Solarthermie

Solar thermal energy is a technology for harnessing solar energy for thermal energy, which is then used to produce electricity. Already in the ancient burning mirrors were used to profit from solar energy. This kind of energy has many advantages: it is independent of fossil and nuclear fuels, doesn’t send out carbon dioxide and produces the solar electricity on the cheapest way which can be transported inexpensively over long distances. The only disadvantages are the high costs and the fact that solar energy can’t be economically exploited everywhere because the solar radiation is unevenly distributed around the world. Solar energy is especially well used at the sunbelt of the earth where the sun shines often and the intensity of the sun is the highest. In the most European countries the usage of solar energy is only effective for households. They use the heat for bathing and showering, as heating assistance and for the heating of drinking water. A typical household solar heating system consists of a solar panel or solar collector with a heat transfer fluid flowing through it to transport the heat energy collected to somewhere useful, usually a hot water tank or household radiators. The solar panel is located somewhere with good light levels throughout the day, often on the roof of the building. A pump pushes the heat transfer liquid (often just treated water) through the panel. The heat is thus taken from the panel and transferred to a storage container. There are three typical kinds of collectors: Parabolic trough collectors, Vacuum tube collectors and Flat plate collectors. Solar energy is used in Solar thermal power plants, as well. There, the heat of the sun is obtained through absorbers and is the primary energy source of the power plant. The cycle for power generation is similar in the different kinds of solar thermal power plants: the radiances of the sun are concentrated, the derived heat produces steaming which moves a turbine with a generator where electricity is produced. Solar thermal power plants are divided in two categories: plants with Integrating direct radiation (like Parabolic trough power plant, Solar power tower and Dish-Stirling system) and plants without Integrating direct radiation (like solar pond power plant). There are these kind of power plants in the US, Spain and France.

Maxi & Mandy