Perspectives for biogas generation from manure on the farms in the Leningrad Region of the Russian Federation

Received: January 27th, 2021 ; Accepted: March 28th, 2021 ; Published: April 8th, 2021 ; Correspondence: [email protected] interest in biogas in the Leningrad Region is consistently growing. Biogas can replace fossil fuels in different applications and reduce greenhouse gas emissions. The study aimed to demonstrate the perspectives for its generation from livestock waste and further farm application. The farm energy audits identified the pattern of fuel and energy consumption. Computational and statistical methods were applied to estimate the biogas generation. First, the study considered a cattle farm with 1,800 head and manure output of 43,300 t year-1 . According to calculations, the farm can fully meet its own needs for electricity or motor fuel by converting the manure into biogas. Meanwhile, the fuel use of biogas can reduce pollutant emissions by almost 30% against conventional fuel. Secondly, the study estimated the biogas production potential from the farm organic waste in the whole Leningrad Region with the total cattle stock of 165,000 head, pig stock of 184,000 head, and poultry stock of 29,180,000 head, producing about 8 million t year-1 of animal/poultry manure. According to calculations, the livestock waste processing will yield up to 500 million m3 of biogas. This is enough to fully cover the energy inputs of the farms in this region. However, the payback period for biogas plants is above eight years. The positive aspects of biogas application are introducing biogas in the farm energy balance as an energy resource; reducing the hazardous emissions owing to the improved processing of organic farm waste; obtaining high-quality fertilisers to consequently increase crop yields

Goldstone mode of Skyrmion Crystal

We discuss the Goldstone mode of skyrmion crystal in a model of two-dimenssional ferromagnet with Dzyaloshinskii-Moriya interaction in magnetic field. We use stereographic projection approach to construct skyrmion crystal and consider skyrmion's displacement field. The small overlap of the individual skyrmion images restricts the potential energy to the interaction of nearest neighboring displacements. The closed form of the Goldstone mode dispersion is found and its dependence on the magnetic field is studied. We use semiclassical quantization to define the Green's function and show that the propagation of displacements through the crystal changes its tensorial form from isotropic to anisotropic one at large distances.Comment: 6 pages, 4 figure

Generation of powerful terahertz emission in a beam-driven strong plasma turbulence

Generation of terahertz electromagnetic radiation due to coalescence of upper-hybrid waves in the long-wavelength region of strong plasma turbulence driven by a high-current relativistic electron beam in a magnetized plasma is investigated. The width of frequency spectrum as well as angular characteristics of this radiation for various values of plasma density and turbulence energy are calculated using the simple theoretical model adequately describing beam-plasma experiments at mirror traps. It is shown that the power density of electromagnetic emission at the second harmonic of plasma frequency in the terahertz range for these laboratory experiments can reach the level of 1 ${MW/cm}^3$ with 1% conversion efficiency of beam energy losses to electromagnetic emission