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28.06.2011

It ferments too long in the tank

Biogas production is becoming increasingly more important in the course of the current energy discussion. It is far from reaching its full achievement potential. Especially in the area of accelerated fermentation processes, there are many opportunities for improvement as shown by recent research. Incubators from BINDER GmbH form the reliable basis of high-quality laboratory.

In biogas production, it can take up to two hundred days to obtain the maximum amount of methane from a substrate such as corn. A cow only needs about 24 to 36 hours. The high-efficiency degradation and transformation processes of the four-chambered stomach of the quadruped and intestines of up to 60 meters in length make the difference. Clearly, there is much room for improvement in the processes of biogas production. In the field of optimized energy production from biogas, Germany has some of the leading research institutes in the world including the Institute for Agricultural Engineering and Animal Husbandry at the Bavarian State Research Center for Agriculture (LfL). One of its current projects to determine the potential gas yield offers new perspectives for the future of biogas production.

Clarity in complex structures

According to experts such as LfL associate Dr.-Ing. Konrad Koch, a crucial factor for efficient energy production from renewable resources is the improvement of fermentation processes. In his view, understanding the complex ongoing processes and the microorganisms involved with the aim of maximizing gas yield is the top priority.

The researchers led by Konrad Koch are constantly faced with the challenge of simulating the complex fermentation processes under different conditions and of deriving specific guidelines for practical implementation based on reproducible process parameters. Among others, the pH value, temperature and average particle size of the energy source used - the so-called substrate - play a crucial role. And the question of obstacles to an efficient fermentation process must be answered, i.e. which substances inhibit or are even toxic to gas production.

Identifying weaknesses in the process

Tests to determine the potential gas yield of substrates such as corn brought light into the darkness of the fermenter, the fermentation tanks for biogas production. The difficulty lies in the analysis of the interplay between different groups of microorganisms. "It is important to understand which bacteria take over at which point in the degradation processes," explains Konrad Koch. "Only after we understand these processes and relationships can we identify weaknesses in the processes and ensure sustainable improvement."
A key step which largely determines the rate of targeted methane formation in agricultural biogas plants is hydrolysis - the transition from non-dissolved to dissolved material. Depending on the substrates used as well as parameters such as pH value and temperature, the time required for hydrolysis can vary.

Reliability accelerates the research

The accuracy of the measurements is of fundamental importance because only then can a reliable degree of comparability of research series be achieved in individual scientific projects. Accuracy is the basis of evaluation and comparison, as well as the grouping of meaningful results. Using exact measurements, a broad basis for decision-making is achieved for far-reaching further developments of the substrates.

The laboratory setups of the research series at the LfL do not look spectacular, but are of great significance for future heterogeneous and comprehensive energy production from renewable resources beyond the borders of Germany and Europe. Reliability is the ace in the hole, for example, when it comes to the incubators used. The success of a research project stands and falls with their consistency and performance. At the Institute for Agricultural Engineering and Animal Husbandry at the Bavarian State Research Center for Agriculture, incubators with mechanical convection of the BF series from BINDER have supported the consistently high quality of research for many years.

The researchers led by Dr.-Ing. Konrad Koch are using the BF 115 incubator in their current research projects. Particularly well-suited for all gentle incubation applications, the BF 115 incubator distinguishes itself by its high throughput even when fully loaded. The high dynamics of the BF 115 keeps the required temperatures absolutely stable with homogeneous distribution.

Over 100 years of raw biogas

Incidentally, biogas has been in use since the beginning of the 20th century. The so-called combined decanter-digester was used at water treatment plants in the Ruhr region of Germany. The system developed by Karl Imhoff in 1906 for clarified water purification produced methane as a by-product that was used to supply gas to street lamps. In addition to these so-called fermentation residues, the active production of biogas based on different substrates such as corn, various grasses and sugar beets has achieved a permanent place in alternative energy production today.

Source: Binder GmbH