In the last decades numerous coal mines have been closed. One way to overtake the costs associated to the mine closure is the geothermal use of the water stored in the closed and flooded mine ...workings. The temperature of the water flooding from the mine voids, in some cases reaching depths of several hundreds of meters, is suitable for space heating and cooling by means of the use of ground source (geothermal) heat pumps (low-enthalpy geothermal systems).
Flooded mine voids constitute new-created pseudokarstic aquifers or reservoirs, which can store significant volumes of groundwater. However, the recharge and the heat capacity of these systems are finite, and this is the main concern when using mine water as a heat source or sink. These reservoirs can be regulated by means of flow extraction and injection depending on the use demands; notwithstanding, these flows have to be limited to a sustainable value, in order to avoid the exhaustion of the capacity of the aquifer to provide or store heat. Several numerical and analytical models have been created with this aim, with the shortage of hydrogeological and thermal data as main drawback.
A literature review of the existent flow and heat transfer models applied to geothermal use of mine water has been undertaken, both analytical and numerical models are considered. The main parameters that have influence in the flow and heat exchange processes, have been analysed. The present paper can be used as basic guidelines to aid when selecting a modelling method for a specific scenario.
•A review of flow and heat transfer models for flooded mines has been undertaken.•Open loop and closed loop geothermal systems are compared.•The main parameters involved in flow and heat exchange processes are revised.•Analytical models give a first approach and numerical models are more comprehensive.
Orphan mine areas around the world are sources of potential toxic elements (PTEs) in environmental compartments. The weathering of sulphide minerals plays an important role in PTEs' fate, especially ...in humid climates. Orphan metal mines in Asturias are principal sources of water metal(oid) pollution in small watersheds. Several abandoned mercury mines were found in the upper Nalon Catchment. Small mining-impacted watersheds exhibit significant metal(oid) pollution, especially arsenic (As), from the seepage of mine waste and metallurgical slug dumps. Low flow and high metal(oid) pollution are characteristic of small mining-impacted watersheds, in contrast to high flow and low metal(oid)s content in principal streams. The systematic monitoring of surface water across watersheds showed that mine-influenced water (MIW) was found in several micro basins in the study area. Circumneutral water, calcium sulphate type, predominant in mine-polluted areas did not generate social alarm by its non-acid character, even presenting high concentrations of metal(oid)s. Multivariate data analysis of the surface water dataset was conducted to delimitate polluted waters and to reduce it to the most important parameters, as hydrochemical factor (defined by relation of As, Pb, Zn, SO4, … vs OD and pH) or base ion-exchange water. A new graphic representation for principal components from multivariate analysis is defined to explain water quality evolution using the concept of multivariate facies, which is a visual way of PCA interpretation.
•Proposal of a graphical representation of PCA loads•Similar interpretation of the hydrochemical facies•Robust tool for pattern recognition
Abandoned and flooded mine networks provide underground reservoirs of mine water that can be used as a renewable geothermal energy source. A complete hydrochemical characterization of mine water is ...required to optimally design the geothermal installation, understand the hydraulic behavior of the water in the reservoir and prevent undesired effects such as pipe clogging via mineral precipitation. Water pumped from the Barredo-Figaredo mining reservoir (Asturias, NW Spain), which is currently exploited for geothermal use, has been studied and compared to water from a separate, nearby mountain mine and a river that receives mine water discharge and partially infiltrates into the mine workings. Although the hydrochemistry was altered during the flooding process, the deep mine waters are currently near neutral, net alkaline, high metal waters of Na-HCO3 type. Isotopic values suggest that mine waters are closely related to modern meteoric water, and likely correspond to rapid infiltration. Suspended and dissolved solids, and particularly iron content, of mine water results in some scaling and partial clogging of heat exchangers, but water temperature is stable (22°C) and increases with depth, so, considering the available flow (>100Ls−1), the Barredo-Figaredo mining reservoir represents a sustainable, long-term resource for geothermal use.
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•Mine water in flooded mines might represent a sustainable resource for geothermal use.•A hydrochemical characterization aid to improve the performance of the installation.•Fe and hardness are key parameters to prevent clogging and scaling in exchangers.•Mine water shows meteoric origin, its chemistry varies with depth and residence time.
► A hybrid GA–MARS model is built as a predictive model of cyanotoxins presence. ► Cyanobacterial HABs are dangerous for environment and people in fresh waters. ► Biological and physical–chemical ...variables in this process are studied in depth. ► The obtained regression accuracy of our method is 98%. ► The results show that GA–MARS model can assist in the diagnosis of cyanotoxins.
Cyanobacteria are one of the major concerns to public health since some of them produce a range of potent toxins (cyanotoxins). This group of microorganism can be present in drinking and recreation waters representing a health risk for animals and human being. For this reason, as prevention, it is important to bring forward their presence. In this study, using physical–chemical and biological parameters, a hybrid approach based on genetic algorithms (GAs) combined with the multivariative adaptative regression splines (MARS) technique, was developed and applied for forecasting the presence of cyanobacteria in a water reservoir (Trasona reservoir, Northern Spain) and in consequence, the cyanotoxin risk. The significance of each biological and physical–chemical variables used for its determination was assessed and a predictive model useful for preventing the presence of cyanobacteria, and consequently of cyanotoxins, was defined.
The commercial sector is part of the so-called diffuse sectors for the purposes of meeting the targets for reducing greenhouse gases which Europe has set as 10% by 2020, Climate and Energy Package. ...Within the commercial sector, the entire supermarket type establishments have one of the highest rates of energy consumption per square metre in all commercial and industrial sectors. This paper presents for the first time the results of emissions related to energy consumption assessment study for supermarkets in Spain. All consumptions are considered, including lighting, cooling system, heating, ventilating and air conditioning (HVAC), bakery ovens, hot water, plugs and others. The results indicate that the cooling system has the largest contribution to most environmental impacts. For example, the global warming potential (GWP) over the 20-year lifetime of a supermarket is 6 kt of CO2 eq. Around 50% of the GWP is from the cooling system, 30% from lighting, 10% from bakery ovens and 8% from HVAC. The measures proposed leads to an overall reduction of the impacts. For instance, the GWP reduces by 44% for the cooling system, by 44% for the lighting, by 11% for the HVAC and by 1% for bakery ovens. The results also highlight that these actions have an amortization period of four years and applied to 50% of large Spanish supermarkets would allow to obtain a 14% annually of the need to reduce GHG emissions generated by diffuse sectors of Spain (258,832 ktCO2/year), agreed in “Objective 20-20-20” by the member states of the European Union by the year 2020.
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•Supermarkets are the commercial models with the highest growth and energy consumption.•Adoptions of energy saving measures in supermarkets are economically profitable.•Supermarkets could contribute significantly to GHG reduction.•The biggest energetic savings of a supermarket are obtained in the refrigeration and lighting.
State-of-charge (SOC) is the equivalent of a fuel gauge for a battery pack in an electric vehicle. Determining the state-of-charge becomes an important issue in all battery applications including ...electric vehicles (EV), hybrid electric vehicles (HEV) or portable devices. The aim of this innovative study is to estimate the SOC of a high capacity lithium iron phosphate (LiFePO4) battery cell from an experimental data-set obtained in the University of Oviedo Battery Laboratory (UOB Lab) using support vector machine (SVM) approach. The SOC of a battery cannot be measured directly and must be estimated from measurable battery parameters such as current, voltage or temperature. An accurate predictive model able to forecast the SOC in the short term is obtained. The agreement of the SVM model with the experimental data-set confirmed its good performance.
Battery State-of-Charge Estimator Using the MARS Technique Álvarez Antón, Juan Carlos; García Nieto, Paulino José; de Cos Juez, Francisco Javier ...
IEEE transactions on power electronics,
08/2013, Volume:
28, Issue:
8
Journal Article
Peer reviewed
State of charge (SOC) is the equivalent of a fuel gauge for a battery pack in an electric vehicle. Determining the state of charge is thus particularly important for electric vehicles (EVs), hybrid ...EVs, or portable devices. The aim of this innovative study is to estimate the SOC of a high-capacity lithium iron phosphate (LiFePO 4 ) battery cell from an experimental dataset obtained in the University of Oviedo Battery Laboratory using the multivariate adaptive regression splines (MARS) technique. An accurate predictive model able to forecast the SOC in the short term is obtained and it is a first step using the MARS technique to estimate the SOC of batteries. The agreement of the MARS model with the experimental dataset confirmed the goodness of fit for a limited range of SOC (25-90% SOC) and for a simple dynamic data profile constant-current (CC) constant-voltage charge-CC discharge.
This work focuses on the analysis of the electrokinetic decontamination of soils with high contents in As. Based on the data obtained from the laboratory on different materials in previous works. It ...has been sought to combine these with current laboratory and field work to infer the environmental and technical implementation implications of the As mobility in sediments and soils.
In astronomy, the light emitted by an object travels through the vacuum of space and then the turbulent atmosphere before arriving at a ground based telescope. By passing through the atmosphere a ...series of turbulent layers modify the light's wave-front in such a way that Adaptive Optics reconstruction techniques are needed to improve the image quality. A novel reconstruction technique based in Artificial Neural Networks (ANN) is proposed. The network is designed to use the local tilts of the wave-front measured by a Shack Hartmann Wave-front Sensor (SHWFS) as inputs and estimate the turbulence in terms of Zernike coefficients. The ANN used is a Multi-Layer Perceptron (MLP) trained with simulated data with one turbulent layer changing in altitude. The reconstructor was tested using three different atmospheric profiles and compared with two existing reconstruction techniques: Least Squares type Matrix Vector Multiplication (LS) and Learn and Apply (L + A).
Cet essai cherche à justifier l'importance sociale que peut avoir l'art à travers le modèle de communication qu'il permet de concevoir pour bâtir un modèle de démocratie créative comme celui dont ...rêvait John Dewey. À partir de l'analyse des principes du langage, cet essai explore la nature culturelle de notre pensée et l'influence que celle-ci a sur notre construction d'une identité et d'une vision du monde. Il cherche, d'autre part, à expliquer comment la nature sociale du langage peut facilement devenir tyrannique quand elle s'assimile à la Vérité et elle nie notre part d'individualité dans toute pensée. Ce travail vise ensuite à présenter l'expérience esthétique comme champ de la pensée individuelle, comme point de vue aux abords de la culture, comme libération de la perception. Finalement ce mémoire se veut une exposition d'une démocratie basée sur l'expérience esthétique dont le principe serait étendu à toute expérience humaine pour trouver une alternative au dilemme de l'identité dans la communauté, du rapport à l'autre sans domination; une voie pour le dialogue et un meilleur vivre-ensemble. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Langage, Expérience esthétique, Démocratie.
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