Institute for Agricultural Engineering and Animal Husbandry

Freising, Germany

Institute for Agricultural Engineering and Animal Husbandry

Freising, Germany
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Tappen S.J.,Institute for Agricultural Engineering and Animal Husbandry | Aschmann V.,Institute for Agricultural Engineering and Animal Husbandry | Effenberger M.,Institute for Agricultural Engineering and Animal Husbandry
Renewable Energy | Year: 2017

The electrical efficiency, ηel, of cogeneration units (CGU) is a key factor for the profitability of electricity production from biogas. We measured the electrical efficiencies of eight biogas-driven CGUs on site over long time periods. The measurements show a decrease of ηel over engine lifetime with average rates of 0.2–0.7%1 per 10,000 operating hours. The lowest rate of electrical efficiency decline was observed for an engine which was operated under a full maintenance contract, including a guarantee of electrical power output over lifetime as well as a complete overhaul. This indicates that plant owners should critically evaluate the cost-effectiveness of their strategy for CGU maintenance. For better integration of RES into the electricity market, biogas driven CGUs can be employed to provide balancing power. Thus engines have to be adapted to varying load conditions and more frequent starts and stops. Compared to full-load conditions, measured electrical efficiencies of the CGUs were 0.9–2.5% lower at 80% load and 2.7 to 5.0 %lower at 60% load. Our measurements indicate that the development of electrical efficiency with load is dependent on engine design and settings, rather than on absolute electrical power output. © 2017 Elsevier Ltd

Lebuhn M.,Bavarian State Research Center for Agriculture | Hanreich A.,Leibniz Institute fur Agrartechnik Potsdam Bornim e.V. | Klocke M.,Leibniz Institute fur Agrartechnik Potsdam Bornim e.V. | Schluter A.,Bielefeld University | And 2 more authors.
Anaerobe | Year: 2014

Biogas production from lignocellulose-rich agricultural residues is gaining increasingly importance in sustainable energy production. Hydrolysis/acidogenesis (H/A) of lignocellulose as the initial rate-limiting step deserves particular optimization. A mixture of straw/hay was methanized applying two-phase digester systems with an initial H/A reactor and a one-stage system at different, meso- and thermophilic temperatures. H/A was intensified with increasing pH values and increasing temperature. H/A fermenters, however, were prone to switch to methanogenic systems at these conditions. Substrate turnover was accelerated in the bi-phasic process but did not reach the methanation efficiency of the single-stage digestion. There was no indication that two different cellulolytic inocula could establish in the given process.Bacterial communities were analyzed applying conventional amplicon clone sequencing targeting the hypervariable 16S rRNA gene region V6-V8 and by metagenome analyses applying direct DNA pyrosequencing without a PCR step. Corresponding results suggested that PCR did not introduce a bias but offered better phylogenetic resolution. Certain Clostridium IV and Prevotella members were most abundant in the H/A system operated at 38°C, certain Clostridium III and Lachnospiraceae bacteria in the 45°C, and certain Clostridium IV and Thermohydrogenium/Thermoanaerobacterium members in the 55°C H/A system. Clostridium III representatives, Lachnospiraceae and Thermotogae dominated in the thermophilic single-stage system, in which also a higher portion of known syntrophic acetate oxidizers was found.Specific (RT-)qPCR systems were designed and applied for the most significant and abundant populations to assess their activity in the different digestion systems. The RT-qPCR results agreed with the DNA based community profiles obtained at the different temperatures. Up to 1012 16S rRNA copiesmL-1 were determined in H/A fermenters with prevalence of rRNA of a Ruminococcaceae subgroup. Besides, Thermohydrogenium/Thermoanaerobacterium rRNA prevailed at thermophilic and Prevotellaceae rRNA at mesophilic conditions. The developed (RT)-qPCR systems can be used as biomarkers to optimize biogas production from straw/hay and possibly other lignocellulosic substrates. © 2014 Elsevier Ltd.

Krapf L.C.,Institute for Agricultural Engineering and Animal Husbandry | Heuwinkel H.,Institute for Agricultural Engineering and Animal Husbandry | Schmidhalter U.,TU Munich | Gronauer A.,University of Natural Resources and Life Sciences, Vienna
Biomass and Bioenergy | Year: 2013

This work reports the development of a near-infrared (NIR) spectroscopy online calibration for monitoring volatile solids (VS) and total volatile fatty acids (VFA) process parameters during anaerobic digestion (AD). The objective was to investigate its potential to estimate the dynamics of AD process parameters after feeding events. A recirculation loop was employed to record online measurements during an eight-month experiment using a 3.3 m3 pilot plant fed with maize silage under mesophilic conditions. Sampling was performed to conduct calibrations and subsequent test-set validations, comparing the NIR spectroscopy estimates to the reference values. The calibrated accuracy in terms of mean prediction errors (RMSEP) was 3 g kg-1 for VS and 0.9 g kg-1 for VFA in the fresh matter. By applying the calibrations to time series spectra, the model accuracy provided adequate indications of the concentration changes, including highly sensitive monitoring of short-term VFA dynamics. © 2012 Elsevier Ltd.

Krapf L.C.,Institute for Agricultural Engineering and Animal Husbandry | Nast D.,Bavarian State Research Center for Agriculture | Gronauer A.,University of Natural Resources and Life Sciences, Vienna | Schmidhalter U.,TU Munich | Heuwinkel H.,Institute for Agricultural Engineering and Animal Husbandry
Bioresource Technology | Year: 2013

A near infrared (NIR) spectroscopy online process analyser was used for in situ monitoring of anaerobic digestion of energy crops and livestock residues. Spectra were measured on a lab instrument and subjected to piecewise direct standardisation for a spectra transfer. The transfer was used in conjunction with samples for which data was recorded online for the partial least squares regression of volatile solids, ammonium, total inorganic carbon, and volatile fatty acids parameters in the fresh matter of a digester slurry. Validation was performed on independent time series spectra. The results confirmed that the procedure is robust in terms of NIR monitoring of these parameters in order to support the high potential for cross-linking different spectrometers, which may help in making this technology practical. © 2012 Elsevier Ltd.

Rath J.,German Maize Committee e.V | Heuwinkel H.,Institute for Agricultural Engineering and Animal Husbandry | Herrmann A.,University of Kiel
Bioenergy Research | Year: 2013

The expansion of biogas production in Germany has raised the question regarding a biogas maize ideotype. The aims of the present study therefore were to estimate the potential specific biogas yield (SBY) of maize from its composition and to derive recommendations for biogas maize breeding. The work was based on a 2-year, multisite field experiment which provided large genetic variations in maize forage quality. SBY was determined via a batch test. A significant interaction between site and fermentation inoculum in the first experimental year required optimization of the batch test procedure before determining the SBY of second year samples to avoid any systematic effects from the measurement method. Correlation analysis revealed significant positive effects of starch, crude fat, enzyme-soluble organic matter, and metabolizable energy on SBY. A negative correlation was found for acid detergent lignin. Since, however, SBY was not clearly determined by a single parameter, a multiple linear regression (MLR) on SBY was conducted. The results of MLR revealed that the contributing biochemical constituents were crude fat, hemicelluloses, acid detergent lignin, and water-soluble carbohydrates, with the first two characters being positively correlated with SBY and the last two showing a negative relationship to SBY. It is concluded that a biogas maize ideotype can be derived, which differs distinctly from that for ruminant nutrition and which can be achieved in different ways through the combination of various biochemical constituents. For farmers and operators of biogas plants, the regression model provides the opportunity to better characterize their substrates and to perform quality-oriented accounting. © 2013 Springer Science+Business Media New York.

Djatkov D.,University of Novi Sad | Effenberger M.,Institute for Agricultural Engineering and Animal Husbandry | Martinov M.,University of Novi Sad
Applied Energy | Year: 2014

From previous research and monitoring of agricultural biogas plants it is known that there are various possibilities and needs for improving their efficiency. However, a reliable methodological approach for this purpose was missing. Therefore, the objective of this research was to develop a method for assessing and improving the efficiency of agricultural biogas plant operation. Firstly, four performance figures for efficiency assessment and eight performance figures for efficiency improvement analysis of the technical aspect of a biogas plant operation were selected. Based on these, the method was developed by applying approaches of fuzzy logic and expert systems. Using these approaches, it was possible to handle uncertainty in the assessment data and to model expert knowledge from the field of biogas technology. The method was tested with performance data from five agricultural biogas plants with combined heat and power production, located in Bavaria. The method was verified and validated, and is proposed as a comprehensive approach for assessing and improving the efficiency of agricultural biogas plants with respect to the technical aspect. To disseminate the method among potential users such as biogas plant operators or consultants, a web application is being developed. According to changes in the state of the art of biogas technology, continuous updating and improvement of the method is needed. For further development, the method should be adapted to other types of biogas plants, and extended to environmental and socio-economic aspects of biogas plant operation. © 2014 Elsevier Ltd.

Hijazi O.,Institute for Agricultural Engineering and Animal Husbandry | Munro S.,Institute for Agricultural Engineering and Animal Husbandry | Zerhusen B.,Institute for Agricultural Engineering and Animal Husbandry | Effenberger M.,Institute for Agricultural Engineering and Animal Husbandry
Renewable and Sustainable Energy Reviews | Year: 2016

Resource strategy concerns and the need for mitigation of environmental impacts associated with energy generation from fossil fuels have increased the deployment of renewable energy carriers such as biogas. Biogas has beneficial environmental aspects such as waste treatment, production of energy from waste and general substrates and a better way to spread the fermented residues through improved nutrient and flow abilities. The objective of this study was to assess the status of biogas production and its effects on the environment due to greenhouse gases (GHG) and other environmental impacts. In this work, 15 life cycle assessment (LCA) studies of biogas systems from around Europe were reviewed. Biogas scenarios in all the studies had lower GHG intensities than their reference systems. The study shows that the type of feedstock, e.g., maize, grass or animal manure is a determining factor for the environmental impacts of biogas systems. Improving biogas plant technology and management by collecting the biogas during the storage of digested residues or installing a gas flare will improve the greenhouse gas balance of biogas systems. In comparison with traditional manure storage, anaerobic digestion of animal manure avoids methane (CH4) and nitrous oxide (N2O) emissions and adds to the substitution of artificial mineral fertilizer. Apart from the impacts resulting from the production of energy crops, acidification (AC) and eutrophication (EP) from biogas systems could be reduced by using combined heat and power units (CHPU) with catalytic converters and high efficiency. © 2015 Elsevier Ltd. All rights reserved.

Lebuhn M.,Bavarian State Research Center for Agriculture | Munk B.,Bavarian State Research Center for Agriculture | Effenberger M.,Institute for Agricultural Engineering and Animal Husbandry
Energy, Sustainability and Society | Year: 2014

Worldwide, anaerobic digestion for sanitation and utilization of the produced biogas as energy carrier have a long-standing history. Concomitantly, digested residues from biogas plants are utilized as valuable fertilizers in crop production. In Germany, guaranteed prices for electricity generated from renewable sources pushed the number of biogas plants from about 140 in 1992 to about 7,720 by the end of 2013, and the share of electricity supply from biogas close to 4.5%. In the midterm, biogas is given considerable potential to fill up the residual load from electricity generation based on wind and photovoltaic. In this review, we give an overview of the state-of-the-art of biogas technology for energy supply from agricultural inputs, based mainly on the situation in Germany. Focus is placed on the monitoring and control (M&C) of biogas plants as a means of meeting the growing demands for productivity and reliability of biogas supply. We summarize prominent factors for the stability and productivity of the anaerobic digestion (AD) process, and present latest findings about molecular biology tools, bioindicators, the ‘metabolic quotient’ and cDNA/DNA ratios for process analysis. In view of the large diversity of agricultural biogas installations, we discuss the cost-benefit ratio of M&C effort and equipment. In the light of the transformation of the energy system in Germany towards renewable sources (‘Energiewende’), we give an outlook on prospects and concepts for the future role of biogas technology in agriculture and energy supply. We also address recent misguided developments, as the sustainable development of biogas technology in agriculture can only be realized within the ecological, economical, and social boundaries of underlying agro-ecological systems. © 2014, Lebuhn et al.; licensee Springer.

Jais C.,Institute for Agricultural Engineering and Animal Husbandry | Oppermann P.,Institute for Agricultural Engineering and Animal Husbandry
Landtechnik | Year: 2012

Rubber mats are still not used in pig housings. This might mainly be caused by the insufficient durability of rubber mats in pig production observed in the past. The mats could not stand the pig's intensive examination. The non-perforated rubber mats used in this study were specially developed for the use in pig housings. They were fitted with a special surface that could resist against the animal's bites. 24 months after having been introduced to pens of pregnant sows these mats still showed a very high durability. The lying area fitted with non-perforated rubber mats, activity area and animals were clearly dirtier than floor and animals in the pen with slatted floor in the lying area. Negative effects on the cleanness of mat surfaces and in consequence of pens and animals must be counteracted by a slope of about 2-4 % of the floor beneath the mats.

Munk B.,Institute for Agricultural Engineering and Animal Husbandry | Bauer C.,Institute for Agricultural Engineering and Animal Husbandry | Gronauer A.,Institute for Agricultural Engineering and Animal Husbandry | Lebuhn M.,Institute for Agricultural Engineering and Animal Husbandry
Engineering in Life Sciences | Year: 2010

Limitations in the supply of essential trace elements for methanogenic Archaea can arise in biogas production from renewable resources in flow-through systems particularly when no manure is added. Without compensating supplementation, primarily Co and Na + can become limiting in long-term mono-digestion of maize silage at threshold values of ca. 0.03 and 10 mg/L, respectively. These deficiencies apparently triggered process acidification. Using molecular biological methods (PCR-SSCP and quantitative real-time PCR), microbial population dynamics were monitored qualitatively and quantitatively at distinct stages during the experiments, investigating mcrA/mrtA, coding for a subunit of the key enzyme of methanogenesis. An exponential correlation between mcrA/mrtA copies and methane productivity was obtained. Members of obligatley acetoclastic Methanosaetaceae were found only at low acetate concentrations (below 1 g/L). At organic loading rates>1 g volatile solids/(L×d) and without acidification symptoms, obligately hydrogenotrophic (oh) Methanobacteriales and versatile Methanosarcinaceae were dominating, and an abundance of up to 10 10 methanogens per mL fermenter content was determined. In the acidified process, however, ca. 4 orders of magnitude less methanogens were detected, and Methanomicrobiales (oh), more specifically Methanospirillum hungatei or Methanoculleus spp., were dominating. Species diversity at the DNA level was highest at efficient process performance without stress symptoms and at a relatively low organic loading rate (1-2 g volatile solids/(L×d)). According to the quantitative real-time PCR data, the process was not sustained below an availability of 10 -8 to 10 -9 μg Co per methanogenic cell. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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