Examinando por Autor "Vera, David"

Mostrando 1 - 13 de 13

A hybrid intelligent model to predict the hydrogen concentration in the producer gas from a downdraft gasifier
(ELSEVIER, 2022-06-05) Aguado-Molina, Roque; Casteleiro-Roca, José Luis; Vera, David; Calvo-Rolle, José Luis
This research work presents an artificial intelligence approach to predicting the hydrogen concentration in the producer gas from biomass gasification. An experimental gasification plant consisting of an air-blown downdraft fixed-bed gasifier fueled with exhausted olive pomace pellets and a producer gas conditioning unit was used to collect the whole dataset. During an extensive experimental campaign, the producer gas volumetric composition was measured and recorded with a portable syngas analyzer at a constant time step of 10 seconds. The resulting dataset comprises nearly 75 hours of plant operation in total. A hybrid intelligent model was developed with the aim of performing fault detection in measuring the hydrogen concentration in the producer gas and still provide reliable values in the event of malfunction. The best performing hybrid model comprises six local internal submodels that combine artificial neural networks and support vector machines for regression. The results are remarkably satisfactory, with a mean absolute prediction error of only 0.134% by volume. Accordingly, the developed model could be used as a virtual sensor to support or even avoid the need for a real sensor that is specific for measuring the hydrogen concentration in the producer gas.
An Experimental Study of Power Smoothing Methods to Reduce Renewable Sources Fluctuations Using Supercapacitors and Lithium-Ion Batteries
(MDPI, 2022-11-09) Benavides, Dario; Arévalo, Paul; Tostado-Véliz, Marcos; Vera, David; Escámez, Antonio; Aguado-Sánchez, José Antonio; Jurado-Melguizo, Francisco
The random nature of renewable sources causes power fluctuations affecting the stability in the utility grid. This problem has motivated the development of new power smoothing techniques using supercapacitors and batteries. However, experimental studies based on multiple renewable sources (photovoltaic, wind, hydrokinetic) that demonstrate the validity of power smoothing techniques under real conditions still require further study. For this reason, this article presents a feasibility study of a renewable grid-connected system, addressing various aspects based on power quality and energy management. The first of them is related to the fluctuations produced by the stochastic characteristics of renewable sources and demand. Two power smoothing algorithms are presented (ramp rate and moving average) combining photovoltaic, wind, and hydrokinetic sources with a hybrid storage system composed of supercapacitors and lithium-ion batteries. Then, the self-consumption for an industrial load is analyzed by studying the energy flows between the hybrid renewable energy sources and the grid. The main novelty of this paper is the operability of the supercapacitor. The experimental results show that when applying the power smoothing ramp rate method, the supercapacitor operates fewer cycles with respect to the moving average method. This result is maintained by varying the capacity of the renewable sources. Moreover, by increasing the capacity of photovoltaic and wind renewable sources, the hybrid storage system requires a greater capacity only of supercapacitors, while by increasing the capacity of hydrokinetic turbines, the battery requirement increases considerably. Finally, the cost of energy and self-consumption reach maximum values by increasing the capacity of the hydrokinetic turbines and batteries.
An integrated gasification plant for electric power generation from wet biomass: toward a sustainable production in the olive oil industry
(Springer, 2022) Aguado-Molina, Roque; Vera, David; Jurado-Melguizo, Francisco; Beltrán-Maza, Gabriel
This research work proposes an integrated gasification plant for simultaneous generation of renewable electricity and drying of olive pomace, a thick sludge with a moisture content close to 60–70% (wet basis), which constitutes by far the most abundant by-product in the Spanish olive oil industry. Due to its massive rate of production and increasing associated transportation costs, olive pomace management currently represents a substantial expense for oil mills. The integrated gasification plant, which can be installed directly at oil mills, consists of a pelletizer, a downdraft gasifier under autothermal operation fueled with dried olive pomace pellets, a producer gas cooling and cleaning unit and a microturbine as power generation unit. The wet olive pomace continuously produced in oil mills is eventually dried in a co-current flow rotary drum dryer with the hot exhaust gases leaving the microturbine at temperatures close to 300 °C, allowing a self-sufficient operation of the integrated gasification plant. The integrated gasification plant was modeled using Aspen Plus® process simulator. The developed model was validated against experimental and simulation results of relevant works. Under optimum operating conditions, the electrical efficiency of the proposed plant is 18.8%, while the additional drying stage allows achieving an overall efficiency of 51.0%. Electricity consumption by the pelletizer and ancillary equipment represents 10–20% of the net electric power generation from the microturbine. However, since the integrated gasification plant is fueled with an inexpensive by-product of olive oil production that is massively produced on-site, the plant performance parameters are remarkably satisfactory.
Biomass gasification as a key technology to reduce the environmental impact of virgin olive oil production: A Life Cycle Assessment approach
(ELSEVIER, 2022-10) Fernández-Lobato, Lázuli; Aguado-Molina, Roque; Jurado-Melguizo, Francisco; Vera, David
The olive oil value chain faces nowadays important challenges toward environmental sustainability, both in terms of waste management and energy efficiency improvement. This research work proposes an integrated gasification plant fueled with olive pomace for combined heat and power (CHP) generation and biochar production, which can be installed directly at oil mills. An alternative scenario for olive oil production incorporating the gasification technology was compared to a baseline scenario based on traditional olive oil production. The environmental impacts of producing 1 kg of unpacked virgin olive oil at the farming and industrial phases were estimated for both scenarios by following the Life Cycle Assessment (LCA) methodology under a “cradle-to-gate” approach. The gasification technology applied to the olive oil industry is able to manage all the pomace from the oil extraction process on site, avoiding transportation to pomace oil extraction plants. The proposed gasification plant generates 0.88 kWh of renewable electricity per kg of olive oil and enough heat to abandon the current practice of burning a significant part of the olive pit production. As a result, the alternative scenario contributes to a 8.25% reduction in the normalized environmental impact of olive oil production. In terms of climate change, the environmental impact of the functional unit is reduced from 2.21 to 1.74 kg CO2 eq. (−21%) and the industrial phase becomes a major carbon sink with −0.51 kg of CO2 eq. per kg of olive oil. In this regard, the integrated gasification plant is viewed as an attractive option for most olive oil mills to invest in sustainability through waste management and recovery.
Continuous decentralized hydrogen production through alkaline water electrolysis powered by an oxygen-enriched air integrated biomass gasification combined cycle
(ELSEVIER, 2023-08) Aguado-Molina, Roque; Baccioli, Andrea; Liponi, Angelica; Vera, David
This research work presents an innovative approach for continuous decentralized production of renewable hydrogen from woody biomass. Alkaline water electrolysis (AWE) is used to produce high-purity hydrogen, while the oxygen by-product is mixed with ambient air and used to fire a biomass-fueled downdraft gasifier in order to produce an upgraded producer gas with a lower heating value (LHV) between 7–8 MJ/Nm³. This fuel gas is then subjected to a conditioning stage and eventually fed to a combined cycle consisting of a recuperative gas turbine as topping unit and a regenerative subcritical organic Rankine cycle as bottoming unit, which together allow for a combined electric power generation efficiency close to 40%. Most of the net AC power from the integrated gasification combined cycle (IGCC) is rectified to DC power and ultimately used to power an alkaline electrolyzer, with a minor share allocated to all the required utilities and ancillary equipment, including hydrogen compression to 200 bar. The results from simulation of the hybrid IGCC-AWE plant under steady-state operating conditions in Aspen Plus V.11 indicate an optimal efficiency of 17.6% based on the LHV of hydrogen. Thus, if sized for a biomass consumption of 1 t/h, the proposed plant is capable of providing around 26 kg/h of compressed hydrogen at 200 bar.
Energy production by using combined heat and power system (CHP) with the gasification of palm wastes: case of Iraq
(2024-07-31) Al-Hassany, Hend Dakhel Skhaal; Jurado-Melguizo, Francisco; Vera, David; Universidad de Jaén. Departamento de Ingeniería Eléctrica
Esta Tesis Doctoral explora el potencial transformador de la gasificación de biomasa para la cogeneración distribuida y la calefacción. Demuestra la viabilidad técnica de gasificar residuos de palmeras en un gasificador de corriente descendente, produciendo energía, calor y biocarbón. El desarrollo de un modelo inteligente garantiza una predicción fiable del gas productor. Al proponer una planta de gasificación integrada como una solución rentable para la energía renovable y la gestión de residuos, esta investigación reduce el impacto ambiental y fomenta la sostenibilidad en la cadena de suministro de residuos de palma. La prueba de concepto para la producción descentralizada de gas de síntesis subraya las ventajas de la gasificación de biomasa. En general, este trabajo proporciona información valiosa sobre los beneficios técnicos, económicos y ambientales de la tecnología de gasificación, destacando su potencial para transformar la gestión de residuos e impulsar la producción de energía renovable en el sector de la palmera datilera. This Doctoral Thesis explores the transformative potential of biomass gasification for distributed cogeneration and heating. It demonstrates the technical feasibility of gasifying palm tree residues in a downdraft gasifier, producing power, heat, and biochar. The development of an intelligent model ensures reliable prediction of producer gas. Proposing an integrated gasification plant as a cost-effective solution for renewable power and waste management, this research reduces environmental impact, fostering sustainability in the palm residue supply chain. The proof-of concept for decentralized syngas production underscores the advantages of biomass gasification. Overall, this work provides valuable insights into the technical, economic, and environmental benefits of gasification technology, highlighting its potential to transform waste management and drive renewable energy production in the date palm sector.
Environmental impact of the most representative Spanish olive oil farming systems: A life cycle assessment study
(Elsevier, 2024-02-25) Fernández-Lobato, Lázuli; Ruiz-Carrasco, Beatriz; Tostado-Véliz, Marcos; Jurado, Francisco; Vera, David
Agricultural production is an essential activity in the global economy that must advance towards the design of sustainability projects hand-in-hand with consumers, companies, and policymakers. An exhaustive study, in line with the guidelines set by government entities, is required to quantify this impact in an ample spectrum of environmental categories. Life Cycle Assessment (LCA) is a powerful tool that enables obtaining such information, as other authors have already demonstrated in different sectors. This study employs LCA to determine the environmental impact of virgin olive oil production, considering different agricultural and industrial production systems in Spain. For this purpose, a wide range of cultivated olive tree crops and different types of olive oil mill facilities in Andalusia have been studied-the territory of Spain with the highest dedication to olive oil production. This area has a strong emphasis on developing projects within this economic sector. The study focuses on olives, virgin olive oil and hectares of cultivation land, adopting a “cradle-to-gate” approach, and including economic allocation, considering the main processes related to its production in the agricultural and industrial phases. The study time covers the five most recent harvests (2017/18 to 2021/22) to obtain appropriate and updated environmental impact values. The results from the study time indicate that higher densification, irrigation, and slope crops lead to a higher environmental impact. Specifically, the climate change category of the functional unit ranges between 1.90 (low yield crops) and 6.09 kg of CO2 equivalent (super-intensive irrigated), while in the most representative cases, extensive crops, it results in 2.90 (rainfed) and 3.49 (irrigated) kg of CO2 equivalent. It should be noted that this study breaks new ground by thoroughly assessing the environmental impact of different olive oil production methods in Spain. It offers unique insights into sustainability within this vital sector, addressing a significant gap in current research.
Experimental assessment of a pilot-scale gasification plant fueled with olive pomace pellets for combined power, heat and biochar production
(ELSEVIER, 2023-07-15) Aguado-Molina, Roque; Escámez, Antonio; Jurado, Francisco; Vera, David
This research work examines the performance of an experimental gasification plant fueled with exhausted olive pomace pellets for the concurrent production of electricity, heat and biochar in the olive oil industry. The gasification plant consists of an air-blown downdraft fixed-bed gasifier that generates a lean fuel gas, termed producer gas, in a self-sustaining autothermal process. After conditioning of the producer gas in a cooling and cleaning unit, a four-stroke spark-ignition engine coupled to an electric generator is eventually used as power generation unit. An extensive experimental assessment of this facility was performed under partial and nominal load operation and was supplemented by a physicochemical analysis of the carbonaceous solid material discharged from the gasifier. The mass and energy balances of the gasification plant were calculated, including the carbon conversion efficiency and diverse energy conversion efficiencies. The results revealed an overall stable operation of the gasification plant in terms of composition and heating value of the producer gas and cogenerative production of electricity and heat in the engine–generator set. Under nominal operating conditions, the net electrical efficiency of the gasification plant was 12%–13%, with an average carbon conversion efficiency of the biomass feedstock into producer gas just above 80% and an average cold gas efficiency close to 70%.
Experimental validation of a wireless monitored solar still for efficient olive pomace drying and distilled water production
(Taylor & Francis, 2023-04-18) Rodríguez-Orta, Antonio; Aguado-Molina, Roque; Sánchez-Raya, Manuel; Vera, David; Gómez-Galán, Juan Antonio
This work presents the prototype of a solar still that can be used as a complement to the traditional fossil fuel-based drying process of olive pomace, a thick sludge with a high moisture content that is massively by-produced in the olive oil industry. In addition, the system allows to recover distilled water, which can be used to irrigate the adjacent fields. The feasibility of the system for the target application was experimentally validated by designing a wireless data acquisition circuit for data collection, remote storage, visualization and analysis in real-time, with access possible from multiple devices. The results from a test campaign revealed that the moisture content of the olive pomace was effectively reduced from 67.17% to 39.90% in a 10-day period. A maximum drying efficiency of 16.64% was achieved, with potential for higher values under favorable weather conditions. The simplicity of the design and the low-cost solution can facilitate the future large-scale implementation of a similar system.
Optimal home energy management including batteries and heterogenous uncertainties
(Elsevier, 2023-04) Tostado-Véliz, Marcos; Hasanien, Hany M.; Turky, Rania A.; Assolami, Yasser O.; Vera, David; Jurado-Melguizo, Francisco
Energy storage will play a vital role in the decarbonization of the electricity sector, especially in domestic installations. In such kind of systems, home energy management applications are becoming essential. These kinds of tools enable active control of domestic appliances and storage systems to pursue a more efficient use of energy in household installations. However, the emergence of renewable generators and electric vehicles makes the operation of residential assets more difficult, as multiple uncertainties should be managed on a whole. These unknowns have a different character, in fact, some of them can be easily predicted while others are subject to a high level of randomness. This paper addresses this issue by developing a novel home energy management tool that accounts for the different levels of the randomness of the uncertainties involved in home operation. To this end, a novel Lexicographic-Interval formulation of the home energy management problem is presented, by which the uncertainties can be easily modelled using interval notation. Unlike conventional tools, the new proposal sorts the uncertainties according to their level of randomness. Then, the energy management mechanism performs the scheduling plan according to the predefined classification so that the more random parameters rule the impact of others, thus giving more importance to those uncertainties that are hardly predictable. A benchmark case study is performed to validate the new proposal and illustrate its capabilities. Different tariffs are compared, showing that the Time-of-Use mechanism is normally more expensive than Real-Time-Pricing tariffs, increasing the electricity bill by 12 % in some cases. However, the level of robustness achieved with Time-of-Use tariffs seems higher, allowing to assume an abruptly unexpected reduction of photovoltaic generation.
Optimal sizing of hybrid PV–diesel–biomass gasification plants for electrification of off-grid communities: An efficient approach based on Benders’ decomposition
(Elsevier, 2024-06-15) Tostado-Véliz, Marcos; Escámez, Antonio; Aguado-Molina, Roque; Sánchez-Lozano, Daniel; Jurado, Francisco; Vera, David
Nowadays, millions of people in remote areas do not enjoy an uninterrupted power supply due to the lack of connectivity to the main power grid. Under such circumstances, the only feasible way to access electricity is typically local power generation, often relying on diesel engine–generator sets or photovoltaic arrays. However, on many occasions, this configuration does not fully exploit all available local resources, including biomass. Indeed, most isolated areas have access to local biomass production from agricultural activities, which can be used for local electricity generation through gasification. This paper addresses this challenge by developing an innovative optimal sizing tool for hybrid power plants integrating biomass gasifiers, specifically designed for isolated areas with access to local biomass production. The novel approach models the particular features of biomass gasification technologies, including long on/off times or restrictive ramping limits. To this end, an efficient methodology based on representative weeks is proposed, which is combined with a solution strategy based on the multi-cut Benders’ decomposition, thus resulting in a tractable framework that can deal with a huge amount of data efficiently. One of the most salient features of the new proposal is the consideration of local biomass production, which is included in the methodology through an original algorithm. Accordingly, a certain amount of biomass is sourced locally, leading to more accurate and reliable results. The new methodology is applied to a benchmark off-grid community in Ghana. The results demonstrate that the use of gasifiers reduces the project cost notably (by 90%) driven by the reduced biomass cost, which can be supplemented by locally generated biomass from agricultural activities. In addition, this technology constitutes a clean source of energy, reducing the total CO emissions by 83% compared to a baseline case in which only diesel generators are used. Moreover, it is demonstrated that biomass gasification can effectively act as base load power generation technology to reliably cover most of the local demand, thereby enabling a clean and inexpensive dispatchable local power generation. Finally, a sensitivity analysis reveals that the economic feasibility of the plant is more sensitive to the biomass cost than the selling price of biochar, resulting in a 33% increment in the total project cost when the price of biomass increases from 0 to 0.4 $/kg. Nevertheless, gasification remains as the predominant power generation technology even under unfavorable prices.
Techno-economic assessment of a gasification plant for distributed cogeneration in the agrifood sector
(MDPI, 2021-01) Aguado-Molina, Roque; Vera, David; López-García, Diego; Pérez-Torreglosa, Juan; Jurado, Francisco
This research work presents a techno-economic analysis of a biomass gasification plant fueled with residues from the olive oil and almond industries for combined heat and power generation in the agrifood sector. The experimental plant consists of a downdraft fixed bed gasifier, a producer gas cleaning and cooling system and a spark-ignition engine–generator set as a power generation unit, which generates about 10–12 kW of rated electric power. With an average consumption between 13–14 kg/h of exhausted olive pomace pellets as feedstock, the producer gas volumetric flow rate was 31 Nm3/h (vol. %: 19.2 H2, 12.9 CO, 1.9 CH4, 19.2 CO2, 46.7 N2). The average cold gas efficiency was nearly 63%. This work also addresses the characterization and potential application of the carbonaceous solid residue (biochar), discharged from the gasifier at 1.7 kg/h. Finally, an economic feasibility analysis was developed, wherein the payback period ranges between 5–9 years.
Techno-economic assessment of a hybrid PV-assisted biomass gasification CCHP plant for electrification of a rural area in the Savannah region of Ghana
(ELSEVIER, 2025-01) Sánchez-Lozano, Daniel; Aguado-Molina, Roque; Escámez, Antonio; Awaafo, Augustine; Jurado-Melguizo, Francisco; Vera, David
In rural areas of sub-Saharan countries, there is great potential for solar and biomass resources to achieve a reliable electricity supply, reduce the dependence on fossil fuels, and mitigate greenhouse gas emissions, thereby tackling energy poverty and promoting sustainable development. This work aims to address the lack of reliable electricity access in rural communities of sub-Saharan countries through biomass gasification assisted by solar photovoltaic (PV) energy and a small back-up diesel engine–generator set. The biomass gasification plant is designed to convert locally available agricultural waste into producer gas, which can then be used to generate electricity. A detailed analysis of the system components, including the PV array, battery bank, biomass gasifier with a combined cooling, heat and power generation unit (CCHP), is carried out to evaluate their performance and efficiency under different operating conditions. The results reveal a CCHP efficiency of 62% for the gasification CCHP unit, accompanied by a remarkable 93.8% reduction in CO2 emissions considering the whole hybrid system. From an economic standpoint under conservative assumptions, the proposed facility can generate a cumulative profit of $157,890 after 20 years, recovering the initial investment within a period of just under 7 years. This is reflected in a levelized cost of electricity (LCOE) of $0.287/kWh, comparable to that of related studies. The outcomes demonstrate that the PV-assisted biomass gasification plant offers a sustainable technical, economical and environmentally friendly solution for electrification of rural communities in sub-Saharan countries.

RUJA: Repositorio Institucional de Producción Científica

Examinando por Autor "Vera, David"