Browsing by Subject "Methane"

Now showing 1 - 7 of 7
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    Biogenic Greenhouse Gas Emissions from Agriculture in Europe - Quantification and Mitigation
    (2002) Freibauer, Annette; Zeddies, Jürgen
    This dissertation analyses relevant potential mitigation strategies of biogenic greenhouse gases (GHGs) in the agriculture of the European Union (EU) in light of the Kyoto Protocol. It identifies where important sources and mitigation potentials are located and what uncertainty, environmental ancillary effects and costs are associated with them. Literature reviews are performed and methodologies for environmental assessment and GHG accounting are further developed. On this basis, GHG emissions are quantified and reduction potentials are assessed at European level. In 1995, European agriculture emitted 0.84 ± 0.29 Tg N2O, 8.1 ± 1.9 Tg methane (CH4) and 39 Tg ± 25 carbon dioxide (CO2), which adds up to 470 ± 80 Tg CO2-equivalents or 11% of the overall anthropogenic greenhouse gas emissions of the EU. The detailed methodology developed here adequately resolves regional specifics of agricultural conditions and reduces the methodological uncertainty in the estimates to half of the one in the official national inventories. European agricultural soils will at maximum sequester carbon in the order of 100 Tg a-1 CO2 over the coming years, which may also provide other environmental benefits. The biological potential of bioenergy in the EU allows to substitute for 400 to 800 Tg a-1 CO2-equivalents. From an environmental perspective, the use of perennials, especially of residues and woody biomass, is preferable to intensively grown annual crops. The biological potential for technical GHG reduction measures in EU agriculture is between 100 and 200 Tg a-1 CO2-equivalents. Promising measures promote the extensivation of arable cropping by reducing nitrogen inputs, technological innovation in animal husbandry, which is best accompanied by a further decline in animal numbers, as well as rewetting drained organic soils. Most measures will provide ancillary environmental benefits. Changing the socio-economic and political frame conditions may enhance the GHG mitigation potential.
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    Development and evaluation of methods for assessing the efficiency of biogas plants
    (2022) Hülsemann, Benedikt Werner; Müller, Joachim
    Biogas is a renewable energy source with main advantages compared to other renewable energy sources. The advantages include the use of organic waste as a substrate, local power and heat production, rural job creation, the possibility of a flexible gas production and a product which can easily stored and transported in a gas grid or on the roof of a digester. However, the development of the biogas sector is highly dependent on the costs of producing gas, electricity and heat. The production costs are higher than the costs for other energy sources. Growth of the biogas sector is therefore only possible if there is political promotion for biogas as there was in Germany through the EEG. Nowadays, due to the reduction of bonus payments in the EEG 2017 and EEG 2021 in Germany as well as the lack of policy promotion in several other countries, lower production costs based on a higher efficiency are essential to help the biogas sector grow further. In order to achieve higher efficiency and to tap the full potential of biogas, the efficiency has to be determined, which is done in this thesis. The input methane potential is determined using 6 different methods. These methods are compared on the basis of an investigation of 33 German agricultural BPs as well as one German and one US BP using food waste as feedstock. The four methods based on the batch test show a high sensitivity. Unfortunately, they also show efficiencies greater than 100% for most BPs, clearly indicating an underestimation of the degradable potential. Only for the US BP can an efficiency less than 70% be reported. This result is probably based on the lack of heating system corresponding to the lack of promotion of heat recovery in the US. The CE according to the BMP method also reveals an average efficiency of 95% for the German BPs. The values of the two gross calorific value-based methods show efficiencies below 100%, but with low sensitivity. The results of these methods can be used to determine the further potential of a bioeconomic process and to compare the biogas process with other industrial processes. There are several impact factors that affect the accuracy of the efficiency measurements. The installed meters are not frequently calibrated at most BPs. Also, some meters are almost completely missing, as only few BPs in Germany have a gas flow meter. Thus, assumptions and calculations are required to determine the efficiency. In the developed method, the gas flow must be calculated from the amount of the power production, the calorific value, the gas quality, the CHP unit efficiency and the conversion loss at the transformer. The last two values must be assumed, even if the database is small. Another important parameter is the feeding mass. It is measured by the German BPs, but in some cases, the data quality is low. For example, different crops are mixed in the silos and measurement of each substrate is not possible. This leads to measurement errors shown by the organic dry matter mass balance, which has a residual value of up to 24%, while only 11% can be occur based on water incorporation into the ODM. Another factor having an impact is the sampling. The results of a monthly sampling throughout the year show a fluctuation in the DM/ODM values. To investigate the accuracy of the methods used to determine the SMP of the substrate, the biochemical methane potential test is examined in detail. The BMP consists of the used inoculum, the substrate, the digestion system and the calculation. The impact of the used inoculum and the digestion system is investigated by using different inocula in one digestion system as well as by using the same inoculum in multiple digestion systems. The inocula used in this thesis are well-known and have been used in interlaboratory tests for several years. Thus, outliners were excluded. A CV of 4.8% can be reported between the different inocula, which is lower than reported in most other publications before. The use of different digestion systems shows a higher CV of up to 12.8%. For the inoculum and the digestion system, the deviation varies strongly and no clear correlation can be identified. Therefore, a correction of this effect is not possible. The biological yield efficiency of 21 of the investigated BPs is in the range of 100 ± 12.8%. This reveals the need of stricter rules for the digestion system. All digestion systems used in this thesis are described in the German guideline VDI 4630. The calculations were also done according to the German guideline VDI 4630. An influence can be neglected. However, if the results of a measurement with already dried gas are compared with the results of a calculation according to VDI 4630, which is based on the measurement with wet gas, a discrepancy can be found. Although, the CV using only one digestion system and one inoculum is only 1-7%. A comparison of the efficiency of different BPs by using the same inoculum and digestion system is hence recommended.
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    Effects of monensin and tannin extract supplementation on methane production and other criteria of rumen fermentation in vitro and in long-term studies with sheep
    (2013) Wischer, Gerald; Rodehutscord, Markus
    Ruminants increasingly attract public concern due to their methane release and contribution to the greenhouse effect. One strategy to reduce the release of methane is to modify microbial fermentation in the rumen by the use of feed additives such as monensin and tannin extracts. However, other characteristics of fermentation including the synthesis of microbial protein may also be affected. The aim of the present studies was to provide a comprehensive evaluation of the effects of monensin and tannin extracts on ruminal fermentation and methane production. The ionophore monensin is known to increase feed efficiency in ruminants. Although the use of silages is common practice in cattle feeding, the effects of monensin on the fermentation of silages in the rumen and microbial protein synthesis are lacking. Monensin has often been described to have indirect effects on methane production resulting from its effects on feed intake, protozoa and Gram-positive bacteria. It has rarely been studied whether monensin can reduce methane production without adverse effects on other criteria of rumen fermentation. The first objective therefore was to investigate the effects of different dosages of monensin on methane production and microbial protein synthesis when supplemented to different silages in two in vitro systems (Study 1). In Experiment 1 of Study 1, 15 g of oven-dried grass silage alone or combined with a concentrate was incubated in a rumen simulation (Rusitec) over a period of 13 d to examine the effects of monensin supplementation (2 or 4 mg/d, n = 4) on the production of total gas, methane, volatile fatty acids (VFA), degradation of nutrients and microbial protein synthesis. In Experiment 2 of Study 1, different dosages of monensin (0.5, 1, 2, 6 and 10 µg) were supplemented to syringes containing 120 mg of grass silage alone, grass silage combined with concentrates, or maize silage alone. After 24 h of incubation the effects of monensin on total gas, methane and VFA production were determined. In Experiment 1 monensin inclusion to grass silage and grass silage combined with concentrate resulted in a decreased total gas, methane and acetate production, while propionate production was increased. Along with a decreased degradation of crude protein, ammonia concentration in the system was reduced. While microbial protein originating from solid associated microbes decreased with monensin inclusion, microbial protein from liquid associated microbes was increased, resulting in an increase in total microbial protein synthesis. In Experiment 2, different dosages of monensin reduced methane production in grass silage (17%), grass silage combined with concentrate (10%) and maize silage (13%) without adverse effects on total gas production. Based on these two in vitro experiments it was concluded that monensin is able to reduce methane production without a major decrease in total gas and VFA production and degradation of organic matter. Although microbial fractions were differently affected, the total microbial protein synthesis was increased upon monensin supplementation. Tannins are secondary plant compounds that are known to complex with feed and microbial proteins. Several products from this heterogeneous group have shown potential to affect rumen fermentation in vivo and, even more, in vitro, but are often accompanied by negative effects on digestibility, feed intake and microbial protein synthesis. In Study 2 of the present work, ten tannin extracts (chestnut, mimosa, myrabolan, quebracho, sumach, tara, valonea, oak, cocoa and grape seed) and four monomers of rapeseed tannin (pelargonidin, catechin, cyanidin and sinapinic acid) were screened in grass silage based diets in successive runs using the Hohenheim Gas Test. The objective was to determine the optimal dosage of each tannin extract to cause a maximal methane reduction without negative effects on total gas production. Whereas the supplementation of pelargonidin and cyanidin to grass silage did not reduce methane production; catechin and sinapinic acid reduced methane production without affecting total gas production. Except tara extract, all tannin extracts reduced methane production by 8 to 28% without adverse effects on total gas production. Based on these results, chestnut, grape seed, myrabolan, sumach and valonea extract were investigated in a second step in a Rusitec to determine their effects on degradation of nutrients, VFA and ammonia production, and particularly on microbial protein synthesis. All tannin extracts were supplemented at similar dosages of 1.5 g to 15 g of grass silage. The supplementation of chestnut resulted in the greatest decrease in methane production (63%), followed by valonea (35%), grape seed (23%), sumach (18%), and myrabolan (7%; not significantly different from the control). While chestnut extract reduced acetate production by 19%, supplementation with grape seed or myrabolan extract increased acetate production; however, degradation of fibre fractions was reduced in all tannin treatments. Degradation of dry and organic matter was reduced by all tannin extracts, but there were no differences between tannin treatments. Crude protein degradation and ammonia production were also reduced by tannin extract supplementation. Microbial protein synthesis and its efficiency were not affected by tannin supplementation, which indicates that a reduction in methane production due to tannin extract supplementation is possible without negatively affecting microbial protein synthesis. Chestnut and valonea extract had the greatest potential in reducing methane production without negative effects on rumen fermentation of grass silage and microbial protein synthesis. Therefore, these tannin extracts were investigated for their long-term effects in sheep (Study 3). In Experiment 1 of Study 3, sheep receiving the control, chestnut or valonea treatment (each n = 4) were fed 842 g/d of hay (fresh weight). The animals on the control treatment also received 464 g/d of concentrate, and animals on the tannin treatments received the same amount of concentrate but were also fed 20 g of the respective tannin extract. Following initiation of tannin feeding, methane release from sheep was measured in 23.5 h intervals in respiration chambers on day 1, 8, 15, 29, 57, 85, 113, 148, and 190. In three balances periods faeces and urine were collected for 6 and 3 days, respectively. Effects on nutrient digestibility, nitrogen and energy metabolism were evaluated, with microbial protein synthesis estimated from the urinary excretion of purine derivatives. Based on the results of Experiment 1, a second experiment was conducted four month after the start of Experiment 1. Experiment 2 had the same study design and data collected, but the dosage of tannin extracts was doubled compared to Experiment 1 (0.9 vs. 1.7 g tannin extract/kg body weight) and the duration was shorter (85 days). Hay and concentrates used in both experiments were also evaluated using the Hohenheim Gas for their effects on total gas and methane production. In both experiments, methane release was not significantly reduced by tannin extract supplementation when analysed over the whole experimental period. In Experiment 1 the supplementation of chestnut extract on day 190 resulted in a reduced methane release. In both experiments, on day 1 a numeric reduction in methane release for the tannin treatments was observed, with a greater reduction recorded for the higher dosage used in Experiment 2. This trend disappeared by day 57. In the third balance period of Experiment 1, digestibility of dry and organic matter was reduced by tannin supplementation. The digestibility of crude protein was reduced in both experiments, whereas the digestibility of fibre fractions was not influenced. In both experiments a long-lasting shift in nitrogen excretion from urine to faeces was observed, which occurred to a greater extent in Experiment 2. The urinary excretion of purine derivatives was not significantly affected by tannin supplementation, indicating that the microbial protein synthesis was not altered in either experiment. The in vitro methane production was reduced for concentrates containing tannin extracts, but it was not significantly affected when concentrates were incubated with hay. It is concluded that monensin added to different silages caused a decrease in methane production without affecting total gas production but with an increased microbial protein synthesis. Nine of the ten considered tannin extracts and two tannin monomers decreased methane production without affecting total gas production. The Rusitec study confirmed the great potential of chestnut and valonea extract to reduce methane production without negative effects on microbial protein synthesis. However, neither chestnut nor valonea extract reduced the methane release in sheep when fed over a longer period of time. It is assumed, that rumen microbes adapted to the tannin dosages in terms of methane release but not nitrogen metabolism, as there were long-lasting effects on nitrogen excretion. The shift in nitrogen excretion can have a positive effect on the environment due to the reduced potential of ammonia emission from the urine. Both in vitro systems used in the present studies showed effects of tannin extracts that were considerably different from those observed in sheep. The monomers investigated in the present study are the basic units of condensed tannins, whereas the tannin extracts selected in vitro only contain hydrolysable tannins. It is possible that monomers of chestnut and valonea extract may reduce methane production, whereas higher dosages of these tannin extracts cause negative effects on feed intake, digestibility and microbial protein synthesis. Further investigations should focus systematically on the transfer of in vitro studies to estimate in vivo responses. Therefore, a parallel implementation of different in vitro and respiration studies would be of great value.
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    Mono-digestion of 5-Hydroxymethylfurfural process-wastewater in continuously operated anaerobic filters: A cascade utilization approach
    (2023) Khan, Muhammad Tahir; Krümpel, Johannes; Wüst, Dominik; Lemmer, Andreas
    A proper remedy for the overexploitation of biomass and biobased materials in the bioeconomy is the valorization of biorefineries’ side streams into meaningful products. Hence, in pursuit of a cascade utilization of renewables, a unique biorefinery byproduct was investigated for its biogas potential, specifically methane, in continuously operated anaerobic filters. For this purpose, 5-Hydroxymethylfurfural process-wastewater, after supplementation of necessary nutrients, was diluted down to 10, 20, 30, 40, and 50 gCOD/L concentrations and thereafter tested individually at 43 °C and 55 °C. Maximum methane conversion efficiency at either temperature was observed for test substrates with 10 gCOD/L and 20 gCOD/L concentrations. At 43 °C, the anaerobic filters exhibited their highest biogas yields when supplied with the 30 gCOD/L feedstock. Further exposure of the mesophilic and thermophilic consortia to the ensuing 5-Hydroxymethylfurfural process-wastewater dilutions compromised the stability of the anaerobic process due to the soaring concentrations of short-chained volatile fatty acids. The supplementation of necessary nutrients to unlock the methane potential of the given recalcitrant substrate appears insufficient. Techniques like micro aeration, photolysis, or the use of activated carbon in the fixed bed might have the ability to enhance the biochemical methane conversion of such feedstock; otherwise, the introduction of trace elements alone may be adequate if aiming for platforms (volatile fatty acids) via anaerobic technologies.
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    Production of lactic acid and methane from renewable resources : an innovative green biorefinery concept for biogas process chains
    (2015) Haag, Nicola Leonard; Jungbluth, Thomas
    The increasing demands of world’s growing population for food, energy and products, the effects of climate change and the depletion of fossil resources forces the development of sustainable industries. Based on renewable resources, state-of-the-art processes have to be transformed to eco-friendly production sequences to lead the industry to a new, bio-based economy. An essential part of the bio-based economy will be biorefineries, as they enable the production of goods and energy from bio-based resources. The aim of this study was to establish an innovative green biorefinery concept to optimize biogas process chains. The green biorefinery concept was set up to both utilize and add value to green biomass, as well as other common raw substrates used in biogas processing, by producing platform chemicals and biogas. New ensiling techniques were applied, in order to increase the amount of valuable ingredients in the silage with a special focus on lactic acid. After solid-liquid separation of the silage to exploit organic acids, the solid residue was used for anaerobic digestion. In particular the objectives were: (1) to clarify which valuable chemicals can be increased in significant amounts, depending on the raw substrate, (2) to examine the technical, chemical and biological parameters affecting the increase of valuable products in the silage and (3) to investigate the methane formation potential of the residual biomass and the fresh silage to identify potential methane losses. Lactic acid was the most promising chemical, increased to highest amounts during the ensiling process. The addition of carbonated lime was the most effective treatment to increase the amount of lactic acid, requiring a high fermentability coefficient of the utilized raw substrate. Additional lactic acid producing bacteria can help to stabilize the silage and promote the growth of lactic acid contents. Supplying the lactic acid bacteria with additional trace elements (manganese) showed no effect on lactic acid production. The comparison of specific methane yields of the fresh silages with the corresponding solid residues always yielded higher values for the fresh silage (not always significant), due to the loss of volatile solids during the fractionating. Furthermore, there is a loss of overall methane production, due to the reduction of mass while fractionating. An initial economic assessment revealed that selected variations of the treated raw substrates maize and grass offer a huge potential for the presented biorefinery concept, as the increase in lactic acid contents was immense while simultaneously having no significant losses in specific methane yields. Crucial importance for the economic feasibility lies on the downstream process of lactic acid. Future research has to be focused on establishing adequate extraction techniques, as the extraction and purity of lactic acid is the primary challenge for the economic viability of the concept. In the context of adding value to existing biogas process chains, the presented green biorefinery concept is an alternative conversion path of biomass and will likely be of monetary interest in the near future. Moreover, the improved silages can be beneficial in other applications, such as the production of middle chain fatty acids for further processing. The presented biorefinery concept is of high value for numerous applications and shows an improved method of green biorefining, which can contribute to leading our society and industry to a sustainable and multifaceted future.
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    Real-time in situ measurements of trace gases from agriculturally cultivated soils by means of laser spectroscopic techniques
    (2008) Hillebrand, Malte; Haas, Ulrich
    Two devices to study the exchange of climate relevant trace gases between arable cultivated soils and the atmosphere in the North China Plain are presented in this thesis. They are based on Tunable Diode Laser Photoacoustic Spectroscopy (TDL-PAS). These devices are capable of real-time in situ detection of trace gases. For methane a detection limit of 85 ppb and for ammonia of 111 ppb was achieved, respectively. For the field campaign at the experimental field Dongbeiwang (DBW) in Beijing it was necessary to optimize the instruments due to the harsh conditions in China, e.g. high variation in temperature, high humidity and particulate matter emissions. This included accurate thermally stabilization of the system as well as long-term stability of the laser diode and the possibility of unattended operation over a period of several days. These prerequisites were fulfilled and evaluated in Germany before the devices were brought to China for the field campaign in the years 2006 and 2007. Additionally, mobile closed chambers for the trace gas exchange measurements were designed in Germany. They consisted of two parts: One frame installed permanently in the soil, therein agricultural crops could be planted, and a hood placed on it during the measurement and removed afterwards again. Altogether seven frames made from stainless steel were constructed by a company located in Beijing. Three hoods of different heights (250, 500 and 1000 mm) were made from 8 mm colorless Plexiglas and were built by a German company. The innovation of this design was the possibility to insert up to eight cooling packs that cooled down the enclosed air in the chambers by mixing it via two fans. By comparing measurements with and without applying cooling packs it was shown that the temperature difference between both situations was increasing up to 10 K. According to ambient air temperature measurements the test also showed that by applying cooling packs the temperature of the enclosed air could be adapted close to ambient conditions. After installation of the closed chambers in DBW a test checking the gas tightness had to be performed. With this test leakages of the frames, hoods and tubes should be discovered. This was done by injection of 2 ml ethane into the closed chambers and studying the concentration decrease within one hour of closure time. For this test the permanently installed gas chromatograph in the measurement container in DBW was used, connected by Teflon tubes to the closed chambers. All closed chambers showed leakages lower than 10% and therefore could be considered as tight. For methane measurements the chambers were operated in the dynamic mode, so the air inside of the chamber was circulated through the TDL-PA system and pumped back into the chamber. The increase or decrease in methane concentration with time was determined and flux rates were calculated. The obtained data confirmed that the soil in DBW, a Calcaric Cambisol according to FAO classification, could be considered as a methane sink. The exchange rate ranged from ?0.17 to ?3.33 mg CH4-C m-² d-¹ for winter wheat and from ?0.68 to ?2.07 mg CH4-C m-²; d-¹ for bare soil. For summer maize the exchange rate was slightly lower and ranged from ?0.51 to ?1.0 mg CH4-C m-² d-¹ and from ?0.53 to ?1.14 mg CH4-C m-² d-¹ for the control plot. Due to the fact that elevated methane concentrations at daybreak were detected during the exchange measurements at the plots planted with winter wheat as well as at the control plot a diurnal variation in methane concentration was assumed. To verify and quantify this diurnal variation in methane concentration at DBW, one plot was selected for a 24 hour measurement campaign. During this measurement campaign ambient air methane concentrations of up to 22 ppm were observed during nighttime, which was elevenfold the normal concentration. Because the previous exchange measurements revealed that methane was not emitted by the soil it must originated from somewhere else. After the 24 hour measurement campaign the ambient air methane concentrations in DBW as well as at other places in the vicinity of DBW were studied to detect the source of the methane emissions. For that purpose an ultrasonic anemometer for wind direction and wind speed measurement was combined with the TDL-PA system. A diurnal variation with maximum methane concentrations of about 40 ppm during nighttime and early morning and minimum concentrations of about 1.4 ppm during the afternoon were detected in DBW. Research conducted at the campus of the CAU, 3.2 km south of DBW, showed a similar pattern. These results confirmed the urban heat island effect where stable atmospheric layering dominates during the night and a mixing layer dominates during daytime. According to literature the height of this atmospheric boundary layer in Beijing in autumn was of 1 km thickness during daytime and of 200 ? 400 m during nighttime. Moreover the high methane concentrations in the night verified the assumption of a methane emission source in the vicinity of DBW and the CAU. The search for a potential emission source revealed a landfill approximately 6 km north-west of the CAU as well as 5.5 km west of DBW. Measurements conducted at the landfill site itself showed a diurnal methane emission pattern as well, with maximum concentrations up to 450 ppm during nighttime and minimum concentrations of about 10 ppm during daytime.
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    Untersuchungen zum Emissionsgeschehen von Ammoniak und Methan in der Mastschweinehaltung
    (2017) Gronow-Schubert, Stephanie; Gallmann, Eva
    The growing of feed crops, the production of farm livestock and the processing of livestock products, along with the associated use of farmland for this entire production chain, all engender greenhouse gases on a worldwide scale. In this respect, ammonia and methane emissions are directly associated with livestock farming including the feeding of pigs for slaughter. The main aim of the work presented in this thesis was investigation of emissions produced in this way, and into selected strategies applied for reducing ammonia and methane release, particularly in management of liquid manure inside a fattening unit. In this context, the paper focusses on the three approaches – measuring, analysing and modelling - which are accordingly established as the following part-targets: • Applying emission reduction strategies as part of liquid manure management in a conventional fattening unit and comparing the resultant emissions with those from a reference system where no emission reduction actions had been taken. The selected emission reduction strategies should be practicable and sustainably applicable in existing livestock housing systems. • Analysing the main factors of influence on emissions throughout the fattening period during different seasons of the year, with special consideration of time series effects and regressions. • Examining the possibilities of substance flow modelling, application to own measurement data rather or for assessing the potential of emission reduction methods as well as evaluation of the selected approach for substance flow modelling. In-barn liquid manure management with fattening pigs markedly influences ammonia and methane emissions whereby the concrete reduction potentials are not yet sufficiently clarified. Within this study, a first work package compares, through a case control approach, the liquid manure management strategies - weekly emptying of the liquid manure channel as well as covering of the underfloor stored liquid manure surface as well as the addition of Effective Microorganisms to the liquid manure – with the strategies tested for emission reduction potential and compared over a feeding cycle in each case with the stored manure method as reference. The pig housing used in the trial was divided into two compartments (experimental and reference compartment) each holding 50 animals. In quasi-continuous measurement, incoming air, compartment and exhaust air ammonia and methane concentrations, temperatures of incoming air, compartment and exhaust air, and the temperature and pH of the liquid manure, were all recorded. Additionally, liquid manure samples were analysed in 14-day rhythm and the level of liquid manure measured as well as the degree of dirtiness of pen floors. Also recorded were pig weights and performance or feeding data. No further differences in terms of feeding, ventilation or management existed between trial and reference compartments. The applied reduction strategies were able to partially reduce ammonia and methane emissions (weekly emptying of liquid manure channel: methane emission rates reduced by 39 % based on emission rate in grams per day and livestock unit; liquid manure cover: 13.8 % ammonia emission rates reduction in grams per day and livestock unit), had in part no effect, or even a negative influence on the emissions (weekly emptying of the liquid manure channel: no effect on ammonia emissions; liquid manure cover: 119.9 % rise in methane emission rates in terms of grams per day and livestock unit). The selected interval of one week between emptying the liquid manure channel was not sufficient as a reduction strategy. With covering of the liquid manure surface underfloor, it is important to consider that the almost airtight sealing of the liquid manure surface delivered favourable conditions for methanogenesis. The influence of the addition of Effective Microorganisms to the liquid manure on the emissions of ammonia and methane was marginal. The emissions of ammonia increased of 8.3 % and the emissions of methane of 5.9 %. The evaluations (time series and regression analyses) of the data from the reference compartments from a total of four feeding cycles (two summer and two winter cycles) comprised the second work package. The time series analysis enabled insight into the relationships between the ammonia and methane emissions in terms of time, and insights into the influential factors affecting release and transport of the gases. For example, the time-related influences of high temperatures on the system “fattening unit” and on the release of emissions, could be graphically shown. The time series analysis gave indications as to how dynamic, or how stable, climatic conditions can be in pig housing. The regression analyses clearly showed that the emission process, with ammonia as well as with methane, is influenced particularly through the amount of liquid manure involved, the temperature and the air volume flow. In the same way, the distance between the liquid manure surface and the slatted flooring (‘headspace’) was found to have direct influence on the release of ammonia and methane from the liquid manure. A larger ‘headspace‘ correlated with reduced emissions and vice versa. Following recording and statistical evaluation of the emission data, the contribution that can be made through substance flow modelling of ammonia emissions towards increasing knowledge on the emission process and on methods for its reduction within pig housing was examined as a third work package. This involved the transfer of selected recorded data into the substance flow model. Serving as basis was the model from CORTUS et al. (2010a) adapted in three steps to take account of the conditions in the pig housing being used. The constructional outline of the trial livestock housing served as system limit. Berkeley Madonna 8.3.18 software was used for numerical integration of the differential equation system. Own data was applied for calibration and validation, in each case taken from the reference compartment of two different feeding cycles. In principle, the adapted model was capable of modelling ammonia concentrations and emissions. In addition, the influence of the liquid manure temperature and pH value of the liquid manure could be depicted. However, the model generally reacted sensitively to temperature and pH values. Because of this, the model underestimated and overestimated recorded values, in part substantially. An important influence on the model accuracy appeared to be related to the submodel considering urine puddles. For the purposes of own modelling, this submodel was cut out of the main model during its adaptation according to the recorded data. Compared to recordings, modelling of gas concentrations and emissions offers the advantage of cost-efficient and time-saving estimations of emission potential for different housing systems, e.g. for feeding pig production. Calibration and validation, as well as adaptation to suit the type of application requires, however, particular care and expertise. Through the various methods for measurement, analysis and modelling that were applied, the work reported here contributes to better understanding of the emission process and the reduction of emissions, particularly in the case of liquid manure management in feeding pig production.