The spent grains are a by-product of the beer production. There are many different possibilities to use these spent grains. One of these possibilities is the thermal utilization directly at the location. This is practiced in the brewery Göss in Leoben. The spent grains are burned in a biomass caldron after being mechanically dried in order to produce steam, which is used in the brewery. The first part of this dissertation is about the biomass as a fuel. Moreover this first part treats of the required properties of biomass e.g. the moisture and also of the different types of firing. The second part of this dissertation describes and evaluates the experiments, which were done in order to optimize the caldron and to stabilize the process of combustion of the spent grains so that the amount of steam increases, which is produced by the caldron. Among these steps of optimization rank a calculation of combustion of the spent grains Göss and furthermore an energy balance of the biomass caldron.