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- Efficient conversion of agricultural and forest residues into bioethanol: BIOFLEXPOR as flexible technology towards sugar-based biorefineries [Poster]Publication . Marques, Susana; Paixão, Susana M.; Alves, Luís; Gomes, Miguel; Eusebio, Ana; Lopes, Tiago; Coelho, Lucas; Diebold, Eduardo; Gírio, FranciscoABSTRACT: Lignocellulosic ethanol is in the upfront of advanced biofuels to be commercialized worldwide. However, the commercial deployment of 2G ethanol is dependent of high biomass availability and cost-effective supply. In Europe, some agricultural residues are presently underused and constitute attractive renewable resources. In addition, residual forest biomass, non-seasonably available at low cost, might be complementarily used as raw material boosting the economy of biorefineries. In this context, the present work deals with the development of an innovative and sustainable technological strategy to produce advanced bioethanol using agricultural and forestry residual biomass. The bioprocess involves enzymatic hydrolysis of major lignocellulose polysaccharides (cellulose and xylan) with commercial enzymes and fermentation of the resulting sugars. A pre-treatment step should firstly be accomplished to make cellulose more amenable to hydrolytic enzymes, and the prototype is based on a proprietary non-catalysed steam explosion technology, i.e., without the addition of acids and using only high-pressure steam, called FLEXBIO™, which was initially developed in Brazil by the company STEX and since 2019 in partnership with LNEG. The proposed technology has been successfully demonstrated in a relevant environment (TRL 5) for the efficient conversion of corn stover, olive tree pruning and eucalyptus-based forest residual biomass, yielding close to 150 L of ethanol per metric tonne (dry basis) of biomass, corresponding to an overall yield close to 75% of maximal theoretical yield for glucan conversion. Both enzymatic hydrolysis and fermentation steps have achieved yields superior to 85% of the maximal theoretical conversion, and the optimization of process configuration, targeting the best integration with pre-treatment, is now under progress and higher yields will be expected. Given the higher xylan content of corn stover, both cellulose and xylan fractions are pursued. In addition, the upgrading potential of all wastewater streams will also be assessed, by studying the feasibility of its combined use to increase the ethanol yield as alternative to its use for biogas production through anaerobic digestion, with the goal to reach near-zero waste. In conclusion, the present study reveals the industrial potential of this flexible technology that might be applied to implement distinct small-scale sugar-based biorefineries by converting several lignocellulosic raw materials into distinct marketable biofuels/biomaterials, promoting the circular bioeconomy.
- Sugarcane bagasse delignification with potassium hydroxide for enhanced enzymatic hydrolysisPublication . Paixão, Susana M.; Ladeira, S. A.; Silva, Tiago; Arez, B. F.; Roseiro, J. Carlos; Martins, M. L. L.; Alves, LuísThe optimization of an alkaline pretreatment process for the delignification of sugarcane bagasse (SCB) to enhance the subsequent enzymatic hydrolysis was performed according to the Doehlert uniform shell design. In this experimental design, the effect of two factors—potassium hydroxide (KOH) concentration and autoclaving time at 121 C (1 atm)—on cellulose, hemicellulose, or the total polysaccharide and lignin content in SCB was evaluated. This response surface methodology revealed that KOH concentration is the factor that most influences the chemical characteristics of treated SCB (SCBt), with optimal conditions for the highest delignification being KOH in the range 5–10% (w/v) and an autoclaving time of 35 min, which provides an average of 97% total polysaccharides without inhibitor accumulation (furfural, 5-hydroxymethyl furfural) and #5% lignin. SCBt samples from two pretreatment conditions (KOH 3.25% – 13 min; KOH 10% – 35 min) were selected, based on the greatest delignification (70–74%) and polysaccharide availability (95–97%) after pretreatment, and further hydrolysed for fermentable sugar production. High sugar yields were obtained from both the pretreated samples (866 to 880 mg sugar per g biomass, respectively) in contrast with the 129 mg sugar per g raw biomass obtained from untreated SCB. These results demonstrate the effectiveness of KOH alkali pretreatments, which improves the overall digestibility of raw SCB polysaccharides from about 18% up to 91%. However, harsh alkali treatment (KOH 10%) is the most effective if the highest glucose/xylose ratio in the final sugar-rich hydrolysate is the aim. Hence, the use of sugar-rich hydrolysates obtained from SCBt as the carbon source for industrial purposes may provide a sustainable and economic solution for the production of bio-based added-value products, such as second generation (2G) bioethanol.
- KOH for enhanced sugarcane bagasse delignification and further production of sugar-rich hydrolyzates by enzymes applicationPublication . Paixão, Susana M.; Ladeira, S. A.; Arez, B. F.; Martins, M. L. L.; Roseiro, J. Carlos; Alves, LuísLignocellulosic biomass is envisaged as an important raw material for bioethanol production due to its low cost and high availability. Sugarcane bagasse (SCB), a fibrous residue of cane stalks left over after crushing and extraction of the juice from sugarcane; it is one of the largest cellulosic agro-industrial by-products. Tons of SCB are produced in Brazil as a waste of sugar and ethanol industries. This lignocellulosic by-product is a potential renewable source for 2G-bioethanol production. Usually, SCB is pretreated using alkaline and/or acid treatments viewing higher ethanol yields. The main goal of this study was to optimize the delignification of SCB towards the higher availability of glucans and xylans for further enzymatic hydrolysis to obtain sugar-rich syrups that will be more readily fermented to bioethanol. The delignification was carried out by autoclaving the biomass with KOH and the influence of KOH concentration (1-10%) and the autoclave time (10-60 min) were evaluated through a statistical design. Experimental distribution for two factors according to the Doehlert uniform design was used to produce response surfaces. The responses studied in this design were the percentage of hemicellulose, lignin and total polysaccharides. The results showed that from the two factors evaluated, the KOH concentration was the one that most influenced the response observed and that the treatments of SCB with KOH 5-10% for 35 minutes of autoclave at 121ºC and 1 atm led to the highest rates of lignin extraction. Using KOH treatment, a significant reduction of lignin content in SCB was observed, namely from 19% to 5%. Scanning electron micrographs of SCB pre-treated with 10% KOH for 35 minutes demonstrated a change in the structure of the material, with the appearance of broken structures, which can be attributed to the alkaline treatment. To validate the experiments, the SCB pretreated in the optimal conditions (95% of total polysaccharides) was further hydrolyzed with commercial enzymes and the enzymatic hydrolysis performance was evaluated.
- Exploring Scenedesmus obliquus and nannochloropsis sp. potential as a sustianable raw material for biofuels amd high added value compoundsPublication . Gouveia, Luisa; Batista, Ana Paula; Nobre, B. P.; Marques, Paula; Moura, Patrícia; Alves, Luís; Passarinho, Paula; Oliveira, Ana Cristina; Villalobos, Fidel; Barragan, Blanca E; Palavra, António F.In this work, the authors propose a microalga-based integrated system, where optimization of several energy vectors (biodiesel, bioethanol and bioH2) is highlighted under the concept of biorefinery (Project PTDC/AAC-AMB/100354/2008). This involves the integration of different processes such as oil and sugar extraction from microalgae for biodiesel and bioethanol production respectively, and bioH2 production from the whole and/or biomass leftovers. The extraction of high value added compounds, such as carotenoids, contributes to the economic viability of the overall process.
- Zygosaccharomyces bailii strain talf1 inulinases: a versatile tool for bioprocessesPublication . Paixão, Susana M.; Teixeira, Pedro D.; Silva, Tiago; Teixeira, A. V.; Alves, LuísFructans are one of the most abundant non-structural polysaccharides found in a wide range of plants. Inulin is a polydisperse fructan polymer composed by linear chains of b-2, 1-linked D-fructofuranose molecules terminated by a glucose residue through a sucrose-type linkage at the reducing end. Inulin or inulin-rich materials can be actively hydrolyzed into fermentable sugars (glucose and fructose) using inulinases and then further used within bioprocesses.
- BIOFLEXPOR Technology towards 2G Bioethanol Biorefineries [Poster]Publication . Marques, Susana; Lopes, Tiago; Paixão, Susana M.; Alves, Luís; Carvalheiro, Florbela; Coelho, Lucas; Diebold, Eduardo; Gírio, FranciscoABSTRACT: By 2030, decarbonizing the transport sector will become mandatory requiring the introduction of advanced biofuels into the market, with minimum targets of 1% in 2025 and 3.5% in 2030 in accordance with the RED II Directive. To avoid future biofuels imports, it is essential that an industrial cluster emerges in Portugal with the capacity to produce advanced biofuels, such as 2G Bioethanol. In this context, the team from Bioenergy and Biorefineries Unit (UBB) of LNEG (Laboratório Nacional de Energia e Geologia) has been actively working on the development of an innovative and fully integrated technological strategy to produce advanced bioethanol using agricultural and forestry residual biomass as sustainable feedstock. The target is the demonstration, at relevant environment, all stages of the production technology, enabling the direct obtention of a biofuel that complies with EN standards, allowing its immediate blending with other fuels, such as gasoline. The prototype is based on a proprietary non-catalyzed steam explosion technology, i.e., without the addition of acids and using only high-pressure steam, called FLEXBIO™, initially developed by the company Stex and since 2019 in partnership with LNEG. The LNEG team has also been conducting R&D aiming at the development of new yeasts and enzymes that enhance the conversion of both cellulosic and hemicellulosic fractions of biomass. All technology will be environmentally sustainable, in terms of GHG emissions and waste production, promoting the circular bioeconomy. This innovative technology for a 2G bioethanol biorefinery, enabling to obtain a biofuel with high energy quality and sustainable origin from different types of biomasses, has been demonstrated in a relevant environment (TRL 5) in a prototype simulating (at scale 1:15) the commercial installation, under the BIOFLEXPOR project. The consortium is led by the company Prio Bio, S.A., the largest producer of biofuels in Portugal, and includes, in addition to LNEG, I.P., teams from CBE (Centro de Biomassa para a Energia) and Florecha – Forest Solutions, S.A. (Forest Solutions). The technology - under optimization but already demonstrated for the conversion of corn stover, olive tree pruning and eucalyptus-based forest residual biomass, yielding close to 150 L Ethanol /ton biomass (oven-dried weight) - will respond to a lack of economically viable technical solutions for small-scale biorefineries that process 200-700 tons/day of biomass, corresponding to a nominal bioethanol production capacity of 10,000-30,000 ton/year. It may therefore be close to a commercial application, which will be of strategic importance for the BIOFLEXPOR consortium, and for the LNEG team.
- Microalgae as a sustainable raw material for biofuels production and high added value compounds extraction by an integrated biorefinary conceptPublication . Gouveia, Luisa; Matos, Cristina T.; Oliveira, Ana Cristina; Passarinho, Paula; Miranda, J. R.; Paulo, V.; Marques, Paula; Batista, Ana Paula; Moura, Patrícia; Alves, Luís; Ortigueira, Joana; Nobre, B. P.; Palavra, António F.
- Evaluation of Jerusalem artichoke as a sustainable energy crop to bioethanol: energy and CO(2)eq emissions modeling for an industrial scenarioPublication . Paixão, Susana M.; Alves, Luís; Pacheco, R.; Silva, Carla M.ABSTRACT: An alternative to the sugar/starch-based crops bioethanol is lignocellulosic biomass, but its utilization to biofuels is still not economically viable. In this context, an increasing interest has arising on the search for specific energy crops that do not require arable lands and are not water intensive, such as Jerusalem artichoke (JA). So, this work consisted on the cultivation of JA on those agricultural conditions and its further evaluation as a sustainable feedstock towards bioethanol. Two strategies of producing bioethanol were evaluated pointing out for the consolidated bioprocessing with the Zygosaccharomyces bailii Talf1 yeast as the best approach for further scale-up, based on energy data analysis and ethanol productivity. Different industrial scenarios were outlined and compared for overall CO(2)eq emissions and energy consumption per liter of ethanol (L-EtOH), using adequate criteria on a cradle-to-gate approach. With no land-use change, no biogenic and no co-products credits, the comparison of the overall energy consumption and CO(2)eq emissions (100% process) from JA ethanol (9 MJ/L-EtOH; 679 g CO2/L-EtOH) with sugarcane/sugar beet ethanol (42/29 MJ/L-EtOH; 731/735 g CO2/L-EtOH) and with gasoline refinery (15 MJ/L-EtOH eq; 1154 g CO2/L-EtOH eq), highlights the JA as an alternative feedstock to be a focus of ethanol research for gasoline blends.