Repositório do LNEG
Repositório Científico do Laboratório Nacional de Energia e Geologia
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Biogas Production from the Anaerobic Co-Digestion of Elephant Grass Juice and CattleWastewater: Batch and Semi-Continuous Performance in Anaerobic Reactors
Publication . da Silva, Guilherme Henrique; Otenio, Marcelo; Reis, Alberto; Martins, Marcio; Borges, Alisson; Lopes, Tiago; Renato, Natalia
ABSTRACT: Considering the limited information available on the use of elephant grass juice (EGJ) as a liquid co-substrate, this study aimed to evaluate its feasibility and biogas production potential for anaerobic co-digestion with dairy cattle wastewater (DCW), focusing on substrate ratios and reactor operating conditions. Initially, batch tests were conducted at different temperatures to evaluate the effects of varying substrate mixture ratios (EGJ/DCW). In the reactor with 20% EGJ/80% DCW at 39 °C, a biogas volume of 414.35 mL was generated, which was considerably higher than that in the test at 25 °C, where 258.7 mL was generated over the 30-day experimental period. Greater efficiency in organic matter removal and other analyzed parameters was also observed under these conditions. The best configuration was selected for the semi-continuous tests. To this end, an Upflow Anaerobic Sludge Blanket (UASB) reactor was operated with hydraulic retention times of 10, 6, 2, and 1 d and volumetric organic loading rates of 2.06, 3.39, 10.40, and 20.70 kg VS m−3 d−1, respectively. Volatile solids were removed by 29–58%, with biogas yields ranging from 0.78 to 2.28 m3 m−3 d−1 and a maximum CH4 concentration of 72% (v/v). The co-digestion of the analyzed agricultural waste substrates proved to be a promising approach for bioenergy recovery. These results provide useful guidelines for optimizing co-digestion systems, improving reactor performance, and waste treatment processes.
Increase the value of wind power plants through the hybridization with solar photovoltaic
Publication . Couto, António; Estanqueiro, Ana
ABSTRACT: The increasing penetration of variable renewable energy sources, such as wind and solar PV, requires these technologies to actively support power system operation through participation in day-ahead and balancing markets, including the provision of ancillary services. In this context, hybrid power plants, where wind and solar PV share a common point of common coupling and are operated as a single unit, can provide technical and economic advantages compared to standalone plants. This work focuses on the “firm capacity” that can be offered in the Portuguese balancing markets using probabilistic power forecasts, considering the hybridisation of existing wind power plants with solar PV units. Results are compared with the standalone wind power plant and feature-based indicators are also explored to assess whether dynamic selection of forecast quantiles can increase the available capacity for balancing market. Two case studies in Portugal with different levels of wind and solar complementarity are considered. Results show that hybrid power plants significantly increase the amount of capacity available for market participation from 20.5% to 66.2% relative to standalone wind power plants. Thus, hybridisation enhances the ability of existing grid assets to provide ancillary services through participation in balancing markets.
Assessing the Market Value of Power Forecasting of Hybrid Power Plants in the Iberian Electricity Market
Publication . Couto, António; Graça, Pedro; Sousa, Vivian; Estanqueiro, Ana
ABSTRACT: This study evaluates the technical and economic performance of wind power plants hybridised with solar photovoltaic (PV) under two 2030 Iberian electricity market scenarios dominated by renewable energy, developed within the Man0EUvRE project. A power forecasting model was optimised to maximise their market value, considering participation in both day-ahead and balancing markets. Compared to wind-only power plants, hybridisation improves forecast accuracy due to the complementary generation profiles of wind and solar PV. As a result, revenue losses due to imbalance penalties decrease by 1528%, enabling the prices captured to increase by up to 6%. The hybrid configurations also achieved the highest market remuneration. However, as the share of low marginal cost technologies increases in the electricity markets, captured prices are expected to decline. These results demonstrate the benefits of hybridising the existing wind power plants, which can provide a short-term and efficient solution to support the ambitious European decarbonisation targets while enhancing both operational performance and their market value.
Iberian Electricity Market Performance under European Energy Transition Scenarios for 2050
Publication . Sousa, Vivian; Couto, António; Graça, Pedro; Estanqueiro, Ana; Löffler, Konstantin; Moskalenko, Nikita
ABSTRACT: The Man0EUvRE project analyses the required energy transition in Europe, extending beyond typical scenarios focused only on renewable integration pace by incorporating key uncertainties such as geopolitical fragmentation, limited
cooperation, and technological innovation. This study evaluates the performance of the Iberian Electricity Market (MIBEL)
between 2030 and 2050 under four distinct scenarios. Long-term capacity expansion is modelled with GENeSYS-MOD, while hourly day-ahead market clearing prices are simulated using PyMIBEL-DAM, capturing both strategic investment decisions and operational dynamics. The results highlight strong growth of variable renewable energy sources (vRES) through 2050, particularly solar photovoltaic, and the resulting price cannibalisation that challenges the conomic viability of solar generation in a market environment. Wind generation, in contrast, maintains more stable capture prices showing differences in the market value across vRES technologies. Therefore, a carefully designed transition pathway, by integrating a balanced generation mix, robust flexibility solutions, and reinforced cross-border interconnections between Portugal and Spain, is essential. Such integration will provide the necessary market signals for sustainable decarbonisation of the Iberian power system while ensuring overall system efficiency.
Preliminary Integrated Analysis of Magnetic Susceptibility, Geochemistry, and Mineralogy in the Neves Corvo VMS District (MAQSIMAL Project)
Publication . Represas, Patricia; Batista, Maria Joao; Albardeiro, Luís; Marques, Fábio; Silva, Teresa; Carvalho, João; Xavier Matos, João Manuel
ABSTRACT: The MAQSIMAL project develops a multimodal airborne quantum-sensor prototype that simultaneously measures the 3D magnetic field, magnetic-field gradients and electromagnetic responses to improve sustainable mineral exploration. The Neves–Corvo mining district (Iberian Pyrite Belt, Portugal), a largely concealed volcanogenic massive sulphide (VMS) system, was selected as a test site to compare prototype data with existing geological and drilling information. This extended abstract reports initial surface-sample characterisation integrating magnetic susceptibility (KT-10; ∼150 outcrops), XRD mineralogy and portable XRF geochemistry (20 samples). Susceptibility values are strongly right-skewed (0–5.81×10−3 SI) and vary systematically with lithology: mafic volcanic rocks show the highest and most variable responses, whereas felsic volcanic, sedimentary and strongly sericitic/argillic rocks are consistently magnetically weak, consistent with magnetite destruction and/or dilution during alteration. XRD identifies alteration minerals (chlorite, sericite, kaolinite) and pXRF data differentiate mafic versus metasedimentary compositions and show a moderate sample-scale correlation between susceptibility and total Fe (r≈0.49). The combined datasets provide an internally consistent basis for early sensor calibration and motivate expanded paired sampling and spatial mapping to better link surface signatures with subsurface VMS-related lithologies and alteration.