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State of the Art Throughout the world, about one-fifth of electricity is generated from hydropower. Hydropower is an emissions-free, renewable and reliable energy source. Hydropower accounts for over 90% of all electricity that comes from renewable resources (e.g., solar, geothermal, wind, biomass). Today's hydropower turbines are capable of converting 90 percent of available energy into electricity - that is more efficient than any other form of generation. Even the best fossil fuel power plant is only about 50 percent efficient. Canada is the largest producer of hydropower in the world (see Fig. 1). The efficiency of the HydropowerPlant is strategically important for the future needs of the world's electricity. One strategy to reduce emissions while increasing generating capacity is to emphasize the development of non-carbon electricity generation alternatives like hydropower. Hydropower's operational flexibility - its unique ability to change output quickly - is highly valued, and will become even more so in a competitive market. Its unique voltage control, load-following and peaking capabilities help maintain the stability of the electric grid ensuring economic growth and a high quality of life. Main interest for hydropower plant management focuses on the Snow/Glacier elements and the estimate of their potential water content. Especially on the border between the temperate and polar regions, substantial annual precipitation combined with low temperatures leaves most of the available water on the ground as snow and ice that cannot be exploited to power production immediately. Moreover the melt water is in great part stored for electricity production, so that a change in the amount of availability water will oblige the hydropower companies to change the operative production schemes or even to increase the electricity price. The importance of snow resource and the climatic change observed during the last years justifies the great interest of the scientific community in monitoring snow cover (Fig. 2). Fig. 1 Top Hydroelectric Generating Countries, EIA Annual Energy Review 1994 (July, 1995).
Fig. 2 Change in spring snow cover extent over the 1972-2000 period from NOAA satellite data. Significant increase/decrease are shown. Strategies for monitoring this fundamental resource are necessary and an EO-based integrated service represents an interest and power instrument that could also integrate conventional methods adopted (like sensors and hydrological models). The most important parameters from this point of view are: snow coverage, snow volume storage or snow water equivalent (SWE), snow temperature and free liquid water in snow pack. Finally, it is important for the hydropower producer to rely on regularly provided information on the status of the catchments. The future Earth Observation system should provide, regardless of weather and daylight, weekly information in all catchments. |
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