Open Access
Accurate thermal prediction model for building-integrated photovoltaics systems using guided artificial intelligence algorithms
(Elsevier Ltd, 2022) Serrano-Luján, Lucía; Toledo, Carlos; Colmenar, José Manuel; Abad, José; Urbina Yeregui, Antonio; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
Progress in development of building-integrated photovoltaic systems is still hindered by the complexity of the physics and materials properties of the photovoltaic (PV) modules and its effect on the thermal behavior of the building. This affects not only the energy generation, as its active function and linked to economic feasibility, but also the thermal insulation of the building as part of the structure's skin. Traditional modeling methods currently presents limitations, including the fact that they do not account for material thermal inertia and that the proposed semi-empirical coefficients do not define all types of technologies, mounting configuration, or climatic conditions. This article presents an artificial intelligence-based approach for predicting the temperature of a poly-crystalline silicon PV module based on local outdoor weather conditions (ambient temperature, solar irradiation, relative outdoor humidity and wind speed) and indoor comfort parameters (indoor temperature and indoor relative humidity) as inputs. A combination of two algorithms (Grammatical Evolution and Differential Evolution) guides to the creation of a customized expression based on the Sandia model. Different data-sets for a fully integrated PV system were tested to demonstrate its performance on three different types of days: sunny, cloudy and diffuse, showing relative errors of less than 4% in all cases and including night time. In comparison to Sandia model, this method reduces the error by up to 11% in conditions of variability of sky over short time intervals (cloudy days).
Open Access
Polycaprolactone/MSMA composites for magnetic refrigeration applications
(Wiley, 2024-09-06) Sánchez-Alarcos Gómez, Vicente; Khanna, Deepali; La Roca, Paulo Matías; Recarte Callado, Vicente; Lambri, Fernando Daniel; Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Royo Silvestre, Isaac; Urbina Yeregui, Antonio; Pérez de Landazábal Berganzo, José Ignacio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
A high filling load (62% weight) printable magnetic composite has been elaborated from the dispersion of magnetocaloric Ni45Mn36.7In13.3Co5 metamagnetic shape memory alloy microparticles into a PCL polymer matrix. The composite material has been prepared by solution method, resulting in a very homogeneous particles dispersion into the matrix. The structural transitions in the polymer are not affected by the addition of the metallic microparticles, which in turn results in a significant increase of the mechanical consistency. The good ductility of the elaborated composite allows its extrusion in flexible printable filaments, from which 3D pieces with complex geometries have been grown. The heat transfer of the composite material has been assessed from finite element simulation. In spite of the achievable magnetocaloric values are moderated with respect to the bulk, numerical simulations confirm that, in terms of heat transference, a PCL/Ni-Mn-In-Co wire is more efficient than a bulk Ni-Mn-In-Co cubic piece containing the same amount of magnetic active material. The quite good magnetocaloric response of the composite and the possibility to print high surface/volume ratio geometries make this material a promising candidate for the development of heat exchangers for clean and efficient magnetic refrigeration applications.
Open Access
Nanoparticles of poly(3-hexylthiophene): toward a solvent-independent performance of electrochromic films
(Elsevier, 2023) Cánovas-Saura, Antonio; Colom, Eduardo; Padilla, Javier; Urbina Yeregui, Antonio; Maser, Wolfgang K.; Benito, Ana M.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Nanoparticles of poly(3-hexylthiophene), P3HT(NP), uniquely enable the preparation of stable dispersions in environmentally-friendly media and thus offer a sustainable liquid phase fabrication of electrochromic device structures. In this work, we assess the electrochromic performance of P3HT(NP) films spray-coated from either tetrahydrofuran (THF)-water or chloroform (CHCl3)-ethanol dispersions on ITO substrates. The nanoparticle films exhibit consistent and reproducible high optical contrast values of around 50 %, t90-switching speeds of about 0.45 s and a cycling stability of approximately 200 cycles for a 20 % performance retention, independent of the solvent being used. Conversely, non-nanostructured P3HT films spray-coated from THF or CHCl3 reveal a strong solvent dependent variability in their electrochromic behavior presenting low optical contrast, high switching speeds and fast degradation rates in the case of CHCl3. The solvent independent electrochromic characteristics of P3HT nanoparticle films is related to a consistent availability of accessible electroactive sites provided by a homogeneous porous P3HT network structure formed on the underlying substrate, as probed by SEM and profilometric studies. Our findings reveal that the use of nanoparticles of P3HT and its environmentally benign liquid phase processing, a concept which is extendable to other electrochromic polymers, opens a sustainable pathway toward the large-area fabrication of electrochromic device structures with favorable and consistent performance parameters.
Open Access
Graphene oxide: key to efficient charge extraction and suppression of polaronic transport in hybrids with poly (3-hexylthiophene) nanoparticles
(American Chemical Society, 2023) Colom, Eduardo; Hernández-Ferrer, Javier; Galán-González, Alejandro; Ansón-Casaos, Alejandro; Navarro-Rodríguez, Mario; Palacios-Lidón, Elisa; Colchero, Jaime; Padilla, Javier; Urbina Yeregui, Antonio; Arenal, Raúl; Benito, Ana M.; Maser, Wolfgang K.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Nanoparticles (NPs) of conjugated polymers in intimate contact with sheets of graphene oxide (GO) constitute a promising class of water-dispersible nanohybrid materials of increased interest for the design of sustainable and improved optoelectronic thin-film devices, revealing properties exclusively pre-established upon their liquid-phase synthesis. In this context, we report for the first time the preparation of a P3HTNPs-GO nanohybrid employing a miniemulsion synthesis approach, whereby GO sheets dispersed in the aqueous phase serve as a surfactant. We show that this process uniquely favors a quinoid-like conformation of the P3HT chains of the resulting NPs well located onto individual GO sheets. The accompanied change in the electronic behavior of these P3HTNPs, consistently confirmed by the photoluminescence and Raman response of the hybrid in the liquid and solid states, respectively, as well as by the properties of the surface potential of isolated individual P3HTNPs-GO nano-objects, facilitates unprecedented charge transfer interactions between the two constituents. While the electrochemical performance of nanohybrid films is featured by fast charge transfer processes, compared to those taking place in pure P3HTNPs films, the loss of electrochromic effects in P3HTNPs-GO films additionally indicates the unusual suppression of polaronic charge transport processes typically encountered in P3HT. Thus, the established interface interactions in the P3HTNPs-GO hybrid enable a direct and highly efficient charge extraction channel via GO sheets. These findings are of relevance for the sustainable design of novel high-performance optoelectronic device structures based on water-dispersible conjugated polymer nanoparticles.
Open Access
Short vs. long-distance avocado supply chains: life cycle assessment impact associated to transport and effect of fruit origin and supply conditions chain on primary and secondary metabolites
(MDPI, 2022-06-19) Pedreschi, Romina; Ponce, Excequel; Hernández, Ignacia; Fuentealba, Claudia; Urbina Yeregui, Antonio; González-Fernández, José J.; Hormaza, José I.; Campos, David; Chirinos, Rosana; Aguayo, Encarna; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Avocado consumption and trade are increasing worldwide, with North America and Europe being the main importing regions. Spain is the major European avocado producer (90% of the production), yet it only supplies 10% of the market. Consequently, more than 90% of the avocados consumed in Europe are imported from overseas, mainly from Chile and Peru. In this work, the Life Cycle Assessment (LCA) impact associated with the transport of two avocado supply chains (short (Spanish) and long (Chilean)) and the effect of the fruit origin and distance of both chains on primary and secondary metabolites from harvest to edible ripeness were evaluated using a gas chromatography-mass spectrometry (GC-MS) and liquid chromatography coupled to diode array detection (LC-DAD) based metabolite analysis. The LCA transport impact of the fresh supply chain from production centers in Chile (Quillota) and Spain (Malaga), and then the distribution to several cities in Europe, suggested road export from Spain to European capitals to have the lowest impact (0.14 to 0.22 kg CO2 eq/kg of avocado). When export from Chile was considered, the option of oceanic freight to European ports closer to final destinations was clearly a better option (0.21 to 0.26 kg CO2 eq/kg) than via the Algeciras port in Spain followed by road transport to final destinations in European capitals (0.34 to 0.43 kg CO2 eq/kg), although the situation could be somewhat different if the avocados are transported from the destination ports in northern Europe to long-distance capitals in other European countries. Fruit origin had a significant impact on avocado primary and secondary metabolites. The conditions of the supply chain itself (10 d in cold storage in regular conditions vs. 30 d cold storage + controlled atmosphere conditions) largely influence the fate of some metabolites that certainly affect the pool of metabolites at edible ripeness. The long-assumed hypothesis that the longer the supply chain the more negative impact on nutritional and functional compounds might not hold in this case, as long as transport conditions are adequate in terms of temperature, atmosphere conditions, and time considering distance from origin to destination.
Open Access
Sustainability of photovoltaic technologies in future net-zero emissions scenarios
(Wiley, 2022) Urbina Yeregui, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Photovoltaic installed cumulative capacity reached 849.5 GW worldwide at the end of 2021, and it is expected to rise to 5 TW by 2030. The sustainability of this massive deployment of photovoltaic modules is analysed in this article. A literature review, completed with our own research for emerging technologies has been carried out following life cycle assessment (LCA) methodology complying with ISO 14040 and ISO 14044 standards. Different impact categories have been analysed for five commercial photovoltaic technologies comprising more than 99% of current market (crystalline silicon ~94% and thin film ~6%) and a representative of an emerging technology (hybrid perovskite). By using data from LCA inventories, a quantitative result for 15 impact categories has been calculated at midpoint and then aggregated in four endpoint categories of damage following ReCiPe pathways (global warming potential, human health damage, ecosystems damage and resources depletion) in order to enable a comparison to other renewable, fossil fuel and nuclear electricity production. In all categories, solar electricity has much lower impacts than fossil fuel electricity. This information is complemented with an analysis of the production of minerals with data from the British Geological Survey; the ratio of world production to photovoltaic demand is calculated for 2019 and projected to 2030, thus quantifying the potential risks arising from silver scarcity for c-Si technology, from tellurium for CdTe technology and from indium for CIGS and organic or hybrid emerging technologies. Mineral scarcity may pose some risk for CdTe and CIGS technologies, while c-Si based technology is only affected by silver dependence that can be avoided with other metals replacement for electrodes. When the risks grow higher, investment in recycling should boost the recovery ratio of minerals and other components from PV module waste.
Open Access
Compact wideband groove gap waveguide bandpass filters manufactured with 3D printing and CNC milling techniques
(MDPI, 2023-07-07) Máximo-Gutierrez, Clara; Hinojosa, Juan; Abad, José; Urbina Yeregui, Antonio; Álvarez-Melcon, Alejandro; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias; Zientziak
This paper presents for the first time a compact wideband bandpass filter in groove gap waveguide (GGW) technology. The structure is obtained by including metallic pins along the central part of the GGW bottom plate according to an n-order Chebyshev stepped impedance synthesis method. The bandpass response is achieved by combining the high-pass characteristic of the GGW and the low-pass behavior of the metallic pins, which act as impedance inverters. This simple structure together with the rigorous design technique allows for a reduction in the manufacturing complexity for the realization of high-performance filters. These capabilities are verified by designing a fifth-order GGW Chebyshev bandpass filter with a bandwidth BW = 3.7 GHz and return loss RL = 20 dB in the frequency range of the WR-75 standard, and by implementing it using computer numerical control (CNC) machining and three-dimensional (3D) printing techniques. Three prototypes have been manufactured: one using a computer numerical control (CNC) milling machine and two others by means of a stereolithography-based 3D printer and a photopolymer resin. One of the two resin-based prototypes has been metallized from a silver vacuum thermal evaporation deposition technique, while for the other a spray coating system has been used. The three prototypes have shown a good agreement between the measured and simulated S-parameters, with insertion losses better than IL = 1.2 dB. Reduced size and high-performance frequency responses with respect to other GGW bandpass filters were obtained. These wideband GGW filter prototypes could have a great potential for future emerging satellite communications systems.
Open Access
Photovoltaic technology as a tool for ecosystem recovery: a case study for the Mar Menor coastal lagoon
(Elsevier, 2024) Toledo, Carlos; Ramos Escudero, Adela; Serrano-Luján, Lucía; Urbina Yeregui, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
A wide range of environmental impacts have been triggered worldwide by intensive agrarian production designed to maximize crop yields. The ecological crisis in the Mar Menor, Europe's largest salt-water lagoon, is an example of how changes in traditional farming practices have had a significant impact on the lagoon ecosystem. In this context, integrated photovoltaic systems can potentially alleviate the pressure for land resources while also contributing to sustainable land use and reducing eutrophication in the lagoon. The case study is an example of balance between two United Nations Sustainable Development Goals (SDGs): Zero hunger (SDG 2) and Affordable and Clean Energy (SDG 7) achieved by sharing land occupation and additionally obtaining an ecosystem restoration, linked to SDGs 6 (Clean Water and Sanitation) and 13 (Climate Action). Based on official information and literature studies on watering, fertilizing needs, and production, we developed an approach for combining geographical data with estimates of the environmental benefits of photovoltaic integrated solutions. The results show that up to 1377 tonnes/year of nitrate fertilizer can be avoided, and water use can be reduced by up to 27 Hm3/year, depending on the distributed photovoltaic power scenario selected. Likewise, the installed capacity of ground-mounted, agrivoltaic, greenhouse-mounted, and floating photovoltaic systems varies from 54 GWp, 16 GWp, 0.4 GWp, and 0.6 GWp, respectively.
Open Access
Metal-free nanostructured-carbon inks for a sustainable fabrication of zinc/air batteries: from ORR activity to a simple prototype
(Wiley, 2024-08-14) Santos, Florencio; Lorca, Sebastián; González-Martínez, Juan F.; Urbina Yeregui, Antonio; Álvarez-Sánchez, Miguel A. ; González-Domínguez, José M.; García-Bordejé, Enrique; Ansón-Casaos, Alejandro; Benito, Ana M.; Maser, Wolfgang K.; Fernández Romero, Antonio J.; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
Zinc/air batteries are convenient energy storage devices for both small and massive applications. While future perspectives indicate the need for low-cost components and sustainable fabrication processes, the battery performance is in part controlled by the kinetics of the oxygen reduction reaction (ORR), which typically involves transition metals as catalysts. In this context, we prepare a series of metal-free water-based carbon inks, which are tested for their catalytic performance, once deposited on a gas-diffusion substrate, in the air cathode of a simple battery prototype. The inks contain a variety of well-defined carbon nanomaterials and additives, exhibiting different physicochemical properties that critically influence the interaction with the gas diffusion hydrophobic substrate. The intrinsic ORR catalytic activity of the ink material is also analyzed on a glassy carbon electrode by the rotating ring-disc electrode (RRDE) method and specific capacitance measurements. The discharge capacity on our zinc/air battery prototype correlates well with the intrinsic catalytic activity in the RRDE. However, only the activity in the RRDE does not actually assure the performance on the commercial cathode of the prototype, since other chemical compatibility issues play a role. Thus, we highlight the importance of catalyst testing, not only on the RRDE but also under realistic device conditions.
Open Access
Passive heating and cooling of photovoltaic greenhouses including thermochromic materials
(MDPI, 2021-01-15) Padilla, Javier; Toledo, Carlos; López-Vicente, Rodolfo; Montoya, Raquel; Navarro, José-Ramón; Abad, José; Urbina Yeregui, Antonio; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2
The integration of photovoltaic technologies into greenhouse envelopes appears to be an innovative and environmentally-friendly way to supply their various energy demands. However, the effect on the inner growing conditions, especially on the temperature, must be assessed in order to effectively implement this solution. In this study, experimental temperature data were obtained over two years for four structures built with different photovoltaic technologies (mono-crystalline silicon, amorphous silicon, cadmium telluride, and an organic polymeric technology) and fitted to a thermal model in order to provide a comprehensive analysis of their potential utilization as a cover material in greenhouses. Additionally, the thermal effect of color in structures composed of several common construction materials (brick, wood, plasterboard and glass) was quantified and modelled, supplementing the thermal analysis of passive solutions for this application. In all cases, inner and ambient temperature differences of up to +20 °C, created by a passive heating effect during the day, and – 5 °C, created by a passive cooling effect during the night, have been observed, suggesting the use of the photovoltaic modules with different degrees of structure coverage, complemented with the color tuning of the modules themselves as passive methods to control the temperature and light spectrum of greenhouses.