New electricity markets: The challenges of variable renewable energy

ABSTRACT: The development and large-scale dissemination of the new and variable renewable technologies took place from 1990 onwards in most developed countries, in a process led by Europe. To promote the renewable sector development financial incentives, both for investment and for the payment of renewable energy, were always present. These incentives usually consisted of guaranteed feed-in tariffs that ensured a return of the investments made in this new business—thus minimizing the financial risks and building a more attractive business for private companies in the renewables sector. That approach was the main basis that essentially supported the remarkable growth of the renewable sector in Europe in the past 30 years. Nowadays, the renewable energy sector is already mature in most aspects. The cost of generating electricity from wind or solar (photovoltaic) resources is competitive with conventional gas or coal-based technologies. However, some challenges still exist in the transition of the electrical power sector to a desirable carbon-free, near 100% renewable-based sector—and one of those main challenges is the negotiation of the electricity generated by these novel technologies, due to the time and spatial variability of the primary resources as well as their poor predictability and dispatchability of the power generated. This chapter addresses those challenges as well as the approaches available to overcome them within competitive electricity markets.info:eu-repo/semantics/publishedVersio

Development of a bench-scale photobioreactor with a novel recirculation system for continuous cultivation of microalgae

ABSTRACT: Microalgae cultivation can be used to increase the sustainability of carbon emitting processes, converting the CO2 from exhaust gases into fuels, food and chemicals. Many of the carbon emitting industries operate in a continuous manner, for periods that can span days or months, resulting in a continuous stream of gas emissions. Biogenic CO2 from industrial microbiological processes is one example, since in many cases it becomes unsustainable to stop these processes on a daily or weekly basis. To correctly sequester these emissions, microalgae systems must be operated under continuous constant conditions, requiring photobioreactors (PBRs) that can act as chemostats for long periods of time. However, in order to optimize culture parameters or study metabolic responses, bench-scale setups are necessary. Currently there is a lack of studies and design alternatives using chemostat, since most works focus on batch assays or semi-continuous cultures. Therefore, this work focused on the development of a continuous bench-scale PBR, which combines a retention vessel, a photocollector and a degasser, with an innovative recirculation system, that allows it to operate as an autotrophic chemostat, to study carbon sequestration from a biogenic CO2-rich constant air stream. To assess its applicability, the PBR was used to cultivate the green microalga Haematococcus pluvialis using as sole carbon source the CO2 produced by a coupled heterotrophic bacterial chemostat. An air stream containing ≈0.35 vol% of CO2, was fed to the system, and it was evaluated in terms of stability, carbon fixation and biomass productivity, for dilution rates ranging from 0.1 to 0.5 d−1. The PBR was able to operate under chemostat conditions for more than 100 days, producing a stable culture that generated proportional responses to the stimuli it was subjected to, attaining a maximum biomass productivity of 183 mg/L/d with a carbon fixation efficiency of ≈39% at 0.3 d−1. These results reinforce the effectiveness of the developed PBR system, making it suitable for laboratory-scale studies of continuous photoautotrophic microalgae cultivation.info:eu-repo/semantics/publishedVersio

New C-3 Substituted 1H- and 2H-Indazolephosphonic Acid Regioisomers: Synthesis, Spectroscopic Characterization and X-Ray Diffraction Studies

ABSTRACT: Indazole is known as an important structural motif in medicinal chemistry and, recently, has also gained attention in other areas, such as materials chemistry, with many studies showing different potential applications for their regioisomers. Phosphonates are also a class of compounds with diverse applications, ranging from medicinal to material applications. Here we present the synthesis of 1H- and 2H-indazolephosphonic acid derivatives substituted at C-3, involving mono- or bisphosphonic acids, from their corresponding carboxylic acid and esters. These compounds were fully characterized, and their spectroscopic data were evaluated to identify and distinguish the structural scaffold of each phosphonic acid. Crystallization of [hydroxy(1-methyl-1H-indazol-3-yl)methanediyl]bis(phosphonic acid) 7 afforded crystals suitable for single crystal X-ray diffraction studies and its crystal structure details are also discussed.info:eu-repo/semantics/publishedVersio

An insight into the firing conditions of Chinese blue-and-white porcelain through XANES

ABSTRACT: Chinese blue-and-white porcelain is found in archaeological excavations worldwide, being significant evidence of global trade routes and cultural exchange. Synchrotron radiation-based techniques have been applied for studying cobalt speciation to establish a correlation between the cobalt and iron oxidation state and local coordination environment in the rich blue shades of Chinese blue-and-white porcelain. However, the relationship between the firing atmosphere conditions and the speciation of cobalt has not been established yet. In this study, underglaze blue models were produced and fired in air or under reducing atmospheres to ascertain the effect of the firing atmosphere in cobalt and iron speciation. The experimental results were compared with data obtained on historical samples of ancient porcelain shards. The microstructure and colour of the produced underglaze blue models were investigated by variable pressure scanning electron microscopy (VP-SEM-EDS), using a hyperspectral imaging camera (Vis-SWIR reflectance spectroscopy) and colorimetry. The formal valence and coordination of cobalt and iron ions of the glaze were determined by X-ray absorption spectroscopy (XAS), particularly X-ray absorption near edge structure (XANES), using synchrotron radiation. Spectral features demonstrated that both cobalt and iron speciation were affected by the firing atmosphere and therefore could be used to ascertain the firing atmosphere.info:eu-repo/semantics/publishedVersio

Are "Smart Cities” also “Climate Smart”? An Assessment of the EU Mission “Climate-Neutral and Smart Cities”

ABSTRACT: Urbanization and the concentration of energy-consuming economic activities make cities responsible for more than 70% of global greenhouse gas emissions. At the same time, cities are becoming increasingly vulnerable to climate change impacts. The EU Mission “Climate-Neutral and Smart Cities”, recently launched a call for starting a pathway towards “100 climate-neutral and smart cities by 2030”. The list of 336 candidate cities (86% from the EU-27 and 14% from associated or negotiating countries) was published in February 2022. The cities constitute a very large and diverse sample that was used to conduct this timely research to identify the main factors that can drive and support a smart and sustainable transition of urban areas. A critical analysis of the main achievements in five main driving factors (local climate planning, climate emergency declaration, participation in networks, international projects and competitions) provides insights on the main factors driving cities towards climate smart actions. Results show that 76% of the cities have a local climate, in 82% of cases developed under the Global Covenant of Mayors for Climate and Energy, which involves about 75% of the candidate cities. URBACT is the most popular funding programme, with 23% of cities involved in at least one funded project. The five selected driving factors seem to capture fairly well the level of "activism" of the sample cities in pursuing smart and climate-related projects and initiatives (15 of the 16 cities that have initiatives and activities in their background that fall into all five sets of the Venn diagram are among the 112 cities selected in this first phase of Mission 100 CNSC). 90% of the sample cities are part of at least one Transnational Municipal Network, which is the most important influencing factor, among the five analysed, for cities applying for this Mission. The original results of this timely study can be useful to decision-makers at all levels, but especially to other cities, to enhance knowledge on steps to be taken to accelerate the transition to carbon neutrality. Moreover, the rich dataset made available by this research represents an important knowledge base not only for future monitoring of the selected cities' progress during the implementation phases, but also for the desired replication effects in other urban areas.N/

New data on the palynostratigraphy and paleoenvironments of the late Miocene (Tortonian) Quifangondo Formation in the Cabo Ledo section, Kwanza Basin, Angola

ABSTRACT: A detailed palynostratigraphic and palynofacies analysis, associated with a lithological control, was carried out on eleven outcrop samples from the Quifangondo Formation in the Cabo Ledo (Petrofina) section, Kwanza Basin, Angola. The samples yield relatively diverse and well-preserved terrestrial and marine palynomorphs. A systematic analysis of the samples enables the identification of nine spore genera and 3 species, 20 pollen genera and 13 species, and 32 dinoflagellate cyst genera and 34 species. In addition, 10 genera of other aquatic palynomorphs, such as Chlorophyceae green algae, are identified. Dinoflagellate cysts and other aquatic palynomorphs typically dominate throughout the assemblages. In this section, a combined pollen - dinoflagellate cyst zonation is used to define two palynoassociations. The first palynoassociation is middle Tortonian in age and is characterized by the presence of the pollen grain Fenestrites spinosus and the first occurrence of the dinoflagellate cyst species Selenopemphix armageddonensis. Additionally, diverse Chlorophyceae green algae dominate most of this interval samples. The second palynoassociation is assigned to the late Tortonian and is characterized by a drastic decrease in Chlorophyceae green algae, as opposed to the gonyaulacales dinoflagellate cysts. The first occurrence of the pollen grain Fenestrites longispinosus marks the transition between the palynoassociations. Lithologically, the Cabo Ledo (Petrofina) section is dominated by a claystone with an increase in the silt and carbonate components towards the upper section. The lithological data, integrated with palynostratigraphy and palynofacies, suggests that the upper part of the Quifangondo Formation was mainly deposited in an inner to middle neritic environment characterized by dysoxic conditions punctuated by periods of terrestrial inflows. Such conditions typically result from seasonal fluctuations. The age and depositional environment of the upper Quifangondo Formation inferred from this new data allows a correlation with the other Quifangondo sequences previously studied by the authors. This multi-proxy approach is important for further stratigraphic analysis with other age-controlled lithostratigraphic units in the basin. Furthermore, the improvement of paleoenvironmental and depositional models for this unit is of great importance for cross-basin correlation and future petroleum exploration plays.info:eu-repo/semantics/publishedVersio

Assessing the industrial effects of the deployment of renewable energy technologies: when product identity matters

ABSTRACT: Investment in renewable energy technologies (RET) produces impacts on economic activity and job creation that are fundamental to increase the social acceptability of those technologies. Previous research that attempted to measure the impacts of RET has mainly focused on its effects in energy production and climate mitigation, but surprisingly little is known about the potential of RET to transform the industrial structure of an economy. This paper proposes a methodology to understand and measure the industrial transformative impact of RET. The paper draws on contributions from the sustainability transitions literature and from the economic literature that analyses the socioeconomic impacts of RET, and combine them with the economic complexity literature in order to address two main gaps: the lack of measurement of industrial transformative effects in the first; and the assumption of product homogeneity in the second that precludes an assessment of more structural impacts. We develop a conceptual approach to the way technology deployment can lead to changes in the industrial structure, centered on the notion of product heterogeneity intrinsic to the economic complexity literature. We advance three main dimensions along which to measure the changes in the industrial structure driven by modifications in the basket of products being produced due to the development of the technology value chain: sophistication, connectivity, and competitiveness. We also propose a more precise delineation of the industrial value chain of the technology, by considering the actual weights of each sector to the technology and the technology to each sector. This approach is applied to the case of wind energy in Portugal (a successful fast follower), compared with three other main wind energy producers (Spain, Denmark, Germany). The results show a strong relationship between the deployment of the technology and the sophistication and the competitiveness of the Æcloud of productsÆ composing the industrial value chain. The paper proposes a novel analytical framework and measurement tools that can support a timely assessment of the effects of sustainable energy technologies in the industrial structure, with relevance for policy.N/

In-Depth Inhomogeneities in CIGS Solar Cells: Identifying Regions for Performance Limitations by PIXE and EBS

ABSTRACT: When considering materials to be used as active layers in solar cells, an important required parameter is the proper knowledge of their elemental composition. It should be heavily controlled during growth in order to obtain the desired band gap and to decrease the recombination defects and then increase the solar cell electrical performance. Ion beam analytical (IBA) techniques and, in particular, particle-induced X-ray emission (PIXE) and elastic backscattering spectrometry (EBS) are quite suitable to determine the thickness and composition of such active layers. Furthermore, if these techniques are performed using a nuclear microprobe, lateral and in-depth inhomogeneities can be clearly observed from 2D maps. In many cases, composition variations can be detected from the classical 2D maps obtained from the PIXE spectra. In this work, it is shown how the in-depth variations can also be studied when considering 2D maps reconstructed from the EBS spectra. Such variations are derived from processing conditions and can be related to (i) composition, (ii) thickness, (iii) roughness, and (iv) other nontrivial issues. Examples obtained on Cu(In,Ga)Se-2-based cells are presented and discussed. Furthermore, the combination of IBA techniques such as PIXE and EBS is shown to be a competitive and alternative method to the more used and established techniques such as X-ray fluorescence for checking the average composition of the solar cell active layers or secondary ion mass spectroscopy for determination of the elemental depth profile.info:eu-repo/semantics/publishedVersio

Alteração hidrotermal ácido-sulfato associada aos jazigos de sulfuretos maciços de Lagoa Salgada, Caveira, Lousal, Aljustrel e São Domingos (Faixa Piritosa Ibérica)

Tese de doutoramento, Geologia (Metalogenia), Universidade de Lisboa, Faculdade de Ciências, 2021RESUMO: A Faixa Piritosa Ibérica é caracterizada por dezenas de jazigos de sulfuretos maciços formados no Famenniano e Tournaisiano em ambiente marinho pela circulação de fluidos hidrotermais através das rochas vulcânicas e sedimentares encaixantes. O seu enquadramento geológico decorre do evento hidrotermal e de processos posteriores como metamorfismo regional, deformação varisca e tardi-varisca e, em alguns casos, exumação, erosão e alteração supergénica. Nos 7 jazigos estudados - Lagoa Salgada, Caveira, Lousal, Algares, São João, São Domingos e Chança, definem-se as seguintes fases de veios de alunite: a) gerados em período sin/tardi-Varisco em deformação dúctil/semi-dúctil e associados a corredores estruturais com cisalhamento - I (paralelos a S1), IIa (oblíquos a S1) e IIb (redes deformadas), sendo a paragénese marcada por alunite/natroalunite ± pirite ± minamiite ± wavellite e acompanhada por argilização precoce (caulinite ± greenalite), apresentando estes veios estrutura em pente, dobramento e génese anterior ou coeva da clivagem S2; b) formados em fases tardi-variscas/eoalpinas/alpinas semi-frágéis/frágeis, com textura porcelanosa e matriz homogénea com pseudocubos de alunite - IIb (redes com veios sub-horizontais) e III (em falhas desligamento) e IV (fraturas irregulares). Em contexto supergénico ocorrem a jarosite e natrojarosite. Não existe uma relação direta entre a argilização supergénica e os veios de alunite I, IIa, IIb e III. A alteração ácido-sulfato foi marcada pela circulação de fluidos muito ácidos e oxidantes, de baixa temperatura, por um período de tempo geológico significativo. O modelo metalogenético infere uma evolução contínua. A caracterização dos chapéus de ferro nos jazigos estudados reflete o seu zonamento: topo com texturas terrosas e cavidades por erosão/dissolução/precipitação; zonas basais mais compactas e maciças, que transitam a muro a níveis de enriquecimento supergénico e, inferiormente, a mineralização primária. Identificaram-se também depósitos coluviais e brechas de preenchimento. A cartografia desenvolvida sobre a alteração ácidosulfato, argilização e oxidação constitui um vetor de prospeção mineral indicador das mineralizações de sulfuretos da Faixa Piritosa.ABSTRACT: Iberian Pyrite Belt (IPB) is characterized by dozens of massive sulfide deposits formed during Famennian and Tournaisian times in a marine environment by the circulation of hydrothermal fluids through the host volcanic and sedimentary rocks. Its geological setting is complex, resulting from the hydrothermal event and subsequent processes such as regional metamorphism, deformation (Variscan to Alpine) and, in some cases, exhumation, erosion and supergenic alteration. It was possible to identify different phases of alunite veins in the seven deposits investigated - Lagoa Salgada, Caveira, Lousal, Algares, São João, São Domingos and Chança: a) formed in the sin-/tardi-Variscan period in ductile/semi-ductile deformation associated with shear structural corridors - I (parallel to S1), IIa (oblique to S1) and IIb (deformed networks) defined by alunite/natroalunite ± pyrite ± minamiite ± wavellite being accompanied by early clay alteration (kaolinite ± greenalite) and common comb structure and folding being formed before or coeval to the S2 cleavage; b) formed in late-Variscan/eo-Alpine/Alpine semi-fragile/fragile systems - IIb (networks with subhorizontal veins), III (in strike-slip faults) and IV (irregular fractures), defined by porcelanous texture and alunite pseudocubes. Jarosite and natrojarosite occur in the supergene environment. There is no direct relationship between supergene clay alteration and the alunite I, IIa, IIb and III veins. Acidsulfate alteration is defined by low temperature acidic and oxidizing fluids, for a large geological time period considering a metallogenetic continuous evolution. The characterization of the gossans at the studied deposits made it possible to understand their zoning: top with earthy textures and cavities by erosion/dissolution/precipitation; more compact and massive basal zones, which gradually pass downward to supergene enrichment levels and to the primary mineralization. Colluvial deposits and filling breccias were also identified. The mapping developed on the acid-sulfate, clay and supergene oxidation hydrothermal systems, supported by detail stratigraphy, can be used as an efficient prospecting method focused on the IPB sulphide mineralization.N/

Synthesis of novel pyrazolo[3,4-b]quinoline-bisphosphonic acids and an unexpected intramolecular cyclization and phosphonylation reaction

ABSTRACT: Novel pyrazolo[3,4-b]quinoline alpha-ketophosphonic and hydroxymethylenebisphosphonic acid compounds were synthesized using different methodologies, starting from 2-chloro-3-formylquinoline 1. New phosphonic acid compounds were obtained as N-1 derivatives with a side chain with 1 or 3 (n = 1 or 3) methylene groups. All phosphonic acid compounds and their corresponding ester and carboxylic acid precursors were fully characterized, and their structures elucidated by spectroscopic data, using NMR techniques and infrared and high-resolution mass spectroscopy. During the process to obtain the N-1 substituted derivative with two methylene groups (n = 2) in the side chain, an unexpected addition-cyclization cascade reaction was observed, involving the phosphonylation of an aromatic ring and the formation of a new six-member lactam ring to afford a tetracyclic ring system. This was an unexpected result since other pyrazolo[3,4-b]quinoline derivatives and all corresponding pyrazolo[3,4-b]pyridine derivatives already prepared, under similar experimental conditions, did not undergo this reaction. This domino reaction occurs with different phosphite reagents but only affords the six-member ring. The spectroscopic data allowed the identification of the new synthesized tetracyclic compounds and the X-ray diffraction data of compound 11 enabled the confirmation of the proposed structures.info:eu-repo/semantics/publishedVersio