Sondersammlungen

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Browsing Sondersammlungen by Classification "620"

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    Energy security through decentralized energy system: Electricity self-sufficient village using agrivoltaics?
    (2025) Bauknecht, Martin
    With the Green Deal, the energy transition in the EU has gained momentum. Almost half of electricity consumption is now covered by renewable energies, with solar technology accounting for a significant share. However, the massive expansion of photovoltaics is increasingly being felt by every individual locally. The electrical grids are reaching their capacity limits. The number of redispatch measures is rising exponentially to keep the system running smoothly. This, in turn, is reflected on the electricity exchange in exorbitantly low exchange prices and, during windy and sunny hours, even in negative exchange prices. These trends raise the question of how energy security can be maintained and achieved in the future. In this context, a decentralized energy system is being modeled to create an electricity self-sufficient village using agrivoltaics. This has the advantage that the land can be used for dual purposes. The shared use of energy between citizens, commercials, municipalities and farmers creates a self-managed energy community. Farmers play a key role in this dual land use. This paper examines the central research question of what contribution an electricity self-sufficient village using agrivoltaics can make to energy security. This paper is based on a survey of 215 German farmers. The survey results show a trend that energy security can be increased through this modelled decentralized energy system. Various policy implications can be formulated for the realization of an electricity self-sufficient village using agrivoltaics. The first step is to achieve electricity self-sufficiency during the sunny months from March to October, until cross-seasonal storage media are available and ready for series production.
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    From coffee waste to wastewater treatment: optimization of hydrothermal carbonization and H₃PO₄ activation for Cr(VI) adsorption
    (2026) Piccoli Miranda de Freitas, Caroline; De Freitas Batista, Gabriel; Dalmolin da Silva, Mariele; Checa Gomez, Manuel; Arauzo, Pablo J.; França da Cunha, Fernando; Kruse, Andrea
    Spent coffee grounds (SCG) are an abundant agro-industrial waste, and their valorization as activated carbon (AC) offers a sustainable approach for wastewater treatment and heavy-metal remediation. However, the high energy demand of SCG activation limits large-scale application. Hydrothermal carbonization (HTC) reduces energy consumption and enhances material properties. This study evaluated the performance of activated carbon (AC) derived from SCG via HTC, followed by H₃PO₄ activation for Cr(VI) removal, and compared it with non-activated carbon obtained by HTC and pyrolysis. The results highlight the effect of chemical activation on enhancing surface area, porosity, and adsorption efficiency. The predicted optimal IN was 1624.7 mg·g⁻¹, closely matching the experimental value of 1640.1 ± 15.5 mg·g⁻¹, achieved at 426 °C, 92 min, and a hydrochar-to-H₃PO₄ ratio of 1:1.6. The optimized AC exhibited a maximum adsorption capacity (Qₑ) of 33 ± 1.1 mg·g⁻¹ and 99.4 ± 0.1 % Cr(VI) removal under pH 2, 25 mg·L⁻¹ initial concentration, and 2 g·L⁻¹ adsorbent dose. In contrast, the non-activated carbon presented a lower iodine number (1411 ± 70 mg·g⁻¹) and inferior adsorption performance, confirming the key role of H₃PO₄ activation in improving surface reactivity and adsorption sites. Chemical activation proved essential for improving Cr(VI) adsorption, with the H₃PO₄-AC exhibiting the highest capacity. These results demonstrate the potential of SCG-derived AC as a low-cost adsorbent for heavy-metal-rich industrial effluents, supporting circular economy strategies.
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    Ingenious wheat starch/Lepidium perfoliatum seed mucilage hybrid composite films: Synthesis, incorporating nanostructured Dy₂Ce₂O₇ synthesized via an ultrasound-assisted approach and characterization
    (2025) Zinatloo-Ajabshir,Sahar; Yousefi, Alireza; Jekle, Mario; Sharifianjazi, Fariborz
    In this study, Dy₂Ce₂O₇ nanostructures were fabricated using an environmentally friendly, ultrasound-assisted method. These nanostructures were then incorporated into a blend of wheat starch (WS) and Lepidium perfoliatum seed mucilage (LPSM), along with sodium montmorillonite (Na-MMT) nanoparticles. The composite films were produced through a casting method, combining these components to enhance the films' structural and functional properties. FTIR results confirmed the chemical interactions between the NPs and the biopolymeric matrix of the nanocomposites. SEM surface morphology and XRD crystallography results indicated that up to a 1 % weight ratio, the dispersion of Dy₂Ce₂O₇ in the nanocomposite matrix was uniform, while at higher percentages, due to nanoparticle aggregation, crystallinity increased. Interestingly, the elongation of nanocomposites containing Dy₂Ce₂O₇ increased, while their tensile strength and elastic modulus decreased. More than 92 % of UV radiation in the 240–360 nm range was absorbed with the inclusion of 1 % wt. Dy₂Ce₂O₇, and the water vapor permeability (WVP) significantly decreased. Among the Dy₂Ce₂O₇-based nanocomposites, TGA results showed that the WS/LPSM/MMT/Dy1 % sample had the highest thermal stability. Overall, based on the results of this study, the WS/LPSM/MMT/Dy1 % sample was introduced as a composite film with suitable physicochemical and mechanical properties for food and pharmaceutical packaging.