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Abstract Sustainability is an important and difficult consideration for the stakeholders/decision-makers when planning a biofuel supply network. In this paper, a Mixed-Integer Non-linear Programming (MINLP) model was developed with the aim to help the stakeholders/decision-maker to select the most sustainable design. In the proposed model, the emergy sustainability index of the whole biodiesel supply networks in a life cycle perspective is employed as the measure of the sustainability, and multiple feedstocks, multiple transport modes, multiple regions for biodiesel production and multiple distribution centers can be considered. After describing the process and mathematic framework of the model, an illustrative case was studied and demonstrated that the proposed methodology is feasible for finding the most sustainable design and planning of biodiesel supply chains.

Abstract The impact of the spatial variation of inertial response and fast frequency services has not been fully investigated in power system scheduling models incorporating constraints on network security. This paper demonstrates the importance of acknowledging the variety of local frequency dynamics in the aftermath of a generation loss. It proposes a novel scheduling methodology that enables the system security in all areas of the system thus preventing potential tripping of distributed generation triggered by locally-measured high rates of change of frequency. The proposed methodology highlights the positive contribution to local frequency dynamics from an HVDC link, whose capacity is optimally dispatched to allocate power flow and fast-frequency services. The novel power system scheduling model is applied to analyze a typical 2030 GB low-carbon scenario. Results show that there are changes in the commitment decisions compared to the solution obtained with a one-area formulation when local security is taken into account. These changes translate into additional operational cost.

Abstract Photovoltaic (PV) connected systems are experiencing rapid market growth. This is due to the continually downward trend in PV cost together with government support programs. A scenario has been assumed to analyse the geographical market of PVs. The results provide clear evidence of the influence that some variables have on the profitability of PV investments. This study presents a model for minimising investment risk and maximising the return of a renewable energy portfolio in Italy. The value of the paper is in showing that the energy and CO 2 reduction potential that can be reached through consumer-oriented policy measures, but the paper also looks at the effectiveness and social implications of such measures. Private households possess immense unused potential for energy reductions (and climate protection) that could be realised through gains in energy efficiency, behavioural changes, and extended use of low-emission energy. The focus of energy policy has been on businesses rather than on private households, which are only partly captured by direct policy measures. To achieve the goals of climate policies, the current political and scientific discussion increasingly considers measures that aim to reduce energy consumption in the private sector. Quantitative estimates are presented for economic indicators and will show the various effects of policy measures on the implemented household types.

Using 40-year experiment data from a mono-modal rainfall area of northern Togo, we analyzed soil fertility dynamics when 2 and 3-year fallows were alternated with 3-year rotation of groundnut, cotton and sorghum. The control treatment consisted to continuous cultivate the soil in a rotation of groundnut/cotton/sorghum without fallow periods. For each rotation, two fertilisation rates were applied: no fertilisation and mineral fertiliser application during the cropping and/or the fallow periods. Yields of unfertilised crops, which averaged 1 t ha-1 during the first years of cultivation, were often nil in the long-term. In the long-term, yields of fertilised cotton and sorghum decreased by 32 and 50 %, respectively compared to the average of 2.4 and 1.6 t ha-1 obtained during the first decade of cultivation. The long-term decline in crop productivity was mitigated when fallow periods were alternated with cropping periods, and consequently there was partial compensation in terms of production for the unproductive fallowed plots. Long-term yields of fertilised cotton and sorghum in the periodically fallowed plots were 40 and 50 % higher than those in continuously cropped plots, respectively; they were 90 and 60 % higher than those in continuously cropped plots without fertilisation. Like for crop productivity, soil C, N and exchangeable Ca and Mg decreased less in periodically fallowed plots than in continuously cropped plots. The limited soil C decline when fallows were alternated with crops appears to be the consequence of no-tillage period rather than the effect of the highest C inputs to the soil.

Alpine grasslands on the Qinghai-Tibetan Plateau are sensitive and vulnerable to climate change and human activities. Climate warming and overgrazing have already caused degradation in a large fraction of alpine grasslands on this plateau. However, it remains unclear how human activities (mainly livestock grazing) regulates vegetation dynamics under climate change. Here, alpine grassland productivity (substituted with the normalized difference vegetation index, NDVI) is hypothesized to vary in a nonlinear trajectory to follow climate fluctuations and human disturbances. With generalized additive mixed modelling (GAMM) and residual-trend (RESTREND) analysis together, both magnitude and direction of climatic (in terms of temperature, precipitation, and radiation) and anthropogenic impacts on NDVI variation were examined across alpine meadows, steppes, and desert-steppes on the Qinghai-Tibetan Plateau. The results revealed that accelerating warming and greening, respectively, took place in 76.2% and 78.8% of alpine grasslands on the Qinghai-Tibetan Plateau. The relative importance of temperature, precipitation, and radiation impacts was comparable, between 20.4% and 24.8%, and combined to explain 66.2% of NDVI variance at the pixel scale. The human influence was strengthening and weakening, respectively, in 15.5% and 14.3% of grassland pixels, being slightly larger than any sole climatic variable across the entire plateau. Anthropogenic and climatic factors can be in opposite ways to affect alpine grasslands, even within the same grassland type, likely regulated by plant community assembly and species functional traits. Therefore, the underlying mechanisms of how plant functional diversity regulates nonlinear ecosystem response to climatic and anthropogenic stresses should be carefully explored in the future.

a b s t r a c t Wheat yields in Europe have shown stagnating trends during the last two decades, partly attributed to climate change. Such developments challenge the needs for increased production, in particular at higher latitudes, to meet increasing global demands and expected productivity reductions at lower latitudes. Cli- mate change projections from three General Circulation Models or GCMs (UKMO-HadGEM1, INM-GM3.0 and CSIRO-Mk3.1) for the A1FI SRES emission scenario for 2000 to 2100 were downscaled at a northern latitude location (Foulum, Denmark) using LARS-WG5.3. The scenarios accounted for changes in tem- perature, precipitation and atmospheric CO2 concentration. In addition, three temperature-variability scenarios were included assuming different levels of decreased temperature variability in winter and increased in summer. Crop yield was simulated for the different climate change scenarios by a cali- brated version of AFRCWHEAT2 to model several combinations of genotypes (varying in crop growth, development and tolerance to water and nitrogen scarcity) and management (sowing dates and nitro- gen fertilization rate). The simulations showed a slight improvement of grain yields (0.3-1.2 Mg ha−1) in the medium-term (2030-2050), but not enough to cope with expected increases in demand for food and feed. Optimum management added up to 1.8 Mg ha−1. Genetic modifications regarding winter wheat crop development exhibit the greatest sensitivity to climate and larger potential for improvement (+3.8 Mg ha −1 ). The results consistently points towards need for cultivars with a longer reproductive phases (2.9-7.5% per 1

Our electrical world is changing. The journey we are on today parallels the era of Edison, Tesla, and Westinghouse in the early race for electrification. Change abounds: energy from nature, inverter-based technology, smart and smarter grids; decentralized power, and intercontinental interconnection. This new age of energy offers new choices and challenges, all heavily influenced by the practices that evolved over the past century and institutionalized in standards, interconnection requirements, grid codes, and technical regulatory policies. These standards drove the development of the electrical world, and now they play an important role in its transformation. We explore here the rapidly evolving standards world, one that is both the product of unprecedented technology and an environment for enabling even more technological advancements.

Abstract Vegetation is usually sparse in the desert regions, but it plays important roles in stabilizing sand dunes and combating desertification. Establishing how desert vegetation responds to changes in both natural forcing and anthropogenic interference is essential for better understanding desertification processes and their future dynamics. In this study, a comprehensive analysis of NDVI time series data in combination with climate reanalysis data and topographic data was conducted to investigate the possible effects of different external factors on desert vegetation in the Tengger desert, one of the largest deserts in northern China. The results show that vegetation is mostly distributed near the desert margins and in the interdune areas with relatively low and flat topography. Multiple NDVI datasets indicate a consistently greening trend over the entire desert during the last forty years, and the greening rates are higher at sites with sand fixation and vegetation restoration practices. After a few decades of restoration practices, vegetation greenness in these sites is approaching their natural states, but they still show large interannual variability associated with precipitation fluctuations. Therefore, the greening trend of the entire desert could be related to recent climate change towards wetter, warmer and less windy conditions, while human efforts have accelerated the rate of vegetation recovery in the restoration sites. Our study implies that the present climate change has produced conditions favorable for continued vegetation increase in the drylands of northern China, and this trend has been facilitated by policy-driven restoration projects. The combined effects of climate change, topography and human interference on desert vegetation should be considered in future restoration practices.