Fruit waste (FW), mainly from agroindustry, is currently left behind in landfills despite its rich composition. The bioactive compounds (e.g., oils, polyphenols), carbohydrates, and lignin present in this biomass type require comprehensive characterization (i.e., identification and quantification) before they can be used as raw materials in biorefineries. This review collected information from scientific papers on FW compositional analysis methods and characterization data; the information needs to be compiled in a systematic, standardized, and comprehensive way to understand and quantify the true potential of FW as feedstocks for biorefineries. The information gathered in this review allowed us to identify the biomass fractions that could be valorized further depending on the kind of FW (peels, seeds, or seed vessels, and pomace or mixed residues). Fruit waste differs from conventional lignocellulosic biomass due to the presence of higher amounts (>5%) of extractives – pectin, and starch. This review describes current compositional analysis methodologies to identify possible strengths and weaknesses that could affect the adequate selection of valorization platforms. As no current methodology allows the composition of FW to be described thoroughly, this work identifies procedures applicable to biorefineries that use FW. Possible improvements are suggested to fill methodological gaps in the quantification of samples with large amounts of extractives and pectin. The standardization of methods for FW's quantification is fundamental for the adequate integration of different valorization platforms into biorefineries. It is essential to consider all the substances present in FW to exploit fully their potential for new value-added molecules, including oils, polyphenols, and pectin.

Sustainable aviation fuels (SAF) are fuels that have potential to be sustainably produced and to generate lower carbon emissions when compared to the conventional kerosene. Wider SAF production and utilization represent nowadays an important step to move towards a more sustainable aviation industry, which has committed to significantly reduce their net carbon emissions by 2050. To reach this target, significant efforts have been done to develop sustainable technologies for the production of aviation fuels able to be implemented in a large scale. This chapter summarizes and discusses the different technologies that have been proposed to produce aviation biofuels, their potential to be upscaled and techno-economic perspectives, as well as the impact of SAF on sustainability. At the end, the industry point of view on the prospects for a wider production and use of aviation biofuels is also presented.

Table 2 in printed publication was miss-set, and should read as follows: [Table presented] The authors would like to apologize for any inconvenience caused.

Development of affordable and low carbon biobased manufacturing depends critically on strategies that reduce cost and emission profiles. This paper indicates that efforts around the reduction of capital costs by intensification of process equipment need to be carefully weighed against the inherently fast increasing financial and climate costs of driving forces used for the intensification. The fundamental relation between capital expenditures (CAPEX) and operational expenditures (OPEX) of intensified and non-intensified biobased processes and their financial and climatic impacts are emphasized and provisionally explored for a few industrial processes. General learnings flag the importance in particular of OPEX minimisation for sustainable bio-economic development.

The enzymatic conversion of lignocellulosic material to sugars can provide a carbon source for the production of energy (fuels) and a wide range of renewable products. However, the efficiency of this conversion is impaired due to product (sugar) inhibition. Even though several studies investigate how to overcome this challenge, concepts on the process to conduct the hydrolysis are still scarce in literature. Aqueous two-phase systems (ATPS) can be applied to design an extractive reaction due to their capacity to partition solutes to different phases in such a system. This work presents strategies on how to conduct extractive enzymatic hydrolysis in ATPS and how to explore the experimental results in order to design a feasible process. While only a limited number of ATPS was explored, the methods and strategies described could easily be applied to any further ATPS to be explored. We studied two promising ATPS as a subset of a previously high throughput screened large set of ATPS, providing two configurations of processes having the reaction in either the top phase or in the bottom phase. Enzymatic hydrolysis in these ATPS was performed to evaluate the partitioning of the substrate and the influence of solute partitioning on conversion. Because ATPS are able to partition inhibitors (sugar) between the phases, the conversion rate can be maintained. However, phase forming components should be selected to preserve the enzymatic activity. The experimental results presented here contribute to a feasible ATPS-based conceptual process design for the enzymatic conversion of lignocellulosic material.

Aqueous two-phase systems (ATPS) can be applied to enzymatic reactions that are affected by product inhibition. In the biorefinery context, sugars inhibit the cellulolytic enzymes in charge of converting the biomass. Here, we present a strategy to select an ATPS (formed by polymer and salt) that can separate sugar and enzymes. This automated and miniaturized method is able to determine phase diagrams and partition coefficients of solutes in these. Tailored approaches to quantify the solutes are presented, taking into account the limitations of techniques that can be applied with ATPS due to the interference of phase forming components with the analytics. The developed high-throughput (HT) platform identifies suitable phase forming components and the tie line of operation. This fast methodology proposes to screen up to six different polymer-salt systems in eight days and supplies the results to understand the influence of sugar and protein concentrations on their partition coefficients.

This study presents a techno-economic analysis and an environmental assessment, of the whole production chain (biomass production, sugar extraction, biomass pretreatment, sugars fermentation, and products recovery and purification), of a fully autarkic sugarcane-based biorefinery for biojet fuel production. All scenarios considered correspond to 1st/2nd generation integrated biorefineries (i.e. simultaneous use of sugarcane juice stream and lignocellulosic fractions) with a production scale of 208 kton (biojet fuel) yr^-1. In this paper, we compared multiple options for the most relevant processing steps of the biorefinery: eight biomass pretreatment technologies (i.e. dilute acid, dilute acid + alkaline treatment, steam explosion, steam explosion + alkaline treatment, organosolv, alkaline wet oxidation, liquid hot water and liquid hot water + alkaline treatment); two biojet fuel production routes from sugars (i.e. ethanol to jet and direct fermentation); one biojet fuel production route from biomass (i.e. fast pyrolysis); two biojet fuel production routes from lignin obtained after biomass pretreatment (i.e. fast pyrolysis and gasification Fischer- Tropsch); and one alternative use for lignin (i.e. co-generation). From the combination of these key features, 81 scenarios are selected and compared. Furthermore, three potential technological improvements were analysed for selected scenarios: i) recovery of acetic acid and furfural (for cases with bagasse pretreatment); ii) production of succinic acid from a fraction of concentrated juice; iii) increase of operation time (from 200 to 320 days yr^-1) by using sweet sorghum as cumulative feedstock. The different scenarios are compared first based on the minimum jet fuel selling price (MJSP) and then based on their environmental performance (i.e. greenhouse gas (GHG) emissions and non-renewable energy use (NREU)). Among the scenarios considering biomass pretreatment, the lower MJSP are obtained when 1G/2G sugars are upgraded via ethanol fermentation (ETJ) (i.e. SO₂ steam explosion: 3409 US $.ton^-1, and wet oxidation: 3230 US $.ton^-1). Additional technological improvements may help to further reduce the MJSP either marginally (2%, by using 1G sugars for succinic acid production) or significantly (30%, by increasing the operation time). Thus, the lowest MJSP here calculated is 1725 US $.ton^-1 (with 1G sugars to biojet fuel via ethanol, and bagasse to biojet fuel via fast pyrolysis). Finally, for all scenarios considered, the GHG emissions and NREU were found to be lower than 42.5 kg CO₂eq.GJ^-1 and 700 MJ GJ ^-1 respectively (except for scenarios with fast pyrolysis of bagasse where those figures were further reduced by 50% and 80% respectively). Although, the MJSP calculated for all scenarios are higher than those of the fossil jet fuel reference, the significant potential for environmental impacts reduction (in terms of GHG emissions and primary energy use) are encouraging for further research in costs reduction and technology development.