Fotovoltaico e Aquaponia: Uma Proposta de Tecnologia para a Segurança Alimentar (ODS2) em Comunidades Vulneráveis
Considerando a necessidade de busca de soluções inovadoras para reduzir a insegurança alimentar em comunidades vulneráveis, este estudo avalia uma proposta de criação de uma árvore fotovoltaica integrada aos sistemas de aquaponia e hidroponia, indo ao encontro do 2º ODS (Objetivo de Desenvolvimento Sustentável), Fome Zero. Nesta abordagem, a árvore fotovoltaica alimenta o sistema aquapônico, onde os peixes fornecem nutrientes para as plantas, e a hidroponia coexiste, devolvendo água limpa aos peixes. Essa interação sinérgica e circular visa otimizar a produção de alimentos de forma sustentável. A metodologia inclui levantamento bibliográfico, análise documental e adaptações locais, focando na aldeia indígena Nova Esperança, afetada pelo denominado “desastre de Mariana”. Os resultados esperados da proposta destacam a contribuição dessa abordagem multifacetada para promover sistemas alimentares sustentáveis para populações vulneráveis. A integração de tecnologias renováveis e participação comunitária, podem ser fundamentais para enfrentar desafios como a insegurança alimentar e alcançar o ODS 2.
Enabling the bulk photovoltaic effect in centrosymmetric materials through an external electric field
We develop a practical approach to electrically tuning the nonlinear photoresponse of two-dimensional semiconductors by explicitly incorporating a static out-of-plane electric field into the electronic ground state prior to optical excitation, as a gate bias. The method is implemented by dressing a Wannier-interpolated Hamiltonian with the field through its position matrix elements, which allows the gate bias to modify orbital hybridization and band dispersion beyond perturbative treatments. Within the independent-particle approximation, the resulting second-order (shift) conductivity is evaluated for both centrosymmetric and noncentrosymmetric layered systems. Applied to MoS2, the approach captures the emergence of a finite shift current in centrosymmetric bilayers and the tunability of intrinsic responses in polar structures. The shift conductivity rises linearly at small fields and saturates at higher intensities, reflecting the competition between the growing shift vector and the weakening interband coupling as resonant transitions move away from high-symmetry valleys. A Taylor expansion of the field-dressed conductivity connects this behavior to the third-order optical response, revealing a unified picture of field-induced nonlinearities. These results establish field dressing of Wannier Hamiltonians as a practical route to model and predict nonlinear photocurrents in layered materials.
Angular-resolved nonlinear optical response as a probe of Lorentz violation in noncentrosymmetric materials
We propose a methodology to detect weak Lorentz-violating (LV) backgrounds through the nonlinear shift photocurrent in noncentrosymmetric crystals. Using a spinful Rice–Mele model, we show that a LV background induces a momentum-odd correction to the Bloch Hamiltonian that reshapes the phase of the interband dipole matrix elements. As a result, the shift conductivity develops a robust π-periodic modulation as a function of the angle of a perpendicularly applied static electric field, in contrast to a weakly 2π-periodic response of the Lorentz-symmetric case. This change in angular periodicity provides a signature of LV effects which can be directly identified through a photocurrent measurement. For realistic optical intensities, the predicted signal lies in the picoampere range, which can be enhanced in a matrix of weakly interacting chains, allowing sensitivity to LV coupling strengths of the order of ξ∼10−24Cm. These results establish nonlinear optical transport as a viable probe of emergent LV effects in solid-state systems.
Post consumer expanded polystyrene as an optical-grade host for lanthanide-doped luminescent solar concentrators
The transition toward net-zero buildings has increased interest in building-integrated photovoltaics (BIPV). Luminescent solar concentrators (LSCs) are particularly attractive due to their transparency, colour tunability, and seamless architectural integration. Yet most LSCs rely on virgin polymers, including polystyrene (PS), a fossil-derived polymer. Expanded polystyrene (EPS) waste is difficult to recycle because of degradation, contamination, and low material value. This study addresses this challenge by converting post-consumer EPS into an optical-grade matrix for LSCs, giving a second life to a hard-to-recycle plastic. Recycled PS (r-PS) was doped with two lanthanide complexes — Eu(TFNB)3Phen and Tb(4BBA)3Phen — and analysed structurally and photophysically. The r-PS retained high transparency and achieved quantum yields of 0.53 ± 0.05 (Eu) and 0.40 ± 0.04 (Tb). Its mechanical properties were preserved, enabling fabrication of functional LSCs with power conversion and optical efficiencies of (0.013 ± 0.001)% and (1.2 ± 0.1)%, respectively. The devices also exhibited dual-mode thermometric sensitivity up to 3.9 ± 0.6 % °C−1. A life-cycle assessment showed significant reductions in acidification, terrestrial eutrophication, and resource use when virgin PS is replaced with r-PS.
Experimental Performance Comparison of a Modular Water-Based Photovoltaic–Thermal System Under Multiple Hydraulic Operating Modes in a Tropical Climate
In Brazil, more than 80% of households rely on electricity for water heating, representing approximately 13% of residential electricity consumption and significantly contributing to peak grid demand. As a prominent alternative for supplying household thermal energy and reducing grid stress, this study experimentally evaluates, under tropical climate conditions, the performance of a modular water-based photovoltaic–thermal (PVT) system and compares it with a conventional photovoltaic (PV) system operating simultaneously under identical environmental conditions. The PVT system, based on commercial PV modules coupled to roll-bond heat exchangers, a storage tank, and a shower outlet, was tested under three hydraulic regimes: natural thermosiphon, closed-loop, and Forced circulation. A dedicated ESP32-based data acquisition system, integrated with a cloud platform, continuously monitors electrical, thermal, and meteorological variables. Results show that PVT modules exhibit a small electrical efficiency reduction due to increased cell temperatures, which is largely compensated by the simultaneous thermal generation, yielding overall efficiency gains of 74.04%, 76.53%, and 7.62% over the reference PV system for Normal, Forced, and Closed circulation, respectively. The comparative analysis identifies Forced-circulation scheduling and the matching between thermal generation and consumption as key factors for performance optimization. The findings provide practical guidelines for deploying PVT systems to replace electric showers in tropical regions, reducing residential electricity consumption and mitigating peak-demand stress on the grid.
Free Energy Market Transition: a Study Case of 32 Consumption Units in Brazil
Given the growing consumption for energy, electricity represents a significant share in the public budget, particularly for the Government of Espírito Santo, approximately 12.46% of the total administrative expenses of the units. Based on this, the present study analyzes the feasibility of migrating Consumer Units of the Executive Branch of the State of Espírito Santo to the Free Contracting Environment, aiming for economic and sustainable gains. Thirty-two units were selected for a case study, based on consumption and demand data between 2024 and 2025, to project future consumption and costs. The analysis considered 32 Consumer Units, including the procurement of 1.25 MW average from conventional and renewable energy sources, indicating a potential savings of up to 30.54%. Although there are challenges characteristic of public administration, in contrast to management in the private sector, particularly due to national and subnational legal frameworks to which it is subject, the results indicate that migration is technically and economically feasible. This positions the Free Contracting Environment as a strategic alternative for optimizing public resources and meeting environmental goals, aligned with the Sustainable Development Goals and the longterm strategic plan entitled “ES 500 anos”.
Parametric vertical photovoltaic system: Fibonacci methodology applied to solar trees design
This study presents a novel Fibonacci-inspired solar tree design to optimize energy efficiency in urban environments while addressing the growing demand for sustainable energy solutions. The objective was to propose a project methodology for Solar Trees, one that can adapt to diverse contexts and enhance the viability of these structures as source of renewable energy within urban landscapes. The research used Rhinoceros 7 and Grasshopper to create a base model, parametrically adjust key design parameters, and simulate solar irradiation through the Ladybug plug-in. The optimized solar tree design achieved an annual solar energy incidence of 84,017 kWh and an irradiation of 3,222 kWh/m2/year, surpassing traditional flat PVS, which would generate only 68,084 kWh/year with an irradiation of 2,611 kWh/m2/year. Comprising 21 modular photovoltaic leaves made from mono-crystalline silicon, the design meets technical energy requirements and offers aesthetic and landscaping benefits in urban settings. This work underscores the importance of a multidisciplinary approach, merging architecture, energy efficiency, and environmental science to propose feasible solutions for contemporary urban challenges. The findings indicate that the proposed solar tree design fulfills energy demands and enhances public spaces, challenging conventional perceptions of photovoltaic systems as fragmented and visually unappealing.