Dish-Stirling Systems

Dish-Stirling systems are at present the least technological­ly mature. Companies in the USA and in Germany are cur­rently working on four different sys­tems worldwide (Figure 1c). The sys­tem which is furthest along in its development originated in Germany and has accumulated several tens of thousands of hours of operation.

Such systems aim at independent power generation, not coupled to a power grid, for example for providing isolated villages with electric power. Their principal advantage is a very high efficiency of up to 30 %: This is provided by the combination of a near­ly ideal paraboloid concentrator with an excellent heat engine. If the sun is not shining, then dish-Stirling systems can in principle be operated with fu­el combustion, in order to meet the de­mand for power. This is a decisive ad-

vantage over photovoltaic cells, which aim at a similar mar­ket: They, however, require expensive storage batteries for energy storage.

These are good reasons why dish-Stirling systems have a favorable market chance in the medium term for inde­pendent power generating applications. For this purpose, they must be capable of autonomous and very reliable op­eration. Subsidized niche markets are, however, only one of the possibilities for dish-Stirling systems. A still greater mar­ket potential lies in the increasing power requirements of developing countries, especially those with a large amount of sunlight, poorly established power grids and high costs for the import and transport of fossil fuels.

Aside from the question of technical maturity, the small number of units produced represents a hurdle to commer­cial marketing of dish-Stirling systems.