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Abstract A unique large scale pilot plant of the CellFlux thermal energy storage concept is experimentally investigated. This storage concept consists of a regenerator type thermal energy storage volume, which is coupled to a finned tube heat exchanger by a circulating intermediate working fluid. The system investigated in this work operates at a temperature of 390 °C and uses air as intermediate working fluid which is conveyed by a centrifugal fan. The storage volume has a bed length of over ten meters and is of a novel design, where the air flows in horizontal direction. Since this approach could cause a flow maldistribution, a thorough analysis is of major interest for the accuracy of subsequent numerical simulations. The experiments reveal that the mass flow along the centerline can be up to 20% higher than the mean bulk flow. A significant maldistribution between top and bottom area, however, is not observed. As an alternative to the typically used rock filling, the storage volume is equipped with standard hollow bricks. These bricks are cost effective but do not have a well-defined shape. Thus, the predictability of the pressure drop by correlations found in the literature is unclear. It turns out that the measured pressure drop is evenly distributed in axial flow direction but generally higher than expected from the assumption of pure channel flow. Further experiments are conducted to validate the heat capacity of the bricks and to derive a correlation for the inner heat transfer between bricks and storage walls. Eventually, the aim of the experimental investigation is a general proof of concept as basis for the numerical investigation. Thus, all specifications of the plant and the storage material are provided. The plant is analyzed towards plausibility of heat losses, showing that heat losses can be predicted well within the given uncertainties.

The high power density, ease of transportation and storage and many years of development of internal combustion engine technologies have put liquid hydrocarbon fuels at a privileged position in our energy mix. Therefore processes that use renewable energy sources to produce liquid hydrocarbon fuels from H2O and CO2 are of crucial importance. Concentrated Solar Power (CSP) can be employed as the only energy source for the renewable production of hydrogen from water either indirectly, e.g. by supplying the electricity for electrolysis, or directly by supplying the necessary heat for thermochemically producing hydrogen. Among the various thermochemical cycles tested so far for CSP-driven hydrogen production via water splitting (WS), those based on redox-pair oxide systems, are directly adaptable to carbon dioxide splitting (CDS) and/or combined CO2/H2O splitting for the production of CO or syngas, respectively. The acknowledgement of this fact has recently revived the interest of the scientific community on such technologies. The current article presents the development, evolution and current status of CSP-aided syngas production via such redox-pair-based thermochemical cycles. At first the various redox oxide material compositions tested for water/carbon dioxide splitting are presented and their redox chemistries are discussed. Then the selection of suitable solar reactors is addressed in conjunction with the boundary conditions imposed by the redox systems as well as the heat demands, technical peculiarities and requirements of the cycle steps. The various solar reactor concepts proposed and employed for such reactions and their current status of development are presented. Finally, topics where further work is needed for commercialization of the technology are identified and discussed.

Abstract Environmental-impact reduction potential is great early in new product development. To exploit this potential, this study evaluates novel combinations of existent processing technologies. Process engineering is combined with an environmental product assessment along the supply chain. In the dairy sector, drying milk into milk powders is a highly energy-intensive process. This study investigates whether switching from milk powders to new products known as milk concentrates diminishes the overall environmental impact along the supply chains of dairy-containing products. A comparative life cycle assessment (LCA) is conducted, which considers individual processing steps that can be combined and operated in various ways to generate a multitude of different skim milk concentrates. For relevant environmental indicators such as cumulative energy demand, global warming potential, eutrophication potential, and acidification potential, concentrates were found to have a lower environmental impact than powders, even if the former are trucked up to 1000 km. This break-even distance is a conservative estimate. It depends upon the environmental impact of raw-milk production. The concentrate with the lowest environmental impact is produced by a combined concentration with reverse osmosis and evaporation to a dry-matter content of 35% and preservation via subsequent pasteurization. This holds for all indicators except eutrophication potential, for which this concentrate is the second-best option. This study identifies the frame within which milk concentrates are an advantageous substitution for milk powder and demonstrates the value of applying environmental assessment to product development and processing-technology selection.

Abstract With the rapidly increasing capacity of renewable energy production, the volatile nature of, e.g., wind and solar power necessitates solutions for storing excess energy. A finite-element model for simulating a geomembrane energy storage system is developed, in order to aid the development of the system and provide first insights into the performance of the system. Conceptually, energy is stored by pumping water from a nearby surface reservoir into a subsurface reservoir confined by a geomembrane, which lifts the overlying mass of soil, thereby increasing the potential energy due to gravity. An axisymmetric finite-element model is developed employing fluid cavity elements and fluid exchange links to simulate inflow and outflow of the reservoir, which resembles energy storage and energy re-harvest, respectively. A sophisticated constitutive model for a granular soil is employed using a hypoplastic model with intergranular strain extension, which includes essential characteristics as stress and density dependency, critical-state behavior as well as stress reversals. Analysis of repeated storage cycles provides realistic but undesirable deformation patterns, encountered by increasing irreversible displacements with advancing cycles. The reliable results of the model directly provides estimates of energy efficiency and can serve as a tool for further development and optimization of the energy storage system.

AbstractRecreational fisheries contribute substantially to the sociocultural and economic well‐being of coastal and riparian regions worldwide, but climate change threatens their sustainability. Fishery managers require information on how climate change will impact key recreational species; however, the absence of a global assessment hinders both directed and widespread conservation efforts. In this study, we present the first global climate change vulnerability assessment of recreationally targeted fish species from marine and freshwater environments (including diadromous fishes). We use climate change projections and data on species’ physiological and ecological traits to quantify and map global climate vulnerability and analyze these patterns alongside the indices of socioeconomic value and conservation effort to determine where efforts are sufficient and where they might fall short. We found that over 20% of recreationally targeted fishes are vulnerable to climate change under a high emission scenario. Overall, marine fishes had the highest number of vulnerable species, concentrated in regions with sensitive habitat types (e.g., coral reefs). However, freshwater fishes had higher proportions of species at risk from climate change, with concentrations in northern Europe, Australia, and southern Africa. Mismatches in conservation effort and vulnerability were found within all regions and life‐history groups. A key pattern was that current conservation effort focused primarily on marine fishes of high socioeconomic value rather than on the freshwater and diadromous fishes that were predicted to be proportionately more vulnerable. While several marine regions were notably lacking in protection (e.g., Caribbean Sea, Banda Sea), only 19% of vulnerable marine species were without conservation effort. By contrast, 72% of freshwater fishes and 33% of diadromous fishes had no measures in place, despite their high vulnerability and cultural value. The spatial and taxonomic analyses presented here provide guidance for the future conservation and management of recreational fisheries as climate change progresses.

Conservation agriculture through no-till based on cropping systems with high biomass-C input, is a strategy to restoring the carbon (C) lost from natural capital by conversion to agricultural land. We hypothesize that cropping systems based on quantity, diversity and frequency of biomass-C input above soil C dynamic equilibrium level can recover the natural capital. The objectives of this study were to: i) assess the C-budget of land use change for two contrasting climatic environments, ii) estimate the C turnover time of the natural capital through no-till cropping systems, and iii) determine the C pathway since soil under native vegetation to no-till cropping systems. In a subtropical and tropical environment, three types of land use were used: a) undisturbed soil under native vegetation as the reference of pristine level; b) degraded soil through continuous tillage; and c) soil under continuous no-till cropping system with high biomass-C input. At the subtropical environment, the soil under continuous tillage caused loss of 25.4 Mg C ha-1 in the 0-40 cm layer over 29 years. Of this, 17 Mg C ha-1 was transferred into the 40-100 cm layers, resulting in the net negative C balance for 0-100 cm layer of 8.4 Mg C ha-1 with an environmental cost of USD 1968 ha-1. The 0.59 Mg C ha-1 yr-1 sequestration rate by no-till cropping system promote the C turnover time (soil and vegetation) of 77 years. For tropical environment, the soil C losses reached 27.0 Mg C ha-1 in the 0-100 cm layer over 8 years, with the environmental cost of USD 6155 ha-1, and the natural capital turnover time through C sequestration rate of 2.15 Mg C ha-1 yr-1 was 49 years. The results indicated that the particulate organic C and mineral associate organic C fractions are the indicators of losses and restoration of C and leading C pathway to recover natural capital through no-till cropping systems.

In recent years, the energy demand has been continuously increasing. At the same time, fossil fuels are being progressively replaced by renewables. However, this shift from fossil fuels such as coal to renewable fuels like wood creates new challenges, as many industrial plants continue to rely on legacy fuels. Unlike coal, the elements present in renewable resources can vary greatly. The differences are influenced by a variety of factors. For example, waste wood can be contaminated by different additives (paints, fire retardants, and others). To understand under which boundary conditions (e.g., temperature, gasification atmosphere) the respective elements are bound in the ash/slag or released into the gas phase, experiments with a molecular beam mass spectrometer (MBMS) with an upstream electrically heated flow reactor were conducted. Pieces of clean wood were impregnated with various heavy metals and examined under several boundary conditions (temperature and gasification atmosphere). Furthermore, impregnated cellulose partly mixed with single ash components served as model fuel for detailed investigations. Additionally, thermochemical equilibrium calculations were carried out. The results of the experiments show that the release of some heavy metals (Cd, Pb, Sb, Sn, Zn) is very strong already at low temperatures, while for others (Cr, Cu) no release can be detected even at high temperatures. The corresponding thermodynamic equilibrium calculations comply with these findings. Since the process management and preparation of the fuels can be adjusted accordingly, these results form an important basis for planning gasification processes using waste wood as fuel.

Infrared solar spectra recorded at the International Scientific Station of the Jungfraujoch (3580 m altitude), Switzerland, in 1950–1951 and from 1984 to 1992 have been analyzed to determine vertical column abundances of nitrous oxide (N2O) above the station. The best fit to the relatively dense set of measurements made between 1984 and 1992 indicates a mean exponential rate of increase equal to 0.36±0.06% yr−1 (1 σ) and a seasonal modulation of 7.2% peak to peak, the minimum occurring at the end of the winter and the maximum in early September. The column abundances for April of the years 1951, 1984, and 1992 were found equal to 3.49×1018, 3.76×1018, and 3.87×1018 molecules cm−2, respectively; they translate into N2O concentrations at the altitude of the Jungfraujoch equal to 275, 296, and 305 parts per billion by volume. These results indicate that the exponential rate of increase for 1951–1984 was equal to 0.23±0.04% yr−1 (1σ), thus substantially lower than for the 1984–1992 time interval and that the so‐called preindustrial levels of N2O pertained until 1951 with most of the increase in atmospheric N2O occurring thereafter.