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Fakultät Life Sciences
Fakultät Life Sciences

Practical Course Biogas Engineering

The practical course “Biogas Engineering” is part of the module “Bioenergy-Biogas” of the international master course “Renewable Energy Systems”. The module includes also the accompanying seminar “Biogas Engineering” (Prof. Dr. Paul Scherer). 2,5 credit points are given for the seminar (with a mark) as well as for the practical course (with a protocol). The course runs as a campaign in the semester. Therefore, it is enough time available for other activities, see separate time schedule. Registry will be made during seminar on Tuesday. Interested students have to come to the seminar.

Possible participants are 2 x 12 students with 6 biogas stations in two cohorts. Every station will be managed by two students as a responsible group.

The research working group of Prof. Dr. Paul Scherer, together with the technician Monika Unbehauen, developed between 1995-2005 automated anaerobic digestion assays as batch mini-fermenters. Such batch fermentation assays are now common for research institutes and companies involved in biogas engineering. But the Hamburg University of Applied Sciences is to our knowledge the only university in Germany which offers a practical biogas master course with batch mini-fermentations as a regular student course, - even with an English instruction manual.

Fermentation tests of biomass and biowaste demonstrate the suitability for biogas production. The estimated gas potential represents the starting point of a biogas plant to determine the electrical capacity of a plant. 1 kg biomass or biowaste produces around 1 m³ biogas with 50-70% methane. And 1 m³ methane is equivalent to 10 kWh or 1 litre petrol fuel.

In Germany we have built up more than 8000 biogas plants with about 100 GWh / day. Now, “Repowering” of these plants is fully on the way. Thereby, the focus lies on the residual gas potential of digester effluents to increase the efficiency of biogas plants by an additional fermenter or other technical changes. 10-20% losss of energy by too short hydraulic retention times or by unfavorable fermenter configurations, pumps or mixing systems can be often found.

Therefore, anaerobic fermentation tests are increasingly becoming compulsory, see standard test ISO / DIN 14853 and VDI guideline fermentation test 4630 (VDI = Verein Deutscher Ingenieure, 75 000 members) or the “Biogas Kalkulator” (see keyword in the internet) for individual input bio-materials of the KTBL (Kuratorium Bauwesen in der Landwirtschaft, Darmstadt, an organization and publisher being financed by the ministry of agriculture). Complex waste mixtures need always a fermentation pre-test to estimate the methane yield.

Furthermore, parallel to the so-called aerobic breathing tests, the biological inertness for safe deposition in landfills has to be tested by anaerobic fermentation tests. In such biological tests, the used microflora plays a crucial role in terms of degradation profile and rate of degradation. Otherwise lag phases and diminished gas yields are the consequence. The bacterial seed sludge should be calibrated. We do this with pure test cellulose. A proper solution relies on seed sludge from sewage digesters operated of easily accessible municipal wastewater treatment plants. Close to Bergedorf lies the wastewater treatment plant of the city Geesthacht. It’s our guarantor for highly active bacterial seed sludge.

The MilligasCounterTM was developed at the HAW Hamburg biogas station as an automatic test apparatus to perform such tests in series. The patent was given to Paul Scherer, the commercial manufacturing is now done by the Dr. Ritter company in Bochum (www.ritter.de, www.milligascounter.de).

In a unique manner we adapted the methane sensors of the company “BlueSens” (Herten, Germany) to measure online the percentage methane concentration of the extremely low gas flow during fermentation in the closed batch mini-fermenters. See publication together with Dr. Müller, the founder of the company BlueSens (Scherer et al. 2004).

Besides that high-tech equipment also quite simple "eudiometers” exist which are filled with water to measure the gas production by replacement (ISO / DIN 14853). But with Eudiometer tubes repeatedly hairline cracks in the acrylic plastic occurred. Therefore, eudiometers are permanently usable only made by glass. But the glass tubes were rejected because of the possibility of broken glass by students.

Principal Scheme of a “Biogas Station” consisting of fermenter vessels (minus or plus BlueSens methane sensors on the top), the datalogger BACCom 12B and PC (PC2).

Letzte Änderung: 26.09.17

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