GIS-basierte Analyse von Nachnutzungsstrategien für Biogasanlagen zur Erzeugung von grünem Wasserstoff in Niedersachsen

Für über ein Drittel der niedersächsischen Biogasanlagen läuft in den nächsten fünf Jahren die Förderung nach dem Erneuerbare-Energien-Gesetz aus. Damit droht einem Großteil dieser Anlagen aus ökonomischen Gründen die Stilllegung. Ziel dieser Arbeit ist die Entwicklung einer Nachnutzungsstrategie für diese Biogasanlagen zur Erzeugung von Wasserstoff und Methan aus erneuerbaren Energien. In einem ersten Schritt wird diese Nachnutzungsstrategie im Rahmen einer Fallstudie anhand zweier Biogasanlagen erarbeitet. In einem zweiten Schritt werden die Ergebnisse der Fallstudie abgeleitet, um die Nachnutzungsstragie auf sämtliche niedersächsischen Biogasanlagen zu übertragen und das Methanisierungspotenzial für ganz Niedersachsen zu ermitteln. Methodisch wird dazu die Biogasanlage um eine Power-to-Gas-Prozesskette zur Erzeugung und Einspeisung von grünem Wasserstoff und Methan erweitert und anhand des CO2-Volumenstroms der Biogasanlage ausgelegt. Als wichtige Voraussetzung für die Wirtschaftlichkeit gilt die Verfügbarkeit von erneuerbaren Energien, weshalb neben einer Wirtschaftlichkeitsberechnung eine GIS-basierte Analyse zur Identifizierung von Potenzialflächen für Windenergie- und Freiflächen-Photovoltaikanlagen durchgeführt wird. Auf Grundlage eines Biogasanlagen-Katasters und einer landesweiten Potenzialflächenanalyse wird mit Hilfe eines GIS das Methanisierungspotenzial für ganz Niedersachsen berechnet. Synergien bei der Kopplung von Biogasanlagen mit einer biologischen ex-situ Methanisierung (Power-to-Gas-Anlage) hinsichtlich der Prozessführung und -technik sowie wirtschaftlicher Parameter konnten im Rahmen der Auslegung aufgezeigt werden. Trotz der Verfügbarkeit günstigen erneuerbaren Stroms ist die Power-to-Gas-Anlage nur unter gewissen regulatorischen Voraussetzungen wirtschaftlich zu betreiben. Durch die niedersachsenweite Analyse aller Biogasanlagen ab einer Größe von 250 kW konnte aufgezeigt werden, dass weder die Distanz zu dem Gasnetz noch die Verfügbarkeit von Potenzialflächen für erneuerbare Energien einen limitierenden Faktor für die Methanisierung darstellen. Daraus ergibt sich ein signifikantes Potenzial der dezentralen Methanisierung in Niedersachsen durch die Kopplung mit Biogasanlagen von ca. 1.397 Mio. Kubikmeter Methan jährlich

Anaerobic ammonium-oxidising bacteria: A biological source of the bacteriohopanetetrol stereoisomer in marine sediments

Bacterially-derived bacteriohopanepolyols (BHPs) are abundant, well preserved lipids in modern and paleo-environments. Bacteriohopanetetrol (BHT) is a ubiquitously produced BHP while its less common stereoisomer (BHT isomer) has previously been associated with anoxic environments; however, its biological source remained unknown. We investigated the occurrence of BHPs in Golfo Dulce, an anoxic marine fjord-like enclosure located in Costa Rica. The distribution of BHT isomer in four sediment cores and a surface sediment transect closely followed the distribution of ladderane fatty acids, unique biomarkers for bacteria performing anaerobic ammonium oxidation (anammox). This suggests that BHT isomer and ladderane lipids likely shared the same biological source in Golfo Dulce. This was supported by examining the BHP lipid compositions of two enrichment cultures of a marine anammox species ('. Candidatus Scalindua profunda'), which were found to contain both BHT and BHT isomer. Remarkably, the BHT isomer was present in higher relative abundance than BHT. However, a non-marine anammox enrichment contained only BHT, which explains the infrequence of BHT isomer observations in terrestrial settings, and indicates that marine anammox bacteria are likely responsible for at least part of the environmentally-observed marine BHT isomer occurrences. Given the substantially greater residence time of BHPs in sediments, compared to ladderanes, BHT isomer is a potential biomarker for past anammox activity

Microbial diversity in waters, sediments and microbial mats evaluated using fatty acid-based methods

The review summarises recent advances towards a greater comprehensive assessment of microbial diversity in aquatic environments using the fatty acid methyl esters and phospholipid fatty acids approaches. These methods are commonly used in microbial ecology because they do not require the culturing of micro-organisms, are quantitative and reproducible and provide valuable information regarding the structure of entire microbial communities. Because some fatty acids are associated with taxonomic and functional groups of micro-organisms, they allow particular groups of micro-organisms to be distinguished. The integration of fatty acid-based methods with stable isotopes, RNA and DNA analyses enhances our knowledge of the role of micro-organisms in global nutrient cycles, functional activity and phylogenetic lineages within microbial communities. Additionally, the analysis of fatty acid profiles enables the shifts in the microbial diversity in pristine and contaminated environments to be monitored. The main objective of this review is to present the use of lipid-based approaches for the characterisation of microbial communities in water columns, sediments and biomats

Biomarkers in the stratified water column of the Landsort Deep (Baltic Sea)

The water column of the Landsort Deep, central Baltic Sea, is stratified into an oxic, suboxic, and anoxic zone. This stratification controls the distributions of individual microbial communities and biogeochemical processes. In summer 2011, particulate organic matter was filtered from these zones using an in situ pump. Lipid biomarkers were extracted from the filters to establish water-column profiles of individual hydrocarbons, alcohols, phospholipid fatty acids, and bacteriohopanepolyols (BHPs). As a reference, a cyanobacterial bloom sampled in summer 2012 in the central Baltic Sea Gotland Deep was analyzed for BHPs. The biomarker data from the surface layer of the oxic zone showed major inputs from cyanobacteria, dinoflagellates, and ciliates, while the underlying cold winter water layer was characterized by a low diversity and abundance of organisms, with copepods as a major group. The suboxic zone supported bacterivorous ciliates, type I aerobic methanotrophic bacteria, sulfate-reducing bacteria, and, most likely, methanogenic archaea. In the anoxic zone, sulfate reducers and archaea were the dominating microorganisms as indicated by the presence of distinctive branched fatty acids: archaeol and pentamethylicosane (PMI) derivatives, respectively. Our study of in situ biomarkers in the Landsort Deep thus provided an integrated insight into the distribution of relevant compounds and describes useful tracers to reconstruct stratified water columns in the geological record.Open Access Publikationsfonds 201

Bacteriohopanepolyols record stratification, nitrogen fixation and other biogeochemical perturbations in Holocene sediments of the central Baltic Sea

The Baltic Sea, one of the world's largest brackish-marine basins, established after deglaciation of Scandinavia about 17 000 to 15 000 yr ago. In the changeable history of the Baltic Sea, the initial freshwater system was connected to the North Sea about 8000 yr ago and the modern brackish-marine setting (Littorina Sea) was established. Today, a relatively stable stratification has developed in the water column of the deep basins due to salinity differences. Stratification is only occasionally interrupted by mixing events, and it controls nutrient availability and growth of specifically adapted microorganisms and algae. We studied bacteriohopanepolyols (BHPs), lipids of specific bacterial groups, in a sediment core from the central Baltic Sea (Gotland Deep) and found considerable differences between the distinct stages of the Baltic Sea's history. Some individual BHP structures indicate contributions from as yet unknown redoxcline-specific bacteria (bacteriohopanetetrol isomer), methanotrophic bacteria (35-aminobacteriohopanetetrol), cyanobacteria (bacteriohopanetetrol cyclitol ether isomer) and from soil bacteria (adenosylhopane) through allochthonous input after the Littorina transgression, whereas the origin of other BHPs in the core has still to be identified. Notably high BHP abundances were observed in the deposits of the brackish-marine Littorina phase, particularly in laminated sediment layers. Because these sediments record periods of stable water column stratification, bacteria specifically adapted to these conditions may account for the high portions of BHPs. An additional and/or accompanying source may be nitrogen-fixing (cyano)bacteria, which is indicated by a positive correlation of BHP abundances with C_org and δ¹⁵N

Aerobic methanotrophy within the pelagic redox-zone of the Gotland Deep (central Baltic Sea)

Water column samples taken in summer 2008 from the stratified Gotland Deep (central Baltic Sea) showed a strong gradient in dissolved methane concentrations from high values in the saline deep water (max. 504 nM) to low concentrations in the less dense, brackish surface water (about 4 nM). The steep methane-gradient (between 115 and 135 m water depth) within the redox-zone, which separates the anoxic deep part from the oxygenated surface water (oxygen concentration 0–0.8 mL L − 1 ), implies a methane consumption rate of 0.28 nM d − 1 . The process of micro- bial methane oxidation within this zone was evident by a shift of the stable carbon isotope ratio of methane between the bottom water ( δ 13 C CH 4 =− 82.4 ‰) and the redox- zone ( δ 13 C CH 4 =− 38.7 ‰). Water column samples be- tween 80 and 119 m were studied to identify the microor- ganisms responsible for the methane turnover in that depth interval. Notably, methane monooxygenase gene expression analyses for water depths covering the whole redox-zone demonstrated that accordant methanotrophic activity was probably due to only one phylotype of the aerobic type I methanotrophic bacteria. An imprint of these organisms on the particular organic matter was revealed by distinctive lipid biomarkers showing bacteriohopanepolyols and lipid fatty acids characteristic for aerobic type I methanotrophs (e.g., 35-aminobacteriohopane-30,31,32,33,34-pentol), cor- roborating their role in aerobic methane oxidation in the redox-zone of the central Baltic Sea

The influence of bacterial activity on phosphorite formation in the Miocene Monterey Formation, California

Authigenic phosphorites from the Miocene Monterey Formation (California) including an autochthonous phosphatic laminite were analyzed for molecular biomarkers, element content, and sulfur isotopic composition of associated pyrite and sulfate to evaluate the role of bacterial activity in the precipitation of phosphate minerals. The phosphorites formed in a depositional environment typified by upwelling with dynamic bottom currents and hardground formation. Pyrite enclosed in the phosphorites shows δ34S values as low as − 36.5‰ VCDT, which is consistent with bacterial sulfate reduction. In a three-step extraction—phosphorite dissolution—extraction procedure, molecular fossils of sulfate-reducing bacteria (di-O-alkyl glycerol ethers and short-chain branched fatty acids i- and ai-C15:0, i- and ai-C17:0, and 10MeC16:0) were preferentially released from the mineral lattice. This suggests that the molecular fossils were tightly bound to carbonate fluorapatite, indicating that sulfate-reducing bacteria were involved in mineral formation. A close association of sulfate-reducing bacteria with large sulfide-oxidizing bacteria, which was previously suggested to favor carbonate fluorapatite precipitation, could neither be confirmed nor excluded for the Miocene Monterey Formation phosphorites