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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.
- Fermentation of xylose-rich substrates by the haloarchaeon halorhabdus utahensis towards high value-added bioproducts [Poster]Publication . Alves, Luís; Paixão, Susana M.; Silva, Tiago; Squillaci, G.; Serino, I.; Morana, A.ABSTRACT: Research that focuses on the use of high value-added bioproducts for industrial applications is essential for the implementation of sustainable approaches forecasting a bio-based economy. The effective use of biomass feedstocks, particularly lignocellulosic materials, in large-scale applications will evolve from innovative research aimed at the development and implementation of biorefineries established for specific feedstocks. In this context, an important step is the concept of fractionating biomass into its core constituents (cellulose, hemicellulose and lignin) for further enhanced valorization. Contrary to the valorization of cellulose fraction, which has been extensively studied, there is a gap in the valorization of the hemicellulose fraction (xylose- rich substrate) towards bioproducts. In this context, the present work aims to explore the ability of the haloarchaeon Halorhabdus utahensis (DSM-12940) to ferment xylose (or xylose-rich substrates) to high added-value bioproducts, such as pigments, exopolysaccharides (EPS) and polyhydroxyalkanoates (PHAs).
- Biodesulfurization biorefinery using Gordonia alkanivorans strain 1B: life cycle inventory of the integrated processPublication . Silva, Tiago; Silva, Carla; Paixão, Susana M.; Alves, LuísABSTRACT: High sulfur concentrations are a problem common to fossil fuels and derivatives (such as oil and coal), as well as many new generation fuels and biofuels (such as pyrolysis oils, syngas, biogas or even biodiesel). If the sulfur present in these fuels is released into the atmosphere it can result in SO2/SOx emissions, leading to environmental damage, and health issues. Transportation fuels have sulfur limits that go below 5000 ppm in ships, 3000 ppm in airplanes and 10 ppm in cars, and without treatment fuels can have several thousand ppm of sulfur. As such, they must be submitted to desulfurization, typically through a thermochemical process known as hydrodesulfurization, in which H2 is combined with the fuel at high temperatures and pressures, in the presence of metal catalysts. However, this process has significant environmental impacts. Usually, it depends on hydrogen and heat/steam produced from natural gas, totalizing 4.17 kg natural gas per 2.89 kg sulfur removed. It also involves high electricity and water consumption (approximately 2.9 kWh and 86.9 kg, respectively, per 2.89 kg sulfur removed). Furthermore, these impacts are greater for lower sulfur demands (Burgess & Brennan, 2001). Thus, there has been a search for alternative/complementary processes, one of which is biodesulfurization (BDS). It consists of the use of microorganism that consume the sulfur present in the fuels, at ambient temperature and pressure, without the need for metal catalysts. BDS still presents several bottlenecks, common to many microbial processes, such as low conversion rates and high production costs for the microbial biocatalyst. To surpass these limitations researchers have pursued different strategies: minimization/optimization of culture medium and culture conditions; employment of cheaper alternative nutrient sources; exploitation of added value products. Gordonia alkanivorans strain 1B is a bacterium known for its biodesulfurization properties. It has demonstrated several characteristics which make it interesting: it can perform BDS of different compounds, several of which extremely recalcitrant for the thermochemical process; it has very low nutritional needs; it can be cultivated on several alternative carbon sources; it has been shown to produce two different types of added value products: carotenoids and biosurfactants (Alves et al., 2015; Silva et al., 2020, 2022). Therefore, G. alkanivorans strain 1B is the ideal candidate for a biodesulfurization biorefinery, that simultaneously removes sulfur from fuels and produces carotenoids and biosurfactants.
- Optimization of a biphasic biodesulfurization systemPublication . Silva, Tiago; Paixão, Susana M.; Roseiro, J. Carlos; Alves, LuísABSTRACT: Many of the new generation fuels, although more sustainable, share some of the problems inherent to fossil fuels. Depending on the biomass/material that originated them, they can present different contaminants that can lead to environmental problems. Sulfur is one of the most common and problematic contaminants in fuels. It is released into the atmosphere in the form of SOx, leading to the formation of acid rains, which cause drastic environmental and infrastructural problems, as well as several types of health issues. High sulfur concentrations in fuels also result in a loss of efficiency of motors and energy generation systems, mostly due to corrosion and catalyst poisoning. The current thermochemical desulfurization process, hydrodesulfurization (HDS), is energy demanding, pollutant and has low efficiency against more complex organosulfur molecules. This led researchers to look for new alternatives. Biodesulfurization (BDS), is, as the name implies, the biological removal of sulfur from fuels using microorganisms as living biocatalysts. If correctly employed this process could be more efficient and less pollutant, since microorganisms directly target the sulfur atoms, even those present in complex molecular structures, such as dibenzothiophene (DBT). Moreover, microbial activity occurs at much lower temperatures and pressures, without the need for metal catalysts, resulting in a lower energy demand. While BDS is a promising technology, it is still at a low development stage, mostly due to some bottlenecks, which have been hindering its large-scale application. Similarly, to other biotechnological processes, it presents lower reaction rates, when compared to HDS, since it depends on the use of living organisms as catalysts. Furthermore, it must be performed under conditions that allow the microorganisms to maintain biological activity, limiting the range of applications. These conditions vary greatly depending on the microorganism selected, and their optimization can significantly increase the biodesulfurization activity of a biocatalyst.
- 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.
- Streamlining the biodesulfurization process: development of an integrated continuous system prototype using Gordonia alkanivorans strain 1B†Publication . Silva, Tiago; Paixão, Susana M.; Tavares, João; Paradela, Filipe; Crujeira, Teresa; Roseiro, J. Carlos; Alves, LuísABSTRACT: Biodesulfurization is a biotechnological process that uses microorganisms as biocatalysts to actively remove sulfur from fuels. It has the potential to be cleaner and more efficient than the current industrial process, however several bottlenecks have prevented its implementation. Additionally, most works propose models based on direct cultivation on fuel, or batch production of biocatalysts followed by a processing step before application to batch biodesulfurization, which are difficult to replicate at a larger scale. Thus, there is a need for a model that can be adapted to a refining process, where fuel is being continuously produced to meet consumer needs. The main goal of this work was to develop the first bench-scale continuous biodesulfurization system that integrates biocatalyst production, biodesulfurization and fuel separation, into a single continuous process, taking advantage of the method for the continuous production of the biodesulfurization biocatalysts previously established. This system eliminates the need to process the biocatalysts and facilitates fuel separation, while mitigating some of the process bottlenecks. First, using the bacterium Gordonia alkanivorans strain 1B, continuous culture conditions were optimized to double biocatalyst production, and the produced biocatalysts were applied in batch biphasic biodesulfurization assays for a better understanding of the influence of different factors. Then, the novel integrated system was developed and evaluated using a model fuel (n-heptane + dibenzothiophene) in continuous biodesulfurization assays. With this system strain 1B surpassed its highest biodesulfurization rate, reaching 21 μmol h−1 g−1. Furthermore, by testing a recalcitrant model fuel, composed of n-heptane with dibenzothiophene and three alkylated derivatives (with 109 ppm of sulfur), 72% biodesulfurization was achieved by repeatedly passing the same fuel through the system, maintaining a constant response throughout sequential biodesulfurization cycles. Lastly, the system was also tested with real fuels (used tire/plastic pyrolysis oil; sweet and sour crude oils), revealing increased desulfurization activity. These results highlight the potential of the continuous biodesulfurization system to accelerate the transition from bench to commercial scale, contributing to the development of biodesulfurization biorefineries, centered on the valorization of sulfur-rich residues/biomasses for energy production.