Artículos (Ingeniería Energética)

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

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Technical review of commercial LT-PEMFC technologies: Performance, applications and challenges
(Elsevier, 2025) Vallejo Cervantes, Carlos; Espinoza Andaluz, Mayken; Iranzo Paricio, José Alfredo; Ingeniería Energética; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
This manuscript presents a comprehensive technical review of low-temperature proton exchange membrane fuel cells (LT-PEMFCs), focusing on their performance, applications and current challenges within commercial contexts. LT-PEMFCs have reached commercial deployment in light-duty vehicles, buses, trains, heavy-duty trucks, stationary combined heat and power units and early maritime platforms. This review consolidates datasheet-based specifications and reconstructed performance parameters from leading manufacturers, complemented by qualitative evidence from large-scale deployments in Japan and China, to provide the first cross-sectoral benchmarking of LT-PEMFC systems. The analysis is structured around the key performance indicators (KPIs) of the Clean Hydrogen Joint Undertaking and the U.S. Department of Energy, which define quantitative targets for 2024 and 2030. Results show that while several light-duty and bus platforms already meet or approach KPI compliance for hydrogen consumption and efficiency, other sectors such as heavy-duty, stationary and maritime remain below target ranges due to integration constraints and limited transparency in datasheet reporting. The study further highlights divergences between laboratory-reported stack metrics and commercial module specifications, demonstrating the need for harmonized definitions of volumetric power density, efficiency at rated power and durability. By situating catalogue-only and prototype systems within the technological pipeline, the review clarifies how near-term developments may close performance gaps and reduce platinum dependency, while also acknowledging the economic and infrastructural dimensions that condition future adoption. This includes recent advances in PGM-free catalysts, alloyed and core–shell architectures, and ionomer-free electrodes, which complement low-PGM approaches in reducing material cost and supply risk. The contribution lies in delivering a transparent and replicable framework that not only maps the current state of LT-PEMFC commercialization but also provides directionality for research, policy and industrial innovation on the pathway to 2030 deployment objectives. This represents the first systematic cross-sectoral benchmarking of LT-PEMFCs that integrates datasheet-derived and reconstructed specifications with DOE and CHJU KPI frameworks, providing both quantitative visualizations and a replicable methodology that clarifies current achievements while indicating where targeted innovation is needed to reach 2030 objectives.
Avoidable exergy performance analysis in the integration of an electrothermal energy system based on transcritical CO2 cycles
(Elsevier, 2026-01-15) Guisado Falante, José Manuel; Carro Paulete, Andrés; Chacartegui, Ricardo; Ingeniería Energética; European Commission (EC)
This paper develops an exergy approach to analyse avoidable exergy destruction in complex systems, which can lead to significant results when applied to storage systems. The proposed methodology in this paper has been applied to a novel CO2 electrothermal energy and geological storage system. The methodology follows a two-step approach. In the first stage, an analysis of the different components individually, considering their operational characteristics, identifies their thermodynamic limits and the related unavoidable exergy destruction in each component. In a second stage, the exergy study at the system level, which comprises off-design models, integrates the components and provides valuable insights into the system’s dynamic behaviour based on the interaction between components. The avoidable exergy performance is defined as the comparison between the avoidable exergy destruction of the system and the unavoidable exergy of the components, which can be used as an indicator of the integration impact. For the case of the novel energy storage concept, the individual study of the components has shown that the unavoidable exergy destruction takes a value of 22.69 kJ/kgCO2, and the compressor is the most critical component. The dynamic behaviour of the system based on integration has shown that the avoidable exergy destruction, under these conditions, is 32.77 kJ/kgCO2 when the load rate takes an optimal value, achieving an avoidable exergy performance of 75.3 %. These results lead that under optimal conditions, the system cannot achieve the unavoidable exergy destruction, which is based on opposing behaviours between the components. The sensitivity analysis based on design parameters leads to an improved avoidable exergy performance of up to 18.2 %.
Indirect power cycles integration in concentrated solar power plants with thermochemical energy storage based on calcium hydroxide technology
(Elsevier, 2023-10-01) Carro Paulete, Andrés; Chacartegui, Ricardo; Ortiz, Carlos; Becerra González, Juan Antonio; Ingeniería Energética; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); European Union (UE); Ministerio de Ciencia e Innovación (MICIN). España
Thermochemical energy storage is attracting interest as a relevant alternative energy storage system in concentrating solar power plants. Efficient, low-cost, and environmentally friendly thermal energy storage is one of the main challenges for the large-scale deployment of solar energy. The reversible hydration/dehydration process of calcium oxide is one of the most promising concepts for energy storage integration at intermediate temperatures in solar plants. The efficient integration of concentrated solar power with a thermochemical energy storage system based on the calcium hydroxide concept, individually or integrated into a hybrid system with sensible heat storage, can be a feasible solution for long-term energy storage. Efficient energy recovery and subsequent power production are crucial. This work presents a novel analysis of the indirect integration of different power cycle configurations to optimise the roundtrip efficiency of the system. Steam Rankine, closed CO2 Brayton, and organic Rankine cycles are considered. The analyses show power block efficiencies in the range of 38–50%, with a global roundtrip efficiency of 37.1% in the case of the CO2 supercritical cycle.
Integration of calcium looping and calcium hydroxide thermochemical systems for energy storage and power production in concentrating solar power plants
(Elsevier, 2023-11-15) Carro Paulete, Andrés; Chacartegui, Ricardo; Ortiz, Carlos; Arcenegui Troya, Juan Jesús; Pérez Maqueda, L. A.; Becerra González, Juan Antonio; Ingeniería Energética; Electrónica y Electromagnetismo; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); European Union; Ministerio de Ciencia e Innovación (MICIN). España
Energy storage is a key factor in the development of renewables-based electrical power systems. In recent years, the thermochemical energy storage system based on calcium-looping has emerged as an alternative to molten salts for energy storage in high-temperature concentrated solar power plants. This technology still presents some challenges that could be solved by integrating the thermochemical energy storage system based on calcium hydroxide. This work studies a novel concentrated solar power system integrating calcium-looping and calcium hydroxide thermochemical energy storage systems. The results show that the combined use of hydration-dehydration cycles in the calcination-carbonation processes of the calcium looping for energy storage could partially solve the issue related to the multicyclic deactivation of calcium oxide. The improvement in the conversion of calcium oxide during carbonation is demonstrated experimentally when hydration-dehydration cycles are combined. Numerical simulations demonstrate the technical feasibility of the integrated process, with efficiencies ranging between 38-46%, improved with the increase in calcium oxide conversion in the carbonator, showing the potential of the proposed integration.
Integration of energy storage systems based on transcritical CO2: Concept of CO2 based electrothermal energy and geological storage
(Elsevier, 2022-01-01) Carro Paulete, Andrés; Chacartegui, Ricardo; Ortiz, Carlos; Carneiro, Julio; Becerra González, Juan Antonio; Ingeniería Energética; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Energy storage systems are crucial for the massive deployment of renewable energy at a large scale. This paper presents a conceptual large-scale thermoelectrical energy storage system based on a transcritical CO2 cycle. The concept is developed through the analysis of three high-efficiency systems: renewable energy storage using a thermoelectric energy storage system based on a reversible heat pump; a CO2 storage system; and novel integration of energy storage using a reversible heat pump and geological injection of CO2. The latter system efficiently integrates energy and CO2 storage, taking advantage of the synergies between the operational requirements of both systems. The system uses CO2 captured in stationary sources as a working fluid to store energy from renewables. The energy is stored and recovered in geological formation and heat/cold tanks, with energy storage based on sensible or latent heat of ice and water. A fraction of the CO2 is expected to be permanently sequestered in the geological formation. The analysis of the time evolution of the system, under different operation profiles, shows the interest of the concept as a feasible integration for energy storage and CO2 capture based on renewable energy, with an electric-to-electric efficiency varying between 40 and 50 %.
Analysis of a thermochemical energy storage system based on the reversible Ca(OH)2/CaO reaction
(Elsevier, 2022-12-15) Carro Paulete, Andrés; Chacartegui, Ricardo; Ortiz, Carlos; Becerra González, Juan Antonio; Ingeniería Energética; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
The development of novel energy storage technologies is crucial for the massive deployment of large-scale renewable energy systems. This paper presents the conceptual study of an integrated system for the large-scale storage of solar thermal energy in the form of thermochemical energy based on calcium hydroxide. Calcium oxide-based storage media are very promising because they are an abundant and inexpensive resource with high energy density and the possibility of storage under ambient conditions. The equilibrium temperature of the reaction is around 500 °C, so the integrated system operates in a temperature range similar to that of concentrating solar power plants and molten salt storage, being able to reach higher temperatures in power production depending on the partial pressure of the steam generated in the reaction. The study discusses the technological challenges of the system, highlighting the importance of recovering the latent heat from condensation of the steam generated in the dehydration reaction, which represents 38% of the solar thermal energy entering the reactor during the charging phase, and proposes recovery mechanisms. The analysis shows the potential competitiveness of the technology as a large-scale energy storage system. By considering the full recovery of the latent heat of the steam, the system achieves a round-trip thermal efficiency of more than 80%, an overall thermal-to-electrical efficiency of 40% and LCOE values of 100 USD/MWhe.
Energy storage system based on transcritical CO2 cycles and geological storage
(Elsevier, 2021-07-05) Carro Paulete, Andrés; Chacartegui, Ricardo; Ortiz, Carlos; Carneiro, Julio; Becerra González, Juan Antonio; Ingeniería Energética
The use of CO2 as a working fluid in power generation and storage applications has experienced a significant boost in recent years, based on its high-performance characteristics in power generation or heat pumps. This work proposes a novel combined use of transcritical CO2 cycles as an energy storage system and carbon dioxide storage inside geological formations. In this work, the layouts for concept integration were developed. They were adapted to operate under different scenarios and operation modes based on storing energy from renewable sources or storing energy to capture CO2. The preliminary results show these cycles as promising energy storage technologies, with a high potential to compete in terms of electric to electric storage efficiencies (42–56%) and costs (70–120 USD/MWh). Besides, results show that more than 1 Mton/year of CO2 could be additionally stored with this renewable energy storage concept depending on the conditions. These results show the opportunity for the concept as an energy storage system, with special interest when combined with carbon-intensive industries as cement or chemicals.
Optimising supercritical CO2 saturation and reservoir conditions for geological energy storage with transcritical carbon dioxide systems
(Elsevier, 2025-12) Behnous, Dounya; Carneiro, Julio; Carro Paulete, Andrés; Canteli, Paula; Chacartegui, Ricardo; Crespo, Jesús G.; Tyrologou, Pavlos; Koukouzas, Nikolaos; Ingeniería Energética; European Commission (EC)
The CO2-based Electrothermal Energy and Geological Storage (CEEGS) system integrates energy storage with CO2 sequestration by storing excess renewable energy as supercritical CO2, which is back-produced for power generation. This study investigates reservoir (porosity, permeability, relative permeability, heterogeneity, anisotropy) and operational (injection rates, shut-in periods) parameters to maximise CO2 saturation near the wellbore and minimise water co-production, critical for the energy storage capacity and operation of the surface transcritical CO2 power cycles. Using CMG-STARS and CMOST-AI, we conducted a sensitivity analysis across injection rates (5–100 kg/s), porosity (0.05–0.25), permeability (10–1000 mD), and heterogeneity (C.V. 0.1–1.5). Results show that injection rates of 30–40 kg/s, porosity of 0.05–0.15, and low heterogeneity (C.V. <0.25) achieve gas saturation up o 76 % with water production below 0.1 kg/s. Shut-in periods should not exceed 3 months to limit saturation losses. These findings provide a robust framework for optimising the CEEGS site selection and operation definition, ensuring supercritical CO2 back production with adequate characteristics for efficient energy storage and operation.
Analysis of fast-ion losses measured in MAST-U via infrared thermography and a Fast Ion Loss Detector
(Elsevier, 2025) Velarde Gallardo, Lina; Hidalgo-Salaverri, J.; Rivero Rodríguez, Juan Francisco; Tookey, A.; Simic, G.; Ryan, P.; Galdón-Quiroga, J.; Chacartegui, Ricardo; García Muñoz, Manuel; Mcclements, K. G.; Ingeniería Energética; Ingeniería Mecánica y Fabricación; Física Atómica, Molecular y Nuclear; European Union (UE); Engineering and Physical Sciences Research Council (UK); Junta de Andalucía
Fast-ion losses need to be monitored to avoid damage to plasma facing components. In existing experimental devices, the scintillator-based fast-ion loss detector (FILD) is the most advanced diagnostic for measuring fast-ion losses. However, FILDs provide only local information about the losses. Infrared (IR) thermography can be used as a complementary tool for more global monitoring of the deposition of fast-ion losses on the wall, at the expense of no velocity-space resolution. IR cameras measure the temperature of the plasma facing components. This measurement, determined by a combined effect of the thermal plasma, radiation, neutrons and fast-ion losses, can be decomposed to infer the fast-ion load on the tokamak wall. In this manuscript, a workflow to estimate fast-ion losses via IR thermography is applied to the MAST-U spherical tokamak, using a 1D approximation to extract the experimental heat flux on the FILD front face from IR data. To numerically estimate the different contributions to this total heat flux, the field-line tracing environment SMITER is used to calculate the thermal plasma contribution, the orbit-following Monte-Carlo code ASCOT to estimate the fast-ion losses, and bolometry measurements for the radiation. To validate the workflow, two discharges, L-mode plasmas with low MHD activity, were executed using on and off-axis beams, respectively. The experimentally and numerically estimated heat flux are of the same order of magnitude for the on-axis heated scenario, with a strong dependence of the estimated fast-ion losses contribution on the fit to the kinetic profiles used as input. This is also true for the off-axis heated scenario, where the total numerically estimated heat flux is 2.1 or 1.3 times higher than the maximum experimentally estimated heat flux, depending on the ASCOT input used.
The Influence of Electrostatic Separation Parameters on the Recovery of Metals from Pre-Crushed PCBs
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) López-Paneque, Antonio Manuel; Gallardo García-Orta, Victoria Humildad; Gallardo Fuentes, José María; Sepúlveda Ferrer, Ranier Enrique; Chicardi Augusto, Ernesto; Ingeniería Energética; Ingeniería y Ciencia de los Materiales y del Transporte; European Institute of Innovation and Technology (EIT)
Electrostatic separation is a promising technology for the recovery of valuable metals from electronic waste, particularly from printed circuit boards (PCBs). This study explores the application of electrostatic separation for the selective recovery of metallic and non-metallic fractions from crushed PCBs (PCBs). The process exploits the differences in electrical properties between conductive metals and non-conductive polymers and ceramics, facilitating their separation through applied electric fields. The raw materials were pre-treated via mechanical comminution using shredders and hammer mills to achieve an optimal particle size distribution (<3 mm), which enhances separation efficiency. Ferrous materials were removed prior to electrostatic separation to improve process selectivity. Key operational parameters, including particle size, charge accumulation, environmental conditions, and separation efficiency, were systematically analysed. The results demonstrate that electrostatic separation effectively recovers high-value metals such as copper and gold while minimizing material losses. Additionally, the process contributes to the sustainability of e-waste recycling by enabling the recovery of non-metallic fractions for potential secondary applications. This work underscores the significance of electrostatic separation as a viable technique for e-waste management and highlights optimization strategies for enhancing its performance in large-scale recycling operations.
Experimental minimization of pilot diesel injection for stable hydrogen combustion in compression ignition engines
(Elsevier, 2025) Vélez Godiño, José Antonio; Serrano Reyes, Javier; Tagua Navarrete, Miguel Ángel; Jiménez-Espadafor Aguilar, Francisco José; Ingeniería de la Construcción y Proyectos de Ingeniería; Ingeniería Energética
Hydrogen has emerged as a promising alternative fuel due to its zero-carbon combustion. However, its use in compression ignition engines presents challenges, including abnormal combustion phenomena, which limit the maximum attainable load, and increased nitrogen oxides emissions. This study explores the use of hydrogen as the primary fuel in a compression ignition engine, implementing a novel strategy where diesel is employed solely as a minimized pilot ignition source. This approach departs from conventional dual-fuel combustion methods by significantly reducing diesel usage while maintaining stable combustion. The main novelties consist of determining the lowest feasible diesel quantity required for stable combustion and demonstrating the improvement in performance resulting from reduced diesel pilot injection. The experimental investigation was conducted on a modified turbocharged compression ignition engine, incorporating water injection as a strategy to mitigate abnormal combustion and nitrogen oxides formation. The study analyses the effects of key operating parameters, including start of injection timing, compression ratio, and engine speed, on combustion stability and performance. The results highlight the critical role of pilot diesel injection in achieving stable combustion while minimizing carbon dioxide emissions. Furthermore, maximizing hydrogen energy share leads to enhanced thermal efficiency without compromising engine operability. Additionally, water injection effectively reduces nitrogen oxides emissions and delays the onset of knock combustion, despite its slight negative impact on efficiency. Compared to other operational strategies, the approach proposed here improves thermal efficiency (by 1–3 %), reduces knock tendency (peak pressure rise rate < 5 bar/CAD), and lowers nitrogen oxides emissions (by 30–50 %).
Upscaling solid oxide electrolysis cell CFD simulations for hydrogen production
(Taylor & Francis, 2025) Stoltze, Finn; Champhekar, Omkar; Iranzo Paricio, José Alfredo; Ingeniería Energética; Ministerio de Ciencia e Innovación (MICIN). España
The role of hydrogen production in the energy transition is of fundamental importance, and Solid Oxide Electrolysers (SOE) are expected to become one of the most efficient hydrogen production technologies. Upscaling Solid Oxide Electrolysis Cells (SOECs) while maintaining overall cell performance and reducing degradation still requires significant experimental and capital resources. This study investigates the effects of grid refinement in Computational Fluid Dynamics (CFD) SOEC simulations and the possibilities of accelerating convergence times. The electrochemical reactions, species transport, fluid dynamics, electron transfer, and heat transfer are modelled through the commercially available CFD software FLUENT. The effects of optimisation measures and scale-up are evaluated through the resulting multidimensional temperature, current density, species, and pressure profiles. The analysis of a 25 cm2 active area design reveals the effect of grid refinement on predicting SOEC performance. The results of a 100 cm2 active area industrial-sized SOEC model prove the accuracy of thermoneutral state simulations with low grid densities of 18,404 cells per square centimetre of active area and reveal challenges in technology scale-up. In addition, the comparison of numerical relaxation methods shows that the pseudo-transient relaxation scheme drastically improves the convergence in CFD SOEC simulations, thus enabling a higher computing performance and therefore lower SOEC development times.
Analysis of the integration of photovoltaic excess into a 5th generation district heating and cooling system for network energy storage
(Elsevier, 2022-01) Quirosa Jiménez, Gonzalo; Torres-García, Miguel; Chacartegui, Ricardo; Ingeniería Energética; TEP137: Máquinas y Motores Térmicos
5th Generation District Heating and Cooling systems are promising technologies for using and storing renewable energy generation excess. An annual simulation using data of a location in the south of Spain is carried out to study this context. The novelty of this work is that a common distribution network is used as an energy storage system and integrates the PV electricity excess from the buildings into the 5GDHC system, at ultra-low temperature. The aim is to analyse if it is interesting to use 5GDHC networks, not designed initially for this purpose, to store energy. For the analysed case, it is estimated that 105 MWh of hot thermal energy and 211 MWh of cold energy are stored. This integration of renewable energy excess would reduce 30.2% of the grid electricity consumption by the 5GDHC energy hub, showing the interest of the strategy for balancing the electricity grid. On the other hand, the storage process implies an annual savings of 2.1% in the grid electricity consumption by the energy hub due to the limited thermal inertia of the network. Moreover, the system can store more energy in hours where storage capacity is still available, so its full potential is not being used.
Energetic and economic analysis of decoupled strategy for heating and cooling production with CO2 booster heat pumps for ultra-low temperature district network
(Elsevier, 2022-01) Quirosa Jiménez, Gonzalo; Torres-García, Miguel; Soltero Sánchez, Víctor Manuel; Chacartegui, Ricardo; Ingeniería Energética; TEP137: Máquinas y Motores Térmicos
The ultra-low temperature district heating and cooling (ULTDHC) systems are among the most interesting solutions for the decarbonisation of heating and cooling sectors. It is a technology where different optimised integrations and operations are still under development. The booster heat pumps (BHPs) or substations associated with this new generation take on a more critical role because the energy supplied by the main network is not enough for covering the user's requirements. Reviewing the literature, it has been seen necessary to make a short and long-term energetic and economic analysis of BHPs operation (considering heating, cooling and SHW requirements) under variable ULTDHC conditions. On this line, this work focuses on the analysis of the operation of two of the most promising BHP types: one with a single CO2 heat pump, type 1, and the other with two CO2 heat pumps with a decoupled operation, type 2. Both BHPs are connected to an ultra-low temperature District Heating and Cooling network with variable parameters throughout the year. The simulation is carried out in a representative building located in Toledo (Spain), in an area with considerable heating and cooling demands throughout the year. The objectives of the work are the following: analyse the daily and annual operations of the two BHPs types, study the effect of outdoor temperature on their optimal operation, point out their main parameter influence and variation and make an economic evaluation of these systems. The BHP type 2 investment is 8.3% more expensive than type 1 but the economic analysis shows an annual saving in heating and cooling operation of the building of 7.7% for BHP type 2 regarding type 1. The size of the BHP, total demand and buildings supplied affects the profitability of the BHP type. For this analysis, type 2 shows more profitable than type 1 when the annual heating demand is greater than a certain threshold.
Critical crystallisation issue in sodium acetate-based latent heat accumulation substance
(Elsevier, 2025-07) Čespiva, J.; Ryšavý, Jiří; Thangavel, S.; Charvát, Matěj; Walter, M.; Yan, W. M.; Skřínský, J.; Chacartegui, Ricardo; Ochodek, Tadeáš; Ingeniería Energética; European Union
The phenomenon of self-crystallisation is scarcely discussed in the context of phase-change materials. However, energy accumulation in supercooled substances can play a significant role and negatively impact long-term energy storage. This paper shows a spontaneous self-crystallisation without external initiation of the sodium acetate trihydrate water solution in several temperature environments (–24 to +21 °C) and different added water contents (0 to 14 %wt.). The stabilised composition of the phase-change solution was determined for each observed temperature environment, and the crystallisation rate was defined. Moreover, a novel approach for determining the density function of such a crystalline structure was successfully investigated for this metastable material. It was found that even the substances with 6 %wt. of water, generally considered stable, crystallises at room temperature if the initiation-free heating cycles are performed several times, which has not been observed before. The crystalline layer characteristics and density varied significantly in different temperature environments. These findings will help design and evaluate future thermal energy storage systems based on SAT with respect to the self-crystallisation phenomenon, providing new knowledge to the state-of-the-art.
Analysis of an ultra-low temperature district heating and cooling as a storage system for renewable integration
(Elsevier, 2022-11) Quirosa Jiménez, Gonzalo; Torres-García, Miguel; Soltero Sánchez, Víctor Manuel; Chacartegui, Ricardo; Ingeniería del Diseño; Ingeniería Energética; TEP137: Máquinas y Motores Térmicos
Sector coupling is necessary for efficient renewable integration since almost all renewable energy sources depend on environmental parameter variations. This paper follows a research line that studies the application of ultra-low temperature district heating and cooling systems, with working temperatures between 6 and 40 °C, to integrate renewable sources with a storage strategy, using the distribution network as a storage system. This work analyses the impact on the annual operation of the water volume, insulation characteristics, demand patterns, photovoltaic generation, design temperature limits and European climates. The optimal design of the district heating and cooling as a storage system will differ depending on the objective, to integrate the maximum amount of renewables excess or obtain maximum electricity savings. For the system located in Seville, hot Mediterranean climate, network insulation is almost negligible with water volumes below 30 m3; for greater values, the self-regulation temperature of the district heating and cooling system is relevant. Moreover, the maximum temperature increment in the distribution network is positive to minimise operational costs. Within the analyses performed in different European regions, the better results of grid consumption savings were obtained in hot Mediterranean areas, 33 %, meanwhile better renewable integration into the district system was obtained in the warm Mediterranean, with 65 % of the photovoltaic excess integrated.
A biomass universal district heating model for sustainability evaluation for geographical areas with early experience
(Elsevier, 2022-03) Soltero Sánchez, Víctor Manuel; Quirosa Jiménez, Gonzalo; Peralta, Estela; Chacartegui, Ricardo; Torres-García, Miguel; Ingeniería del Diseño; Ingeniería Energética
Biomass district heating systems are an optimal economic and environmental solution for generating and distributing thermal energy. One of the main challenges for a broader development of these systems is the complexity of its implementation in the absence of established regulations in the legal, commercial, technical, or economic fields, a situation that occurs in geographical areas with early experience. This work proposes a model for the sustainability of biomass district heating systems, including the whole value chain, taking into account the role of the stakeholders. The design of this Biomass Universal District Heating (BioUnivDH) optimises the implementation and sustainability of the district heating system in geographical areas with early experience. It is conceived to identify implementation barriers and to contribute to their elimination. The model identifies the stakeholders of the project through the analysis of their relationships, objectives, and expectations. This model allows comparison between different systems, and it improves the decision-making process with a holistic approach that identifies strategies for successful implementation and operation based on economic, environmental, and social acceptance criteria. Finally, to show the application of the BioUnivDH model, it is applied in four heating system projects based on biomass and implemented in four Spanish cities.
Vegetable oils as renewable fuels for power plants based on low and medium speed diesel engines
(Elsevier, 2020-06) Torres-García, Miguel; García-Martín, Juan Francisco; Jiménez-Espadafor Aguilar, Francisco José; Fernandes Barbin, Douglas; Álvarez-Mateos, María Paloma; Ingeniería Energética; Ingeniería Química; Universidad de Sevilla; TEP137: Máquinas y Motores Térmicos; AGR155: Obtención de Biocombustibles
There is a high potential for plant oils as alternative fuel for low and medium speed diesel engines, making petroleum-derived fuels likely to be replaced in these types of engines. Vegetable oils have important advantages over both heavy fuel oil (HFO) and marine gas oil (MGO), the fuels currently used in diesel power plants by large two stroke low-speed diesel engines and by medium speed diesel engines, respectively. The emission of certain pollutants and greenhouse gases like SOx, soot and, mainly, CO2 can be reduced by using vegetable oils in these types of engines. This work discusses the potential of vegetable oils as fuel for power plant diesel engines and the problems that can be derived from their use. Current experiences with medium speed diesel engines together with the analysis carried out in this paper indicate that vegetable oils can substitute HFO and MGO, without almost any engine modification.
Joint data reconciliation and artificial neural network based modelling: application to a cogeneration power plant
(Elsevier, 2024-01) Vélez Godiño, José Antonio; Jiménez-Espadafor Aguilar, Francisco José; Ingeniería de la Construcción y Proyectos de Ingeniería; Ingeniería Energética; Junta de Andalucía; TEP137: Máquinas y Motores Térmicos; TIC152: Ingeniería de la Construcción y Proyectos de Ingeniería
This contribution represents a practical application of predictive thermal modelling of an existing cogeneration plant. The analysed cogeneration plant consists of a gas turbine coupled to a heat recovery steam generator, which produces two streams of superheated steam (65 bar and 10 bar) and a thermal oil stream at 350 °C. The proposed model was based on an artificial neural network and was trained using real operational data. However, although data acquisition systems currently used in power generation plants allow for the recording of multiple measurements using small sampling intervals, this does not guarantee a satisfactory analysis of operational data. Therefore, the potential of artificial neural networks can result in incorrect or imprecise results if the calibration of the network is performed with inconsistent or highly uncertain datasets. The novelty of this work consisted on the application of data reconciliation to the real dataset before the model training, in order to minimize the typical uncertainty associated with plant instrumentation measurements. The results obtained demonstrated the advantage of training the network with reconciled data and that modelling error is reduced for all analysed outputs when the model is based on artificial neural networks instead of polynomial models.
Investigation of multi-ion heat and neoclassical transport using new edge main ion measurements at ASDEX Upgrade
(IOP Publishing Ltd, 2025-08-21) Cano Megías, Pilar; Viezzer, Eleonora; McDermott, R.M.; Angioni, C.; Jansen van Vuuren, A.; Cavedon, M.; Cruz Zabala, Diego José; Dux, R.; Manas, P.; P.-Gonzalez, J.; Zimmermann, C.F.B.; Chacartegui, Ricardo; Ingeniería Energética; Física Atómica, Molecular y Nuclear; European Union (UE). H2020; EUROfusion Consortium
This study provides new insights into multi-ion heat transport and the validation of neoclassical theory at the edge of H-mode plasmas. Utilizing a high-resolution main ion charge exchange recombination spectroscopy system, the first characterization of edge deuterium temperature (TD) and toroidal velocity (vϕ,D) in a metal wall environment is presented. Dedicated experiments which examine the impact of the heating mix on TD and vϕ,D in the ASDEX Upgrade tokamak are discussed. An unexpected temperature difference between main ions (TD) and impurities (Tz) was discovered when increasing PECRH, TD > Tz. The new temperature measurements have been used to solve the multi-ion heat transport equations with the astra transport code. The interpreted deuterium (χD) and impurity (χz) heat diffusivities have been compared to fluid (tglf) and gyrokinetic (gkw) models. While the dependence of a qualitatively similar χD/χz on the ion to electron heat flux (Qi/Qe) was identified in both experiment and simulation, discrepancies in the absolute value between the two are found when temperature differences between deuterium and impurities are present. The mechanism for the χD/χz dependence on Qi/Qe is the stronger resonant interaction of impurities with low drift frequency turbulence modes in comparison to deuterium. Importantly, it is shown that considering a single ion species (i), and assuming TD = Tz gives reasonable estimates of χD ≈χi for the cases studied here. On the contrary, the evaluation of χz is very sensitive to ion temperature differences, which must be considered for accurate impurity ion heat transport description. Additionally, differences between vϕ,D and vϕ,z were compared to neoclassical calculations. Neoclassical theory can accurately describe vϕ,D (provided an independent measurement of vϕ,z or Er) in the steep gradient region, but not at the pedestal top nor bottom, highlighting the complexity of edge transport phenomena.

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