• Energy Research
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Several dairy farms in the Netherlands aim at reducing their environmental impact by improving the internal nutrient cycle (INC) at farm level. Practices to improve nutrient cycling at these INC farms, however, might not only reduce the environmental impact on-farm, but alter also the off-farm environmental impact associated with supply chain processes (production and transport) related to inputs entering the farm, such as purchased feed or fertilizer or the economic or societal performance of these farms. We compared, therefore, a set of sustainability indicators of nine INC farms with a group of benchmark farms, comparable in terms of farm size, intensity and site-specific circumstances. This benchmark group was composed using statistical matching to exclude the effect of these characteristics on economic, environmental and societal performance. Economic indicators used were: farm income per unpaid annual working unit and the costs to revenues ratio. Environmental indicators used were derived from a cradle-to-farm-gate life cycle assessment: land occupation (LO), non-renewable energy use (NREU), global warming potential (GWP), acidification potential (AP) and eutrophication potential (EP), expressed per kg fat-and-protein-corrected milk (FPCM). In addition, we quantified the soil content of organic carbon and phosphorus, and the soil nitrogen supply. Societal indicators used were: payments for agri-environmental measures, grazing hours and penalties for aberrant milk composition. Results showed that INC farms had a lower non-renewable energy use per kg FPCM, higher soil organic carbon content and received higher annual payments for agri-environmental measures, whereas economic and other environmental, societal indicators did not differed. Furthermore, we demonstrated the need for a sound benchmark to assess the effect of INC-farming on the economic, environmental and societal performance. Statistical matching enabled us to define, for each INC farm, a benchmark group with similar farm characteristics, which are known to affect sustainability indicators. Observed differences in sustainability indicators between both farm groups, therefore, truly resulted from aiming at internal nutrient cycling, and not from differences in other farm characteristics.

Abstract The Mediterranean region is one of the most vulnerable regions to climate change. The majority of climate models forecast a rise in temperatures and less rainfall, which have been observed in recent decades. These changes will affect several vegetation properties, especially phenological dynamics and traits, by increasing drought intensity and recurrence. In this climate change context, the present study aims to assess the evolution of vegetation state and its relation with the climate dynamics in the Mediterranean forest region of northeast Tunisia using Land Surface Phenology (LSP) metrics and the vegetation index (NDVI) analysis from 2000 to 2017. To conduct this work, we used precipitation and temperature data from the two closest weather stations and 16-day NDVI composite images from the MODIS satellite source, with 250-m spatial resolution. Three phenological metrics— start of season (SOS), end of season (EOS), and length of season (LOS) — were obtained and compared for different vegetation types. The LSP variation in response to climatic metrics was also analyzed. The results showed that the LSP in our study area changed significantly during the 2000–2017 period, which includes an average 7.8 days delay in the SOS, an average advance in the EOS by 5 days, and LOS shortened by an average 12.8 days. Autumn (Pr_9) and spring (Pr_3 and P3_4) precipitations, as well as maximum temperature (Tx9+10), represent the best climate parameters to explain the changes in LSP. Both the NDVI and SPEI showed a significant high correlation (p

In this study we examine the determination accuracy of both the mean radiant temperature (Tmrt) and the Universal Thermal Climate Index (UTCI) within the scope of numerical weather prediction (NWP), and global (GCM) and regional (RCM) climate model simulations. First, Tmrt is determined and the so-called UTCI-Fiala model is then used for the calculation of UTCI. Taking into account the uncertainties of NWP model (among others the HIgh Resolution Limited Area Model HIRLAM) output (temperature, downwelling short-wave and long-wave radiation) stated in the literature, we simulate and discuss the uncertainties of Tmrt and UTCI at three stations in different climatic regions of Europe. The results show that highest negative (positive) differences to reference cases (under assumed clear-sky conditions) of up to -21°C (9°C) for Tmrt and up to -6°C (3.5°C) for UTCI occur in summer (winter) due to cloudiness. In a second step, the uncertainties of RCM simulations are analyzed: three RCMs, namely ALADIN (Aire Limitée Adaptation dynamique Développement InterNational), RegCM (REGional Climate Model) and REMO (REgional MOdel) are nested into GCMs and used for the prediction of temperature and radiation fluxes in order to estimate Tmrt and UTCI. The inter-comparison of RCM output for the three selected locations shows that biases between 0.0 and ±17.7°C (between 0.0 and ±13.3°C) for Tmrt (UTCI), and RMSE between ±0.5 and ±17.8°C (between ±0.8 and ±13.4°C) for Tmrt (UTCI) may be expected. In general the study shows that uncertainties of UTCI, due to uncertainties arising from calculations of radiation fluxes (based on NWP models) required for the prediction of Tmrt, are well below ±2°C for clear-sky cases. However, significant higher uncertainties in UTCI of up to ±6°C are found, especially when prediction of cloudiness is wrong.

An exergy analysis is performed to analyse the possibilities of fuel saving in the cryogenic distillation process, which is the main method of air separation. It is shown that more than half of the exergy loss takes place in the liquefaction unit and almost one-third in the air compression unit. Minor exergy losses are taking place in the distillation unit and the main heat exchanger. The major cause of exergy loss is the use of compressors and to a lesser extent the use of turbines. Especially, the relatively low rational efficiency of the turbines operating in the cryogenic region is striking. Improvements are suggested which save one-fourth of the exergy loss. For more substantial reductions of the exergy losses in air separation alternative processes have to be used or developed.

AbstractBackgroundN2O is a powerful greenhouse gas emitted in nitric acid plants, and emission control technologies are required.ResultsA 0.25%Rh/50%Ce0.9Pr0.1O2/γ‐Al2O3 catalyst has been prepared and tested for N2O decomposition in a real nitric acid plant gas stream. The catalyst is active enough to achieve 100% N2O removal, maintaining a constant catalytic activity after 40 h operation without deactivating. Characterization of the fresh and used catalyst, using different techniques, revealed no changes during the N2O decomposition experiments: (i) XRD and Raman spectroscopy show the fluorite structure of the Ce–Pr mixed oxide before and after the catalytic tests, (ii) the crystal size of the Ce–Pr mixed oxide particles and the BET surface area of the catalyst is maintained, evidencing no sintering of ceria particles, (iii) H2‐TPR indicates that the reducibility of the catalyst is similar before and after the catalytic tests, revealing chemical stability, and (iv) TEM and XPS analysis indicated the high stability of the rhodium particle size and oxidation state.ConclusionAn active and stable catalyst with formulation 0.25%Rh/50%Ce0.9Pr0.1O2/γ‐Al2O3 has been prepared and successfully tested for N2O decomposition in a real nitric acid plant gas stream. © 2013 Society of Chemical Industry

The Vietnamese Mekong Delta (VMD) is one of the world’s most vulnerable deltas to climate change and sea level rise. Adequate understandings of future hydrological changes are crucial for effective water management and risk-proofing, however, this knowledge body is currently very limited. This study quantifies the responses of the VMD’s river flow regime to multiple stimuli, namely future upstream inflow variation, local climate change, and sea level rise. The one-dimensional hydrodynamic model MIKE 11 was used to simulate discharges and water levels across the delta. We developed four scenarios to represent changes in the upstream discharges, precipitation changes and sea level rise, covering the 2036–2065 period. We downscaled climate data and applied three bias-correction methods for five General Circulation Models (GCM), and two Representative Concentration Pathways (RCPs). The climate change projections show similar trends of increasing wet season precipitation and decreasing dry season precipitation. However, cross-scenario variations are sometimes large, depending on the individual GCMs, the RCPs and specific locations. The hydraulic simulation results indicate that, under discharge changes between −20% and +10%, combined with in-delta precipitation variations during the dry season, river discharges at the four representative stations could reduce substantially from −2.5% to −100.2%. During the wet season, the calculated river discharges show increase between 7.3% and 46.7% under four considered scenarios. Substantial changes in the VMD’s river flow regime could have potentially serious implications for water management, especially saltwater intrusion, and therefore calling for timely adaptation measures.

AbstractThe achievements of the last two decades in using solar energy for naturally ventilating and heating buildings of any size and scope across the world are remarkable, though comprising a niche market and being generally poorly known to this point. Air quality, thermal and hygrometric comfort, and reduced energy costs are some of the benefits provided by solar ventilated spaces. We identify the remaining hurdles to be addressed prior to forthcoming widespread adoption of this technology in the building environment across the world, well beyond the cold‐climate countries.

Abstract This paper defines two electric grids for the area of Jutland in Denmark, namely the existing grid versus a “nature protection grid”, in which all 400 kV AC overhead lines are replaced by 150 kV lines. According to official Danish policies for laying underground cables, such a replacement makes it economically feasible on a long-term basis to replace all overhead lines with underground cables. The two grids are then tested against different energy demand and supply systems in a load-flow analysis. It is found that the “nature protection grid” is well suited for the implementation of sustainable energy systems exploiting both CHP and renewable energy sources such as wind power if certain strategies for the technical regulation of decentralised CHP units are used.