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AbstractAgeratum conyzoides, an herb found throughout the year, is generally considered as a weed: it causes reduction in soil productivity and leads to health hazards for cattle and humans. However, its biomass can easily represent a cost‐effective source, which can be used for lignocellulosic biofuel production. The conversion of lignocellulosic biomass to ethanol has drawn much attention in recent times due to abundance of biomass. In the present study, the cellulose and hemicellulose biomass of the leaf and stem of A. conyzoides was converted to sugars using acid hydrolysis.146.01 ± 02 mg/g of fermentable sugar was obtained from A. conyzoides. The maximum ethanol concentration 11.89 g/L was obtained after 7 days. Scanning electron microscopy was used to characterize the surface morphology after acid hydrolysis of biomass. In the current study, the residues of acid hydrolysis and fermented wastewater was used for biogas production through anaerobic digestion. The yield of biogas from the residues of acid hydrolysis and fermented wastewater was 204 L kg−1VS. The results obtained indicate that A. conyzoides may be considered as a promising feedstock for bioethanol and biogas production.

Abstract An overview is given of status of projects for the disposal of radioactive waste in very deep boreholes in crystalline rocks which demonstrates all main pros and cons of this technology. New opportunities offered by drilling long horizontal drillholes in ductile formations can provide the basis for projects that have the potential to overcome many of the disadvantages of deep boreholes. The concept of disposal in horizontal drillholes brings together the technologies of borehole and mined repositories using the advantages of both, and therefore deserves an expert discussion at international level.

The expansion of the production and use of bioenergy is one of the most efficient mechanisms to reduce greenhouse gas (GHG) emissions. Nevertheless, the environmental impact of the production processes for many raw materials remains unexplored. Several studies have pointed to macauba palm as a promising species for biofuel production in the tropics, but investigations on the environmental benefits of its cultivation have not been reported so far. In this work, an analysis of macauba production system in terms of GHG emissions and CO2 uptake has been conducted for a productive cycle. The energy conversion efficiency per unit area of land has been put in relationship with crop productivity and related to the dilution effect of production inputs. Simulation results estimate GHG emissions of 180 Mg CO2eq·ha-1 and a CO2 fixation ranging from 796 to 1137 Mg CO2eq·ha-1. The net energy balance would reach 512.3 GJ·ha-1 and energy efficiency would be 24.2 GJ·GJ-1. These results suggest that macauba would outperform traditional energy crops such as sugarcane, oil palm, sunflower, corn or jatropha in terms of efficiency. The domestication and exploitation in extensive farming of this species as an agroforestry crop, although still at an early stage, has a bright future.

The article presents results from analyzing the state of the art achieved in the coal gasification technologies developed around the world and the demand for them. It is shown that such technologies have presently arrived at a crossroad in their development. Their future will be determined by the development prospects of coal energy as a whole. Coal still continues to play the most important role in the world energy. In recent years, external factors have become extremely negative for the development of coal energy. Among other fuels, coal produces the largest specific emissions of CO2 during its combustion, in view of which it may become the first victim of the unfolding energy decarbonization policy. Under such conditions, there is a need to diversify the coal utilization fields, primarily through manufacturing a wide range of chemical products with a high added value. This generates the need to develop the appropriate technologies, and, first of all, gasification technologies, the use of which opens the possibility of making almost the entire range of products from coal that are obtained from petroleum and natural gas. It has been determined that gasification technologies have already reached a high level of technical maturity, and a large number of gasifier designs have been proposed. It has been determined that the majority of operating coal gasification plants are presently used for manufacturing various chemical products, first of all, natural gas substitute (which is then forwarded to gas networks) and also methanol and ammonia. It is pointed out that only a few integrated gasification combined cycle plants have been implemented and planned for construction, which means that the private sector shows little interest in this technology. At the same time, such plants have quite a high potential for being used in low-carbon energy, of course, provided that the problem of disposing the captured CO2 is solved. It is shown that a large number of gasifier equipment manufacturers are available around the world. However, gasifiers are produced in single units or in a small series, which unavoidably leads to the high cost of this equipment. For the further innovative development of the gasification technology, combined efforts should be taken by the private sector and the state.

We have developed a technique and a programming-computing suite (PCS) to estimate the effect of equipment reliability indices, schedules, and regular overhaul scopes on reliability and efficiency of combined heat and power plants (CHPPs). We describe the approach to predict heat and electric loads for the investigated CHPP operation period, taking into account the features of the power cogeneration. We performed optimization studies of two operation periods (different in overhaul resources) for an industrial-heating CHPP.

Abstract Low renewable energy source (RES) accommodation and energy utilization efficiency impose great challenge to reliable energy supplies for rural residents. This paper proposes an optimal coordinated multi-energy conversion and management framework with a biogas-dominated hybrid renewable microgrid for multi-carrier energy supplies in off-grid remote areas. In this framework, multi-energy multi-timeframe couplings among biomass and other renewables are modeled based on biogas digesting thermodynamics for the coordinated interaction among electricity, biogas and thermal energy carriers, and a sustainable energy hub is formulated for mapping various renewables into diversified energy loads. The proposed energy hub can facilitate mitigating the fluctuating outputs of RES by harvesting hydro-wind-solar energies into the form of biogas, and an evaluation model is proposed based on hydrodynamic networking mechanisms to calculate the state of energy (SOE) in the biogas storage. Furthermore, a hierarchical multi-energy management strategy is presented to dynamically optimize the production, conversion, storage and consumption of multi-carrier energy flows for system energy-efficiency enhancement. Case studies on a stand-alone microgrid demonstration validate that the biogas yield can be improved by 31.75% with digesting thermodynamic effects, and the battery degradation cost can be reduced by at least 22.63% considering the SOE of biogas storage with hydrodynamic effects.

AbstractThe object of this paper is to investigate the dynamic causal relationship between economic growth and renewable energy in Canada. The causal relationship is examined under the neoclassical production function framework. We employed a panel autoregressive distributed lag model controlling for different states of the economy by incorporating a dummy variable, which indicates the economic peak and trough. The data set consists of annual real GDP, capital formation, labor, and electricity generation by renewables for nine Canadian provinces covering from 1981 to 2015. The empirical results find that there is a unidirectional causality from renewable energy to economic growth in the long run. In the short run, a unidirectional causality going from renewable energy to economic growth only during the expansion period is observed. Our study suggests that renewable energy policies should be designed and implemented in a way that takes into account the nonlinear relationship between renewable energy and economic growth. This could involve promoting the development and deployment of renewable energy sources as part of their economic stimulus packages during economic upturns.

The main aspects limiting the widespread development of nuclear energy—the consequences of possible severe accidents and the problem of radioactive waste management—are considered. It is shown that modern computational tools and digital technologies can successfully solve the problems of substantiating and ensuring the safety of nuclear facilities, including modeling the states and processes occurring in a reactor installation, and the entire complex of nuclear power plant (NPP) systems, the spread of contaminants in emergency situations, the choice and justification of solutions on decommissioning nuclear and radiation hazardous facilities, and the disposal of radioactive waste (RW).