terms of specific energy consumption, maturity, oxygen purity, production scale, and integration suitability. To support performance interpretation, reported power-block efficiencies are assessed together with the Carnot Factor (CF), used as an auxiliary temperature-normalized indicator, and statistical methods are applied to identify outliers and uncommon operating conditions based on temperature and pressure extremes. Since practical screening also depends on configuration complexity, a capital expenditure (CAPEX)-intensity indicator based on layout complexity is introduced to complement the thermodynamic comparison. Reported power-block efficiencies range from 30.0 to 71.2%, excluding hybrid SOFC-assisted SOS-CO2 configurations, which are treated separately due to their different conversion boundary. The results show that power-block efficiency is only weakly correlated with individual boundary variables, suggesting that cycle architecture, heat-recovery strategy, CO2 recycle management, oxygen-supply integration, and reporting assumptions play a more decisive role. The Allam cycle stands out as the most mature configuration, having reached demonstration in a relevant environment. Overall, the proposed classification, performance indicators, oxygen production technology comparison, and CAPEX-intensity indicator based on cycle complexity provide a structured basis for screening directly-fired oxy-combustion systems and for guiding future thermodynamic, integration, and techno-economic studies.
Techno-economic analysis of Allam-cycle systems integrating Air Separation Unit-derived nitrogen for power generation
(Elsevier, 2026-10-15) López Muñoz, Giovanny Andrés; Colnago, Alessandro; Rodríguez de Arriba, Pablo Enrique; Alfarano, Emanuela; Crespi, Francesco Maria; Sánchez Martínez, David Tomás; Ingeniería Energética; European Union (UE)
Directly fired supercritical CO2 (sCO2) power cycles have attracted growing attention for their potential to deliver high efficiency with inherent CO2 capture. Among them, the Allam cycle stands out for its advanced development stage but remains limited by the high auxiliary demand of the Air Separation Unit (ASU). This work investigates the techno-economic potential of utilizing the ASU’s nitrogen byproduct as a secondary working fluid for additional power generation. A coupled MATLAB-Thermoflex framework was developed to model both the ASU and an Allam-based power block, incorporating thermal integration and oxygen supply constraints. The proposed configuration includes an open-Brayton N2 expansion train integrated to enhance net power output without altering CO2 recirculation. Monte Carlo analysis was applied to quantify uncertainty in component cost correlations and derive percentile-based capital expenditure (CAPEX). Results show that nitrogen integration increases net power output by 16.6% with only a 0.9% rise in total CAPEX, reducing the Levelized Cost of Electricity (LCOE) by up to 8.6% under adverse natural gas price conditions. The recuperator remains the main cost driver, representing 54.4% of the power-block investment. Although the integration yields clear thermodynamic and economic benefits, the system remains below break-even (Profitability Index, PI < 1) under current cost assumptions, indicating that further CAPEX reductions or policy support would be required for commercial feasibility.
Technoeconomic assessment of an Allam-cycle-based oxygen storage system under market-driven operation
(Elsevier, 2026-12) López Muñoz, Giovanny Andrés; Rodríguez de Arriba, Pablo Enrique; Colnago, Alessandro; Alfarano, Emanuela; Crespi, Francesco Maria; Sánchez Martínez, David Tomás; Ingeniería Energética; European Union (UE)
This work presents a technoeconomic assessment of an Allam cycle-based energy storage system, evaluated under Spanish electricity market conditions, where oxygen is produced, stored, and later used to decouple power generation from air separation. The analysis compares two configurations, a conventional Allam cycle and an Allam-storage system, benchmarked against a reference Natural Gas Combined Cycle (NGCC). Three natural gas (NG) price scenarios representative of recent Spanish market conditions were examined, and two capital expenditure (CAPEX) levels were considered through a Monte Carlo-based uncertainty analysis. The Allam-storage configuration operates under a peak–off-peak strategy, purchasing low-price electricity for oxygen production and selling power during high-price periods. Across all scenarios, integrating storage consistently improved performance, reducing the Levelized Cost of Electricity (LCOE) by up to 13.1% and increasing the Profitability Index (PI) by up to 13.0%. Compared with the NGCC including carbon taxes (65.29 €/tCO2), both Allam-based systems achieved better technoeconomic performance despite 47%–79% higher CAPEX, with PI improvements of up to 59%. Optimal storage capacities ranged between 25 and 29 h depending on fuel price. Although still unprofitable under current market conditions, the inclusion of oxygen storage enhances technoeconomic performance and market adaptability, enabling the Allam cycle to exploit price volatility and potentially contribute to future high-renewable power systems.
A profitability index for rural biomass district heating systems evaluation
(Elsevier, 2023-11) Soltero Sánchez, Víctor Manuel; Quirosa Jiménez, Gonzalo; Rodríguez Pastor, Diego Antonio; Peralta, Estela; Ortiz Domínguez, Carlos; Chacartegui, Ricardo; Ingeniería del Diseño; Ingeniería Energética; TEP137: Máquinas y Motores Térmicos; TEP992: Diseño e Ingeniería
Biomass heating networks are an efficient and low-emission alternative for rural municipalities without natural gas supply. One of the main challenges for their implementation on a larger scale is to reduce the uncertainty in the profitability evaluation. The linear heat density is the index commonly used to evaluate the potential for heating networks investments. It provides highly accurate estimations in high-density building networks. However, it does not provide accurate enough evaluations for low-building-density networks, resulting in relevant deviations when applied to biomass district heating networks. This work proposes a new index to evaluate the profitability of biomass heating networks in rural environments based on the analysis of investment, operation, and biomass costs. It is developed based on the cost-benefit analysis of biomass heating networks. The new index has been applied to 499 rural municipalities in Spain, showing a high accuracy in estimating the profitability of investments, with R2 values between 0.8179 and 0.9442, compared to 0.2408 if linear heat density was used for the same cases. The analyses show the interest of this approach for the evaluation of biomass district heating potential in areas with dispersed populations.
A new predictive model for the design and evaluation of bifacial photovoltaic plants under the influence of vegetation soils
(Elsevier, 2023-01-20) Rodríguez Pastor, Diego Antonio; Franco Ildefonso Sánchez, Alexander; Soltero Sánchez, Víctor Manuel; Peralta, Estela; Chacartegui, Ricardo; Ingeniería Energética; Ingeniería del Diseño; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla; TEP137: Máquinas y Motores Térmicos; TEP992: Diseño e Ingeniería
The rapid expansion of photovoltaics within the global energy market requires increasing use of land, a limited resource where different uses compete. In this respect, photovoltaic systems that combine electricity generation with land use for crops are becoming increasingly important. This article proposes an analytical model validated in an operating bifacial photovoltaic plant during the summer months. This analytical model considers view factors and heat transfer calculations, as well as an electrical model of the photovoltaic modules. A study was carried out on a commercial solar power plant (11.24 MWp) in Seville, southern Spain, where different vegetal species were planted in two strings, and string performance was monitored. Nine crop species with different irrigation and light requirements, offering different albedo parameters and thermal characteristics. The results show advantages from the point of view of module temperature and power gain. This paper provides regressions for the characterisation of the photovoltaic agricultural plant, with R² higher than 85%, both for module temperature and energy exported in the string with crops.
Overview of the MAST Upgrade physics programme: testing novel concepts at low aspect ratio to inform future devices
(IOP Publishing, 2026) Harrison, J.R.; Aboutaleb, A.; Aljunid, M.; Allan, S.Y.; Allan, R.; Alli, A.; Cano Megías, Pilar; Galdón Quiroga, Joaquín; Rivero Rodríguez, Juan Francisco; Viezzer, Eleonora; Ingeniería Energética; Física Atómica, Molecular y Nuclear; Ingeniería Mecánica y Fabricación; European Union (UE)
The research programme performed on the Mega Amp Spherical Tokamak (MAST) Upgrade experiment has made significant advances in developing the physics understanding of low aspect ratio tokamaks in support of the operation of ITER and design of fusion powerplants. High performance plasma scenarios have been developed to facilitate a broad programme of experiments, in which confinement is constrained by the presence of m/n = 2/1 modes that cause substantial losses of fast ions. The onset of these modes coincides with the q = 2 surface residing in a local minimum in the toroidal current density profile. The maximum electron temperature at the pedestal top, Te,ped is limited with gas fuelling to ∼350 eV to maintain regular ELMs; higher Te,ped results in a transition to a non-stationary ELM-free regime. The operational space of spherical tokamaks has been expanded into small and ELM-free regimes. Strong shaping of the last closed flux surface can induce a transition from large to small ELMs, and ELM suppression with resonant magnetic perturbations has been observed for the first time in a low aspect ratio tokamak. Negative triangularity shaping has induced a transition from ELMy H-mode to a high-performance L-mode regime for the first time in a low aspect ratio tokamak. In studies of fast ion confinement, losses of fast particles due to Global Alfvén Eigenmodes have been identified. Interactions between fast ions generated by off-axis neutral beam injection and thermal neutrals can result in significant losses of fast ions. Experiments with on- and off-axis neutral beam injection exhibit a flux pumping mechanism, where the central safety factor is held to ∼1 in the absence of sawteeth. In studies of pedestal physics, it has been found that elevated main chamber neutral pressures result in an increase in the electron density and reduction in the temperature at the pedestal top. Advances in understanding plasma exhaust include the integration of a high-performance plasma core with detached outer divertors in the X-point target configuration. A newly commissioned lower divertor cryopump reduces the lower divertor neutral pressure by up to 50%, with minimal effect on the main chamber or upper divertor. New measurements and SOLPS-ITER simulations emphasise the importance of plasma–neutral interactions on divertor detachment in the conditions accessible in experiments. Real-time control of the ionisation front location in both divertor chambers independently has been demonstrated in double null experiments, enabled by the tightly baffled divertor chambers.
Separatrix ion to electron temperature ratio in the TCV and ASDEX Upgrade tokamaks
(IOP Publishing, 2025-09) Cavedon, M.; Brida, D.; Bagnato, F.; Coosemans, R. A.; Reimerdes, H.; Cano Megías, Pilar; Dux, R.; Eich, T.; Février, O.; EUROfusion Tokamak Exploitation Team; Ingeniería Energética; European Union (UE); EUROfusion Consortium; Swiss National Science Foundation (SNFS); Swiss State Secretariat for Education, Research and Innovation (SERI)
Increased focus has been recently given to the ion temperature Ti near the separatrix and in the scrape-off layer (SOL) due to its impact on plasma confinement, wall sputtering, heat fluxes, and edge turbulence. In current tokamaks, high pedestal collisionality often clamps pedestal top ion and electron temperatures together. However, thermal decoupling occurs in the SOL due to the different ion and electron masses, leading to Ti/Te > 1 at the separatrix and in the SOL. Despite consistently observing elevated Ti relative to Te near the separatrix in various tokamaks, a comprehensive study remains missing due to the measurement complexity. This study, for the first time, explores the primary dependencies of Ti/Te at the separatrix, focusing on the variation of electron density and connection length to scan SOL collisionalities, and the variation of input power to scan ion and electron heat fluxes, in the ASDEX Upgrade and TCV tokamaks. Surprisingly, Ti/Te shows weak or no dependence on electron density and connection length, despite their expected role in the SOL coupling. However, the Ti/Te ratio is strongly influenced by ion and electron heating levels in the plasma core. This suggests that the upstream Ti/Te is primarily regulated by relative ion and electron heat fluxes from the core, with coupling playing a minor role.
Observation of bi-directional global Alfvén eigenmodes in the MAST-U tokamak
(IOP Publishing, 2025) Dreval, M.B.; Oliver, H.J.C.; Sharapov, S. E.; Rivero Rodríguez, Juan Francisco; Fitzgerald, M.; Michael, C.; Ochoukov, R.; Velarde Gallardo, Lina; Cecconello, M.; The MAST-U team; Ingeniería Energética; European Union (UE); Engineering and Physical Sciences Research Council (UK); National Research Foundation of Ukraine
The first observations and classification of deuterium beam-driven sub-cyclotron frequency range Alfvén eigenmodes (AEs) are presented for the MAST-Upgrade tokamak. Sets of observed eigenmodes are separated in frequency by approximately 200 kHz. We observe a lower frequency separation of ∼10 kHz within each set, and the toroidal mode number n increases with frequency sequentially. The ∼200 kHz step between the sets coincides with the interval between successive curves of the Shear Alfvén continuum according to linear ideal MHD modeling. The sub-cyclotron frequency AEs can be identified as the global AEs (GAEs) localized at the continuum extrema regions. Each set contains the same range of n. These observations are consistent with our GAE modeling. In low plasma current (Ip) discharges, we observe only GAEs propagating counter to the plasma current and the beam direction. These GAEs are located near the magnetic axis. We observe counter and co-propagating GAEs simultaneously in higher Ip discharges. The co-propagating GAEs occur because of the formation of second continuum minima. Very flat safety factor profiles in higher Ip MAST-U discharges give rise to these minima. They are located at around half of the plasma radius. The GAEs have properties that are very different to those of compressional AEs previously reported for the MAST tokamak with low magnetic fields (Sharapov et al 2014 Phys. Plasmas 21 082501) before the upgrade.
CO2 sequestration potential in Depleted Hydrocarbon fields – A geochemical approach
(2025) Gianni, Eleni; Tyrologou, Pavlos; Behnous, Dounya; Pál Farkas, Márton; Fernández-Canteli Álvarez, Paula; García Crespo, Jesús; Chacartegui, Ricardo; Koukouzas, Nikolaos; Carneiro, Júlio; Ingeniería Energética; European Union (UE)
Background The CO2 emissions reduction is crucial for the energy transition. New technologies for CO2 capture and storage are under development, such as CEEGS 1,2 . Porous media and rock caverns are geological formations of high interest for such technology. Among them, depleted hydrocarbon fields (DHF) gain ground due to existing reservoir knowledge and already established infrastructure which decreases the cost. However, one of the major problems caused during CO2 storage in DHF is the interactions between the injected CO2 and the remaining fluids. Methods In this study, the potential CO2 storage in DHF was investigated. Marismas 3 was used as a hypothetical model area for the examination of CO2 interactions with a carbonate-silisiclastic reservoir. PHREEQC software 1 was used to investigate reservoir rock/water/remained gas (CH4) interactions followed by interactions taking place after the CO2 injection. Different scenarios were used for the CO2 concentration and behaviour in the reservoir. To make the system more complex and generic, the CMG-GEM software 3 was utilized to examine the long-term sequestration of CO2 through dissolution trapping, residual trapping, and lateral migration in a reservoir analogue to the Marismas field, but at higher depth, compatible with the CEEGS technology. Results During the CO2 injection, carbonic acid was formed, causing a dissolution of several minerals, leading to siderite and clay minerals precipitation, which may cause problems to the permeability of the system. The colloidal nature of siderite and the Ca-montmorillonite swelling properties are of high concern for pore throat clogging. The other newly formed mineralogical phases are not threatening the reservoir quality. CMG-GEM validated the critical phase of CO2 plume establishment. Conclusions The proposed DHF is promising for real-world underground applications fitting to CEEGS technology as the newly formed minerals that could cause failures can be easily controlled by anthropogenic changes in the reservoir parameters.
Operational dynamics and long-term stability in the novel CO2-based electrothermal energy and geological storage system in salt cavities
(Elsevier, 2026) Carro Paulete, Andrés; Carneiro, J.; Unger, S.; Behnous, D.; Fogel, S.; Chacartegui, Ricardo; Ingeniería Energética; European Commission (EC); Ministerio de Ciencia, Innovación y Universidades (MICIU). España
The massive integration of renewable energy sources and the development of advanced technologies to mitigate climate change are key factors in the energy transition towards a sustainable model. Increasing the contribution of renewables to the electricity market requires developing new energy storage systems. The novel CO2-based electrothermal energy and geological storage system could be a viable option for large-scale storage in renewable power generation plants in the near future. This system utilises transcritical CO2 cycles to convert electrical energy into thermal and mechanical energy, enabling integration with carbon capture and storage systems in geological formations, with an initial efficiency range of 52.8–61.5%. This dual approach enhances energy storage capabilities and contributes to reducing atmospheric CO2 levels, offering a sustainable solution to address both energy and environmental challenges. This study evaluates, for the first time, the subsurface potential as a thermohydraulic buffer that ensures long-term operational stability and pressure management. Through long-term temporal simulations, a numerical model featuring coupled thermohydraulic simulations has been developed to incorporate subsurface heat transfer processes, considering a salt cavern scenario. Different scenarios are analysed depending on the characteristics of the production/injection processes, well depth, cavern size, or storage time. The research identifies a critical transition from an initial transient phase to a dynamic steady state. The results demonstrate that while operational fluid streams almost entirely govern the system’s short-term energetic response, geothermal interaction could be critical for long-term stabilisation. The energy gain during injection directly influences the required CO2 conditions at the wellhead. Wellhead pressure and temperature must be adjusted according to the desired conditions at the bottomhole. Maintaining high-pressure conditions in the salt cavern is essential to ensure proper coupling with the surface cycles and to operate with high electricity-to-electricity conversion efficiencies, reaching the range of 50.3–65.6% when the pressure approaches the upper limit. Active management of mass flow rates and pressures, along with advanced thermal control strategies, will be essential to improve system efficiency and flexibility.
Power Consumption and Rubber Phase Evolution in an Intermeshing Mixer: A Three-Dimensional Non-Newtonian Volume-of-Fluid Computational Fluid Dynamics Analysis
(Multidisciplinary Digital Publishing Institute (MDPI), 2026-05) Osman, Fareed Konadu; Hou, Dandan; Han, Lei; Zhou, Qi; Gao, Jie; Zhang, Chunsheng; Miao, Leilei; Iranzo Paricio, José Alfredo; Ingeniería Energética; National Natural Science Foundation of China
This study investigates the influence of key operating parameters of fill factor, rotor speed, and rotor wear on the power consumption of an isothermal intermeshing internal mixer. A three-dimensional computational fluid dynamics (CFD) model incorporating dynamic remeshing was developed using the finite volume method to solve the continuity and momentum equations for non-Newtonian rubber flow. The dynamic remeshing approach enabled accurate tracking of the moving rotor geometry and maintained mesh quality under varying operating conditions. The model integrates the actual mixer geometry and rheological properties of the rubber, and was validated against plant-scale power consumption data, showing good agreement. Simulations were performed across a range of operating conditions to quantify the effects of each parameter. Results indicate that increasing the fill factor from 50% to 82% raises normalized power from 14–19 kW/% to 17–22 kW/%, with higher levels producing extensive shear stress coverage to the rotor barrels but at the cost of potential clogging and reduced energy efficiency. Increasing rotor speed from 35 to 60 rpm increases normalized power from 20–22 kW/rpm to 22–23 kW/rpm, as higher rotor speeds intensify the local shear stress and strain rate fields near the rotor tips, thereby increasing power consumption. Rotor wear was found to significantly influence power consumption, with increasing wear leading to a progressive reduction in energy demand. The results indicate that worn rotor conditions reduce mechanical energy transfer due to diminished rotor–material interaction and increased clearances, resulting in lower shear stress generation within the mixing chamber. These findings identify operational windows that minimize energy costs while maintaining effective wall shear stress, offering practical guidance for optimizing mixer performance.
Overview of the ASDEX Upgrade results
(IOP Publishing, 2026-05) Pütterich, T.; Albrecht, F.; Alessi, E.; An, S.; Cano Megías, Pilar; Cruz Zabala, Diego José; Zohm, H.; Zoletnik, S.; Ingeniería Energética; European Union (UE)
After a 26-month vent ASDEX Upgrade (AUG) went back in operation with a newly designed upper W-divertor suitable for alternative divertor configurations (featuring in-vessel coils and cryo-pump). Parameter scans and an extensive set of measurements were obtained and their interpretation is ongoing. Prompted by the ITER wall change, dedicated experiments on non-boronized plasma startup were contrasted to that employing asymmetric and more symmetric boronizations. The asymmetric boronization proved to be as beneficial as the more symmetric one, which is in contrast to previous model calculations assuming perfect sticking of boron (measurements suggest sticking ≈ 0.3). In the startup phase also the impurity influxes at the outboard limiters were investigated contrasting the unboronized case featuring cold edges (low-Z radiation) to the boronized case, in which the lifetime of the boron layers could be estimated. Pedestal stability investigations revealed that the quasi-continuous exhaust (QCE) regime is obtained when ballooning modes are active in the vicinity of the separatrix and the global peeling-ballooning stability is high enough. Thus, at high enough shaping and high gas flux both can be achieved and QCE is a consequence. The closely related enhanced D-alpha (EDA) mode is not clearly distinguishable from QCE, e.g. the quasi-coherent mode characteristic for EDA also shows up in QCE. In QCE the impurity transport is behaving benign as could be measured for Ne with a novel analysis method making use of a comprehensive set of CXRS measurements. For high radiative fractions the regime of the X-point radiator (XPR) is accessible at AUG and the understanding of its access conditions and behaviour is further developed. Due to the localized radiative cooling at the X-point the XPR can be well diagnosed and thus controlled. For negative triangularity shapes, further experiments at increased shaping resulted in strongly heated L-mode plasmas avoiding ELMs. Two integrated modelling approaches towards ITER suggested that core W-accumulation will be no issue for ITER and that the fusion yield in ITER may be Q = 12 (i.e. ITPA20-IL scaling is too pessimistic). Further, investigations of the ITER ramp-down in AUG provide insights into maintaining position control. Various aspects of shattered pellet injection were investigated in AUG and one of the results show that with increasing Ne fraction the radiation during the current quench increases and the current decay becomes faster.
Combined cooling for CSP plants: Modeling, experimental validation and optimization analysis
(Elsevier, 2026-02) Serrano, Juan Miguel; Palenzuela, Patricia; Ruiz, Javier; Navarro, Pedro; Muñoz-Cámara, José; Ortega Delgado, Bartolomé; Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
The global development of Concentrated Solar Thermal Power (CSP) projects demands new technologies that enhance the thermal efficiency of power cycles without increasing costs or environmental impact. Among the subsystems of the power cycle, the cooling circuit plays a critical role, as it must minimize water consumption while maintaining high efficiency; a challenge that is particularly relevant in arid regions where many CSP plants are installed. This paper presents a model for a cooling system that combines Dry Cooling (DC) and Wet Cooling Tower (WCT) technologies, enabling multiple operating configurations (parallel, series, parallel–series, only-WCT, and only-DC). The model was validated using experimental data from a 200 kWth pilot plant, achieving a Mean Absolute Error (MAE) below 0.97 ºC for system temperatures and 19.4 l/h for water consumption. An optimization analysis was also performed, demonstrating the potential of the proposed technology to provide adaptive cooling for CSP plants under varying seasonal and operating conditions. For the pilot plant during summer, optimally combining DC and WCT in a parallel series configuration enabled a nearly continuous variation in specific electricity consumption, ranging from 0.06 kWe/kWth in only-DC operation to values up to 90 % lower in only-WCT mode, at a water usage cost of 1.48 l/kWhth.
Thermal conductivity of phase change materials in solid state at high temperature
(Elsevier, 2026-10) Mani Kala, Saranprabhu; Ribezzo, Alessandro; Borri, Emiliano; Prieto Ríos, Cristina; Cabeza, Luisa F.; Ingeniería Energética; European Union (UE); Ministerio de Ciencia e Innovación (MICIN). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
The portfolio of phase change material (PCM) candidates available for high temperature applications that are fully characterized in the solid-phase within these elevated temperature ranges is limited. In this study, 11 PCM candidates—previously proposed for high-temperature applications—were experimentally characterized in terms of solid-phase thermal conductivity at both room (20 °C) and high temperature (300 °C). The results revealed a substantial and general decrease in solid-phase thermal conductivity with increasing temperature, highlighting the importance of conducting thermal characterization at high temperature. These PCM candidates were subsequently compared with the few PCMs reported in the literature for similar applications and characterized within the same temperature ranges, by considering the solid-phase thermal conductivity analyzed in study, as well as the melting temperature and latent heat obtained from a previous study. Thanks to this, a comprehensive comparative map of PCM candidates fully characterized in the solid state at high temperature was finally presented (≥300 °C).
Life cycle assessment of a novel CO2-based electrothermal energy and geological storage system
(Elsevier, 2026-10) Marques Valderrama, Abraham; Carro Paulete, Andrés; Peralta-Álvarez, María Estela; Farkas, Márton Pál; Carneiro, J.; García-Crespo, J.; Papadopoulou, Simira; Gianni, E.; Chacartegui, Ricardo; Ingeniería Energética; Ingeniería del Diseño; European Commission (EC)
Long-duration energy storage is increasingly required to support power systems with high shares of variable renewable energy. The CEEGS (CO₂-based Electrothermal Energy and Geological Storage) system is an emerging, low-TRL Carnot battery concept that combines a transcritical CO₂ electrothermal cycle with geological CO₂ storage to provide long-duration electricity storage. This study presents the first life cycle assessment (LCA) of the CEEGS concept, focusing on identifying environmental hotspots and the influence of plant scale and electricity supply at an early stage of technology development. An attributional cradle-to-gate LCA was conducted in accordance with ISO 14040/44 standards using the ReCiPe H method, with a functional unit of 1 MWh of electricity delivered. Six scenarios were analysed, combining two plant capacities (5 and 100 MW) and three electricity supply options for the charging phase. The results show that electricity supply dominates the environmental profile when grid-mix electricity is used, whereas the use of renewable electricity substantially reduces overall impacts and shifts the contribution toward electrothermal equipment, geological infrastructure and CO₂ transport. Scenarios based on surplus renewable electricity represent lower-bound estimates under conditions of high renewable availability. Increasing plant size leads to lower impacts per unit of electricity delivered, particularly for CO₂ transport and electrothermal components, due to infrastructure amortisation effects. Scaling the system from 5 to 100 MW reduces the impacts of CO₂ transport by over 50% and of electrothermal equipment by 5–10%, showing that larger systems amortise infrastructure more effectively. The study highlights the key parameters governing the environmental performance of the CEEGS concept and how it can achieve competitive environmental performance, based on LCA, environmental decision-making, and design optimisation at low technology readiness levels.

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