Cleaning, drying, dyeing, pasteurising, bleaching and melting – at first glance, the potential for utilising solar process heat in industry seems enormous. The aforementioned selection of cross-sector processes is at least partly suitable for provision with solar thermal energy. Despite this, the number of applications that actually use solar process heat lags far behind its theoretical potential. This is partly due to the fact that this is a new application area for solar thermal energy.

A closer examination shows, however, that the necessary system technology is relatively expensive for processes with operating temperatures above 100 °C. This technology will only be available after successful testing of pilot applications. At this temperature level, the low and inconsistent solar irradiance in Germany has also prevented more widespread use. In the lowtemperature area below 100 °C, the technology is fully mature and the solar thermal systems are more efficient. The greatest challenge is integrating the systems within the complex array of different industrial processes.

The independent Hofmühl brewery in Eichstätt and the Hütt brewery in Kassel-Baunatal have risen to this challenge and support their brewing processes with solar thermal systems. This enables them to reduce their oil and gas requirements in the long term. Both research projects are not yet finally concluded. The first results will become available in 2011.

Breweries generally offer good conditions for integrating solar thermal energy. As with the rest of the beverage industry, they mostly require heat in summer when the most solar energy is available. For example, the Hofmühl brewery brews twice as much beer during the summer months than in winter. Furthermore, most process stages are conducted at a relative low temperature level and the heat requirement is distributed relatively consistently throughout the day and week. This means that no unnecessarily large storage tanks are required. Although all breweries brew beer according to the same basic principle, a closer examination reveals considerable differences in terms of the technical processes. That is also shown in the case of the aforementioned research projects, which have been subsidised by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety as part of its Solarthermie2000plus funding programme.