Biogas production from reed and biomass from low input areas from the national park Lake Neusiedl

Through the comdined fermentation of economic fertilizers and energy plants in biological gas facilities annually about 4900 GWh electricity and 6700 GWh warmth could be generated in Austria. From the point of view of climate protection the production of biogas becomes more and more important. Annually climate-relevant emissions can be decreased by more than 5 million tons of CO2. In the present investigation four different groups of plants, namely reed, grass of protected surfaces, makrophyten and algae were examined. On the basis of the available test results the following conclusions can be derived: - Influence of the preparation of the silage: The ensiling of crude-fibre rich reed and grass caused an increase of the specific fermentation gas and methane output in comparison to the fresh biomass. By contrast the preparation of the silage with protein-rich makrophyten and algae caused an easy decrease in the specific fermentation gas and methane output, which possess a small crude-fibre content, compared with fresh biomass. - Process parameters: No inhibitions of the anaerobic metabolism during the process of the fermentation could be observed due to the plants used. During the entire attempt the pH value lay in the optimal range for the fermentation process. - Gas quality: The methane content in the fermentation gas laid between 43,3 and 53,5 Vol. %. The crude-fibre -rich reed and grass showed a generally smaller methane content than the protein-rich makrophyten and algae. - Methane yield: The test results show that all examined biomasses are suitable for anaerobic fermentation in biological gas facilities, supply comparatively high fermentation gas and methane yields and represent thus a valuable potential of energy production. - Retention time: The determination of the necessary retention time plays an important role with the dimensioning of the biological gas facilities. The test results show that for the fermentation of reed and grass a minimum retention time of 30 days is necessary. For the fermentation of algae and makrophyten a minimum retention time of 20 days is recommended. In the biological gas facilities the use of substrates is common which leads to a nutrient surplus that negatively can affect the retention time. Therefore additionally + 10 to 15% of retention time is necessary for the biological gas facilities.