3,406 research outputs found
World natural gas endowment as a bridge towards zero carbon emissions
We use global energy market (GEM) model to show that natural gas has the potential to help stabilize global carbon emissions in a span of about 50-100 years and pave the way towards low and zero carbon energy. The GEM provides a close fit of the global energy mix between 1850 and 2005. It also matches historical carbon and CO2 emissions generated by the combination of fossil fuels. The model is used them to forecast the future energy mix, as well as the carbon and CO2 emissions, up to the year 2150. Historical data show relative decarbonization and an increase in the amount of hydrogen burned as a percent of fossil fuel use between 1850 and 1970. The GEM indicates that with a larger contribution of natural gas to the future energy market, the burned hydrogen percentage will increase. This decarbonization will help to advance economic and environmental sustainability
Link Between Endowments, Economics and Environment in Conventinal and unconventional Gas Reservoirs
This paper presents a methodology for connecting endowments, economics and the environment in conventional, tight, shale and Coalbed Methane (CBM) reservoirs. The volumetric estimates are generated by a Variable Shape Distribution model (VSD). The VSD has been shown in the past to be useful for the evaluation of conventional and tight gas reservoirs. However, this is the first paper in which the method is used to also include shale gas and CBM formations. Results indicate a total gas endowment of 70,000 tcf, split between 15,000 tcf in conventional reservoirs, 15,000 tcf in tight gas, 30,000 tcf in shale gas and 10,000 tcf in CBM reservoirs. Thus, natural gas formations have potential to provide a significant contribution to global energy demand estimated at approximately 790 quads by 2035. A common thread between unconventional formations is that nearly all of them must be hydraulically fractured to attain commercial production. A significant volume of data indicates that the probabilities of hydraulic fracturing (fracking) fluids and/or methane contaminating ground water through the hydraulically-created fractures are very low. Since fracking has also raised questions about the economic viability of producing unconventional gas in some parts of the world, supply curves are estimated in this paper for the global gas portfolio. The curves show that, in some cases, the costs of producing gas from unconventional reservoirs are comparable to those of conventional gas. The conclusion is that there is enough natural gas to supply the energy market for nearly 400 years at current rates of consumption and 110 years with a growth rate in production of 2% per year. With appropriate regulation, this may be done safely, commercially, and in a manner that is more benign to the environment as compared with other fossil fuels
Valoración de escenarios futuros a través de la conectividad del paisaje
En este trabajo se presenta una metodología SIG de valoración de la conectividad del paisaje aplicada a la valoración de escenarios futuros para el Área Metropolitana de Granada. Esta metodología será empleada para realizar un análisis comparado de las pérdidas de conectividad que los tres escenarios introducen unos con respecto a otros y se revela, junto con la generación de escenarios futuros como un instrumento útil para ayudar en la toma de decisiones en lo que respecta a las formas, lugares e intensidades del crecimiento urbano.This paper presents a GIS methodology to assess landscape connectivity through urban growth scenarios in the Metropolitan Area of Granada. This methodology will be useful to assess landscape connectivity loss in a compared evaluation of the scenarios. Thus, this evaluation will be show as a useful tool, combined with the scenario simulation, to help in the metropolitan decision making process
Simultaneous Optical Model Analyses of Elastic Scattering, Breakup, and Fusion Cross Section Data for the He + Bi System at Near-Coulomb-Barrier Energies
Based on an approach recently proposed by us, simultaneous
-analyses are performed for elastic scattering, direct reaction (DR)
and fusion cross sections data for the He+Bi system at
near-Coulomb-barrier energies to determine the parameters of the polarization
potential consisting of DR and fusion parts. We show that the data are well
reproduced by the resultant potential, which also satisfies the proper
dispersion relation. A discussion is given of the nature of the threshold
anomaly seen in the potential
Spin-one color superconductivity in compact stars?- an analysis within NJL-type models
We present results of a microscopic calculation using NJL-type model of
possible spin-one pairings in two flavor quark matter for applications in
compact star phenomenology. We focus on the color-spin locking phase (CSL) in
which all quarks pair in a symmetric way, in which color and spin states are
locked. The CSL condensate is particularly interesting for compact star
applications since it is flavor symmetric and could easily satisfy charge
neutrality. Moreover, the fact that in this phase all quarks are gapped might
help to suppress the direct Urca process, consistent with cooling models. The
order of magnitude of these small gaps (~1 MeV) will not influence the EoS, but
their also small critical temperatures (T_c ~800 keV) could be relevant in the
late stages neutron star evolution, when the temperature falls below this value
and a CSL quark core could form.Comment: 7 pages, 7 figures, revised version, accepted for the Conference
Proceedings of "Isolated Neutron Stars: from the Interior to the Surface",
London, 24-28. April 200
A basis for variational calculations in d dimensions
In this paper we derive expressions for matrix elements (\phi_i,H\phi_j) for
the Hamiltonian H=-\Delta+\sum_q a(q)r^q in d > 1 dimensions.
The basis functions in each angular momentum subspace are of the form
phi_i(r)=r^{i+1+(t-d)/2}e^{-r^p/2}, i >= 0, p > 0, t > 0. The matrix elements
are given in terms of the Gamma function for all d. The significance of the
parameters t and p and scale s are discussed. Applications to a variety of
potentials are presented, including potentials with singular repulsive terms of
the form b/r^a, a,b > 0, perturbed Coulomb potentials -D/r + B r + Ar^2, and
potentials with weak repulsive terms, such as -g r^2 + r^4, g > 0.Comment: 22 page
Neutron Transfer reactions induced by 8Li on 9Be
Angular distributions for the elastic scattering of 8Li on 9Be and the
neutron transfer reactions 9Be(8Li,7Li)10Be and 9Be(8Li,9Li)8Be have been
measured with a 27 MeV 8Li radioactive nuclear beam. Spectroscopic factors for
8Li|n=9Li and 7Li|n=8Li bound systems were obtained from the comparison between
the experimental differential cross section and finite-range DWBA calculations
with the code FRESCO. The spectroscopic factors obtained are compared to shell
model calculations and to other experimental values from (d,p) reactions. Using
the present values for the spectroscopic factor, cross sections for the direct
neutron-capture reactions 7Li(n,g)8Li and 8Li(n,g)9Li were calculated in the
framework of a potential model.Comment: 24 pages, 8 Figures, submitted as regular article to PR
The interaction of 11Li with 208Pb
Background: 11Li is one of the most studied halo nuclei. The fusion of 11Li
with 208Pb has been the subject of a number of theoretical studies with widely
differing predictions, ranging over four orders of magnitude, for the fusion
excitation function.
Purpose: To measure the excitation function for the 11Li + 208Pb reaction.
Methods: A stacked foil/degrader assembly of 208Pb targets was irradiated
with a 11Li beam producing center of target beam energies from above barrier to
near barrier energies (40 to 29 MeV). The intensity of the 11Li beam (chopped)
was 1250 p/s and the beam on-target time was 34 hours. The alpha-decay of the
stopped evaporation residues was detected in a alpha-detector array at each
beam energy in the beam-off period (the beam was on for <= 5 ns and then off
for 170 ns).
Results: The 215At evaporation residues were associated with the fusion of
11Li with 208Pb. The 213,214At evaporation residues were formed by the breakup
of 11Li into 9Li + 2n, with the 9Li fusing with 208Pb. The 214At evaporation
residue appears to result from a "quasi-breakup" process.
Conclusions: Most of 11Li + 208Pb interactions lead to breakup with a small
fraction (<= 11%) leading to complete fusion.Comment: 25 pages, 11 figure
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