Small-Scale Energy Use of Agricultural Biogas Plant Wastes by Gasification

In Poland, there are 78 biogas plants producing a total electrical power of 85.94 MW. The byproduct of biogas plants is called a digestate. A single biogas plant with a power of 500 kW produces more than 10,000 ton of digestate per year. The goal of this chapter is to present a low-cost method of raw digestate processing with water content of about 94.55%, and also the results of thermal gasification of dried and pelletized digestate. Initial dehydration method is based on mechanical separation of the solid fraction in screw separator with a slot filter. Pre-dewatered digestate had been dried in biodrying process in semi-technical scale bioreactor. Afterward, the digestate was dried in tubular dryer and pelletized. The chapter covers the energy consumption for each stage of preparation of digestate for thermal gasification process. The gasification tests were conducted in fixed bed downdraft reactor. The chapter also features the physicochemical properties of digestate used in gasification process. The result of research on the gasification of drier digestate was gaseous fuel that does not differ from the quality of fuels obtained from the thermal treatment of other types of biomass

Magnetoresistance in LuBi and YBi semimetals due to nearly perfect carrier compensation

Monobismuthides of lutetium and yttrium are shown as representatives of materials which exhibit extreme magnetoresistance and magnetic-field-induced resistivity plateaus. At low temperatures and in magnetic fields of 9 T, the magnetoresistance attains orders of magnitude of 104% and 103%, on YBi and LuBi, respectively. Our thorough examination of electron-transport properties of both compounds shows that observed features are the consequence of nearly perfect carrier compensation rather than of possible nontrivial topology of electronic states. The field-induced plateau of electrical resistivity can be explained with Kohler scaling. An anisotropic multiband model of electronic transport describes very well the magnetic field dependence of electrical resistivity and Hall resistivity. Data obtained from the Shubnikov–de Haas oscillation analysis also confirm that the Fermi surface of each compound contains almost equal amounts of holes and electrons. First-principle calculations of electronic band structure are in a very good agreement with the experimental data

Electronic properties of RX2Al20 (R = La, Ce, Yb, Th, U; X = Ti, V, Cr and Mn) cage compounds

Here, non-spin-polarized electronic structures and Fermi surface properties of RX 2Al 20 (R = La, Ce, Yb, Th, U; X = Ti, V, Cr, Mn) intermetallic compounds were calculated using the full potential all-electron local orbital (FPLO) approach in the framework of the local density approximation (LDA). Trends of the magnetism are discussed in terms of the characteristics of X- 3d bands with a quantitative analysis of the relationship between band electron filling and crystal electric field splitting. Since coordination icosahedra of X-atoms have small trigonal distortion, crystal electric field splits the fivefold degenerate X- 3d state into low-energy singlet and two higher-energy doublets e g. In RTi 2Al 20 and RV 2Al 20 the population of the related 3d sub-band is not sufficient to cause energetically favorable spin polarization, whereas magnetic instabilities develop in the RCr 2Al 20 series. Finally, a manifestation of strong repulsive interactions between itinerant Mn-d electrons become most pronounced in ferromagnetic UMn 2Al 20. The influence of non-magnetic R-f states on magnetic and thermodynamic properties is discussed with special emphasis on the role of the f–p and f–d hybridization. For LaTi 2Al 20 and LaV 2Al 20 the calculated quantum oscillation frequencies are in accord with experimental report