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EN
Biogas production has a big potential to provide clean energy. To evaluate the future production and maturity of biogas technology the generalized Weng model was proved to be effective, due to it has the minimum error. The simple algorithms to determine its parameters have been proposed. The simulation results for China, USA, and EU have been presented. The quantity and quality analysis for biogas feedstock has been carried out. Energy Return on Energy Invested (EROEI) indicator for different biofuels was considered. According to analysis done biogas from maize residue and chicken manure has high EROEI. Shannon Index was suggested to evaluate the diversity of feedstock supply. Biomass energy cost indicator was grounded to be used for feedstock energy and cost assessment. Biogas utilization pathways have been shown. Biogas boilers and CHP have the highest thermal efficiency, but biogas (biomethane) has the highest potential to earn as a petrol substitute. Utilization of biogas upgrading by-product (carbon dioxide) enhances profitability of biogas projects. Methods to assess the optimal pathways have been described.
2
Content available Energy efficiency of a biofuel production system
EN
Manufacturing engineering is supposed to provide analyses related to various aspects of manufacturing and production in order to maximise technological, energy, and economic gains in relevant production processes. The present paper gives a recapitulation of several publications by present authors, presenting considerations of the energy efficiency of biofuel production. The energy efficiency is understood as the ratio of energy obtained from biofuels produced basing on crops from a particular area to the energy required to satisfy needs of all subsidiary processes assuring correct functioning of the production system, starting from operations aimed to obtain agricultural crops, and ending with the conversion of the crops onto biofuels. Derived by the present authors, the mathematical model of energy efficiency of biofuel production is extended to a more general form, and applied to the analysis of quantitative relations between energy efficiency of sc. “energy plantations”, and further elements of biofuel production system converting harvested biomass into biofuel. Investigations are aimed towards the determination of the role of biomass as a source of energy.
EN
The model, developed earlier, have been designed to the studies of energy gain in the biofuels production, as compared to the sum of energy inputs on various production steps, and in processes enabling biomass conversion to energy. The present paper shows application of that model towards estimation of the contribution of energy used for commuting between agricultural production sites for a chosen example of plantation’s topological characteristics. Algorithm for computations is elaborated, and numerical example is shown. The sizes of the fields as well as distances between them determine the amount of energy spend for the agricultural work in addition to the tillage technologies being applied.
EN
Biofuel production, as well as any other production processes, involves a number of conversion steps each of those is connected with unavoidable consumption of energy. Since biofuels are intended to replace fossil fuels it is important that the sum of energy inputs into subsequent technological steps does not exceed the energy output from the system. Basing on theoretical model derived recently by present authors, energy require-ments for several agricultural technologies are computed, and used for estimation of energetic efficiency of rapeseed plantations dedicated for biodiesel fuel production. The effects of technological choices on energetic efficiency of plantations are demonstrated basing on numerical compu-tations performed using realistic data.
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