2,404 research outputs found

    Cryomagma ascent on Europa

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    Europa's surface exhibits morphological features which, associated with a low crater density, might be interpreted to have formed as a result of recent cryovolcanic activity. In particular, the morphology of smooth deposits covering parts of the surface, and their relationship to the surrounding terrains, suggest that they result from liquid extrusions. Furthermore, recent literature suggests that the emplacement of liquid-related features, such as double ridges, lenticulae and chaos could result from the presence of liquid reservoirs beneath the surface. We model the ascent of liquid water through a fracture or a pipe-like conduit from a subsurface reservoir to Europa\textquoteright s surface and calculate the eruption time-scale and the total volume extruded during the eruption, as a function of the reservoir volume and depth. We also estimate the freezing time of a subsurface reservoir necessary to trigger an eruption. Our model is derived for pure liquid water and for a briny mixture outlined by Kargel (1991): 81 wt% H2_{2}O + 16 wt% MgSO4_{4} + 3 wt% Na2_{2}SO4_{4}. Considering compositional data for salt impurities for Europa, we discuss the effect of MgSO4_{4} and Na2_{2}SO4_{4} on the cryomagma freezing time-scale and ascent. For plausible reservoir volumes and depths in the range of 106m3V1010m3\mathrm{10^{6}\:m^{3}\leq V\leq10^{10}\:m^{3}} and 1kmH10km\mathrm{1\:km\leq H\leq10\:km} respectively, the total extruded cryolava volume ranges from 103m310^{3}\,\mathrm{m^{3}} to 108m310^{8}\,\mathrm{m^{3}} and the duration of the eruptions varies from few minutes to few tens of hours. The freezing time-scale of the cryomagma reservoirs varies with cryomagma composition and the temperature gradient in the ice shell: from a few days to a thousand years for pure water cryomagma, and from a few months to a 104^{4} years for briny cryomagma.Comment: 31 pages, 11 figure

    Capturing industrial CO2 emissions in Spain: Infrastructures, costs and break-even prices

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    This paper examines the conditions for the deployment of large-scale pipeline and storage infrastructure needed for the capture of CO2 in Spain by 2040. It details a modeling framework that allows us to determine the optimal infrastructure needed to connect a geographically disaggregated set of emitting and storage clusters, along with the threshold CO2 values necessary to ensure that the considered emitters will make the necessary investment decisions. This framework is used to assess the relevance of various policy scenarios, including (i) the perimeter of the targeted emitters for a CCS uptake, and (ii) the relevance of constructing several regional networks instead of a single grid to account for the spatial characteristics of the Spanish peninsula. We find that three networks naturally emerge in the north, center and south of Spain. Moreover, the necessary CO2 break-even price critically depends on the presence of power stations in the capture perimeter. Policy implications of these findings concern the elaboration of relevant, pragmatic recommendations to envisage CCS deployment locally, focusing on emitters with lower substitution options toward low-carbon alternatives

    Construction of a fuel demand function portraying interfuel substitution, a system dynamics approach

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    Most of the recent numerical market equilibrium models of natural gas markets use imperfect competition assumptions. These models are typically embedded with an oversimplified representation of the demand side, usually a single-variable affine function, that does not capture any dynamic adjustment to past prices. To remedy this, we report an effort to construct an enhanced functional specification using the system dynamics-based model of Moxnes (1987, 1990). Thanks to a vintage representation of capital stock, this putty-clay model captures the effect of both past and current energy prices on fuel consumption. Using a re-calibrated version of this model, we first confirm the pertinence of this modeling framework to represent interfuel substitutions at different fuel prices in the industrial sector. Building on these findings, a dynamic functional specification of the demand function for natural gas is then proposed and calibrated.

    Austerlitz. La prose fictionnelle de W.G. Sebald au miroir du roman de Balzac

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    L'intertexte balzacien dans Austerlitz de Sebald

    Austerlitz. La prose fictionnelle de W.G. Sebald au miroir du roman de Balzac

    No full text
    L'intertexte balzacien dans Austerlitz de Sebald
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