4161 research outputs found
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An optimized probabilistic forecasting approach for hybridized wind power plants
Get PDFABSTRACT: Accurate forecasts are essential for efficiently integrate variable renewable power plants into power systems and electricity markets. Since hybrid power plants are a new area of research, several key challenges need to be addressed. This work presents a probabilistic power forecast approach to hybridised wind power plants with solar power. The forecasting metho dology uses a sequential forward feature selection algorithm, employing distinct objective functions and an artificial neural network approach. The probabilistic power forecasts are obtained using a quantile spline regression technique. The approach supports the identification of the: i) optimal quantile and ii) exogenous features (e.g., meteorological input features from numerical weather prediction – NWP models) to increase the profitability of the hybrid power plants in an electricity market environment. As expected, hybridization increases the remuneration of the producer when compared to existing wind plants, regardless of complementarity levels. This increase in remuneration of hybrid plants is superior for the highest generation complementarity case. The use of quantiles to calibrate the forecast approach proves to be crucial for increasing the remuneration compared to the traditional deterministic approach based on the power forecast expected value.info:eu-repo/semantics/publishedVersio
Path disturbing in the process of path development: The case of (onshore & floating offshore) wind energy in Portugal [Resumo]
No full textABSTRACT: The paper addresses the “disturbing” effects that new generations of technology can introduce in the early trajectory of a regional industrial path built around wind offshore technology, focusing on the dimensions along which such disturbance occurs and the actors’ responses to them. We look at the case of the industry formed around wind energy technology. The first generation – onshore wind - drove the development of new industrial paths in some regions. The introduction of new generations (fixed & floating offshore wind) that increasingly diverge from the onshore technology, leading to significant changes in the industry concerned with their production and deployment (Van Der Loos et al., 2020). It is argued that the emergence of the new technology generations potentially produced disturbance along several dimensions (Gong & Binz, 2023) that could affect the industrial and institutional configuration of the wind energy path. The industrial development required, not only innovation activity in the existing manufacturing industry, but also the involvement of a new set of industries. The location at sea made proximity to the natural resource more pertinent, required new infrastructures, demanded regulatory changes and raised new acceptance issues (MacKinnon et al., 2019). Thus path-disturbance would occur at different assets level and actors’ agency. The paper empirically analyses the case of Portugal, which developed an onshore wind energy (Bento & Fontes, 2015) and has engaged early in the experimentation with the new generation of floating offshore wind (Castro-Santos et al., 2020).info:eu-repo/semantics/publishedVersio
Contribution of the time domain electromagnetic method to the study of the Kalahari transboundary multilayered aquifer systems in Southern Angola
Get PDFABSTRACT: The Cunene Province (Southern Angola) is facing recurrent and pluriannual droughts. Surface water supply could be reinforced using the groundwater resources of the multilayered aquifer systems (MAS) hosted in the siliciclastic sediments of the Kalahari Group. The MAS were first identified in the early 2000s in Northern Namibia and recently in the Cunene Province, by studies of the PLANAGEO project based on modern processing and reinterpretation of legacy data from the 1960s and 1970s (electrical resistivity data and deep boreholes). This article presents the results of a time domain electromagnetic (TDEM) survey conducted in the Cunene Province to: (i) contribute to the design of the hydrogeological conceptual model of the transboundary MAS, namely their geometry and extension; (ii) validate the reprocessing of the legacy data; and (iii) guide the future location of boreholes. Results depict the geometry of the sedimentary basin and the characterization of the MAS, with particular emphasis on the intermediate and deep aquifers. The borehole siting, based on the interpretation of the new TDEM data and the legacy data (clay markers in borehole logs), was successful, with a good agreement between estimated and observed horizons of the deep aquifers. However, the presence of clayey layers, a clay-rich matrix in the detrital deposits and saline/brackish groundwater led to uncertainties in the interpretation of the electrical transects. As such, recommendations are made to improve future data collection and mapping of the MAS.info:eu-repo/semantics/publishedVersio
European patterns of local adaptation planning : a regional analysis
Get PDFABSTRACT: While European regions face a range of different climate hazards, little is known about how these differences affect local climate adaptation planning. We present an analytical framework for evaluating local climate adaptation plans (LCAPs) and apply it to 327 cities in 28 countries across different European regions. To do this, we use statistical methods to identify regional clusters based on overall plan quality, impacts, vulnerable population groups, and sectors addressed by LCAPs. By comparing both geographic and statistical clusters, we found (1) significant spatial heterogeneity across European cities but (2) higher average plan quality scores and more consistent strategies across cities in Central and Eastern Europe. Notably, we found no regional differences regarding (a) the climate impacts and vulnerable communities identified in plans: (b) the most commonly addressed impacts, which were urban temperature and changing precipitation patterns; and (c) the residents that cities identified as most vulnerable, namely older people, women, infants, and the sick. Our study provides a spatial analysis of European LCAPs to uncover regional policy perspectives on local climate adaptation issues. Such approaches can effectively inform broader EU, national and regional strategies that aim to support local adaptation planning in a context of multi-level governance.info:eu-repo/semantics/publishedVersio
Polyhydroxyalkanoate Production from Eucalyptus Bark's Enzymatic Hydrolysate
Get PDFABSTRACT: In recent years, polyhydroxyalkanoates (PHAs) have gained notoriety because of their desirable properties that include proven biodegradability, biocompatibility, and thermal stability, which make them suitable alternatives to fossil-based polymers. However, the widespread use of PHAs is still challenging because of their production costs, which are greatly associated with the cultivation medium used for bacterial cultivation. In Portugal, one-quarter of the forest area is covered by Eucalyptus globulus wood, making its residues a cheap, abundant, and sustainable potential carbon source for biotechnological uses. In this work, eucalyptus bark was used as the sole feedstock for PHA production in a circular bioeconomic approach. Eucalyptus bark hydrolysate was obtained after enzymatic saccharification using Cellic (R) CTec3, resulting in a sugar-rich solution containing glucose and xylose. Although with differing performances, several bacteria were able to grow and produce PHA with distinct compositions, using the enzymatic hydrolysate as the sole carbon source. Pseudomonas citronellolis NRRL B-2504 achieved a high cellular growth rate in bioreactor assays (24.4 +/- 0.15 g/L) but presented a low accumulation of a medium-chain-length PHA (mcl-PHA) comprising the monomers hydroxydecanoate (HD, 65%), hydroxydodecanoate (HDd, 25%), and hydroxytetradecanoate (HTd, 14%). Burkholderia thailandensis E264, on the other hand, reached a lower cellular growth rate (8.87 +/- 0.34 g/L) but showed a higher biopolymer accumulation, with a polyhydroxybutyrate (PHB) content in the cells of 12.3 wt.%. The new isolate, Pseudomonas sp., revealed that under nitrogen availability, it was able to reach a higher accumulation of the homopolymer PHB (31 wt.%). These results, although preliminary, demonstrate the suitability of eucalyptus bark's enzymatic hydrolysate as a feedstock for PHA production, thus offering an exciting avenue for achieving sustainable and environmentally responsible plastic products from an undervalued forestry waste.info:eu-repo/semantics/publishedVersio
Comprehensive Wheat Straw Processing with Deep Eutectic Solvent to Deliver Reducing Sugar
Get PDFABSTRACT: Pretreatment is one of the bottlenecks in the cost and energy-efficient biomass valorization. Deep eutectic solvents are potential candidates for being used to address these challenges. In this work, the deep eutectic solvent composed of choline chloride, and acetic acid was studied for its use in wheat straw fractionation. The pretreated biomass was assessed concerning the lignin and glucan content. Under optimized time and temperature conditions, defined using Doehlert matrix chemometric tool, of 3 h 47 min and 139.6 degrees C, the processed wheat straw contained as much as 42.5 +/- 0.42 wt.% and 38.59 +/- 1.26 wt.% of glucan and lignin contents, respectively. The need for biomass washing after the pretreatment with deep eutectic solvents and before the enzymatic hydrolysis step was also evaluated. The obtained enzymatic hydrolysis results, i.e., glucan to glucose yield of 27.13 +/- 0.25 vs. 25.73 +/- 0.08 for washed or unwashed biomass correspondingly, are equally good substrates. Fractal kinetic analysis of the data showed similar values of k and h for both glucose and xylose reactions between washed and unwashed biomass. This confirmed that biomass washing is an unnecessary step, which in turn opens room for biomass processing intensification.info:eu-repo/semantics/publishedVersio
Biogas reforming as a sustainable solution for hydrogen production: Comparative environmental metrics with steam-methane reforming and water electrolysis in the Portuguese context
Get PDFABSTRACT: This study delves into the dynamics of hydrogen production, with a specific focus on biogas reforming (BGSMR) for hydrogen generation. It compares the environmental impact of this solution with hydrogen production from natural gas-steam reforming (NGSMR) and commercial electrolysis in the Portuguese context. Various metrics, including carbon footprint, water depletion, energy utilization, and waste valorization are employed for a comprehensive comparison. The assessment explores the impact of operational parameters and different off-gas combustion scenarios, incorporating water recycling practices. Due to challenges in obtaining detailed data on the actual reforming process, the study relies on process simulation techniques, primarily using DWSIM. Commercially available data for water electrolysers were used for comparison. In the context of decarbonizing power systems, hydrogen from water electrolysis emerges as a competitive option only in a scenario where the power system is 100% reliant on renewable sources, particularly with respect to the carbon footprint metric. Biogas systems, characterized by near-zero carbon emissions, stand out as a favourable option from the near future to the long run. This research contributes valuable insights into the dynamics of hydrogen production, shedding light on environmentally viable alternatives across a range of power system scenarios.info:eu-repo/semantics/publishedVersio
Decoding Portuguese Azulejos: the intersection of art, history, and science [Resumo]
No full textABSTRACT: In recent decades, the production techniques of azulejos (Portuguese glazed tiles with predominantly blue color) remain a subject of ongoing research. Combining historical research with advanced
analytical techniques, this communication aims to show that pigments and materials that define the azulejo colour palette, along with their production recipes and the chemical and structural composition of the glazed tiles. This communication highlights the application of synchrotron radiation to the analysis of Portuguese azulejos. Some examples will be presented, namely the Co and Cu K-edge Xray absorption near-edge spectroscopy (XANES) results performed on glazed tiles from the Fronteira Palace, in Lisbon and the speciation of pigments from Pena National Palace, Sintra. The speciation state of certain chemical elements provides an understanding of their role as chromophores, glass network formers or modifiers, contributing to a deeper knowledge of the production techniques, provenance, and the tiles’ history of use. The non-destructiveness nature allied to the high-resolution capabilities of synchrotron radiation chemical imaging offer a unique tool for investigating cultural heritage materials, enhancing our understanding of their composition, structure, and degradation processes, and contributing to their long-term preservation and interpretation for future conservation efforts.N/
User guide for TradeRES models and tools (D6.2.1): 2nd Edition
No full textProject TradeRES - New Markets Design & Models for 100% Renewable Power SystemsN/
An expedite methodology for identification of inorganic contaminants in biomass origin feedstock: wavelength dispersive x-ray fluorescence (WD-XRF) spectrometry
No full textABSTRACT: The use of biomass feedstock for bioenergy production has increased in recent years. In the context of a circular economy, wastes such as municipal solid wastes and industrial wastes (namely by-products from agrofood wastes, agro-livestock wastes and sewage sludge) have been tested as new feedstocks of biomass origin. However, the presence of some inorganic contaminants in these new feedstocks might be problematic for thermochemical and biochemical conversion processes. Wavelength Dispersive X-Ray Fluorescence (WD-XRF) spectrometry is an easy and fast technique that uses only a small amount of sample, presenting a low contamination risk and is a non-destructive methodology. Thus, if potential contaminants are identified, then samples remain available for subsequent analysis.info:eu-repo/semantics/publishedVersio