Browsing by Issue Date, starting with "2025-07"
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- Techno-economic analysis of a renewable energy based multigeneration system for zero energy buildingsPublication . Aelenei, Laura Elena; Rodrigues, Carlos; Brites, Maria João de Sousa; Viana, SusanaABSTRACT: The present study explores the contribution and benefits of a renewable energy based multigeneration prototype integrating a luminescent compound parabolic concentrator, a photovoltaic/thermal system and thermal storage using phase change materials. A numerical model was developed for assessing the energy performance of the prototype and the results are presented for three different European locations. A simplified economic analysis was also developed and presented for two different scenarios and the same European locations. The results reveal that the installation of the IDEAS system in Lisbon, with a total estimated yearly use of solar energy of 1215 kWh and an amount of energy sold to the grid of 40.6 kWh, results in savings of 266 (26 % of energy bill). For the Ferrara location, with a total estimated yearly use of solar energy of 967 kWh and 19.8 kWh of energy sold to the grid of, results on 229 (16 % of energy bill) of annual savings. In Dublin, with a total estimated yearly use of solar energy of 862 kWh and an amount of energy sold to the grid of 20.5 kWh, results on annual savings of 257 (14 % of energy bill).
- Industrial Off-Gas Fermentation for Acetic Acid Production: A Carbon Footprint Assessment in the Context of Energy TransitionPublication . Pacheco, Marta; Brac de la Perrière, Adrien; Moura, Patrícia; silva, carlaABSTRACT: Most industrial processes depend on heat, electricity, demineralized water, and chemical inputs, which themselves are produced through energy- and resource-intensive industrial activities. In this work, acetic acid (AA) production from syngas (CO, CO2, and H2) fermentation is explored and compared against a thermochemical fossil benchmark and other thermochemical/biological processes across four main Key Performance Indicators (KPI)—electricity use, heat use, water consumption, and carbon footprint (CF)—for the years 2023 and 2050 in Portugal and France. CF was evaluated through transparent and public inventories for all the processes involved in chemical production and utilities. Spreadsheet-traceable matrices for hotspot identification were also developed. The fossil benchmark, with all the necessary cascade processes, was 0.64 kg CO2-eq/kg AA, 1.53 kWh/kg AA, 22.02 MJ/kg AA, and 1.62 L water/kg AA for the Portuguese 2023 energy mix, with a reduction of 162% of the CO2-eq in the 2050 energy transition context. The results demonstrated that industrial practices would benefit greatly from the transition from fossil to renewable energy and from more sustainable chemical sources. For carbon-intensive sectors like steel or cement, the acetogenic syngas fermentation appears as a scalable bridge technology, converting the flue gas waste stream into marketable products and accelerating the transition towards a circular economy.
- Oceanos e continentes: no fim dos séculos XV e XX, e no início do século XXIPublication . Ribeiro, AntónioRESUMO: Durante os séculos XV e XVI, os descobridores portugueses substituíram a geografia Mediterrânica pela Atlântica. De algum modo, é possível estabelecer um paralelo com a perspetiva atual da Tectónica de Placas Macias, em que a litosfera oceânica arrasta a litosfera rígida dos escudos pré-câmbricos.
- Comparison of the corrosion of ferritic and austenitic stainless steel (AISI 430 and AISI 316L) with LiNaK carbonate salts for thermal energy storage in CSP/CST applicationsPublication . Gil, Mafalda; Pedrosa, Fátima; Paiva Luís, Teresa; Figueira Vasques, Isabel; Oliveira, Fernando; Cunha Diamantino, TeresaABSTRACT: This study focuses on the corrosion rates and mechanisms of two stainless steels, austenitic AISI 316L and ferritic AISI 430, in contact with a eutectic mixture of LiNaK carbonates in long-term tests at 650 degrees C. The selection of these two stainless steels was based on their differences, both in their intrinsic characteristics and in the cost associated with each one. The research also underscores the importance of optimizing the descaling methods used to evaluate the corrosion rate. Corrosion rates were measured gravimetrically according to ISO 17245:2015, revealing an asymptotic behavior for both steels, with AISI 430 with a corrosion rate of 237 f 21 mu m and AISI 316L of 151 f 13 mu m after 2000 h of testing. Corrosion mechanisms were analyzed using SEM/EDS, GDOES, and XRD techniques, which identified well-defined oxide layers with varying compositions. Given the observed corrosion mechanisms and its lower cost, AISI 430 steel seems to have great applicability in CSP/CST plants, provided it is paired with an appropriate protective coating.