Suchergebnisse

Summarization: A lot of autonomous power systems have been designed and operated with different power levels and with special requirements for climatic conditions, availability, operation/maintenance cost, fuel consumption, environmental impacts, etc. In this paper a novel design of an autonomous power system with photovoltaic panels and electrochemical batteries for a shoreline electrode station is analyzed. This station will be constructed on the small island of Stachtoroi for the new high voltage direct current (HVDC) link of Attica–Crete in Greece. The general guidelines of the International Council on Large Electric Systems (CIGRE) and of the International Electrotechnical Committee (IEC) for the power system of lighting and auxiliary loads for these HVDC stations are supplied from the medium voltage or the low voltage distribution network, whereas they do not take into account the criticality of this interconnection, which will practically be the unique power facility of Crete island. The significance of Crete power system interconnection demands an increased reliability level for the power sources, similar to military installations and hospital surgeries. In this research a basic electrical installation design methodology is presented. First, the autonomous photovoltaic power system with the energy storage system (ESS) consisting of electrochemical batteries is preliminary designed according to the relative bibliography. The station power and energy consumption are analytically determined taking into consideration the daily temperature variation annually. Afterwards, a techno-economic optimization process based on a sensitivity analysis is formed modifying the size/power of photovoltaic panels (PVs), the type and the energy capacity of the batteries taking into consideration the operation cycle of PVs—batteries charge and discharge and the battery ageing based on the relationship between battery cycles—the depth of discharge, the daily solar variation per month, the installation cost of PVs and batteries, ...

Summarization: Climate change is one of the most urgent problems facing the earth. Its facets are multiple: environmental, economic, and social, and its consequences could become dire if drastic and concerted action is not taken immediately. This paper uses existing economic and physical models to devise CO2 emission trajectories for the whole world that optimize a neo-classical welfare function as well as an alternative function inspired by research on subjective well-being, while keeping temperature rise at 2 °C above preindustrial levels. These trajectories are then linked with certain behavioral traits that are strongly connected with the attitudes that would realize such policies. It is demonstrated that the 2 °C target is still feasible but the corresponding behavioral changes are quite demanding. Difficult as the problem might be, it is encouraging that humanity can still resolve it if no time is wasted and political action is taken immediately. ; Presented on: Environmental Development

Summarization: Climate change has repercussions on national security. Yet, no widely accepted definition of climate security exists to date. In this paper, we present a mathematical model that defines and assesses climate security as a function of 37 indicators of exposure, sensitivity, and adaptive capacity. The model combines the indicators using statistical methods and fuzzy logic which encapsulates the subjective part of the assessment, to derive an overall climate security score from 0 to 1, and then rank 187 countries. A sensitivity analysis points to those indicators with the highest potential to improve climate security and indicates regional priorities for action. It turns out that globally the highest priorities are the economy which is necessary for climate adaptation, population growth which should be contained, political rights, renewable energy use, and sea level rise. Although several results such as the high ranks of Scandinavian countries are intuitive, the model uncovers unexpected facts such as the higher rank of Uruguay than Denmark and Japan or the higher rank of Costa Rica than Italy. However, a closer look at the intermediate results reveals that Uruguay and Costa Rica are far superior to Denmark, Japan, and Italy in the areas of water and energy. ; Παρουσιάστηκε στο: Climatic Change

Summarization: Carbon dioxide (CO2) is the main greenhouse gas (GHG) in the atmo- sphere responsible for long-term global warming, and scientific evidence indicates that the current CO2 concentration is proba- bly the highest in the last 15 million years (World Bank 2012)—more than 391 parts per million (ppm), com- pared to the preindustrial level of 278 ppm. CO2 emis- sions grew 1.1 percent per year from 1990 to 1999 but since 2000 they have been growing by more than 3 per- cent per year (Gowdy 2010). The National Oceanic and Atmospheric Administration (NOAA) reported a reading of CO2 at Mauna Loa of 400.03 ppm on May 9, 2013, crossing for the first time the 400 ppm mark.1 Global warming due to past anthropogenic CO2 emis- sions is irreversible for at least 1,000 years, and current and future CO2 emissions will result in additional warm- ing (Matthews and Solomon 2013). The international community has set the goal of stabilizing global warm- ing at no more than 2°C above preindustrial levels by 2100, while the Small Island Developing States (SIDS; www.sidsnet.org) have set it at 1.5°C. But given cur- rent emission levels and minimal international action to mitigate climate change, "there is roughly a 20 per- cent likelihood of exceeding 4°C by 2100" (World Bank 2012, p. 1). It is still possible, however, to keep global warming within tolerable limits through the use of appropriate technologies to replace fossil fuel consumption with other energy sources and the application of interna- tional political will to change course and control cli- mate change. Any delay of such action will commit the planet to higher and higher temperatures that will become irreversible in the foreseeable future. The likely consequences will be dire. ; Παρουσιάστηκε στο: The Bridge