Browsing by Issue Date, starting with "2022-02"
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- Increasing energy efficiency with a smart farm - An economic evaluationPublication . Pereira, Filipe; Caetano, Nídia; Felgueiras, CarlosRural farms are typically energy-intensive facilities with relatively low energy efficiency. In this sector, the introduction of renewable energies and integrated resource management technologies has been slower than in the domestic and industrial sector. The introduction of renewable energy sources was an mportant step in the past, but they are currently insufficient, as they do not allow for adequate energy management. The development of new solutions with integrated energy control is especially attractive for these installations as they present the least limitations in terms of space and adaptation to new technologies. This work describes a solution that was developed and implemented in a farm located in central Portugal. The results show that 83.2% reduction in energy from the grid can be achieved, with 5527 kg CO2 savings, and the return on investment (of C 32,434) is about 8 years. However, this period can be shortened if evolutionary options are taken, such as upgrading to electric driven agricultural equipment
- Evaluation of activated carbons produced from Maize Cob Waste for adsorption-based CO2 separation and biogas upgradingPublication . Surra, Elena; Ribeiro, Rui P.P.L.; Santos, Tiago; Bernardo, Maria; Mota, José P.B.; Lapa, Nuno; Esteves, Isabel A.A.C.Two activated carbons (AC) resulting from CO2 activation of Maize Cob Waste (MCW) were investigated as adsorbent materials for biogas upgrading to bio-methane applying a biorefinery concept. The porous carbons were originated from different times of activation and the one resulting from 3 h with CO2 (MCW(PA)3 h) showed better textural properties, higher working capacity, and selectivity towards CO2 than the carbon resulting from 2 h of activation (MCW(PA)2 h), making it the best candidate for biogas purification. The adsorption equilibrium measurements of CO2 and CH4 on MCW(PA)3 h carbon showed that the Sips isotherm model, as well as the Adsorption Potential Theory (APT), can be confidently employed to accurately correlate the adsorption equilibrium data of the adsorbates employed. In the range of the partial pressures typical for biogas upgrading units, MCW(PA)3 h showed higher CO2 uptakes than the ones reported for coal-based commercial ACs and similar uptakes to the ones reported for bio-based ACs. Moreover, the axial dispersed plug-flow and Linear Driving Force (LDF) approximation for lumped solid-diffusion mass transfer model used for the prediction of the dynamic behaviour of the adsorbate-adsorbent system, provided a good agreement with the experimental results, demonstrating its applicability to the studied system. This work represents the basis of future modelling works of a Pressure Swing Adsorption (PSA) cycle based on the use of MCW(PA)3 h as adsorbent material and demonstrates the high potential of this novel material to be applied in biogas upgrading processes
- Continuous adsorption studies of pharmaceuticals in multicomponent mixtures by agroforestry biocharPublication . Puga, Antón; Moreira, Manuela M.; Pazos, Marta; Figueiredo, Sónia; Sanromán, M. Ángeles; Delerue-Matos, Cristina; Rosales, EmilioIn this study, the adsorption of a multicomponent mixture of active pharmaceutical compounds, such as Venlafaxine (VLX), Trazodone (TRZ) and Fluoxetine (FLX), was studied in a biochar fixed-bed column. The selection of appropriate biochar (eucalyptus, grapevine cane and holm tree biochar) as an adsorbent was carried out through batch assays. An insight into the adsorption mechanism and its correlation with the chosen biochars was performed, showing that electron donor/acceptor interaction is the main mechanism involved. Equilibrium and kinetic batch adsorption experiments were performed and the results demonstrated that eucalyptus biochar was the most viable option for the removal of the pollutants, individually and combined. Column adsorption experiments were performed and Thomas, Yoon-Nelson and Yan models were adjusted to the breakthrough curves. This multicomponent system exhibited a synergetic behavior for TRZ and an antagonist for VLX and FLX, when compared to the single and multicomponent systems previously evaluated in batch assays. The treatment of real wastewaters, spiked with pollutants, has demonstrated the removal efficiency of multicomponent mixtures. Finally, the adsorbent regeneration by elution in different solutions was also investigated and methanol proved to be the most effective eluent for the column regeneration
- A Strategy to Assess Water Meter PerformancePublication . Cordeiro, Clara; Borges, Ana; Ramos, M. RosárioApparent water losses can be problematic to water companies’ revenues. This type of loss is very difficult to detect and quantify and is often associated with water meter anomalies. This study was motivated by a water company’s challenge that links a decrease in water consumption to water meters’ malfunction. The aim is to develop a strategy to detect decreasing water usage patterns, contributing to meter performance assessment. The basis of the approach is a combination of statistical methods. First, the time series of billed water consumption is decomposed using Seasonal-Trend decomposition based on Loess. Next, breakpoint analysis is performed on the seasonally adjusted time series. After that, the Mann–Kendall test and Sen’s slope estimator are used to analyze periods of progressive decrease changes in water consumption, defined by breakpoints. A quantitative indicator of this change is proposed. The strategy was successfully applied to eight-time series of water consumption from the Algarve, Portugal.
- Impact of a ten-minute typing task in the development of trapezius myalgiaPublication . Santiago, Rui José; Baptista, João Santos; Magalhães, André; Costa, José TorresComputer use, as in typing, might contribute to trapezius myalgia (TM) development by increasing upper trapezius (UT) muscle fatigue. The purpose of this study is to investigate whether 10 min of performing a typing task by a population at risk would show significant changes in surface electromyography (sEMG) and pressure pain threshold (PPT) measurements. Supported and unsupported forearms postures are compared. Sixteen asymptomatic volunteers with minimum daily use of a computer of 5 h were randomized into two groups: fully supported forearms (n = 8) and unsupported forearms (n = 8). The protocol consisted of 10 min of a typing task, and the workstation was set according to the usual participant profile. sEMG and PPT readings were collected from both UT muscles. PPT and sEMG readings were not significantly different among the two groups. Supported forearms had less reduction of PPT and a smaller increase in electrical activity. Ten minutes of typing seems insufficient to observe any significant changes that could lead to TM development.
- The role of adipose tissue analysis on Environmental Pollutants Biomonitoring in women: The European scenarioPublication . Sousa, Sara; Maia, Maria Luz; Delerue-Matos, Cristina; Calhau, Conceição; Domingues, Valentina F.Humans are exposed every day to assorted environmental pollutants namely, polychlorinated biphenyls (PCB), organochlorine pesticides (OCP), brominated flame-retardants (BFR), polycyclic aromatic hydrocarbons (PAH), synthetic musks, heavy metals (e.g. cadmium) and plastic additives (e.g. bisphenol A, BPA). Besides environmental persistence, biomagnification and bioaccumulative properties, these pollutants are classified as endocrine disruptors (EDs), metabolic disruptors, neurologic disruptors. These compounds affect the normal function of several mechanisms in the human body being linked to human health issues as cancer development (e.g. breast, uterine and endometrial), miscarriage, birth defects, premature delivery and infertility. In order to prevent future health issue of women and possible progeny, the assessment of EDs accumulated is essential, particularly in adipose tissue. These samples have been referred as the ideal matrix to establish over time accumulation and long-term exposure of persistent and non-persistent lipophilic EDs. However, the invasive sample collection procedure and methodology processing discourages the usage of this matrix for biomonitoring studies. In this review, a Web of Science search without any publishing year restriction on the analysis in adipose tissue of PCB, OCP, BPA, cadmium, BFR and synthetic musks was performed. A total of 313 studies were found, 158 were European studies from which the studies with data on women EDs accumulation were selected for detailed analysis (n = 90). The results were structured and presented in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The present paper is an overview on the existent EDs analytical methods and levels accumulated in women adipose tissue, with the correspondent health implications across Europe. The limits of detection and quantification were compared and a discussion with results obtained about the presence of ED was performed
- Life cycle energy and carbon analysis of a road-safety barrier produced using recycled tire rubberPublication . Monteiro, H.; Ribeiro, I.; Gonçalves, M.; Iten, M.; Caetano, Nídia S.Increasing end-of-life material recovery and its application in new products is essential to reduce resource consumption. This paper assesses the cradle-to-gate life cycle energy and carbon dioxide (CO2) emissions of a new road safety barrier product to be installed around guardrails’ poles. To analyze the potential life cycle benefit of incorporating recycled materials, a base case product A, produced with conventional virgin synthetic rubber and polypropylene (PP), was compared with two equivalent alternatives under study: B (using recycled end-of-life tire rubber granulate (TRG) and PP), and C (using TRG and recycled polypropylene). The results show that the incorporation of recycled TRG has a positive effect in primary energy and carbon emissions. Product B presents less 38% CO2 emissions and 47% non-renewable primary energy than product A. The combination of TRG and recycled polypropylene (C), presents even more benefits: less 69% CO2 and 86% nonrenewable primary energy than A. Supply chain processes and material production have much higher impacts than the product manufacturing (e.g. product molding only represents 5% of the primary energy of product A). To conclude, recycled materials incorporation should be strongly encouraged since it has a great potential to reduce current carbon emissions and primary energy of products.
- Life cycle energy of vehicles on lightweighting and alternative powertrain strategies—A reviewPublication . Monteiro, Helena; Alonso, Rita; Gonçalves, Margarida; Iten, Muriel; Caetano, Nídia S.To improve vehicles environmental performance, different strategies have been explored namely to reduce the use stage energy. In order to avoid problem shifting, a life cycle perspective should be used to compare alternative solutions. This paper aims to compare existing studies focused on life cycle energy (LCE) of vehicles to analyze the impacts and benefits regarding two trending improvement strategies: lightweight materials and alternative powertrain selection. A Literature review was performed to systematize quantitatively the LCE results of different studies (e.g. presented among figures, tables, and literature text). The LCE results were compiled and normalized for the same driving distance, 200 000 km, per life cycle stage. Moreover, the study discusses research findings on the application of the two strategies to improve overall vehicles’ LCE. As lightweight materials have generally higher embodied energy, the material selection is highly influenced by end-of-life scenarios. It was observed that carbon/glass fiber composites generally have the highest embodied energy, being a preferable option for vehicles that last longer driving distances. Innovative powertrains sourced by renewable energy sources, electric mixes, can significantly reduce vehicles’ LCE use stage, counteracting the benefit of lightweight design. Thus, the benefit of both strategies should be studied together.
- Improving WiFi communication with surface nodes at near-shore on tidal watersPublication . Gutiérrez Gaitán, Miguel; d'Orey, Pedro; Santos, Pedro Miguel; Ribeiro, Manuel; Pinto, Luis; Almeida, Luís; de Sousa, J. BorgesWireless radio links deployed in aquatic areas (e.g., sea, rivers, lakes, estuaries) are affected by the conductive properties of the water surface, strengthening signal reflections and increasing destructive interference. Recurrent natural phenomena (e.g. tides or waves) cause shifts in water levels further impairing propagation over water surfaces. In this work, we aim to mitigate the detrimental impact of tides on link quality by providing tailored link distance/height-design regions that minimize average path losses. We focus on line-of-sight (LOS) over-water links between onshore stations and different types of surface nodes, namely AUVs, buoys, or USVs, using 2.4 GHz and 5 GHz frequency bands. Analytical results targeting mission data transfer scenarios demonstrate that the proposed method outperforms, in both frequency bands, the common practice of placing (i) onshore antennas at the largest possible height and/or (ii) surface nodes at a short but arbitrary distance from the shore. A longer version of this summary was presented at IEEE/MTS OCEANS 2021.
- Life cycle assessment of bioethanol from corn stover from soil phytoremediationPublication . Mata, Teresa M.; Rodrigues, Sara; Caetano, Nídia; Martins, António A.Bioethanol is the most widely used biofuel in the world. Bioethanol production from biomass is a way to reduce crude oil consumption and the environmental pollution. This work aims to evaluate the potential environmental impacts of bioethanol production from corn stover obtained from phytoremediation, comparing four different acids (Sulfuric, Nitric, Hydrochloric and Acetic acids) to perform the biomass pre-treatment. The study follows a life cycle thinking perspective, accounting for all the life cycle stages from corn stover grinding, to biomass pre-treatment, enzymatic hydrolysis, fermentation, filtration and ethanol distillation, on a “gate-to-gate” approach. The life cycle inventory was developed using mainly primary data from laboratorial experiments, and complemented whenever necessary with information from literature and from the Ecoinvent V3.0 database available in the SimaPro 8.0.2 software. For the environmental impact assessment, the ILCD Midpoint 2011 methodology was used. Results show that in general, the sulfuric and hydrochloric acids have a better environmental performance than the acetic and nitric acids. Also, results show that pre-treatment, followed by enzymatic hydrolysis are the process steps with the highest relative contribution to the potential environmental impacts. Thus, an improvement analysis should focus on these process steps, for example to reduce fossil energy consumption by implementing renewable energy sources.