525 research outputs found
AnnRG
No full textAnnRG - An artificial neural network solute geothermometer
- Version 0.03: M. Vollmer (KIT), L. H. Ystroem (KIT) - June 2023
An artificial neural network solute geothermometer trained by data from the measured reservoir temperatures worldwide. Using a feedforward multilayer perceptron to solve the regression analysis of fluid chemistry and reservoir temperature
MulT_predict
No full textMulT_predict is a MATLAB tool to facilitate the application of multicomponent geothermometry on geochemical data. Saturation indices of mineral phases were automatically calculated via IPhreeqC and evaluated by sensitivity analyses. The result is a best-fit temperature estimation
MALEG - Maschinelles Lernen zur Verbesserung der Geothermischen Energienutzung
No full textMöglichen Effizienzsteigerungen von geothermischer Energieproduktion durch Verringerung der Reinjektionstemperatur stehen meist hydrochemische Randbedingungen entgegen. Hoch mineralisierte Thermalwässer tendieren verstärkt zu unkontrollierten Mineralausfällung (Scalings) bei größerer Druckentlastung oder Abkühlung. Sie sind ein stark limitierender Faktor für den effizienten und kontinuierlichen Betrieb von Geothermieanlagen. Komplexe standortspezifische Thermalwasserchemie erschwert deren Vorhersage und Quantifizierung mittels deterministischer geochemischer Modelle. Im MALEG Projekt werden geochemische Modelle durch eine künstliche Intelligenz ergänzt, welche mit hydrogeochemischen Daten aus vor Ort Experimenten trainiert wird
MulT_predict - An optimised comprehensive multicomponent geothermometer
No full textIn this study, we introduce MulT_predict as a fully integrated solute multicomponent geothermometer, combining numerical optimisation processes for sensitive parameters to back-calculate to chemical reservoir conditions. This results in a state of the art geothermometer, providing an accurate reservoir temperature estimation validated by geothermal borehole measurements on a worldwide scale. In addition, a universally valid mineral assemblage for an unknown reservoir composition is developed, focusing on worldwide applicability. Using the evolved methodology, the limits of the optimisation processes are determined by using a synthetic brine (150 ◦C, pH 6, aluminium concentration 0.003 mmol/l) and successively perturbing its geochemical equilibrium state. Individual back-calculation of reservoir conditions lead to valid temperature estimations of 145 ◦C, 3.4% lower than the initial temperature while a simultaneous and interdependent optimisation reconstructs the sensitive parameters even more precisely with a deviation of 0.056 for the initial pH value, and 0.164 μmol/l for the aluminium concentration
Does remediation save lives? On the cost of cleaning up arsenic-contaminated sites in Sweden
No full textSwedish environmental policy is based on 16 environmental quality objectives (Gov. Bill 2000/01:130 and Gov.Bill 2004/05:150).1 One of the most challenging objectives,‘A non toxic environment’, has two interim targets that concern remediation of contaminated sites. In sum, they state that the highest priority should be given to sites posing the highest risks to human health and the environment.2 By eliminating pollutants in soil, groundwater and sediment, the interim targets aim to reduce risks to human health and the environment. In Sweden, 83,000 sites are potentially contaminated due to previous industrial activities. According to the Swedish Environmental Protection Agency (EPA), the administrator of the governmental funds for remediation, approximately 1500 of these sites contain contaminant concentrations that could seriously harm human health and the environment (Swedish EPA, 2008a). To reach the interim targets, all these sites need to be remediated by 2050. Remediation of contaminated sites has so far cost more than SEK 3,000 million.3 The approximated cost to mitigate the potential risks at the most harmful sites is estimated at SEK 60,000 million.4 The Swedish government’s funding for remediation presently comes in the form of a directed grant (sakanslag). The directed grant, administrated by the Swedish EPA, subsidises remediation of contaminated sites that were contaminated prior to modern environmental legislation (in 1969) or for which no liable party can be found. The directed grant amounts to approximately 455 millions annually, which corresponds to about 10 percent of the annual national funds for environmental protection (Gov. Bill 2007/08:1). To make it possible to prioritise among contaminated sites, the Swedish EPA has developed a method for risk assessment called the ‘MIFO’ (i.e. the Method for Inventory of Contaminated Sites). The risk assessment does not take into account the actual exposure at a contaminated site. Risk is instead assessed based on divergence from guideline values for acceptable concentrations given a standardised (i.e. worst case) exposure situation on an individual level. This means that a site can be remediated without any individuals actually being exposed. The expected risk reduction is consequently not quantified. This eliminates the possibility of valuing the risk reduction, which should be weighed against the remediation cost. The purpose of this paper is to analyse how health effects, in the form of cancer risks, from sites contaminated by arsenic are valued implicitly in remediation. By using an environmental medicine approach that takes exposure into account, and without underestimating the potential health consequences of arsenic exposure, our purpose is to place arsenic risk management in the overall picture of live-saving interventions. In the case of cancer prevention, it is necessary to recognise that focus on an environmental carcinogen like arsenic may draw public attention – and funding – away from mental health risks like ambient air pollution and indoor radon. Although environmental pollution accounts for less than ten percent of all cancer cases (Harvard Centre for Cancer Prevention, 1996; Saracci and Vineis, 2007), environmental factors are important to recognize since they may be preventable. We emphasise, however, the inefficiency in becoming overly concerned about small risks while, at the same time, losing sight of the large risks. If society’s spending on lifesaving measures with small effects (i.e. a small number of lives saved) crowds out spending on lifesaving measures with large effects, then remediation can, in fact, even be said to waste lives. By using data on 23 arsenic-contaminated sites in Sweden, we estimate the sitespecific cancer risks and calculate the cost per life saved by using the sites’ remediation costs. Our results show that the cost per life saved through remediation is much higher than that associated with other primary prevention measures, indicating that the ambition level of Swedish remediation may be too high.
H alpha emission in local galaxies: star formation, time variability, and the diffuse ionized gas
No full textThe nebular recombination line H ?? is widely used as a star formation rate (SFR) indicator in the local and high-redshift Universe. We present a detailed H ?? radiative transfer study of high-resolution isolated Milky-Way and Large Magellanic Cloud simulations that include radiative transfer, non-equilibrium thermochemistry, and dust evolution. We focus on the spatial morphology and temporal variability of the H ?? emission, and its connection to the underlying gas and star formation properties. The H ?? and H ?? radial and vertical surface brightness profiles are in excellent agreement with observations of nearby galaxies. We find that the fraction of H ?? emission from collisional excitation amounts to fcol ???5-10per cent, only weakly dependent on radius and vertical height, and that scattering boosts the H ?? luminosity by ~40 per cent. The dust correction via the Balmer decrement works well (intrinsic H ?? emission recoverable within 25 per cent), though the dust attenuation law depends on the amount of attenuation itself both on spatially resolved and integrated scales. Important for the understanding of the H ??-SFR connection is the dust and helium absorption of ionizing radiation (Lyman continuum [LyC] photons), which are about fabs??? 28per cent and fHe??? 9 per cent, respectively. Together with an escape fraction of fesc??? 6 per cent, this reduces the available budget for hydrogen line emission by nearly half (fH??? 57per cent). We discuss the impact of the diffuse ionized gas, showing - among other things - that the extraplanar H ?? emission is powered by LyC photons escaping the disc. Future applications of this framework to cosmological (zoom-in) simulations will assist in the interpretation of spectroscopy of high-redshift galaxies with the upcoming James Webb Space Telescope. ?? 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Optimised multicomponent geothermometer MulT_predict
No full textGeothermometry is used for reservoir temperature estimation since the 1960s. Different kind of solute, gas, and isotopic geothermometers has been evolved and further developed. We are focusing on solute geothermometery, using the multicomponent approach by Reed and Spycher (1984) and combined it with an optimisation process suggested by Nitschke et al. (2017). Therefore, IPhreeqC by Parkhurst and Appelo (2013) and Matlab were coupled. Thus, the geochemical output of IPhreeqC is numerically evaluated and optimised with Matlab. Sensitive parameters, e.g. pH-value, and aluminium concentration etc. are varied simultaneously to minimise the temperature difference between multiple mineral phases, used as geothermometer. MulT_predict with its implemented optimisation leads to more accurate temperature estimations with lesser variance of error
An Integrated Sensitivity Analysis for Multicomponent Geothermometer for High Temperature Settings
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