Experimental determination of barium isotope fractionation during diffusion and adsorption processes at low temperatures

Variations in barium (Ba) stable isotope abundances measured in low and high temperature environments have recently received increasing attention. The actual processes controlling Ba isotope fractionation, however, remain mostly elusive. In this study, we present the first experimental approach to quantity the contribution of diffusion and adsorption on mass-dependent Ba isotope fractionation during transport of aqueous Ba²+ ions through a porous medium. Experiments have been carried out in which a BaCl₂ solution of known isotopic composition diffused through u-shaped glass tubes filled with silica hydrogel at 10 °C and 25 °C for up to 201 days. The diffused Ba was highly fractionated by up to -2.15 ‰ in δ¹³⁷⁄¹³⁴Ba, despite its high atomic mass. The time-dependent isotope fractionation can be successfully reproduced by a diffusive transport model accounting for mass-dependent differences in the effective diffusivities of the Ba isotope species (D₁₃₇Ba ⁄D₁₃₄Ba =(m₁₃₄⁄m₁₃₇ )β ). Values of β extracted from the transport model were in the range of 0.010 to 0.011. Independently conducted batch experiments revealed that adsorption of Ba onto the surface of silica hydrogel favoured the heavier Ba isotopes (α = 1.00015 ± 0.00008). The contribution of adsorption on the overall isotope fractionation in the diffusion experiments, however, was found to be small. Our results contribute to the understanding of Ba isotope fractionation processes, which is crucial for interpreting natural isotope variations and the assessment of Ba isotope ratios as geochemical proxies

Life cycle-based environmental impacts of energy system transformation strategies for Germany: Are climate and environmental protection conflicting goals?

In the development of climate-friendly energy system transformation strategies it is often ignored that environmental protection encompasses more than climate protection alone. There is therefore a risk of developing transformation strategies whose climate friendliness comes at the expense of higher other environmental impacts. Consequently, an assessment of environmental impacts of energy system transformation strategies is required if undesired environmental side effects of the energy system transformation are to be avoided and transformation strategies are to be developed that are both climate and environmentally friendly. In this paper, ten structurally different transformation strategies for the German energy system were re-modeled (in a harmonized manner). Five of these scenarios describe pathways for a reduction of direct, energy related CO$_2$ emissions by 80%, the other five by 95%. Life cycle-based environmental impacts of the scenarios were assessed by coupling the scenario results with data from a life cycle inventory database focusing on energy and transport technologies. The results show that the transformation to a climate-friendly energy system reduces environmental impacts in many impact categories. However, exceptions occur with respect to the consumption of mineral resources, land use and certain human health indicators, which could increase with decreasing CO$_2$ emissions. The comparison of environmental impacts of moderately ambitious strategies (80% CO$_2$ reduction) with very ambitious strategies (95% CO$_2$ reduction) shows that there is a risk of increasing environmental impacts with increasing climate protection, although very ambitious strategies do not necessarily come along with higher environmental impacts than moderately ambitious strategies. A reduction of environmental impacts could be achieved by a moderate and – as far as possible – direct electrification of heat and transport, a balanced technology mix for electricity generation, by reducing the number and size of passenger cars and by reducing the environmental impacts from the construction of these vehicles

Decarbonization scenarios for the iron and steel industry in context of a sectoral carbon budget: Germany as a case study

Industrial Ecolog

Integrated multidimensional sustainability assessment of energy system transformation pathways

Sustainable development embraces a broad spectrum of social, economic and ecological aspects. Thus, a sustainable transformation process of energy systems is inevitably multidimensional and needs to go beyond climate impact and cost considerations. An approach for an integrated and interdisciplinary sustainability assessment of energy system transformation pathways is presented here. It first integrates energy system modeling with a multidimensional impact assessment that focuses on life cycle-based environmental and macroeconomic impacts. Then, stakeholders’ preferences with respect to defined sustainability indicators are inquired, which are finally integrated into a comparative scenario evaluation through a multi-criteria decision analysis (MCDA), all in one consistent assessment framework. As an illustrative example, this holistic approach is applied to the sustainability assessment of ten different transformation strategies for Germany. Applying multi-criteria decision analysis reveals that both ambitious (80%) and highly ambitious (95%) carbon reduction scenarios can achieve top sustainability ranks, depending on the underlying energy transformation pathways and respective scores in other sustainability dimensions. Furthermore, this research highlights an increasingly dominant contribution of energy systems’ upstream chains on total environmental impacts, reveals rather small differences in macroeconomic effects between different scenarios and identifies the transition among societal segments and climate impact minimization as the most important stakeholder preferences

an association between diversity and exoticism

Focusing on contemporary Iranian artists and intellectuals, I examine the creation of collective identifications from an internal perspective. Drawing on research on migrant associations and ethnic and racial boundaries in Germany, the ethnographic account alternates between internal relations, member's participation in the transnational field of Iranian artists, and representative activities in the German public sphere. It explains how the members' unequal resources and varying politics of value caused a shift in the association's system of value. From a critique of assimilationism and the promotion of the value of diversity, the group came to largely comply with the system of value prevailing in the German public sphere, sustained by its intersection with the one that shapes the transnational social field of Iranian artists

High renewable energy penetration scenarios and their implications for urban energy and transport systems

© 2018 Elsevier B.V. To meet the terms of the 2015 Paris Agreement, the global energy system must be entirely decarbonized by the end of this century. Two scenarios have been developed: a reference case (REF) and an advanced 100% renewable energy scenario (ADV). ADV reflects the trends in global energy systems and will decarbonize the entire energy system by 2050. Those results are compared with the IPCC AR5 450 ppm scenarios, in terms of the 2050 energy demand projections — primary and final energy — and the demands for the transport and building sectors because they are important in urban environments. The results are further discussed with regard to the impact on urban infrastructures and the role of megacities in the global energy consumption pattern. Under the assumption that urbanization rates will remain at the 2015 level until 2050, the annual energy demand for buildings in urban areas is expected to increase by 27 EJ under the reference scenario (REF), from 57 EJ to 84 EJ per year, whereas ADV would lead to an overall reduction to 46 EJ per year by 2050, while the population and GDP continue to grow. Overall, the global energy demand in the transport sector is expected to increase by over 60% by 2050 under REF, whereas the deep mitigation pathway (ADV) reduces the transport energy demand below that of the base year, to 70 EJ per year. This is a significant reduction, even compared with other 450 ppm scenarios, and can be achieved by a drastic shift to electric mobility in response to vehicle efficiency standards, a phasing-out of combustion engines in the transport sector by 2030, and a modal shift in favor of urban public transport. The global energy demand for the building sector in ADV shows a smaller deviation in comparison to other 450 ppm scenarios than that for the transport sector

Energy scenario results

© The Author(s) 2019. Results for the 5.0 C, 2.0 C and 1.5 C scenarios for ten world regions in regard to energy-related carbon-dioxide emissions, final-, primary-, transport- and heating demand and the deployment of various supply technologies to meet the demand. Furthermore, the electricity demand and generation scenarios are provided. The key results of a power sector analysis which simulates further electricity supply with high shares of solar- and wind power in one hour steps is provided. The ten world regions are divided into eight sub-regions and the expected development of loads, capacity-factors for various power plant types and storage demands are provided. This chapter contains more than 100 figures and tables

Excess radiocarbon constraints on air-sea gas exchange and the uptake of CO 2 by the oceans

International audienceWe reassess the constraints that estimates of the global ocean excess radiocarbon inventory (I E) place on air-sea gas exchange. We find that the gas exchange scaling parameter a q cannot be constrained by I E alone. Non-negligible biases in different global wind speed data sets require a careful adaptation of a q to the wind field chosen. Furthermore, a q depends on the spatial and temporal resolution of the wind fields. We develop a new wind speed-and inventory-normalized gas exchange parameter a q N which takes into account these biases and which is easily adaptable to any new estimate of I E. Our study yields an average estimate of a q of 0.32 ± 0.05 for monthly mean winds, lower than the previous estimate (0.39) from Wanninkhof (1992). We calculate a global annual average piston velocity for CO 2 of 16.7 ± 2.9 cm/hr and a gross CO 2 flux between atmosphere and ocean of 73 ± 10 PgC/yr, significantly lower than results from previous studies