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Lignocellulosic biomass is currently widely used in many biorefining processes. The full exploitation of biomass from uncultivated or even marginal lands for the production of biobased chemicals has deserved huge attention in the last few years. Among the sustainable biomass-based value chains, cardoon crops could be a feedstock for biorefineries as they can grow on marginal lands and be used as raw material for multipurpose exploitation, including seeds, roots, and epigeous lignocellulosic solid residue. This work focused on the technical analysis of a novel integrated flowsheet for the exploitation of the lignocellulosic fraction through the assessment of thermochemical, biochemical, and extractive technologies and processes. In particular, high-yield thermochemical processes (gasification), innovative biotechnological processes (syngas fermentation to ethanol), and extractive/catalyzed processes for the valorization of cardoon roots to FDCA and residual solid biomass were modeled and simulated. Inulin conversion to 2,5-Furandicarboxylic acid was the main conversion route taken into consideration. Finally, the novel process flowsheet, treating 130,000 t/y of residual biomass and integrating all proposed technologies, was modeled and assessed using process simulation tools to achieve overall mass and energy balances for comparison with alternative options. The results indicated that cardoon biorefining through the proposed flowsheet can produce, per 1000 tons of input dry biomass, 211 kg of 2,5-Furandicarboxylic acid and 140 kg of ethanol through biomass gasification followed by syngas fermentation. Furthermore, a pre-feasibility analysis was conducted, revealing significant and potentially disruptive results in terms of environmental impact (with 40 ktCO2eq saved) and economic feasibility (with an annual gross profit of EUR 30 M/y).

To achieve sustainable development, the transition from a fossil-based economy to a circular economy is essential. The use of renewable energy sources to make the overall carbon foot print more favorable is an important pre-requisite. In this context, it is crucial to valorize all renewable resources through an optimized local integration. One opportunity arises through the synergy between bioresources and green hydrogen. Through techno-economic assessments, this work analyzes four local case studies that integrate bio-based processes with green hydrogen produced via electrolysis using renewable energy sources. An analysis of the use of webGIS tools (i.e., Atlas of Biorefineries of IEA Bioenergy) to identify existing biorefineries that require hydrogen in relation to territories with a potential availability of green hydrogen, has never been conducted before. This paper provides an evaluation of the production costs of the target products as a function of the local green hydrogen supply costs. The results revealed that the impact of green hydrogen costs could vary widely, ranging from 1% to 95% of the total production costs, depending on the bio-based target product evaluated. Additionally, hydrogen demand in the target area could require an installed variable renewable energy capacity of 20 MW and 500 MW. On the whole, the local integration of biorefineries and green hydrogen could represent an optimal opportunity to make hydrogenated bio-based products 100% renewable.

A reliable assessment of the availability of bioresources represents the first step to defining local value chains of particular interest. More than 190 and 50 Mt/y of bioresources are currently available in Europe and Italy, respectively, even if they are not fully valorized. The best end use of these feedstocks is strictly dependent on specific territorial/regional peculiarities, that consequently affect the products' final properties. In this work, the Italian web-GIS-based tool “Atlante delle biomasse” was used to determine the availability of many bioresources in Italy at the regional level. A lump classification criterion was used to categorize the available biomasses, and, then, an optimization algorithm based on a process superstructure was applied to find out the available fraction of bioresources, the amount of biofuels potentially obtainable and, consequently, the regional fuel demand coverable by biofuels. In particular, only the energy-self-sufficient technologies with higher TRLs were considered in the mathematical model. The integration between the different selected bioresources led to three biofuels to be considered, evaluating the percentage of biofuel demand that could be covered for each Italian region. The final potential production of biofuels derived from local bioresources in Italy settles down on the range 9 107 – 1.6 108 GJ/y covering about 5, 50, and 100 % of methane, biodiesel and bio-LPG demand respectively. Bio-LPG demand for all regions was to be considered completely satisfied, biodiesel production was also sufficient to cover high demands, on the other hand, low values of biomethane requirements coverable were obtained.

The agro-food industry generates important quantities of by-products, often considered waste, which represent for the companies huge costs of handling and disposal. On the other hand, they contain copious amounts and varieties of compounds that, appropriately extracted, purified, and processed, can be valued in several industrial sectors. Their exploitation generates an improvement of the sustainability performance of the supply chains, since it generates economic advantages, making available new commercial products and reducing disposal costs, improves the environmental performance of the agro-industrial productions, and allows new employment opportunities, thanks to the development of new industrial sectors. The Percival project aims to valorize the by-products of agro-industrial supply chains of South of Italy, converting them into high-added value products, through innovative, efficient, and low environmental impact processes, going for the development of technologies that could represent new business opportunities for this territory. Particularly, the project deals with the development of processes for pretreatment, extraction, separation, and chemical/biotechnological transformation, using a biorefinery cascade approach. Indeed, the study of processes having the purpose of converting the residues from the above-mentioned transformations into advanced biofuels (biomethane) and agricultural products (e.g. soil improver and bio-stimulants) are also included in the project’s scope. The present paper provides an overview of the Percival project, along with the evaluation of the availability of residual biomasses from the supply chains of typical Southern agricultural products, and the valuable bioproducts achievable from these feedstocks, through a biorefinery processing scheme.

This work investigates the use of biochar-based materials for the selective simultaneous capture of CO2 and CH4 by Pressure Swing Adsorption (PSA) in simulated feeds of biogas to biomethane. Two biochar batches were produced by pyro-gasification at Equivalence Ratios (ER) of 0.15 and 0.30, in a bench scale rotary kiln fed with vineyard pruning pellets. Samples of these two batches underwent activations treatments with KOH and HCl. Biochar-based materials were tested in a laboratory-scale packed-bed rig, performing PSA of a CO2 (46.50 vol%) / CH4 (53.50 vol%) synthetic mixture, 5-9 bara at ambient temperature. The highest CO2 and CH4 sorption capacities were obtained at all pressures by the material treated with both KOH and HCl, which had by far the highest surface area. The biochar produced with ER=0.30 showed higher the selectivity towards CO2. Results are promising to develop selective sustainable materials for the PSA upgrading of biogas.

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.

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.

Lignocellulosic biomass can be converted to biofuels and biochemicals through several process pathways: pretreatment and sugars fermentation, thermochemical conversion (pyrolysis, gasification) and syngas synthesis. A promising syngas valorization process consists of the syngas fermentation, able to maximize the biomass fraction used for the fermentation. The limits of this process are the need for high-quality syngas, fermentation rate optimization and the two-phase bioreactor design. This work aims to analyze the two effects (fermentation and gas to liquid mass transfer) distinctly. A syngas fermentation kinetics was modeled in order to optimize the fermentation conditions in terms of substrate and microorganism concentrations maximizing the acetic acid yield. Under the hypothesis of constant CO and H2 concentration, the gas-liquid mass transfer coefficients were estimated considering a syngas composition coming from the Cynara cardunculus L. residual biomass gasification. Results presented identify the optimal CO and H2 concentrations 0.01 and 0.1 mmol/L respectively, with an initial microorganism concentration equal to 2 g/L, obtaining a maximum acetic acid yield and an acetic acid maximum concentration of 12.5 % and 4.2 g/L respectively.

The lignocellulosic biomass valorisation is a central challenge of the bioeconomy transition, which passes through optimization of the entire value chain, from feedstock availability, sustainable conversion processes, to final target products. In this framework, the 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 lignocellulosic biomass, and this characteristic makes them excellent candidates for integrated biorefinery processes through the production of microbial lipids/oils. This work aims at a techno-economic analysis of a lignocellulosic biorefinery producing microbial oils by oleaginous yeasts (Lipomyces tetrasporus). The wheat straw residues were considered as the lignocellulosic feedstock thanks to a huge amount in the European territory. Experimental data obtained by a complete lab-scale 2G-sugars platform (steam explosion pretreatment, enzymatic hydrolysis, fermentation) were used for the analysis until microbic growth. Commercial/literature data were considered for the lipids extraction and purification stages. An assessment of the mass and energy balances, equipment sizing, costs estimation was carried out with the main results showing a production cost of the microbial oil about 4 €/kg with the enzymes supply as the major cost contribution.

Inulin is accumulated as a reserve carbohydrate in the roots and tubers of many plants belonging to the Asteraceae family. At present, most of the inulin for nutraceutical purposes is produced from Jerusalem artichoke (Helianthus tuberosus L.) and Chicory (Cichorium intybus L.), and cardoon is proved to synthetize and store a high quantity of inulin in roots. Inulin in the roots of cardoon reaches the maximum content before the beginning of flowers formation in May. Due to the limited favorable period for harvesting the roots, storage plays a key role in the supply chain. The complete drying of cardoon roots before the storage has been proved to prevent the degradation of inulin up to 6 months of storage. Because drying is a costly operation, in the present study, energy-saving and the effect on percentage inulin content in cardoon roots dried at different moisture contents before storage were assessed. From 48.2% inulin retrievable at the beginning of the investigated period (100% dry matter), after 1 month of storage, about 2% reduction was recorded on average in H0 and H12.5 treatments, while about 10% reduction was shown (with no statistical differences) in treatments at higher moisture contents (TQ, H50, and H25). These values remained constant until the end of storage, except for TQ treatment, where inulin content decreased progressively up to 38.7% w/w. From an economic point of view, limiting the drying time and storing roots at a moisture content higher than 0% leads to an income loss of 2,000–3,000 €/t of roots. Therefore, full drying is the most cost-effective solution in the optic of producing the highest possible amount of inulin and could be avoided just in the case of immediate roots extraction and processing in a few days.

Microbial lipids are renewable platforms for several applications including biofuels, green chemicals, and nutraceuticals that can be produced from several residual carbon sources. Lignocellulosic biomasses are abundant raw materials for the production of second-generation sugars with conversion yields depending on the quality of the hydrolysates and the metabolic efficiency of the microorganisms. In the present work, wheat straw pre-treated by steam explosion and enzymatically hydrolysed was converted into microbial lipids by Lipomyces tetrasporus DSM 70314. The preliminary optimization of the enzymatic hydrolysis was performed at the bench scale through the response surface methodology (RSM). The fermentation medium and set-up were optimized in terms of the nitrogen (N) source and carbon-to-nitrogen (C/N) ratio yielding to the selection of soy flour as a N source and C/N ratio of 160. The bench scale settings were scaled-up and further optimized at the 10 L-scale and finally at the 50 L pilot scale bioreactor. Process optimization also included oxygen supply strategies. Under optimized conditions, a lipid concentration of 14.8 gL−1 was achieved corresponding to a 23.1% w/w lipid yield and 67.4% w/w lipid cell content. Oleic acid was the most abundant fatty acid with a percentage of 57%. The overall process mass balance was assessed for the production of biodiesel from wheat straw.

Kraft lignin conversion to value-added products is an alternative way to manage the main pulp and paper secondary stream thus contributing to reducing avoid greenhouse gas emissions compared to equivalent fossil-based processes. Process simulation and integration can help to identify the most promising pathways and increase the profitability of the process. This work presents results of a comparison between the process optimization of two different potential products that were modeled and analyzed. Aromatic monomers and phenol-formaldehyde resins were considered as possible products by means of alternative process pathways, including hydrothermal liquefaction, hydrodeoxygenation, pyrolysis, dissolution with deep eutectic solvents, hot water extraction, and resin synthesis. Mixed-integer nonlinear programming was applied to optimize the superstructure and obtain the maximum lignin cost. A sensitivity analysis in terms of the final products selling price was performed to consider the market variability. Minimum selling prices of aromatic monomers and phenol-formaldehyde resins for a feasible lignin process were calculated. Maximum lignin cost larger than 100 €/t resulted acceptable only for phenol-formaldehyde resins selling price larger than 0.6 €/kg or for AM selling price larger than 1.80 €/kg. Aromatic monomers turned out to be the optimal product if its selling price is larger 1.20 €/kg and the phenol-formaldehyde resins cost is lower than or equal to 0.6 €/kg. Higher phenol-formaldehyde resins selling prices make this product more convenient.

Lignocellulosic biomass, including both herbaceous and woody feedstock, is currently widely used in many biorefineries. The lignin fraction (20-35 %DRY) is typically thermochemically converted into the cogeneration section of the biorefinery to produce heat and electricity. However, lignin holds a greater potential in several industrial sectors to produce biobased materials and several chemical building blocks. In particular, novel technologies allow obtaining low molecular weight compounds, such as aromatic or hydrocarbons. In this work, a mathematical methodology was developed to evaluate the best option in terms of lignin valorization. A process superstructure was built to compare alternative process pathways from lignocellulosic biomass. The following conversion options were considered: jet-fuels (JF), phenol-formaldehyde resins (PFR), polyurethane foams (PUF), and syngas for green electricity generation. By AIMMS optimization software, a Mixed Integer Linear Programming (MILP) was applied to obtain a simplified mathematical analysis and, consequently, the maximum lignin cost maximization for each lignin valorization process. In particular, process conversion, required utilities, product values were assessed for each process technology. Preliminary results show that the production of phenol-formaldehyde resins is the process closer to the market uptake. On the other side, polyurethane and jet-fuels appear still far from the market and their production would be feasible at a polyurethane foams and jet-fuel selling price at 300 % of the current selling price.

Crude glycerol is the main by-product of the biodiesel manufacturing industry (10% w/w). Its use as a substrate in microbial fermentations is a concrete strategy to efficiently address its market surplus. In this study, the conversion of crude glycerol to citric acid, a key biochemical in the emerging bioeconomy, by a wild-type yeast Yarrowia lipolytica DSM 8218 was modelled using the Response Surface Methodology. The model relates C/N mass ratio and crude glycerol concentration to maximize the citric acid yield in flask scale using two different N sources, yeast extract and ammonium sulphate. Under the optimal conditions (yeast extract, C/N 141, glycerol 33 g/L), the conversion yield was 0.249 g/g. The optimal conditions were used for up-scaling a fed-batch fermentation in a 2 L bioreactor highlighting a metabolic shift from mannitol to citric acid when high stirring rates were applied (800 rpm). In these conditions, a morphic transition from pseudo-mycelial form to round-shaped yeast-like cells was observed too.

Abstract Background Some lignocellulosic biomass feedstocks occur in Mediterranean Countries. They are still largely unexploited and cause considerable problems due to the lack of cost-effective harvesting, storage and disposal technologies. Recent studies found that some basidiomycetous yeasts are able to accumulate high amount of intracellular lipids for biorefinery processes (i.e., biofuels and biochemicals). Accordingly, the above biomass feedstocks could be used as carbon sources (after their pre-treatment and hydrolysis) for lipid accumulation by oleaginous yeasts. Results Cardoon stalks, stranded driftwood and olive tree pruning residues were pre-treated with steam-explosion and enzymatic hydrolysis for releasing free mono- and oligosaccharides. Lipid accumulation tests were performed at two temperatures (20 and 25 °C) using Leucosporidium creatinivorum DBVPG 4794, Naganishia adeliensis DBVPG 5195 and Solicoccozyma terricola DBVPG 5870. S. terricola grown on cardoon stalks at 20 °C exhibited the highest lipid production (13.20 g/l), a lipid yield (28.95%) close to the maximum theoretical value and a lipid composition similar to that found in palm oil. On the contrary, N. adeliensis grown on stranded driftwood and olive tree pruning residues exhibited a lipid composition similar to those of olive and almonds oils. A predictive evaluation of the physical properties of the potential biodiesel obtainable by lipids produced by tested yeast strains has been reported and discussed. Conclusions Lipids produced by some basidiomycetous yeasts grown on Mediterranean lignocellulosic biomass feedstocks could be used as supplementary sources of oils for producing biofuels and biochemicals.

Wheat straw is an abundant source of lignocellulosic biomass that is generally not utilized for biofuel production, nor for other uses. Recent EU renewable energy directive fosters bioethanol production through lignocellulosic sugars fermentation, but the cost of this process is an issue that often depends on biomass characteristics. Lignin is a class of three-dimensional polymers providing structural integrity of plant tissues. Its complex structure, together with hemicelluloses and uronic acids content, could affect the ability of hydrolyzing biomass to fermentable sugars. To get insights into this variation, a set of 10 durum wheat genotypes was analyzed to determine variation of straw digestibility to fermentable sugars. The results showed that the lignin content was the major factor determining the recalcitrance to enzymatic process. The analysis of Spearman’s correlation indicated that the sugar released after enzymatic hydrolysis had a negative connection with the lignin content, while it was positively correlated with the culm length. The possible role of other cell wall components, such as arabinose and uronic acids, was also discussed. This work aimed at analyzing the diversity of lignocellulosic digestibility to fermentable sugars of wheat straw in a small germplasm collection. Some of the selected genotypes were characterized by high sugars digestibility and high grain yield, characteristics that could make biorefining of wheat straw profitable.

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.