Search results:
Found 32
Listing 1 - 10 of 32 | << page >> |
Sort by
|
Choose an application
Le méthane contenu dans le charbon a longtemps constitué un danger pour les exploitations minières (c'est le « grisou » des mineurs) du fait des risques d'explosion qu'il présente. Aujourd'hui, alors que le passé minier tend à s'effacer progressivement, ce gaz naturel pourrait être capté par forage depuis la surface pour servir de nouvelle source d'énergie. En Lorraine, cette perspective soulève de nombreuses interrogations, teintées tantôt d'enthousiasme, tantôt d'inquiétude. D'avril 2013 à décembre 2015, une équipe pluridisciplinaire de chercheurs et d'enseignants-chercheurs de dix laboratoires universitaires français et québécois ont conduit une action de recherche dénommée « GazHouille » portant sur le projet d'exploitation du gaz de charbon en Lorraine et son intégration dans le territoire. L'originalité de leur travail réside dans son caractère transverse, car il apporte des éclairages géographiques, géologiques, de psychologie sociale, économiques, juridiques, politiques, etc., permettant d'appréhender le projet d'exploitation dans plusieurs de ses dimensions. Cet ouvrage rend compte des résultats majeurs de leur étude. Il n'a pas la prétention d'être exhaustif, mais peut servir à alimenter un débat ou une consultation publique sur le thème de gaz de charbon en Lorraine, ainsi qu'à expliciter et formuler les interrogations soulevées par les perspectives de son éventuelle exploitation.
géologie --- société --- exploitation minière --- grisou --- méthane --- gaz naturel
Choose an application
Understanding the link between microbial diversity and ecosystem processes is a fundamental goal of microbial ecologists, yet we still have a rudimentary knowledge of how changes in diversity affect nutrient cycling and energy transfer in ecosystems. Due to the complexity of the problem, many published studies on this topic have been conducted in artificial or manipulated systems. Although researchers have begun to expose some possible mechanisms using these approaches, most have not yet been able to produce conclusive results that relate directly to natural systems. The few studies that have explored the link between diversity and activity in natural systems have typically focused on specific nutrient cycles or processes, such as nitrification, denitrification, and organic carbon degradation pathways, and the microbes that mediate them. What we have learned from these studies is that there are often strong associations between the physical and chemical features of the environment, the composition of the microbial communities, and their activities, but the rules that govern these associations have not been fully elucidated. These earlier studies of microbial diversity and processes in natural systems provide a framework for additional studies to broaden our understanding of the role of microbial diversity in ecosystem function. The problem is complex, but with recent advances in sequencing technology, -omics, and in-situ measurements of ecosystem processes and their applications to microbial communities, making direct connections between ecosystem function and microbial diversity seems more tractable than ever.
ecosystem --- diversity --- Nitrogen --- Nitrification --- DNRA --- Microbialites --- Metagenomics --- Methane Seeps --- stable isotope probing --- metacommunity
Choose an application
The deep subsurface is, in addition to space, one of the last unknown frontiers to human kind. A significant part of life on Earth resides in the deep subsurface, hiding great potential of microbial life of which we know only little. The conditions in the deep terrestrial subsurface are thought to resemble those of early Earth, which makes this environment an analog for studying early life in addition to possible extraterrestrial life in ultra-extreme conditions. Early microorganisms played a great role in shaping the conditions on the young Earth. Even today deep subsurface microorganisms interact with their geological environment transforming the conditions in the groundwater and on rock surfaces. Essential elements for life are richly present but in difficultly accessible form. The elements driving the microbial deep life is still not completely identified. Most of the microorganisms detected by novel molecular techniques still lack cultured representatives. Nevertheless, using modern sequencing techniques and bioinformatics the functional roles of these microorganisms are being revealed. We are starting to see the differences and similarities between the life in the deep subsurface and surface domains. We may even begin to see the function of evolution by comparing deep life to life closer to the surface of Earth. Deep life consists of organisms from all known domains of life. This Research Topic reveals some of the rich diversity and functional properties of the great biomass residing in the deep dark subsurface.
Terrestrial deep biosphere --- Eukaryotes --- Groundwater --- microbiome --- Heavy metal resistance --- MINE --- Nitrogen Cycle --- Iron oxidation --- Methane --- cave
Choose an application
Gases with a mixing ratio of less than one percent in the lower atmosphere (i.e. the troposphere) are considered as trace gases. Numerous of these trace gases originate from biological processes in marine and terrestrial ecosystems. These gases are of relevance for the climate as they contribute to global warming or to the troposphere’s chemical reactive system that builds the ozone layer or they impact on the stability of aerosols, greenhouse, and pollutant gases. These reactive trace gases include methane, a multitude of volatile organic compounds of biogenic origin (bVOCs) and inorganic gases such as nitrogen oxides or ozone. The regulatory function of microorganisms for trace gas cycling has been intensively studied for the greenhouse gases nitrous oxide and methane, but is less well understood for microorganisms that metabolize molecular hydrogen, carbon monoxide, or bVOCs. The studies compiled in this Research Topic reflect this very well. While a number of articles focus on nitrous oxide and methane or carbon monoxide oxidation, only a few articles address conversion processes of further bVOCs. The Research Topic is complemented by three review articles about the consumption of methane and monoterpenes, as well as the role of the phyllosphere as a particular habitat for trace gas-consuming microorganisms, and point out future research directions in the field. The presented scientific work illustrates that the field of microbial regulation of trace glas fluxes is still in its infancy when one broadens the view on gases beyond methane and nitrous oxide. However, there is a societal need to better predict global dynamics of trace gases that impact on the functionality and warming of the troposphere. Upcoming modelling approaches will need further information on process rates, features and distribution of the driving microorganisms to fulfill this demanding task.
trace gases --- methane --- methanotroph --- nitrous oxide --- denitrification --- volatile organic compounds --- bVOCs --- carbon monoxide --- phyllosphere
Choose an application
Deep subsurface microbiology is a highly active and rapidly advancing research field at the interface of microbiology and the geosciences; it focuses on the detection, identification, quantification, cultivation and activity measurements of bacteria, archaea and eukaryotes that permeate the subsurface biosphere of deep marine sediments and the basaltic ocean and continental crust. The deep subsurface biosphere abounds with uncultured, only recently discovered and – at best - incompletely understood microbial populations. In spatial extent and volume, Earth’s subsurface biosphere is only rivaled by the deep sea water column. So far, no deep subsurface sediment has been found that is entirely devoid of microbial life; microbial cells and DNA remain detectable at sediment depths of more than 1 km; microbial life permeates deeply buried hydrocarbon reservoirs, and is also found several kilometers down in continental crust aquifers. Severe energy limitation, either as electron acceptor or donor shortage, and scarcity of microbially degradable organic carbon sources are among the evolutionary pressures that have shaped the genomic and physiological repertoire of the deep subsurface biosphere. Its biogeochemical role as long-term organic carbon repository, inorganic electron and energy source, and subduction recycling engine continues to be explored by current research at the interface of microbiology, geochemistry and biosphere/geosphere evolution. This Research Topic addresses some of the central research questions about deep subsurface microbiology and biogeochemistry: phylogenetic and physiological microbial diversity in the deep subsurface; microbial activity and survival strategies in severely energy-limited subsurface habitats; microbial activity as reflected in process rates and gene expression patterns; biogeographic isolation and connectivity in deep subsurface microbial communities; the ecological standing of subsurface biospheres in comparison to the surface biosphere – an independently flourishing biosphere, or mere survivors that tolerate burial (along with organic carbon compounds), or a combination of both? Advancing these questions on Earth’s deep subsurface biosphere redefines the habitat range, environmental tolerance, activity and diversity of microbial life.
deep subsurface --- marine sediment --- deep biosphere --- ocean crust --- subseafloor sediment --- Methane --- Peru margin --- Hydrogen --- acetogenesis --- sulfate reduction
Choose an application
Anaerobic digestion of the organic fraction of municipal solid waste as such or together with food waste, press water or patatoes sludge was investigated to equilibrate methane production within a day or over the weekend, when no OFMSW was available. A stable co-digestion process could be achieved with COD degradation between 60 and 80 %. The max. organic loading rates were 28 kg COD/L,d. For stable methane production the OLR during Co-digestion should not excede 22,5 kg/L,d.
Choose an application
This volume provides unique views of combustion from many technical and international research perspectives.
steam methane reformer --- computational fluid dynamics --- tube surface temperature --- hydrogen yield --- wall shear stress --- swirling burner --- flaring angle --- fuel rich/lean combustion --- low load --- combustion adjustment --- flue gas mercury removal --- activated carbon sorbent --- CeO2 doping --- density functional theory(DFT) calculations --- air-pollution control --- battery recycling --- heavy metals --- control system efficiency --- chemical analysis --- short stroke engine --- bioethanol --- Atkinson cycle --- solid fuel --- cooking stove --- field study --- biofuel burner --- combustion --- ecological fuels --- energy management --- cleaner combustion --- fluidized bed --- powder coke --- MP-PIC method --- emission characteristics --- tubular diffusion flame --- methane/air --- NO emissions --- quantitative reaction pathway diagrams --- oxy-fuel combustion --- porous plate reactor --- oxidizer ratio --- methane --- CFD --- iso-octane --- high-pressure turbulent burning velocity --- Lewis number --- general correlations --- self-similar spherical flame propagation --- methane hydrate --- gas hydrate --- methane clathrate --- hydrate combustion --- hydrate flame spectrum --- hydrate ignition --- watery flames --- mitigation --- climate change --- ultra-lean methane flame --- lean flames --- methane–air combustion --- PIV --- GRI-Mech 3.0
Choose an application
This Special Issue reports research spanning from the analysis of indirect data, modeling, and laboratory and geological data confirming the intrinsic multidisciplinarity of gas hydrate studies. The study areas are (1) Arctic, (2) Brazil, (3) Chile, and (4) the Mediterranean region. The results furnished an important tessera of the knowledge about the relationship of a gas hydrate system with other complex natural phenomena such as climate change, slope stability and earthquakes, and human activities.
BSR --- gas hydrate --- methane --- seepage --- active margin --- Chile Triple Junction --- Amazon fan --- gas hydrate --- thermogenic gas --- biogenic gas --- molecular composition --- isotopic composition --- gas hydrates --- seep-carbonates --- clathrites --- Miocene --- northern Apennines --- Arctic shelf --- permafrost --- gas hydrate --- salt migration --- thawing --- hydrate dissociation --- methane emission --- environmental impact --- geohazards --- gas hydrates --- gas seeps --- ocean acidification --- gas hydrate --- modelling --- climate change --- Chilean margin --- slope stability --- earthquake --- carbon dioxide --- Santos Basin --- potential methods --- gravimetric data --- magnetic data --- mantellic source --- Bouguer anomaly --- São Paulo Plateau --- gas hydrates --- methane stability --- seismic interpretation --- Levant Basin --- Eastern Mediterranean --- climate change --- modeling --- gas hydrate --- subaqueous permafrost --- Arctic shelf --- permafrost --- gas hydrate --- temperature increase --- hydrate dissociation --- methane emission --- environmental impact --- geohazard --- natural gas hydrate --- methane cycle --- global change --- ecosystem --- geohazards --- risk assessment --- environmental impact --- multidisciplinary --- blue growth
Choose an application
Compared to conventional chemical technologies and other similar industrial processes, bioprocesses represent a more sustainable and environmentally-friendly alternative for the production of fuels and platform chemicals. In biorefineries, different kinds of feedstocks, such as biomass or lignocellulosic materials in general, can be used and fermented by microorganisms (e.g., bacteria, fungi, algae), after some pretreatment steps, to produce high added-value metabolites. More recently, wastes, wastewaters and also waste gases have been shown to be suitable for resource recovery or for their bioconversion to (bio)fuels (e.g., ethanol, butanol, hexanol, biodiesel, biohydrogen, biogas) or other commercial products (e.g., biopolymers). In this sense, much effort has also been made to bioconvert greenhouse gases, such as CO2, into useful products.The goal of this Special Issue is to publish both recent innovative research data, as well as review papers on the fermentation of different types of substrates to commercial (bio)fuels and (bio)products, mainly focusing on the bioconversion of pollutants in solid, liquid, or gas phases (wastes, wastewaters, waste gases).
Acetogens --- Algae --- Bioalcohols --- Biodiesel --- Biogas --- Biohydrogen --- Bioreactor --- Carbon dioxide (CO2) --- Carbon monoxide (CO) --- Clostridia --- Fungi --- Life cycle assessment (LCA) --- Metabolic engineering --- Methane (CH4) --- Microbial electrosynthesis (MES) --- Polyhydroxyalkanoates --- Solid waste --- Syngas --- Waste gas --- Wastewater
Choose an application
This book describes recent advances in geomechanics for energy and the sustainable environment. Four research articles, related to high-level radioactive nuclear waste disposal stability, geological effect and wellbore stability considerations for methane gas hydrate production, and artificial soil freezing, are presented in this book. In addition, a comprehensive state-of-the-art review verifies the strong correlation between global climate change and the occurrence of geotechnical engineering hazards. The review also summarizes recent attempts to reduce CO2 emissions from civil and geotechnical engineering practices. Readers will gain ideas as to how we can deal with conventional and renewable energy sources and environment-related geotechnical engineering issues.
lattice Boltzmann method --- artificial frozen soil wall --- temperature field --- phase change --- numerical simulation --- global warming --- climate change --- greenhouse gas --- carbon dioxide --- extreme precipitation --- disaster --- geotechnical engineering hazard --- ground improvement --- soil stabilization --- triaxial shear --- methane hydrate --- clay content --- mechanical property --- hydrate mining --- shear shrinkage --- methane hydrate --- shear/normal coupling stiffness --- slippage at the interface --- wellbore stability analysis --- depressurization method --- granite --- HLW disposal --- plastic strain --- temperature --- CWFS --- damage process --- yield condition --- strength criterion --- dilation angle --- HLW disposal --- direct shear experiment --- normal stress --- plastic shear strain --- constitutive model
Listing 1 - 10 of 32 | << page >> |
Sort by
|