CO2 gasification of elephant grass in a fixed bed reactor

In order to supply the growing world demand of energy and relieve the global warming, biomass is considered a potential clean energy source. In this work, the thermochemical conversion of the elephant grass, through CO2 gasification, for the production of a combustible gas was evaluated. The gasification experiment was conducted at the temperature of 900 °C for 90 min under a carbon dioxide atmosphere. CO presented a maximum production rate of 2.25 mmol/min.gbiomass and a maximum concentration of 82 %mol/mol. The fuel gas produced had an average high heating value of 8.5 MJ/Nm³. Considerable hydrogen production rates were observed throughout the experiment. The experiment had an energy yield of 28.4 kJ/gbiomass. Tar produced was mainly composed of primary products and phenolic derivatives compounds. The results showed that CO2 gasification of elephant grass has the potential to produce a combustible gas allowing the reduction of CO2emissions to the atmosphere

The power spectrum and bispectrum of SDSS DR11 BOSS galaxies - I. Bias and gravity

We analyse the anisotropic clustering of the Baryon Oscillation Spectroscopic Survey CMASS Data Release 11 sample, which consists of 690 827 galaxies in the redshift range 0.43<z<0.70 and has a sky coverage of 8498deg2 corresponding to an effective volume of ∼ 6 Gpc3. We fit the Fourier space statistics, the power spectrum and bispectrum monopoles to measure the linear and quadratic bias parameters, b1 and b2, for a non-linear non-local bias model, the growth of structure parameter f and the amplitude of dark matter density fluctuations parametrized by σ8. We obtain b1(zeff)1.40σ8(zeff)=1.672±0.060 and $b_2^{0.30}(z_{\rm eff})\sigma _8(z_{\rm eff})=0.579\pm 0.082$ at the effective redshift of the survey, zeff=0.57. The main cosmological result is the constraint on the combination f 0.43(zeff)σ8(zeff)=0.582±0.084, which is complementary to fσ8 constraints obtained from two-point redshift-space distortion analyses. A less conservative analysis yields f 0.43(zeff)σ8(zeff)=0.584±0.051. We ensure that our result is robust by performing detailed systematic tests using a large suite of survey galaxy mock catalogues and N-body simulations. The constraints on f 0.43σ8 are useful for setting additional constraints on neutrino mass, gravity, curvature as well as the number of neutrino species from galaxy surveys analyses (as presented in a companion paper

The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Baryon Acoustic Oscillations in the Data Release 9 Spectroscopic Galaxy Sample

We present measurements of galaxy clustering from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of the Sloan Digital Sky Survey III (SDSS-III). These use the Data Release 9 (DR9) CMASS sample, which contains 264,283 massive galaxies covering 3275 square degrees with an effective redshift z=0.57 and redshift range 0.43 < z < 0.7. Assuming a concordance Lambda-CDM cosmological model, this sample covers an effective volume of 2.2 Gpc^3, and represents the largest sample of the Universe ever surveyed at this density, n = 3 x 10^-4 h^-3 Mpc^3. We measure the angle-averaged galaxy correlation function and power spectrum, including density-field reconstruction of the baryon acoustic oscillation (BAO) feature. The acoustic features are detected at a significance of 5\sigma in both the correlation function and power spectrum. Combining with the SDSS-II Luminous Red Galaxy Sample, the detection significance increases to 6.7\sigma. Fitting for the position of the acoustic features measures the distance to z=0.57 relative to the sound horizon DV /rs = 13.67 +/- 0.22 at z=0.57. Assuming a fiducial sound horizon of 153.19 Mpc, which matches cosmic microwave background constraints, this corresponds to a distance DV(z=0.57) = 2094 +/- 34 Mpc. At 1.7 per cent, this is the most precise distance constraint ever obtained from a galaxy survey. We place this result alongside previous BAO measurements in a cosmological distance ladder and find excellent agreement with the current supernova measurements. We use these distance measurements to constrain various cosmological models, finding continuing support for a flat Universe with a cosmological constant.Comment: 33 page

Impure Public Goods and Technological Interdependencies

Impure public goods represent an important group of goods. Almost every public good exerts not only effects which are public to all but also effects which are private to the producer of this good. What is often omitted in the analysis of impure public goods is the fact that – regularly – these private effects can also be generated independently of the public good. In our analysis we focus on the effects alternative technologies – independently generating the private effects of the public good – may have on the provision of impure public goods. After the investigation in an analytical impure public good model, we numerically simulate the effects of alternative technologies in a parameterized model for climate policy in Germany