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Green diesel is a real solution for the decarbonization process of the world, reducing in this way, carbon dioxide emissions to the atmosphere. The present work proposes a flexible biorefinery design where green diesel is produced by catalytic hydrotreatment of four vegetable oils: soybean, sunflower, palm, and cardoon oil feedstock. The process was simulated in Aspen Plus®. A multi-bed reactor composed of four catalytic beds with quenching cooling is designed and simulated in the presence of Ni-W/SiO2-Al2O3 catalyst, in addition to a separation phase train to obtain the green diesel. Sensitivity analyses were carried out to determine the parameter conditions of the unit operations. The results of the model reflex a molar conversion of triglycerides above 97% and overall mass yield into diesel fraction above 79%. Total capital costs and operating costs of the process were determined in the economic analysis, where a base case is considered for the calculations, obtaining the maximum vegetable oil market price can be sustainable to make economically convenient the biorefinery. Soybean oil resulted in the worst feedstock due to the high percentage of unsaturated bonds, while cardoon oil can be considered the best source to produce green diesel thanks to higher conversion yields. [ABSTRACT FROM AUTHOR]

In recent years there was an increase in the use of renewable energy resources but there are still technological limits regarding the not constant power productivity. To face this problem, a possibility is to convert the surplus of renewable electricity into chemical energy producing hydrogen through electrolysis. The main drawback of this solution is that hydrogen is still hardly usable and so a good choice could be to convert this fuel into a more common one, such as methane. This work aims to carry out a techno-economic analysis of an upgrade section for a biogas plant to convert CO2 into biomethane. The used methodology consists in sizing the methanation reactor considering kinetic and catalyst effectiveness, membrane separation and simulating the whole process changing operating conditions such as temperature and pressure. The results of this study show that methanation can be extremely efficient in terms of energy consumption and carbon conversion. The methane production cost without accounting for hydrogen cost is between 0.15-0.19 €/kg, the same cost range as commercial natural gas. This value mainly depends on the capital and operating cost of the compression system. However, by including the high cost of hydrogen obtained by electrolysis, equal to 5 €/kg, this process is not economically feasible. On the other hand, by exploiting the surplus of renewable energy production, the cost of green hydrogen is expected to radically decrease shortly. [ABSTRACT FROM AUTHOR]

The agri-food industry annually produces huge amounts of crops residues and wastes, the suitable management of these products is important to increase the sustainability of agro-industrial production by optimizing the entire value chain. This is also in line with the driving principles of the circular economy, according to which residues can become feedstocks for novel processes. Oleaginous yeasts represent a versatile tool to produce biobased chemicals and intermediates. They are flexible microbial factories able to grow on different side-stream carbon sources such as those deriving from agri-food wastes, and this characteristic makes them excellent candidates for integrated biorefinery processes through the production of microbial lipids, known as single cell oils (SCOs), for different applications. This review aims to present an extensive overview of research progress on the production and use of oleaginous yeasts and present discussions on the current bottlenecks and perspectives of their exploitation in different sectors, such as foods, biofuels and fine chemicals. [ABSTRACT FROM AUTHOR]