South African Energy Policies for Sustainable Development

This report models a range of energy policies for sustainable development in South Africa and evaluates the results against energy indicators of sustainable development. Demand- and supply-side policies exist that can contribute both to energy objectives, and also to broader sustainable development goals. The report builds on previous work on a South African profile on energy for sustainable development (ERC 2004a), identifying, modelling and evaluating future policy options. The purpose of the report is to present possible energy futures for the country and to demonstrate how indicators of sustainable development can be used to assess options. This method, we argue, provides the means for policymakers to identify synergies and trade-offs between options, and to evaluate them in economic, social and environmental dimensions

Three billion new trees in the EU’s biodiversity strategy:low ambition, but better environmental outcomes?

The EU Biodiversity strategy aims to plant 3 billion trees by 2030, in order to improve ecosystem restoration and biodiversity. Here, we compute the land area that would be required to support this number of newly planted trees by taking account of different tree species and planting regimes across the EU member states. We find that 3 billion trees would require a total land area of between 0.81 and 1.37 Mha (avg. 1.02 Mha). The historic forest expansion in the EU since 2010 was 2.44 Mha, meaning that despite 3 billion trees sounding like a large number this target is considerably lower than historic afforestation rates within the EU, i.e. only 40% of the past trend. Abandoned agricultural land is often proposed as providing capacity for afforestation. We estimate agricultural abandoned land areas from the HIstoric Land Dynamics Assessment+ database using two time thresholds (abandonment since 2009 or 2014) to identify potential areas for tree planting. The area of agricultural abandoned land was 2.6 Mha (potentially accommodating 7.2 billion trees) since 2009 and 0.2 Mha (potentially accommodating 741 million trees) since 2014. Our study highlights that sufficient space could be available to meet the 3 billion tree planting target from abandoned land. However, large-scale afforestation beyond abandoned land could have displacement effects elsewhere in the world because of the embodied deforestation in the import of agricultural crops and livestock. This would negate the expected benefits of EU afforestation. Hence, the EU’s relatively low ambition on tree planting may actually be better in terms of avoiding such displacement effects. We suggest that tree planting targets should be set at a level that considers physical ecosystem dynamics as well as socio-economic conditions.</p

Impact experiments into multiple-mesh targets: Concept development of a lightweight collisional bumper

The utility of multiple-mesh targets as potential lightweight shields to protect spacecraft in low-Earth orbit against collisional damage is explored. Earlier studies revealed that single meshes comminute hypervelocity impactors with efficiencies comparable to contiguous targets. Multiple interaction of projectile fragments with any number of meshes should lead to increased comminution, deceleration, and dispersion of the projectile, such that all debris exiting the mesh stack possesses low specific energies (ergs/sq cm) that would readily be tolerated by many flight systems. The study is conceptually exploring the sensitivity of major variables such as impact velocity, the specific areal mass (g/sq cm) of the total mesh stack (SM), and the separation distance (S) between individual meshes. Most experiments employed five or ten meshes with total SM typically less than 0.5 the specific mass of the impactor, and silicate glass impactors rather than metal projectiles. While projectile comminution increases with increasing impact velocity due to progressively higher shock stresses, encounters with multiple-meshes at low velocity (1-2 km/s) already lead to significant disruption of the glass impactors, with the resulting fragments being additionally decelerated and dispersed by subsequent meshes, and, unlike most contiguous single-plate bumpers, leading to respectable performance at low velocity. Total specific bumper mass must be the subject of careful trade-off studies; relatively massive bumpers will generate too much debris being dislodged from the bumper itself, while exceptionally lightweight designs will not cause sufficient comminution, deceleration, or dispersion of the impactor. Separation distance was found to be a crucial design parameter, as it controls the dispersion of the fragment cloud. Substantial mass savings could result if maximum separation distances were employed. The total mass of debris dislodged by multiple-mesh stacks is modestly smaller than that of single, contiguous-membrane shields. The cumulative surface area of all penetration holes in multiple mesh stacks is an order of magnitude smaller than that in analog multiple-foil shields, suggesting good long-term performance of the mesh designs. Due to different experimental conditions, direct and quantitative comparison with other lightweight shields is not possible at present

Three billion new trees in the EU’s biodiversity strategy: low ambition, but better environmental outcomes?

The EU Biodiversity strategy aims to plant 3 billion trees by 2030, in order to improve ecosystem restoration and biodiversity. Here, we compute the land area that would be required to support this number of newly planted trees by taking account of different tree species and planting regimes across the EU member states. We find that 3 billion trees would require a total land area of between 0.81 and 1.37 Mha (avg. 1.02 Mha). The historic forest expansion in the EU since 2010 was 2.44 Mha, meaning that despite 3 billion trees sounding like a large number this target is considerably lower than historic afforestation rates within the EU, i.e. only 40% of the past trend. Abandoned agricultural land is often proposed as providing capacity for afforestation. We estimate agricultural abandoned land areas from the HIstoric Land Dynamics Assessment+ database using two time thresholds (abandonment since 2009 or 2014) to identify potential areas for tree planting. The area of agricultural abandoned land was 2.6 Mha (potentially accommodating 7.2 billion trees) since 2009 and 0.2 Mha (potentially accommodating 741 million trees) since 2014. Our study highlights that sufficient space could be available to meet the 3 billion tree planting target from abandoned land. However, large-scale afforestation beyond abandoned land could have displacement effects elsewhere in the world because of the embodied deforestation in the import of agricultural crops and livestock. This would negate the expected benefits of EU afforestation. Hence, the EU\u27s relatively low ambition on tree planting may actually be better in terms of avoiding such displacement effects. We suggest that tree planting targets should be set at a level that considers physical ecosystem dynamics as well as socio-economic conditions

Energy policies for sustainable development in South Africa: options for the future

The purpose of this publication is to present a profile of energy in South Africa, assess trends and analyse some options for the future. It is divided into two parts – Part I presents a profile of energy and sustainable development in South Africa, while Part II uses modelling tools and indicators to assess future policy options for the country

Bamberg im Zeitalter der Aufklärung und der Koalitionskriege

Die das 18. Jahrhundert prägende geistige Strömung, die Aufklärung, hinterließ auch in Bamberg Spuren. Nachdem sich die ältere regionalgeschichtliche Forschung vor allem auf die Persönlichkeit und das Wirken des Fürstbischofs Franz Ludwig von Erthal in den Jahren 1779 bis 1795 konzentriert hatte, haben neuere Arbeiten auch höhere Beamte, Professoren und Publizisten als Protagonisten aufgeklärter Reformpolitik identifiziert. An diese Forschungsperspektiven anknüpfend, beleuchten die hier versammelten fünf Studien auf der Basis bislang nicht ausgewerteter Quellen Aspekte der Herrschafts-, Bildungs-, Sozial- und Kulturgeschichte der Stadt und des Hochstifts Bamberg an der Wende vom 18. zum 19. Jahrhundert. Konkret thematisieren sie die zunehmende Verwissenschaftlichung des Regierungs- und Verwaltungshandelns, den Unterricht in lebenden Fremdsprachen, die Reform der Mädchenbildung, Strafjustiz und abweichendes Verhalten sowie die Auswirkungen der Koalitionskriege.The intellectual movement of the enlightenment, which decisively shaped the eighteenth century, left its traces in Bamberg as well. While the older literature focused on the personality and the activities of prince-bishop Franz Ludwig von Erthal (1779-1795), more recent studies have also identified high-ranking public officials, university professors and publicists as important actors in the shaping of enlightened reform policies. Building on these works, the five essays published in this volume, which are largely based on unknown or underused archival sources, illuminate aspects of the political, educational, social and cultural history of the town and the prince-bishopric of Bamberg in the late eighteenth and early nineteenth centuries. They cover the influence of the sciences on administrative and governance practices, the teaching of foreign languages, the reform of girls’ schooling, delinquency and criminal justice, and the impact of the French revolutionary and Napoleonic wars

Cratering and penetration experiments in teflon targets at velocities from 1 to 7 km/s

Approximately 20 sq m of protective thermal blankets, largely composed of Teflon, were retrieved from the Long Duration Exposure Facility after the spacecraft spent approximately 5.7 years in space. Examination of these blankets revealed that they contained thousands of hypervelocity impact features ranging from micron-sized craters to penetration holes several millimeters in diameter. We conducted impact experiments to reproduce such features and to understand the relationships between projectile size and the resulting crater or penetration hole diameter over a wide range of impact velocities. Such relationships are needed to derive the size and mass frequency distribution and flux of natural and man-made particles in low-earth orbit. Powder propellant and light-gas guns were used to launch soda-lime glass spheres into pure Teflon targets at velocities ranging from 1 to 7 km/s. Target thickness varied over more than three orders of magnitude from finite halfspace targets to very thin films. Cratering and penetration of massive Teflon targets is dominated by brittle failure and the development of extensive spall zones at the target's front and, if penetrated, the target's rear side. Mass removal by spallation at the back side of Teflon targets may be so severe that the absolute penetration hole diameter can become larger than that of a standard crater. The crater diameter in infinite halfspace Teflon targets increases, at otherwise constant impact conditions, with encounter velocity by a factor of V (exp 0.44). In contrast, the penetration hole size in very thin foils is essentially unaffected by impact velocity. Penetrations at target thicknesses intermediate to these extremes will scale with variable exponents of V. Our experimental matrix is sufficiently systematic and complete, up to 7 km/s, to make reasonable recommendations for velocity-scaling of Teflon craters and penetrations. We specifically suggest that cratering behavior and associated equations apply to all impacts in which the shock-pulse duration of the projectile is shorter than that assigned a unique projectile size, provided an impact velocity is known or assumed. This calibration seems superior to the traditional ballistic-limit approach

Penetration experiments in aluminum 1100 targets using soda-lime glass projectiles

The cratering and penetration behavior of annealed aluminum 1100 targets, with thickness varied from several centimeters to ultra-thin foils less than 1 micrometer thick, were experimentally investigated using 3.2 mm diameter spherical soda-lime glass projectiles at velocities from 1 to 7 km/s. The objective was to establish quantitative, dimensional relationships between initial impact conditions (impact velocity, projectile diameter, and target thickness) and the diameter of the resulting crater or penetration hole. Such dimensional relationships and calibration experiments are needed to extract the diameters and fluxes of hypervelocity particles from space-exposed surfaces and to predict the performance of certain collisional shields. The cratering behavior of aluminum 1100 is fairly well predicted. However, crater depth is modestly deeper for our silicate impactors than the canonical value based on aluminum projectiles and aluminum 6061-T6 targets. The ballistic-limit thickness was also different. These differences attest to the great sensitivity of detailed crater geometry and penetration behavior on the physical properties of both the target and impactor. Each penetration experiment was equipped with a witness plate to monitor the nature of the debris plume emanating from the rear of the target. This plume consists of both projectile fragments and target debris. Both penetration hole and witness-plate spray patterns systematically evolve in response to projectile diameter/target thickness. The relative dimensions of the projectile and target totally dominate the experimental products documented in this report; impact velocity is an important contributor as well to the evolution of penetration holes, but is of subordinate significance for the witness-plate spray patterns

Picosecond carrier recombination dynamics in chalcogen-hyperdoped silicon

Intermediate-band materials have the potential to be highly efficient solar cells and can be fabricated by incorporating ultrahigh concentrations of deep-level dopants. Direct measurements of the ultrafast carrier recombination processes under supersaturated dopant concentrations have not been previously conducted. Here, we use optical-pump/terahertz-probe measurements to study carrier recombination dynamics of chalcogen-hyperdoped silicon with sub-picosecond resolution. The recombination dynamics is described by two exponential decay time scales: a fast decay time scale ranges between 1 and 200 ps followed by a slow decay on the order of 1 ns. In contrast to the prior theoretical predictions, we find that the carrier lifetime decreases with increasing dopant concentration up to and above the insulator-to-metal transition. Evaluating the material's figure of merit reveals an optimum doping concentration for maximizing performance.Center for Clean Water and Clean Energy at MIT and KFUPMNational Science Foundation (U.S.) (Grant Contract ECCS-1102050)National Science Foundation (U.S.) (United States. Dept. of Energy Contract EEC-1041895

Seasonal pattern of apoplastic solute accumulation and loss of cell turgor during ripening of Vitis vinifera fruit under field conditions

Using a novel pressure membrane (PM) apparatus for the extraction of apoplastic fluid from field-grown grape (Vitis vinifera L.) berries, our hypothesis that significant apoplast solutes accumulate at the beginning of the ripening process (i.e. veraison), and that this accumulation might contribute to progressive berry softening due to a progressive loss of mesocarp cell turgor pressure (P) was tested. It was necessary to correct the solute potential (Ψs) of fluid collected with the PM for dilution due to the presence of a dead volume in the apparatus, but after correction, the Ψs obtained with the PM agreed with that obtained by low speed centrifugation. A clear decline in fruit apoplastic solute potential (ψSA) began approximately 10 d prior to fruit coloration, and it was found to be coincident with a decline in mesocarp cell P and fruit elasticity (E). By late in fruit development when berry growth ceased (90 d after anthesis), both apoplast and fruit Ψs reached almost –4 MPa. These results support the hypothesis that a decrease in ψSA is responsible for the observed loss in mesocarp cell P, and is the mechanistic cause of berry softening