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.
Due to environmental, energy, and operating cost constraints, the number of liquefied natural gas (LNG)–powered ships is increasing. To avoid decreasing the thermal efficiency of two-stroke, low-speed diesel engines, high-pressure gas injection is used. The specific energy consumption of a gas fuel compressor is around 0.35 kWh/kg, which has a negative impact on the efficiency of ship power plants. To reduce the primary energy consumption of a gas fuel supply system, waste heat recovery (WHR) technologies may be used. This study investigated whether WHR metal hydride technology was suitable for improving the efficiency of low-grade heat waste in marine diesel engines. The key factors of this technology were revealed, and the design scheme was described. Working fluids were also analyzed, and a mathematical model of a WHR metal hydride plant was developed, and the results were represented. The calculations showed that the above technology could increase the operating power of a propulsion plant by 5.7–6.2%. The results demonstrate the possibility of applying WHR metal hydride equipment for gas fuel compressor drives in LNG-powered ships. The novelty of this study lies in the investigation of metal hydride technology for application in the waste heat recovery systems of LNG-powered ships.
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