An evaluation of the use of renewable energy to pump water in Sacala las Lomas,Guatemala

An evaluation has been conducted to establish if using renewable energy is technically and economically feasible to pump water in Sacala las Lomas, Guatemala. A deep groundwater well has been proposed and a multi-stage pump system is being considered to distribute groundwater to users’ homes. A weather station was erected in Sacala to collect site-specific data. Wind velocity, wind direction, solar insolation, temperature, precipitation, and barometric pressure data were collected over a 1-year study period. The analysis of the data indicated that the potential power generated by a photovoltaic array or wind turbine would be insufficient to economically pump water to the village under current conditions. Although there may be reasons other than economics that make the potential renewable energy applications attractive, the space and maintenance required to install and operate a sufficient off-grid system outweigh the benefits. A grid-intertie system would allow any number of solar panels to be used in the system while still providing the electricity demand using grid-power.     

The use of model compounds to investigate the release of covalently bound biomarkers via hydropyrolysis

This study describes the reduction of functionalised model compounds to their corresponding hydrocarbons by catalytic hydropyrolysis to provide information on the release of biomarkers from kerogens and asphaltenes covalently bound through the functional groups investigated. Five model compounds were investigated, the n-C₁₈ carboxylic acids, stearic and oleic acids; the C₂₄ steroidal acid, 5β-cholanic acid; and the saturated and unsaturated C₂₇ sterols, 5α-cholestanol and cholesterol. The yield and distribution of the hydrocarbons generated were assessed for the model compounds adsorbed to silica and carbon substrates, and unsupported on a bed of catalyst. The n-C₁₈ acids are shown to be reduced to the n-C₁₈ alkane, with a selectivity of >95% for stearic acid, although due to its unsaturated structure, oleic acid is prone to cracking, with shorter chained n-alkanes also being formed. The conversion of these compounds, adsorbed to either silica or carbon is relatively low, even at hydropyrolysis temperatures significantly above their boiling point, suggesting that interactions between the acids and substrate leading to the formation of stable entities (Si–O–C linkages in the case of silica) significantly retard volatilisation. The yield can be increased by placing the compounds directly onto a bed of catalyst, but for low boiling compounds such as stearic acid this can result in volatilisation and cracking at temperatures below that of the activation point of the catalyst. This method produced improved yields of >95% pure product for higher boiling compounds such as 5β-cholanic acid. The presence of the functional group attached to the ring system of compounds such as 5α-cholestanol does not diminish the selectivity of the technique. The double bond in cholesterol resulted in more incomplete hydrogenation with sterenes being generated, and in addition to 5α and 5β-cholestane, diasteranes were also generated via migration of the double bond.     

Bergmännische Auffahrung eines U-Bahnhofes unter geringer Überdeckung

ZusammenfassungBergmännische Auffahrung eines U-Bahnhofes unter geringer Überdeckung Ein 600 m langes Baulos der Stadtbahn Bochum wurde in den Jahren 1975 und 1976 bergmännisch aufgefahren. Dabei waren ein unterirdischer Bahnhof sowie eingleisige und zweigleisige Streckenröhren herzustellen. Die Höhe der Überdeckung betrug 8 bis 3 m, wobei der gesamte Tunnelbereich entweder unter Straßen oder unter Gebäuden liegt. Der Untergrund besteht aus Mergeln stark unterschiedlicher Festigkeit und aus kohäsionsarmen, feinsandigen Schluffen und Kiesen. Teilweise wurden bei den Tunnelarbeiten auch alte Fundamentreste und Bombenschutt angetroffen. Die Tunnelarbeiten erfolgten entsprechend den Grundsätzen der Neuen Österreichischen Tunnelbauweise und wurden durch ein umfangreiches Meßprogramm kontrolliert. An keiner Stelle sind Beschädigungen an Gebäuden aufgetreten. Die Setzungen lagen im allgemeinen in Größenordnungen um 20 mm.Besondere Beachtung verdient die erstmals zur Anwendung gekommene Bauweise für die Erstellung unterirdischer Bahnhöfe. Dabei werden zwei zueinander parallel verlaufende Röhren nacheinander aufgefahren, die sich im Kämpferbereich schneiden, wobei die Kämpferlasten durch eine gemeinsame Mittelwand aufgenommen werden. Der hierfür notwendige Bauablauf und die erforderlichen Baumaßnahmen sowie die durchgeführten Messungen über und unter Tage werden beschrieben und diskutiert.

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SummaryConstruction of a Subway Station With Low Cover A 600 m long lot of the Stadtbahn Bochum has been constructed by tunnelling in 1975 to 1976. A subway station as well as a one-rail- and a two-rail-tube had to be built. The height of the cover was between 8 and 3 m; the tunnel is laying either under roads or under buildings. The underground consists of marls with very different strength and of sandy silts and gravels with little cohesion. In some areas old building foundations and bomb ruins had to be passed. Tunnelling was executed according to the principles of the New Austrian Tunnelling Method and was controlled by an extensive measuring programme. Nowhere damages of the buildings occurred. The surface subsidences generally were measured in a magnitude of about 20 mm.Special attention should be drawn to the method applied for the first time to construct an underground station. The excavation of the whole cross-section is executed by tunnelling of two parallel tubes overlapping one the other in the middle. A central concrete wall is constructed in the first tube before driving the second tube. The sequence of operation and the necessary construction measures as well as the measurements on the surface and in the underground are described and discussed.

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RésuméCreusement foré d'une station souterraine sous une couverture mince Un lot d'adjudication de 600 m de la métro de Bochum a été creusé par forage pendant 1975 et 1976. Une station souterraine et des tubes à voie unique et à double voie ont été à construire. La couverture a eu une épaisseur de 8 à 3 m, le rayon total du tunnel étant situé ou sous des rues ou sous des bâtiments. Le sous-sol consiste en marne de résistance très différente et en silt et gravier de cohésion minime et de sable fin. Partiellement aussi des restes de fondations de bâtiments anciens et de décombres de bombes ont été trouvés pendant les travaux, qui ont été exécutés d'après les principes de la méthode autrichienne de construction de tunnels. Un programme large de mesurages a contrôlé les travaux. En aucun lieu on a trouvé des dommages de bâtiments. En général les tassements étaient dans une étendue de 20 mm.Une considération particulière doit être attribuer à cette méthode pour la construction de stations souterraines, là employée pour la première fois. Deux tubes parallèles ont été creusés l'un après l'autre, se coupant dans la zone de culée, les charges des culées étant absorbées par un mur central commun. Le déroulement des travaux, les mesures de construction nécessaire pour cela et les mesurages exécutés à ciel ouvert et souterrain, sont décrits et discutés.

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Vortrag gehalten auf dem XXV. Geomechanik-Kolloquium in Salzburg, 1976.

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Mit 14 Abbildungen