Collinear versus non-collinear magnetic order in Pd atomic clusters: ab-initio calculations

We present a thorough theoretical assessment of the stability of non-collinear spin arrangements in small palladium clusters. We generally find that ferromagnetic order is always preferred, but that antiferromagnetic and non-collinear configurations of different sorts exist and compete for the first excited isomers. We also show that the ground state is insensitive to the choice of atomic configuration for the pseudopotential used and to the approximation taken for the exchange and correlation potential. Moreover, the existence and relative stability of the different excited configurations also depends weakly on the approximations employed. These results provide strong evidence on the transferability of pseudopotential and exchange and correlation functionals for palladium clusters as opposed to the situation found for the bulk phases of palladium.Comment: 5 pages, 4 figure

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

Exact thermodynamics of a planar array of Ginzburg-Landau chains with nn and nnn interactions

The exact expression of the free energy of a planar array of a Ginzburg-Landau chains with nn and nnn interaction is obtained. The critical behaviour of the specific heat is not qualitatively modified by taking into account the nnn interaction

The role of natural gas in a low carbon Asia Pacific

As the Asia Pacific region continues to experience rapid economic growth, natural gas may have an important role in satisfying regional demand and transitioning to a low carbon economy. In this study, a Global Energy Market Model (GEM) is used to analyze the market shares of gases, liquids and solids in the Asia Pacific. The model matches the historical energy mix from 1850 to 2010 as well as the historical hydrogen to carbon (H/C) ratio. The GEM is then used to present scenarios of the Asia Pacific energy mix and H/C ratio to the year 2030. The scenarios vary according to policies and technologies that either encourage or discourage gas use. Estimates of conventional and unconventional gas quantities and costs are also presented, partly with a Variable Shape Distribution Model (VSD) and supply curves. The Asia Pacific is found to have vast natural gas resources, though suitable policies are needed to develop the potential. For instance, incentives will be necessary for investment in gas and LNG technology, as increased market share will not occur if investment does not take place in a timely fashion. In addition, it is important that government intervention not create disincentives for development of the regional gas and LNG industries

The Economics of Oil and Gas Supply in the Former Soviet Union

Supply costs curves for the Former Soviet Union (FSU) are constructed for conventional petroleum, which is defined as conventional oil, natural gas and natural gas liquids (NGL). The supply figures show how petroleum quantities vary with production costs over time. Five resource quality categories, distinguishable according to production costs, are used in the estimation. The quantities are allocated across the five categories in a fixed proportion in order to generate the supply cost curves. The role of annual productivity gains, i.e., technological progress, to the year 2030 is also included. Results indicate that petroleum in the FSU is abundant and can be produced economically. In addition, production costs are found to decrease further over time as technology advances. With appropriate energy policy, FSU petroleum resources should assist in meeting domestic and international energy demand