Solar Stirling
In solar Stirling systems, solar thermal energy is converted into mechanical energy using a Stirling engine. In this way, electrical energy is usually generated in a directly coupled generator.
description
Solar Stirling systems - also called Dish Stirling systems because of the bowl-shaped mirror - achieve an efficiency of around 20% on average with an electrical generator , which means that they have a slightly better efficiency of power generation than photovoltaic systems , albeit at great expense . That was the result of an experiment in France. With a parabolic mirror with a diameter of 8.5 m (area 56.7 m²), a net power of 9.2 kW was achieved, which corresponds to an efficiency of 16%. With modern technologies, such as a magnetic decoupling of the pistons from the output, the efficiency (and the service life) of a solar Stirling system can also be increased significantly; a world efficiency record of 29.4% from 1984 lasted a long time before it was broken on January 31, 2008 by a Series 3 system from the US manufacturer Stirling Energy Systems with an efficiency of 31.25%.
Solar Stirling systems can also be operated when it is cloudy or at night by using other heat sources, such as the combustion of natural gas . Further applications of solar Stirling systems could be solar cooling or seawater desalination or driving pumps.
There are also mixed forms between Dish-Stirling systems and conventional photovoltaic systems ("PV Dish systems"). The parabolic mirror is retained, but the Stirling engine and generator are replaced by a solar cell. Since this only needs to be as large as the area of the focal point (i.e. only a very small fraction as large as normal solar cells, which would be required for the same output), extremely efficient solar cells can be used that would be far too expensive for conventional applications . Water cooling of the solar cells is essential for this use; the resulting hot water can simply be used for heating or washing. Combined with electricity and heating capacity, these systems can, according to the manufacturer, achieve a total degree of utilization of more than 75%.
After the cost reduction in photovoltaic systems, there are increasing signs that Dish-Stirling could be left out in the race for small solar systems. One example of this is the bankruptcy of the operating company Stirling Energy Systems in 2011 due to liquidity problems.
See also
literature
- Chapter 3. Parabolic Power Plants . In: M. Mohr, P. Svoboda, H. Unger: Practice of solar thermal power plants. Springer, Berlin / Heidelberg 1999, ISBN 978-3-642-63616-5 , pp. 91-120.
- Chapter 5.2.4. Dish-Stirling systems. In: Kaltschmitt, Streicher, Wiese (Hrsg.): Renewable energies: system technology, economic efficiency, environmental aspects. Springer-Vieweg, 5th edition from 2014, ISBN 978-3-642-03248-6 , pp. 308-315.
Web links
Individual evidence
- ↑ Results in southern France ( Memento of the original from May 28, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Steffan Heuer, Wolfgang Stieler: Stirling engine gives wings to solar power plants. Heise online . January 28, 2010.
- ^ US solar company Stirling Energy Systems applies for creditor protection
