Generation Of Potential Energy Research Articles

A Mechanism of the MJO Invoking Scale Interactions

This chapter distinguishes the mechanism of tropical convective disturbances, such as a hurricane, from that of the Madden–Julian oscillation (MJO). The hurricane is maintained by organized convection around the azimuth. In a hurricane the organization of convection, the generation of eddy available potential energy, and the transformation of eddy available potential energy into eddy kinetic energy all occur on the scale of the hurricane and these are called “in-scale processes,” which invoke quadratic nonlinearity. The MJO is not a hurricane type of disturbance; organized convection simply does not drive an MJO in the same manner. The maintenance of the MJO is more akin to a multibody problem where the convection is indeed organized on scales of tropical synoptic disturbances that carry a similar organization of convection and carry similar roles for the generation of eddy available potential energy and its conversion to the eddy kinetic energy for their maintenance. The maintenance of the MJO is a scale interaction problem that comes next, where pairs of synoptic-scale disturbances are shown to interact with a member of the MJO time scale, thus contributing to its maintenance. This chapter illustrates the organization of convection, synoptic-scale energetics, and nonlinear scale interactions to show the above aspects for the mechanism of the MJO.

Effects of Saharan Dust on the Linear Dynamics of African Easterly Waves

Abstract The direct radiative effects of Saharan mineral dust aerosols on the linear dynamics of African easterly waves (AEWs) are examined analytically and numerically. The analytical analysis combines the thermodynamic equation with a dust continuity equation to form an expression for the dust-modified generation of eddy available potential energy . The dust-modified is a function of the transmissivity and spatial gradients of the dust, which are modulated by the Doppler-shifted frequency. The expression for predicts that for a fixed dust distribution, the wave response will be largest in regions where the dust gradients are maximized and the Doppler-shifted frequency vanishes. The numerical analysis uses the Weather Research and Forecasting (WRF) Model coupled to an online dust model to calculate the linear dynamics of AEWs. Zonally averaged basic states for wind, temperature, and dust are chosen consistent with summertime conditions over North Africa. For the fastest-growing AEW, the dust increases the growth rate from ~15% to 90% for aerosol optical depths ranging from τ = 1.0 to τ = 2.5. A local energetics analysis shows that for τ = 1.0, the dust increases the maximum barotropic and baroclinic energy conversions by ~50% and ~100%, respectively. The maxima in the generation and conversions of energy are collocated and occur where the meridional dust gradient is maximized near the critical surface—that is, where the Doppler-shifted frequency is small, in agreement with the prediction from the analytical analysis.

Evaluation of renewable energy deployment scenarios for building energy management

According to International Energy Agency (IEA), 35% of total energy is consumed in buildings. Proper management of building energy would effectively improve fossil fuel consumption by integrating Renewable Energy Sources (RES). This paper introduces novel methodology to deploy Renewable Energy Sources (RES) for buildings. The developed methodology composed of two steps: evaluation of RES deployment to a building and evaluation of load-generation scenarios in buildings. At first, the proposed algorithm obtains information about building facilities and structure that can be used to deploy PV, wind turbine and gas generator. Solar and wind profiles are analyzed and integrated with building energy model, which is used to evaluate potential energy generation scenarios. The second step includes the evaluation of different supply—generation scenarios based on load profiles and solar and wind generation profiles. This step will include the minimization of energy loss and will seek effective utilization of generated energy. A case study of domestic home in Toronto, Canada, was chosen as an example to demonstrate the proposed algorithm. Results are shown and analyzed which demonstrate the different scenarios generated for the selected case study based on loads and generation profiles.

Design of a base Case Mixed-use Community and its Energy Performance

This paper presents the design of a solar mixed-use community and the analysis of its performance, in term of total energy consumption and potential energy generation. The sample community, assumed located in northern climate combines residential and commercial buildings. It forms a base-case scenario, as part of a wide scope research program aimed at assessing the effects of multiple design parameters on the performance of such neighbourhoods and the development of design guidelines for energy sustainable neighbourhoods. Residential buildings include single-family houses and apartment buildings, while the commercial amenities include a primary school, an office building, retail and a supermarket. Energy simulations indicate that detached and attached houses can achieve an energy positive status, while apartment buildings and offices are capable of supplying only a small portion of their energy consumption, due to limited available roof surface. While apartment buildings represent 69% of the total annual energy demand of the neighbourhood, they contribute just 51% to total energy generation. The community as a whole generates annually 63% of its energy demand. These results suggest that efforts at optimizing energy performance of such neighbourhoods should be focussed on medium- to high-rise buildings such as office and apartment blocks.

A model for studying the performance of P3HT:PCBM organic bulk heterojunction solar cells

In the study of bulk heterojunction (BHJ) solar cells based on poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM), P3HT/PCBM device performance is strongly depending on the thickness of active region, materials in use and fabrication methods. In such devices, optoelectronic behaviors such as charge carrier generation and recombination, photocurrent generation and charge transport mechanism are different in devices of different fabrication methods. An electrical model accounting for study of the performance of P3HT:PCBM organic bulk heterojunction solar cells is developed to achieve the device parameter for high performance of the polymer-fullerene bulk heterojunction solar cells. In this model, by solving the drift–diffusion equations by considering the boundary condition and uniform potential energy, the effects of the active region thickness, potential energy and photocurrent generation on the performance of P3HT:PCBM bulk heterojunction solar cell have been studied. Simulated current–voltage characteristics as a function of active layer thickness reveal relatively good agreement between the model's predictions and published modeling and experimental reports.

Centrifugal Instability and Mixing in the California Undercurrent

AbstractA regional numerical study of the California Current System near Monterey Bay, California, is conducted using both hydrostatic and nonhydrostatic models. Frequent sighting of strong anticyclones (Cuddies) have occurred in the area, and previous studies have identified Monterey Bay as an apparent region of strong unbalanced flow generation. Here, by means of a downscaling exercise, a domain just downstream of Point Sur is analyzed and argued to be a preferred site of diapycnal mixing. The scenario suggested by the simulations involves the generation of negative relative vorticity in a bottom boundary layer of the California Undercurrent on the continental shelf break. At Point Sur, the current separates from the coast and moves into deep waters where it rapidly develops finite-amplitude instabilities. These manifest as isopycnal overturnings, but in contrast to the normal Kelvin–Helmholtz paradigm for mixing, this study argues that the instability is primarily centrifugal. The evidence for this comes from comparisons of the model with linear results for ageostrophic instabilities. Mixing increases background potential energy. The authors argue the regional potential energy generation near Point Sur in the upper few hundred meters is comparable to that found in open-ocean regions of strong diapycnal mixing, either by abyssal tides and lee waves near topography. This study computes diapycnal fluxes and estimates turbulent diffusivities to argue mixing by centrifugal instability is characterized by diffusivities O(10−4) m2 s−1, although the potential for contamination by explicit diffusivities exists.

Spatio-temporal modeling of roof-top photovoltaic panels for improved technical potential assessment and electricity peak load offsetting at the municipal scale

Integrated spatial and energy planning has become a major field of interest to meet the current renewable energy share expansion and CO2 emissions reduction targets. Geographic Information Systems (GIS) play a considerable role in supporting decision making in this field. Solar potential maps are a popular strategy to promote renewable energy generation through photovoltaic (PV) panel installations at city and municipal scales. They indicate the areas of roofs that would provide the maximum amount of energy in kWh per year. These are often used to suggest “optimal locations” for PV-panels and/or recommend system sizes to achieve a certain level of yearly autarchy. This approach is acceptable if PVs have only a minor share in the local energy supply system. However, increased PV-penetration can lead to instability of the local grid, create hazards for the security of the supply, and considerably escalate the storage and system back-up requirements. To obtain a proper understanding of the consequences for the local energy balance when selecting or rejecting a certain installation, examining the hourly and intra-hourly time series of the potential energy generation from PVs is necessary. This paper introduces a GIS-based procedure to estimate the potential PV-electricity generation time series for every roof-top section within a study area using open source software. This procedure is complemented by a series of strategies to select suitable PV-installations considering the time series analysis of supply and demand. Furthermore, thirteen technical indicators are considered to evaluate the PV-installation sets selected with every strategy. The capabilities of the procedure are tested using data from a German rural municipality. The proposed procedure constitutes an efficient and accessible way to assess solar potentials at the municipal scale and to design roof-top PV exploitation plans, which are more appropriate to fulfill the local energy requirements.

The potential of using olive cake in power generation in the Palestinian territories

Palestine faces considerable challenges relating to its energy supply, which is reflected in its dependency on imported electricity and fuels. This makes it vulnerable to changing political and economic situations and emphasises the urgent need to search for alternative and sustainable sources of energy from within Palestine itself. This study explores the potential energy generation from olive cake (OC) in the Palestinian territories. The findings of the study confirmed that there is a high-energy potential to be derived from OC and that powering olive mills by small-scale generators using OC is feasible. It was found that the amount of electricity that can be produced by OC combustion constitutes about 1.3% of all electricity consumption in 2009. Furthermore, numerous environmental benefits can be derived from using OC as biomass, notably the reduction of hazardous emission and the reduction of untreated OC.

Depletion of reduction potential and key energy generation metabolic enzymes underlies tellurite toxicity in Deinococcus radiodurans.

Oxidative stress resistant Deinococcus radiodurans surprisingly exhibited moderate sensitivity to tellurite induced oxidative stress (LD50 = 40 μM tellurite, 40 min exposure). The organism reduced 70% of 40 μM potassium tellurite within 5 h. Tellurite exposure significantly modulated cellular redox status. The level of ROS and protein carbonyl contents increased while the cellular reduction potential substantially decreased following tellurite exposure. Cellular thiols levels initially increased (within 30 min) of tellurite exposure but decreased at later time points. At proteome level, tellurite resistance proteins (TerB and TerD), tellurite reducing enzymes (pyruvate dehydrogense subunits E1 and E3), ROS detoxification enzymes (superoxide dismutase and thioredoxin reductase), and protein folding chaperones (DnaK, EF-Ts, and PPIase) displayed increased abundance in tellurite-stressed cells. However, remarkably decreased levels of key metabolic enzymes (aconitase, transketolase, 3-hydroxy acyl-CoA dehydrogenase, acyl-CoA dehydrogenase, electron transfer flavoprotein alpha, and beta) involved in carbon and energy metabolism were observed upon tellurite stress. The results demonstrate that depletion of reduction potential in intensive tellurite reduction with impaired energy metabolism lead to tellurite toxicity in D. radiodurans.

Impact of global warming on the energetics of lower tropospheric ultra-long waves and the Indian summer monsoon

Analyses of 60 years (1949–2008) of monthly energetics of the zonal waves derived from NCEP/NCAR data indicate that ultra-long waves (waves 1 and 2) dominate the spectrum of lower tropospheric zonal waves during monsoon season (June–September). Westerlies over the Indian subcontinent are a source of energy to wave 1. Two oceanic anticyclones, one over Pacific and the other over Atlantic are sources of energy to wave 2. These two waves are inversely correlated. Climatology of the energetics of ultra-long waves for the two epochs 1949–1978 (CLP1) and 1979–2008 (CLP2) of 30 years indicates that the intensity of wave 1 has decreased by about 33% whereas the intensity of wave 2 has increased by about 27%. Northward transport of sensible heat during CLP1 changes to southward during CLP2. Larger generation of zonal mean Available Potential Energy (APE) during CLP2 indicates more heating. A larger conversion of kinetic energy (KE) of wave 1 into APE of wave 1 leads to weakening of wave 1 during CLP2. In case of wave 2, lower rate of conversion of KE to APE leads to stronger wave 2 during CLP2.

Evaluation of Trigger Functions for Convective Parameterization Schemes Using Observations

Abstract Realistic simulation of different modes of atmospheric variability ranging from diurnal cycle to interannual variation in global climate models (GCMs) depends crucially on the convection trigger criteria. In this study, using the data from constrained variational analysis by the Atmospheric System Research program for single-column models (SCM), the performance of the commonly used convective trigger functions in GCMs is evaluated based on the equitable threat score (ETS) value, a widely used forecast verification metric. From the ETS score, three consistently better-performing trigger functions were identified. They are based on the dilute and undilute convective available potential energy (CAPE) generation rate from large-scale forcing in the free troposphere (hereafter dCAPE) and parcel buoyancy at the lifting condensation level (Bechtold scheme). The key variables used to define these trigger functions are examined in detail. It is found that the dilute dCAPE trigger function performs the best consistently in both the tropical and midlatitude convective environment. Analysis of the composite fields of key variables of the trigger functions, based on the correct prediction, overprediction and underprediction of convection, and correct prediction of no-convection cases for convective onset, brings to light some critical factors responsible for the performance of the trigger functions. The lower-tropospheric advective forcing in dilute dCAPE trigger and vertical velocity in Bechtold trigger are identified to be the most importance ones. Suggestions are offered for further improvements.

Ekman Pumping and the Energetics of the Southern Hemisphere Eddy Life Cycle

Abstract In the framework of the Lorenz energy cycle, the climatological and eddy life cycle characteristics of the generation of eddy available potential energy through Ekman pumping (EEPE) are evaluated using Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) data (1979–2011). EEPE exhibits an annual cycle that is maximized during a given hemisphere’s winter, with maximum values in the midtroposphere of the midlatitudes. Spectral analysis of the Southern Hemisphere storm track reveals that positive EEPE is associated with an anomalously small vertical phase tilt. A composite analysis of the Southern Hemisphere eddy life cycle reveals a maximum in EEPE that occurs after the peak eddy amplitude. Eddy life cycles during winter with large values of EEPE have higher values of eddy available potential energy and eddy kinetic energy than life cycles with small EEPE. However, baroclinic energy conversion remains unenhanced in life cycles with large values of EEPE. The lack of enhancement of baroclinic conversion is related to the small vertical phase tilt associated with positive EEPE. Instead, barotropic energy conversion is muted, and it is this muted barotropic decay that results in an amplification of eddy kinetic energy. There is no evidence of reflecting critical latitudes playing a role in this reduction of barotropic decay, as found in previous modeling studies. Rather, during Southern Hemisphere winter, this reduction coincides with the presence of a turning latitude on the equatorward side of the storm track.

Modelling piezoelectric energy harvesting potential in an educational building

In this paper, potential application of a commercial piezoelectric energy harvester in a central hub building at Macquarie University in Sydney, Australia is examined and discussed. Optimization of the piezoelectric tile deployment is presented according to the frequency of pedestrian mobility and a model is developed where 3.1% of the total floor area with the highest pedestrian mobility is paved with piezoelectric tiles. The modelling results indicate that the total annual energy harvesting potential for the proposed optimized tile pavement model is estimated at 1.1MWh/year. This potential energy generation may be further increased to 9.9MWh/year with a possible improvement in piezoelectric energy conversion efficiency integrated into the system. This energy harvesting potential would be sufficient to meet close to 0.5% of the annual energy needs of the building. The study confirms that locating high traffic areas is critical for optimization of the energy harvesting efficiency, as well as the orientation of the tile pavement significantly affects the total amount of the harvested energy. A Density Flow evaluation is recommended in this study to qualitatively evaluate the piezoelectric power harvesting potential of the considered area based on the number of pedestrian crossings per unit time.

Implications of diurnal and seasonal variations in renewable energy generation for large scale energy storage

Large scale implementation of solar and wind powered renewable electricity generation will use up to continent sized connected electricity grids built to distribute the locally fluctuating power. Systematic power output variation will then become manifest since solar power has an evident diurnal period, but also surface winds—which are driven by surface temperatures—follow a diurnal periodic behavior lagging about 4 h in time. On an ordinary day a strong diurnal varying renewable electricity generation results when combining wind and solar power on such continent sized grid. Comparison with possible demand patterns indicates that coping with such systematically varying generation will require large scale renewable energy storage and conversion for timescales and storage capacities of at least up to half a day. Seasonal timescales for versatile, high quality, generally applicable, energy conversion and storage are equally essential since the continent wide insolation varies a factor ∼3, e.g., in Europe and Northern Africa together. A first order model for estimating required energy storage and conversion magnitudes is presented, taking into account potential diurnal and seasonal energy demand and generation patterns. A few scalable energy storage methods are briefly indicated.

Has influence of extratropical waves in modulating Indian summer monsoon rainfall (ISMR) increased?

In the paper, influence of extratropical circulation features on Indian Summer Monsoon Rainfall (ISMR) is examined. Energetics of extratropics, north of Indian subcontinent for deficient and non-deficient ISMR years, during two periods 1951–1978 and 1979–2005, are calculated and critically analyzed. It is observed that for the period 1951–1978, only two out of the 10 energetics parameters, viz., the zonal available potential energy (high) and conversion of zonal kinetic energy to eddy kinetic energy (low) differed significantly in JJA months of the deficient years from that of the non-deficient years. However, during the 1979–2005 period, as many as six out of the 10 energetics parameters, viz., eddy available potential energy, zonal available potential energy, eddy kinetic energy, generation of zonal available potential energy, conversion of zonal available potential energy to zonal kinetic energy and conversion of zonal kinetic energy to eddy kinetic energy differed significantly in JJA months of the deficient years from that of the non-deficient years. These results confirm growing influence of the transient stationary waves in deficient years after the climate shift year, 1979. Analysis of energetics parameters of the pre-monsoon season of the two periods also reveals similar results. This suggests that forcings apparently responsible for energetics in JJA months of the deficient years of the later period were present even before the advent of Indian summer monsoon season.

Generation of available potential energy due to the long-wave radiation influx in the atmosphere

Investigated are the features of the distribution of the generation of available potential energy (APE) due to the influx of long-wave radiation in the atmosphere. The reanalysis (ERA-Interim) data of the European Center for Medium-Range Weather Forecast are used as the reference values of fields for computing APE generation. The obtained results indicate the influence of cloudiness and atmospheric stratification on APE generation due to the inflow of long-wave radiation which values are by 4–5 times smaller than the values of APE generation due to the phase transitions of moisture in the atmosphere.

Environmental impacts of integrating wind energy systems and supplemental energy generation and storage systems

Wind energy systems offer a promising alternative energy source due to the environmental, economic, and social benefits and, as a result, have garnered support for development and implementation. One of the major drawbacks of wind energy, however, is its variability due to the stochastic nature of wind, thus, supplemental energy generation or storage technologies are required. In this study, a life cycle assessment approach is applied to estimate the environmental impacts of potential supplemental energy generation (biomass, natural gas, and hydropower) and potential supplemental energy storage (zinc-bromine batteries) systems for a wind park. Cradle-to-grave environmental impacts for the systems are compared to those for a coal-based energy system. Results indicate that the environmental impacts from the wind park and zinc-bromine battery are lower than the impacts from coal power generation, but greater than the impacts of wind energy with supplemental energy generation from biomass, hydropower, or natural gas.

Absorbing aerosol‐induced change in the early monsoon Arabian Sea low‐level jet: Modeled transfer from anomalous heating to nondivergent kinetic energy

This study examines the impact of anomalous differential generation of available potential energy by absorbing aerosols on the transition and early active phases of the South Asian summer monsoon. Aerosol direct and indirect radiative forcings can modify tropospheric temperature profiles through direct absorption, scattering, and extended cloud lifetimes. Recent studies have suggested that over monthly and seasonal time scales, these effects can lead to modified flow and rainfall regimes in the South Asian monsoon region. Of special interest is the covariance of heating and temperature prior to active monsoon onset. It can be shown that anomalous generation of available potential energy due to absorption of shortwave radiation by aerosols can impact the cascade of energy from the local Hadley circulation to the monsoon nondivergent flow. In order to quantify the potential impact of aerosol radiative forcing and the resulting changes in monsoon onset timing and intensity, an ensemble of Weather Research and Forecasting with Chemistry regional weather and chemistry model forecasts are created for the South Asian summer monsoon region during May, June, and July. The forecasts including shortwave absorption by aerosol are compared to control forecasts in which aerosols only scatter shortwave radiation. The evolution of irrotational and nondivergent kinetic energy, generation of available potential energy and rainfall are presented. It is found that the ensemble with aerosol shortwave absorption contains on average a more intense dynamical onset over South India which is statistically significant compared to the ensemble variability. The more intense monsoon onset is related to a more intense Arabian Sea low‐level jet. In the ensemble with shortwave absorption by aerosol, the early season monsoon rainfall is diminished over South India and enhanced over the Northeastern Indian states.

Completing the Mechanical Energy Pathways in Turbulent Rayleigh-Bénard Convection

A new, more complete view of the mechanical energy budget for Rayleigh-Bénard convection is developed and examined using three-dimensional numerical simulations at large Rayleigh numbers and Prandtl number of 1. The driving role of available potential energy is highlighted. The relative magnitudes of different energy conversions or pathways change significantly over the range of Rayleigh numbers Ra ~ 10(7)-10(13). At Ra < 10(7) small-scale turbulent motions are energized directly from available potential energy via turbulent buoyancy flux and kinetic energy is dissipated at comparable rates by both the large- and small-scale motions. In contrast, at Ra ≥ 10(10) most of the available potential energy goes into kinetic energy of the large-scale flow, which undergoes shear instabilities that sustain small-scale turbulence. The irreversible mixing is largely confined to the unstable boundary layer, its rate exactly equal to the generation of available potential energy by the boundary fluxes, and mixing efficiency is 50%.

Contributions of Individual Atmospheric Diabatic Heating Processes to the Generation of Available Potential Energy

Abstract The generation of zonal and eddy available potential energy (Gz and Ge) as formulated by Lorenz are computed on a global-, daily-, and synoptic-scale basis to consider the contribution of each diabatic heating component separately and in combination. Using global, mostly satellite-derived datasets for the diabatic heating components and the temperature enables us to obtain Gz and, especially, Ge from observations for the first time and at higher temporal and spatial resolution than previously possible. The role of clouds in maintaining G is investigated. The global annual mean Gz is 1.52 W m−2. Values reach a minimum of 0.63 W m−2 in the Northern Hemisphere during spring and a maximum of 2.27 W m−2 in the Southern Hemisphere during winter. The largest contributors to Gz are latent heating in the tropical upper troposphere, associated with the intertropical convergence zone in the summer hemisphere and surface sensible heat fluxes in the winter pole. Diabatic cooling by radiative fluxes (mostly longwave) generally destroys Gz. The value of Ge is negative and is about an order of magnitude smaller than Gz, with a global annual mean of −0.29 W m−2. However, the small value of Ge results from the cancellation of the contributions from the individual diabatic heating terms, which are actually roughly similar in magnitude to their Gz contributions. The results presented herein suggest that the large-scale dynamics of the atmosphere organize the spatial and temporal distribution of clouds and precipitation in such a way as to increase the energy available to drive the circulation, a kind of positive feedback.