The use of energy generated by the Sun, inexhaustible on the terrestrial scale of time, both as a source of heat and light, is now one of the most promising energy alternatives to provide the energy necessary for human development. For engineering purposes, it is possible to speak of solar energy for photovoltaic generation and for heliothermic generation, presented below.
Photovoltaic solar energy is the energy obtained through the direct conversion of light into electricity (photovoltaic effect). Within this research line, projects are carried out and tests are carried out with photovoltaic systems, connected or not connected to the grid.
Among the main activities carried out, we can mention the support for the 3 MW Furnas photovoltaic plant to be installed in Jaíba, MG, in a Public Call R & D project no. 13/2011 of the National Electric Energy Agency (Aneel ); the support for the Chesf 3 MW photovoltaic power plant project to be installed in Petrolina, PE, also in Aneel Public Call R & D project No 13/2011; the support to the Ministry of Mines and Energy (MME), in the framework of the ProGD (Program for the Development of Distributed Generation of Electric Power), in the aspects related to photovoltaic generation, and in the Prodeem Decommissioning Committee (commission responsible for evaluating and proposing allocation for all the remaining equipment of the Program of Energy Development of States and Municipalities - Prodeem). In addition, work in support of the Light for All Program can be mentioned, such as conducting tests and studies on the suitability of different SIGFI systems to feed consumers' loads and the design of the photovoltaic system, installed by the Navy, to feed the Scientific Station of the São Pedro and São Paulo Archipelago.
Finally, the researchers of this line participate in the working group dedicated to photovoltaic systems within the scope of the Brazilian Labeling Program, coordinated by the National Institute of Metrology, Quality and Technology (Inmetro).
The team, with national and international training, elaborates technical courses on photovoltaic systems, which have been given to Eletrobras System companies. The activities of the research line are supported by the Reference Center for Solar and Wind Energy Sérgio de Salvo Brito (Cresesb), in the Fundão Unit.
Solar thermal energy is characterized by the use of solar radiation incident on a body in the form of heat. The most widespread equipment with the specific purpose of using solar thermal energy are known as solar collectors.
The solar collectors are fluid heaters (liquid or gaseous), being classified in concentrator collectors and flat collectors, due to the existence or not of solar radiation concentration devices. The heated fluid can be kept in thermally insulated reservoirs until its final use. The concentrator collectors are associated with applications in temperatures above 100oC, reaching temperatures of up to 400oC for the steam turbine drive and subsequent generation of electricity. Flat collectors are mainly used for residential and commercial applications in low temperature (around 60oC), such as: heated water for bath, hot air for drying grain, heating of swimming pools, heated water for cleaning in hospitals and hotels , etc .. Flat solar collectors are already widely used in Brazil for heating water in homes, hospitals, hotels, etc., aiming at reducing the consumption of electricity or gas.
Medium and large plants using optical systems (lenses, mirrors) for concentration of solar radiation and heating of fluids at high temperatures are called CSP (Concentrated Solar Power). Four CSP technologies are used: parabolic cylinders, solar towers, linear Fresnel collectors and parabolic concentrators ("disks"). In the first three technologies, the heat collected is usually used in the production of steam and subsequent activation of turbines for the purpose of generating electric energy. In the latter, the electric power is generated in stirling engines. The technologies have different levels of maturity, varying from the commercial viability of parabolic cylinders - which dominate the market with 90% of the installed power, passing commercial pilot plants with solar towers, to pilot projects with Fresnel concentrators. The potencies of these plants can vary from a dozen of kW, in the stirling systems, to hundreds of MW, in plants with parabolic cylinders.
By 2013, CSP installations of different solar concentrator technologies reached an overall installed capacity of around 2.8 GW, where approximately 90% of the installations were in operation. Spain accounts for about 65%
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