Community energy storage: A smart choice for the smart grid?

Energy storage can help integrate local renewable generation, however the best deployment level for storage remains an open question. Using a data-driven approach, this paper simulates 15-min electricity consumption for households and groups them into local communities of neighbors using real locations and the road network in Cambridge, MA. We then simulate PV for these households and use this framework to study battery economics in a high PV adoption, high electricity cost scenario, in order to demonstrate significant storage adoption. We compare the results of storage adoption at the level of individual households to storage adoption on the community level using the aggregated community demands. Under the simulated conditions, we find that the optimum storage at the community level was 65% of that at the level of individual households and each kWh of community battery installed was 64–94% more effective at reducing exports from the community to the wider network. Therefore, given the current increasing rates of residential battery deployment, our research highlights the need for energy policy to develop market mechanisms which facilitate the deployment of community storage

أزمة الشرعية السياسية في الأنظمة العربية

هدف المقال إلى اعطاء لمحة تاريخية عن مفهوم الشرعية السياسية انطلاقاً من الفكر اليوناني وحتى الوقت الحالي، ونظريات نشوئها، كما تطرق المقال إلى أهم مصادر ومؤشرات بناء الشرعية السياسية، وقد استخدمت الدراسة منهجية معمقة شاملة تكونت من المنهج التاريخي ومقترب تحليل النظم ونظرية النخبة، وتوصلت النتائج إلى أن أزمة الشرعية السياسية تنشأ نتيجة لعجز الأنظمة السياسية عن التوفيق ما بين مصالحها ومصالح الشعوب. The article aimed to give a historical overview of the concept of political legitimacy, starting from Greek thought until the present time, and the theories of its emergence. The study also touched on the most important sources and indicators of building political legitimacy. The crisis of political legitimacy arises because of the inability of political systems to reconcile between their interests and the interests of the people

Demand and Congestion in Multiplex Transportation Networks.

Urban transportation systems are multimodal, sociotechnical systems; however, while their multimodal aspect has received extensive attention in recent literature on multiplex networks, their sociotechnical aspect has been largely neglected. We present the first study of an urban transportation system using multiplex network analysis and validated Origin-Destination travel demand, with Riyadh's planned metro as a case study. We develop methods for analyzing the impact of additional transportation layers on existing dynamics, and show that demand structure plays key quantitative and qualitative roles. There exist fundamental geometrical limits to the metro's impact on traffic dynamics, and the bulk of environmental accrue at metro speeds only slightly faster than those planned. We develop a simple model for informing the use of additional, "feeder" layers to maximize reductions in global congestion. Our techniques are computationally practical, easily extensible to arbitrary transportation layers with complex transfer logic, and implementable in open-source software

Site Assessment and Layout Optimization for Rooftop Solar Energy Generation in Worldview-3 Imagery

With the growth of residential rooftop PV adoption in recent decades, the problem of effective layout design has become increasingly important in recent years. Although a number of automated methods have been introduced, these tend to rely on simplifying assumptions and heuristics to improve computational tractability. We demonstrate a fully automated layout design pipeline that attempts to solve a more general formulation with greater geometric flexibility that accounts for shading losses. Our approach generates rooftop areas from satellite imagery and uses MINLP optimization to select panel positions, azimuth angles and tilt angles on an individual basis rather than imposing any predefined layouts. Our results demonstrate that shading plays a critical role in automated rooftop PV optimization and significantly changes the resulting layouts. Additionally, they suggest that, although several common heuristics are often effective, they may not be universally suitable due to complications resulting from geometric restrictions and shading losses. Finally, we evaluate a few specific heuristics from the literature and propose a potential new rule of thumb that may help improve rooftop solar energy potential when shading effects are considered

Validation of assigned flows.

<p>Our estimated travel times agree quite closely with Google Maps estimates in the free flow case (left). Some curvature is evident in the congested case, suggesting a small amount of systematic disagreement between models.</p

Multiplex flows for varying metro speeds.

<p><i>J</i>_<i>m</i> is the percentage of all person-kilometers which are traveled through the metro network. For slow speeds (higher <i>β</i>), congestion is concentrated along major thoroughfares in the downtown area in the center-west. The introduction of the metro at <i>β</i> = 1.4 has small impact on flows, handling just 2% of total. As effective speed increases, progressively more flow passes through the metro. Simultaneously, global congestion is reduced, but increases locally near key metro access points under very high speeds. Maps produced using Python’s networkx package [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0161738#pone.0161738.ref032" target="_blank">32</a>] v. 1.10, using road network data provided by the Arriyadh Development Authority (ADA).</p

Behavior of multiplex flows with variable metro speed.

<p>(a) For very high speed ratios, proportional flow through the metro approaches a limiting value of 58%, reflecting the partial geographic extent of the metro network. (b) As metro speed increases, total travel times decrease monotonically. However, most of the reduction in time spent on the road is achieved for relatively slow metro speeds, indicating that environmental returns to very fast metro schemes may be limited. (c) Dependence of travel time distributions on metro speed. A small number of travelers have very long commutes even for low <i>β</i>, corresponding to origins or destinations that are far removed from the metro network. (d) Increasing the metro speed also changes the qualitative structure of travel time distributions, as the metro smooths out heterogeneities introduced by empirical OD travel demand by linking distant areas of the city.</p

CCN and INP activity of middle eastern soil dust

The term mineral dust encompasses a myriad of particle compositions from both fertile and arid regions. Due to this diversity, the quantitative understanding of mineral dust as Cloud Condensation Nuclei (CCN) and Ice Nucleating Particles (INPs) in the Earth’s atmosphere demand further investigation. This study characterizes the CCN and INP activity of mineral dust particles from samples collected from one of the Earth’s major arid regions, Saudi Arabia. Samples were size selected at particle diameters (Dp) of 300, 700, and 950 nm and introduced into a Cloud Condensation Nuclei Counter (CCNC) and a SPectrometer for Ice Nuclei (SPIN) chamber to investigate cloud nucleation activity. The chemical composition of the particles was analyzed with laser mass spectrometry and mineralogical information was provided by polarized light microscopy. Transmission electron microscopy was used to ascertain particle morphology. Each particle size was exposed to water supersaturations of 0.06–1.0% in the CCNC and to ice supersaturation ratios of 1.1 to 1.5 at temperatures from −25 to −42 °C in SPIN. The CCN activity ranged from hygroscopicity values (κ) of 0.001 to 0.01. This is towards the lower range of critical supersaturations found for other mineral dust samples from e.g. the Sahara, North Africa, China and Asia. The INP activity, defined by fractional activation and supersaturation at the onset of ice nucleation was in the range of other natural mineral dusts (e.g., the Sahara, Canary Islands), and somewhat lower than industrially processed Arizona Test Dust. This study highlights the importance of considering size-resolved compositional data when interpreting the cloud-nucleation activity of natural mineral and soil dusts.ISSN:1875-963