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On its way to becoming a cool draught: the wort is prepared in the brewing kettle.
© Universität Kassel, Bastian Schmitt
Sector concept for breweries

Solar heat for a cool draught

The privately-owned Hofmühl brewery in Eichstätt is doing it – and so is the Hütt brewery in Kassel-Baunatal. They use solar heat to support their production processes. With around 1,300 breweries in Germany, there is significant potential here for solar-supported brewing processes. The Department of Thermal Power Engineering at the University of Kassel has published a guide on using solar process heat which describes how this potential can be exploited. Now, scientists are following suit with a detailed concept for the sector.

The brewhouse is the core of any brewery. Here, a sugared fluid – the wort – is created from hops, malt and water. This process requires the most heat. The share needed is around half that of the entire production process. Solar heat can be used for “mashing”. Here, the coarse malt meal is mixed with brewing water and then heated in the mash tun . The tun is heated via a hot water circuit. This is brought to the required temperature, first using solar heat and then using steam, via serially connected heat exchangers. While there is a high demand for heat in the brewhouse, the fermenting and storage cellar needs a high level of cooling, and the power consumption is accordingly high. In the filling hall, the third stage of beer production, the ratio between the thermal and electric energy required is balanced, however. Overall, breweries need three-quarters of the energy consumed for generating heat.

The question of “where?” is a decisive factor

Which stages of the brewing process are best suited for incorporating solar heat?
Initially, the process temperature is an important criterion. The higher the temperature which needs to be provided, the lower the yield of the solar energy system. Conversely, processes with a low target temperature or for which preheating is possible are particularly suitable for solar support. These should have long running times during the course of a week. With the same running time, a process which is conducted every second day is better suited for incorporating solar heat than a process which runs on successive days. In this case, several days must be bridged using a storage system. Another decisive factor is the level of cost involved in integrating solar heat into a process. For example, when brewing water is produced, only a heat exchanger and some peripheral equipment are required, together with a connection to the existing brewing water reserves. If solar support is used for mashing, the existing mash tun must be replaced or extensively modified. Solar support is particularly suitable for heating the brewing and operating water, and for supporting the water preparation or tunnel pasteurisation.

BINE-Projektinfo on this topic

The BINE-Projektinfo brochure, “Brewing beer with solar heat”, issue 13/2010, describes how the privately-owned Hofmühl brewery in Eichstätt and the Hütt brewery in Kassel-Baunatal have integrated solar heat into their brewing process.


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