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The biodiesel from lignocellulosic materials has been widely recognized as an alternative fuel to meet energy requirements worldwide, facing fossil fuel depletion, and emerging energy policies. In this work, the biorefinery approach was applied for biodiesel production from jatropha and palm oils in order to make it economically competitive by the utilization of residual biomass as the feedstock for obtaining hydrogen via steam reforming of glycerol and gasification. The linear chains for hydrogen and diesel were simulated using UniSim software and main stream properties were collected from the literature or predicted by correlations. The proposed scheme of biorefinery was analyzed through environmental and techno-economic assessment to identify the feasibility of this process to be implemented. Three different blends of oils (JO10-PO90, JO20-PO80, and JO30-PO70) were considered in the environmental analysis to determine alternatives for reducing potential environmental impacts (PEIs). It was found that the acidification potential highly contributed to the environmental impacts attributed to the use of fossil fuels for heating requirements, and JO30-PO70 blend exhibited the lowest PEI value. The economic indicators were calculated to be 8,455,147.29 $USD and 33.18% for the net present value and internal rate of return, respectively. These results revealed that the proposed combined biomass biorefinery is feasible to be scaled up without causing significant negative impacts on the environment.

In the last decade, the interest worldwide in microalgae-based processes has increased. The culture techniques and the transformation of the algal biomass in high-value products such as biofuels are of special relevance. The production of the high-value substances from microalgae requires the application of several stages such as harvesting, extraction, and transformation in a biorefinery-based platform. However, some issues in the biomass transformation process must be overcome to improve the overall efficiency. Therefore, strategies to compare the microalgae-to-products pathways are required in order to define which products and technologies are the most suitable alternative. Hence, exergy analysis combined with process systems engineering offers a tool to establish the actual sustainability of the process with information about irreversibilities, losses, environmental impact, and improvement opportunities to identify challenges that need be overcome. In this chapter, a review of the main concepts related to exergy analysis of microalgae-based biorefinery sustainability assessment is presented. Exergy analysis strategies to the production of high-value products from microalgae are applied to a case study to compare two routes of biofuels production.

The aim of this work was to define optimum conditions to perform the mechanical and chemical pretreatment of empty fruit bunches (EFBs) and kernel shell (KS). Mechanical pretreatment was based on particle size reduction to 0.5, 1, and 2 mm. For chemical pretreatment, a solution of urea (2, 4, and 6 %w/v) was added to the residues under stirring for 18 h and 80 °C. Then, samples were hydrolyzed with sulfuric acid and the resulting reducing sugars were quantified using the 3,5- dinitrosalicyclic acid method. In addition, Van Soest and FTIR analyzes were performed to characterize the biomass suggesting acceptable cellulose contents (EFBs: 36.47%; KS: 20.06 %) and high lignin values (EFBs: 31.27%; KS: 66.49%). Results showed that the highest amount of TRS for EFBs was 105.3 g/L with urea concentration of 4% w/v and a particle size of 0.5 mm. For the KS, the highest amount of TRS was 98.62 g/L using a urea concentration of 6% w/v and a particle size of 0.5 mm. According to these results, it was concluded that pretreatments of oil palm biomass significantly enhance the performance of lignocellulosic material conversion into reducing sugars.