886 resultados para 710701 Electricity, gas and water services and utilities


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One of the most common Demand Side Management programs consists of Time-of-Use (TOU) tariffs, where consumers are charged differently depending on the time of the day when they make use of energy services. This paper assesses the impacts of TOU tariffs on a dataset of residential users from the Province of Trento in Northern Italy in terms of changes in electricity demand, price savings, peak load shifting and peak electricity demand at substation level. Findings highlight that TOU tariffs bring about higher average electricity consumption and lower payments by consumers. A significant level of load shifting takes place for morning peaks. However, issues with evening peaks are not resolved. Finally, TOU tariffs lead to increases in electricity demand for substations at peak time.

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In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around ‘climate response functions’ (CRFs), i.e. the response of the climate to ‘step’ changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Ein eindimensionales numerisches Modell der maritimenGrenzschicht (MBL) wurde erweitert, um chemische Reaktionenin der Gasphase, von Aerosolpartikeln und Wolkentropfen zu beschreiben. Ein Schwerpunkt war dabei die Betrachtung derReaktionszyklen von Halogenen. Soweit Ergebnisse vonMesskampagnen zur Verfuegung standen, wurden diese zurValidierung des Modells benutzt. Die Ergebnisse von frueheren Boxmodellstudien konntenbestaetigt werden. Diese zeigten die saeurekatalysierteAktivierung von Brom aus Seesalzaerosolen, die Bedeutung vonHalogenradikalen fuer die Zerstoerung von O3, diepotentielle Rolle von BrO bei der Oxidation von DMS und dievon HOBr und HOCl in der Oxidation von S(IV). Es wurde gezeigt, dass die Beruecksichtigung derVertikalprofile von meteorologischen und chemischen Groessenvon grosser Bedeutung ist. Dies spiegelt sich darin wider,dass Maxima des Saeuregehaltes von Seesalzaerosolen und vonreaktiven Halogenen am Oberrand der MBL gefunden wurden.Darueber hinaus wurde die Bedeutung von Sulfataerosolen beidem aktiven Recyceln von weniger aktiven zu photolysierbarenBromspezies gezeigt. Wolken haben grosse Auswirkungen auf die Evolution und denTagesgang der Halogene. Dies ist nicht auf Wolkenschichtenbeschraenkt. Der Tagesgang der meisten Halogene ist aufgrundeiner erhoehten Aufnahme der chemischen Substanzen in die Fluessigphase veraendert. Diese Ergebnisse betonen dieWichtigkeit der genauen Dokumentation der meteorologischenBedingungen bei Messkampagnen (besonders Wolkenbedeckungsgrad und Fluessigwassergehalt), um dieErgebnisse richtig interpretieren und mit Modellresultatenvergleichen zu koennen. Dieses eindimensionale Modell wurde zusammen mit einemBoxmodell der MBL verwendet, um die Auswirkungen vonSchiffemissionen auf die MBL abzuschaetzen, wobei dieVerduennung der Abgasfahne parameterisiert wurde. DieAuswirkungen der Emissionen sind am staerksten, wenn sie insauberen Gebieten stattfinden, die Hoehe der MBL gering istund das Einmischen von Hintergrundluft schwach ist.Chemische Reaktionen auf Hintergrundaerosolen spielen nureine geringe Rolle. In Ozeangebieten mit schwachemSchiffsverkehr sind die Auswirkungen auf die Chemie der MBL beschraenkt. In staerker befahrenen Gebieten ueberlappensich die Abgasfahnen mehrerer Schiffe und sorgen fuerdeutliche Auswirkungen. Diese Abschaetzung wurde mitSimulationen verglichen, bei denen die Emissionen alskontinuierliche Quellen behandelt wurden, wie das inglobalen Chemiemodellen der Fall ist. Wenn die Entwicklungder Abgasfahne beruecksichtigt wird, sind die Auswirkungendeutlich geringer da die Lebenszeit der Abgase in der erstenPhase nach Emission deutlich reduziert ist.

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The cometary coma is a unique phenomenon in the solar system being a planetary atmosphere influenced by little or no gravity. As a comet approaches the sun, the water vapor with some fraction of other gases sublimate, generating a cloud of gas, ice and other refractory materials (rocky and organic dust) ejected from the surface of the nucleus. Sublimating gas molecules undergo frequent collisions and photochemical processes in the near‐nucleus region. Owing to its negligible gravity, comets produce a large and highly variable extensive dusty coma with a size much larger than the characteristic size of the cometary nucleus. The Rosetta spacecraft is en route to comet 67P/Churyumov‐Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. Both, interpretation of measurements and safety consideration of the spacecraft require modeling of the comet’s dusty gas environment. In this work we present results of a numerical study of multispecies gaseous and electrically charged dust environment of comet Chyuryumov‐Gerasimenko. Both, gas and dust phases of the coma are simulated kinetically. Photolytic reactions are taken into account. Parameters of the ambient plasma as well as the distribution of electric/magnetic fields are obtained from an MHD simulation [1] of the coma connected to the solar wind. Trajectories of ions and electrically charged dust grains are simulated by accounting for the Lorentz force and the nucleus gravity.

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Hydrocarbon seepage is a widespread process at the continental margins of the Gulf of Mexico. We used a multidisciplinary approach, including multibeam mapping and visual seafloor observations with different underwater vehicles to study the extent and character of complex hydrocarbon seepage in the Bay of Campeche, southern Gulf of Mexico. Our observations showed that seafloor asphalt deposits previously only known from the Chapopote Knoll also occur at numerous other knolls and ridges in water depths from 1230 to 3150 m. In particular the deeper sites (Chapopopte and Mictlan knolls) were characterized by asphalt deposits accompanied by extrusion of liquid oil in form of whips or sheets, and in some places (Tsanyao Yang, Mictlan, and Chapopote knolls) by gas emission and the presence of gas hydrates in addition. Molecular and stable carbon isotopic compositions of gaseous hydrocarbons suggest their primarily thermogenic origin. Relatively fresh asphalt structures were settled by chemosynthetic communities including bacterial mats and vestimentiferan tube worms, whereas older flows appeared largely inert and devoid of corals and anemones at the deep sites. The gas hydrates at Tsanyao Yang and Mictlan Knolls were covered by a 5-to-10 cm-thick reaction zone composed of authigenic carbonates, detritus, and microbial mats, and were densely colonized by 1-2 m-long tube worms, bivalves, snails, and shrimps. This study increased knowledge on the occurrences and dimensions of asphalt fields and associated gas hydrates at the Campeche Knolls. The extent of all discovered seepage structure areas indicates that emission of complex hydrocarbons is a widespread, thus important feature of the southern Gulf of Mexico.

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In the current uncertain context that affects both the world economy and the energy sector, with the rapid increase in the prices of oil and gas and the very unstable political situation that affects some of the largest raw materials’ producers, there is a need for developing efficient and powerful quantitative tools that allow to model and forecast fossil fuel prices, CO2 emission allowances prices as well as electricity prices. This will improve decision making for all the agents involved in energy issues. Although there are papers focused on modelling fossil fuel prices, CO2 prices and electricity prices, the literature is scarce on attempts to consider all of them together. This paper focuses on both building a multivariate model for the aforementioned prices and comparing its results with those of univariate ones, in terms of prediction accuracy (univariate and multivariate models are compared for a large span of days, all in the first 4 months in 2011) as well as extracting common features in the volatilities of the prices of all these relevant magnitudes. The common features in volatility are extracted by means of a conditionally heteroskedastic dynamic factor model which allows to solve the curse of dimensionality problem that commonly arises when estimating multivariate GARCH models. Additionally, the common volatility factors obtained are useful for improving the forecasting intervals and have a nice economical interpretation. Besides, the results obtained and methodology proposed can be useful as a starting point for risk management or portfolio optimization under uncertainty in the current context of energy markets.

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Rate of CO2 assimilation was determined above the Broken Spur and TAG active hydrothermal fields for three main ecosystems: (1) hydrothermal vents; (2) 300 m near-bottom layer of plume water; and (3) bottom sediments. In water samples from warm (40-45°C) vents assimilation rates were maximal and reached 2.82-3.76 µg C/l/day. In plume waters CO2 assimilation rates ranged from 0.38 to 0.65 µg C/l/day. In bottom sediments CO2 assimilation rates varied from 0.8 to 28.0 µg C/l/day, rising up to 56 mg C/kg/day near shrimp swarms. In the most active plume zone of the long-living TAG field bacterial production of organic matter (OM) from carbonic is up to 170 mg C/m**2/day); production of autotrophic process of bacterial chemosynthesis reaches about 90% (156 mg C/m**2/day). Thus, chemosynthetic production of OM in September-October is almost equal to that of photosynthetic production in the oceanic region. Bacterial production of OM above the Broken Spur hydrothermal field is one order lower and reaches only 20 mg C/m**2/day.

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This paper investigates the impact that electric vehicle uptake will have on the national electricity demand of Great Britain. Data from the National Travel Survey, and the Coventry and Birmingham Low Emissions Demonstration (CABLED) are used to model an electrical demand profile in a future scenario of significant electric vehicle market penetration. These two methods allow comparison of how conventional cars are currently used, and the resulting electrical demand with simple substitution of energy source, with data showing how electric vehicles are actually being used at present. The report finds that electric vehicles are unlikely to significantly impact electricity demand in GB. The paper also aims to determine whether electric vehicles have the potential to provide ancillary services to the grid operator, and if so, the capacity for such services that would be available. Demand side management, frequency response and Short term Operating Reserve (STOR) are the services considered. The report finds that electric cars are unlikely to provide enough moveable demand peak shedding to be worthwhile. However, it is found that controlling vehicle charging would provide sufficient power control to viably act as frequency response for dispatch by the transmission system operator. This paper concludes that electric vehicles have technical potential to aid management of the transmission network without adding a significant demand burden. © 2013 IEEE.

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Terrestrial ecosystems, occupying more than 25% of the Earth's surface, can serve as

`biological valves' in regulating the anthropogenic emissions of atmospheric aerosol

particles and greenhouse gases (GHGs) as responses to their surrounding environments.

While the signicance of quantifying the exchange rates of GHGs and atmospheric

aerosol particles between the terrestrial biosphere and the atmosphere is

hardly questioned in many scientic elds, the progress in improving model predictability,

data interpretation or the combination of the two remains impeded by

the lack of precise framework elucidating their dynamic transport processes over a

wide range of spatiotemporal scales. The diculty in developing prognostic modeling

tools to quantify the source or sink strength of these atmospheric substances

can be further magnied by the fact that the climate system is also sensitive to the

feedback from terrestrial ecosystems forming the so-called `feedback cycle'. Hence,

the emergent need is to reduce uncertainties when assessing this complex and dynamic

feedback cycle that is necessary to support the decisions of mitigation and

adaptation policies associated with human activities (e.g., anthropogenic emission

controls and land use managements) under current and future climate regimes.

With the goal to improve the predictions for the biosphere-atmosphere exchange

of biologically active gases and atmospheric aerosol particles, the main focus of this

dissertation is on revising and up-scaling the biotic and abiotic transport processes

from leaf to canopy scales. The validity of previous modeling studies in determining

iv

the exchange rate of gases and particles is evaluated with detailed descriptions of their

limitations. Mechanistic-based modeling approaches along with empirical studies

across dierent scales are employed to rene the mathematical descriptions of surface

conductance responsible for gas and particle exchanges as commonly adopted by all

operational models. Specically, how variation in horizontal leaf area density within

the vegetated medium, leaf size and leaf microroughness impact the aerodynamic attributes

and thereby the ultrane particle collection eciency at the leaf/branch scale

is explored using wind tunnel experiments with interpretations by a porous media

model and a scaling analysis. A multi-layered and size-resolved second-order closure

model combined with particle

uxes and concentration measurements within and

above a forest is used to explore the particle transport processes within the canopy

sub-layer and the partitioning of particle deposition onto canopy medium and forest

oor. For gases, a modeling framework accounting for the leaf-level boundary layer

eects on the stomatal pathway for gas exchange is proposed and combined with sap

ux measurements in a wind tunnel to assess how leaf-level transpiration varies with

increasing wind speed. How exogenous environmental conditions and endogenous

soil-root-stem-leaf hydraulic and eco-physiological properties impact the above- and

below-ground water dynamics in the soil-plant system and shape plant responses

to droughts is assessed by a porous media model that accommodates the transient

water

ow within the plant vascular system and is coupled with the aforementioned

leaf-level gas exchange model and soil-root interaction model. It should be noted

that tackling all aspects of potential issues causing uncertainties in forecasting the

feedback cycle between terrestrial ecosystem and the climate is unrealistic in a single

dissertation but further research questions and opportunities based on the foundation

derived from this dissertation are also brie

y discussed.

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In this dissertation I quantify residential behavior response to interventions designed to reduce electricity demand at different periods of the day. In the first chapter, I examine the effect of information provision coupled with bimonthly billing, monthly billing, and in-home displays, as well as a time-of-use (TOU) pricing scheme to measure consumption over each month of the Irish Consumer Behavior Trial. I find that time-of-use pricing with real time usage information reduces electricity usage up to 8.7 percent during peak times at the start of the trial but the effect decays over the first three months and after three months the in-home display group is indistinguishable from the monthly treatment group. Monthly and bi-monthly billing treatments are not found to be statistically different from another. These findings suggest that increasing billing reports to the monthly level may be more cost effective for electricity generators who wish to decrease expenses and consumption, rather than providing in-home displays. In the following chapter, I examine the response of residential households after exposure to time of use tariffs at different hours of the day. I find that these treatments reduce electricity consumption during peak hours by almost four percent, significantly lowering demand. Within the model, I find evidence of overall conservation in electricity used. In addition, weekday peak reductions appear to carry over to the weekend when peak pricing is not present, suggesting changes in consumer habit. The final chapter of my dissertation imposes a system wide time of use plan to analyze the potential reduction in carbon emissions from load shifting based on the Ireland and Northern Single Electricity Market. I find that CO2 emissions savings are highest during the winter months when load demand is highest and dirtier power plants are scheduled to meet peak demand. TOU pricing allows for shifting in usage from peak usage to off peak usage and this shift in load can be met with cleaner and cheaper generated electricity from imports, high efficiency gas units, and hydro units.

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Exhaust emissions from thirteen compressed natural gas (CNG) and nine ultralow sulphur diesel in-service transport buses were monitored on a chassis dynamometer. Measurements were carried out at idle and at three steady engine loads of 25%, 50% and 100% of maximum power at a fixed speed of 60 kmph. Emission factors were estimated for particle mass and number, carbon dioxide and oxides of nitrogen for two types of CNG buses (Scania and MAN, compatible with Euro 2 and 3 emission standards, respectively) and two types of diesel buses (Volvo Pre-Euro/Euro1 and Mercedez OC500 Euro3). All emission factors increased with load. The median particle mass emission factor for the CNG buses was less than 1% of that from the diesel buses at all loads. However, the particle number emission factors did not show a statistically significant difference between buses operating on the two types of fuel. In this paper, for the very first time, particle number emission factors are presented at four steady state engine loads for CNG buses. Median values ranged from the order of 1012 particles min-1 at idle to 1015 particles km-1 at full power. Most of the particles observed in the CNG emissions were in the nanoparticle size range and likely to be composed of volatile organic compounds The CO2 emission factors were about 20% to 30% greater for the diesel buses over the CNG buses, while the oxides of nitrogen emission factors did not show any difference due to the large variation between buses.

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Water is a current major global, national and local issue. Historic drought and unprecedented restriction levels are now substantially influencing almost all Australia’s major cities. Residential design and adoption of appropriate technologies plays a key role in urban water efficiency. This project, the first of the CRC-CI Sustainable subdivisions program with a focus on water, explores the existing technologies available for sustainable suburbs.