Large-scale Biorefineries Research Articles

Application of P-graph Techniques for Efficient Use of Wood Processing Residues in Biorefineries

It is anticipated that demand for chemicals and fuel derived from sustainably grown bio-mass will increase over the coming decades. Forest and wood processing residues and waste are likely to become a significant feedstock to large scale biorefineries to produce both renewable fuels and chemicals. Maximising the economic value of these residues whilst simultaneously minimising the environmental impact of the manufactured product is an important task in process and product selection and design. Multiple processing and product pathways exist and it is often unclear what the best options are without detailed assessment or preliminary design. The P-graph framework was used to examine the economically feasibility of utilising five types of wood processing residues: wood chip, pulp logs, saw dust, and landing and cutover residues. Twenty different products were considered, based on three main production platforms or routes, sugars, pyrolysis, and gasification. Kraft pulp production and energy products were also considered as viable options for residues. Only six of the products considered were found to be profitable with the most economically viable uses being kraft pulp production and boiler fuel. Products included in the feasible solutions and the source of residues are all finely balanced, and slight changes in feedstock cost, product price, and operational and capital costs can cause major changes to the feasible structures. When heat integration for using Total Site was incorporated into the P-graph there was no economic benefit for the routes and scale of production considered here.

Utilization of Seawater for the Biorefinery of Lignocellulosic Biomass: Ionic Liquid Pretreatment, Enzymatic Hydrolysis, and Microbial Lipid Production

The biorefineries of lignocellulosic biomass have attracted increasing interest recently. However, large water consumption in the large-scale biorefineries remains a major problem. In this work, utilization of abundant seawater as an alternative to freshwater for ionic liquid (IL) pretreatment of lignocellulosic biomass was reported for the first time. In addition, enzymatic hydrolysis of IL-pretreated biomass and microbial lipid production from wheat straw hydrolysate were conducted in seawater. It was found that seawater had no significantly negative effect on enzymatic hydrolysis as well as IL pretreatment. After grass lignocelluloses were pretreated by 50% cholinium IL–seawater mixtures at 90 °C for 6 h and washed by seawater, the residues became highly susceptible to enzymatic hydrolysis; the reducing sugar yields of 54–72% were obtained in pH 4.8 seawater in the subsequent enzymatic hydrolysis of the residues. The lipid yield of 4.5 g/L and lipid coefficient of 0.21 g/g of sugar were achieved after cultivation of Trichosporon fermentans on wheat straw hydrolysate with the sugar concentration of approximately 30 g/L for 3 days.

English

Every year large amounts of residues accumulate from potato processing. The aim of this study is to develop a process to valorize these residues as feedstock for lactic acid fermentation in a way that is suitable for industrial production. An enzymatic hydrolysate obtained from potato residues (46 % w/w dry mass starch) was used as a substrate in batch and fed-batch fermentations with Lactobacillus casei. Supplementation of yeast extract (3 g L–1) was required to improve productivities. Despite the inhibitory effect exerted by phenolic compounds in the medium, reasonably high lactic acid concentrations (102 g L–1) and yields (92 %) were obtained, with 92 % (L-isomer) optical purity. It was clearly demonstrated that potato residues are suitable as feedstock for large-scale production of technical grade lactic acid and that the developed process is promising for large-scale biorefinery applications.

Salt-responsive lytic polysaccharide monooxygenases from the mangrove fungus Pestalotiopsis sp. NCi6.

BackgroundLytic polysaccharide monooxygenases (LPMOs) belong to the “auxiliary activities (AA)” enzyme class of the CAZy database. They are known to strongly improve the saccharification process and boost soluble sugar yields from lignocellulosic biomass, which is a key step in the efficient production of sustainable economic biofuels. To date, most LPMOs have been characterized from terrestrial fungi, but novel fungal LPMOs isolated from more extreme environments such as an estuary mangrove ecosystem could offer enzymes with unique properties in terms of salt tolerance and higher stability under harsh condition.ResultsTwo LPMOs secreted by the mangrove-associated fungus Pestalotiopsis sp. NCi6 (PsLPMOA and PsLPMOB) were expressed in the yeast Pichia pastoris and produced in a bioreactor with >85 mg L−1 for PsLPMOA and >260 mg L−1 for PsLPMOB. Structure-guided homology modeling of the PsLPMOs showed a high abundance of negative surface charges, enabling enhanced protein stability and activity in the presence of sea salt. Both PsLPMOs were activated by a cellobiose dehydrogenase (CDH) from Neurospora crassa, with an apparent optimum of interaction at pH 5.5. Investigation into their regioselective mode of action revealed that PsLPMOA released C1- and C4-oxidized cello-oligosaccharide products, while PsLPMOB released only C4-oxidized products. PsLPMOA was found to cleave polymeric cellulose in the presence of up to 6 % sea salt, which emphasizes the use of sea water in the industrial saccharification process with improved ecological footprints.ConclusionsTwo new LPMOs from the mangrove fungus Pestalotiopsis sp. NCi6 were found to be fully reactive against cellulose. The combined hydrolytic activities of these salt-responsive LPMOs could therefore facilitate the saccharification process using sea water as a reaction medium for large-scale biorefineries.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0520-3) contains supplementary material, which is available to authorized users.

Appropriate biorefining strategies for multiple feedstocks: Critical evaluation for pretreatment methods, and hydrolysis with high solids loading

Efficient utilization of a wide range of feedstocks requires appropriate biorefining strategies based on pretreatment methods. This study showed that alkali pretreatment was significantly more effective than acid pretreatment at similar processing conditions for grass and hardwood biomass samples; but, both methods were ineffective for softwood biomass. Separate glucose and xylose streams can be obtained for efficient fermentation from acid-pretreated biomass; nevertheless, need for more severe processing conditions to achieve effective pretreatment necessitates an additional detoxification step. High sugars concentration (10.6%, w/v) in hydrolyzates was obtained from alkali-pretreated biomass using optimum solids loading of 17.5% (w/v), which opens up an opportunity to produce high concentrations of biofuels and biochemicals in fermentation broth at reduced downstream processing costs. We propose a schematic for innovative biorefining strategies based on established pretreatment methods for different types of feedstocks. This information is very pertinent for choosing the appropriate processing methods and for setting up large-scale biorefineries utilizing multiple feedstocks.

Magnetic Co/Al2O3 catalyst derived from hydrotalcite for hydrogenation of levulinic acid to γ-valerolactone

The efficient hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) over a hydrotalcite-derived non-precious metal Co/Al2O3 catalyst was achieved. Its core-shell structure and a strong interaction between Co and Al species stabilized the Co particles against leaching and sintering. This magnetic non-precious metal catalyst showed a comparable catalytic performance to a commercial Ru/C for the liquid hydrogenation of LA. It was easily separated from the reaction medium with an external magnet. The catalyst exhibited excellent recyclability, complete LA conversion and >99% GVL selectivity, and would be useful in a large scale biorefinery.

Comparing alternative cellulosic biomass biorefining systems: Centralized versus distributed processing systems

This study explores how two different cellulosic ethanol production system configurations (distributed versus centralized processing) affect some aspects of the economic and environmental performance of cellulosic ethanol, measured as minimum ethanol selling price (MESP) and various environmental impact categories. The eco-efficiency indicator, which simultaneously accounts for economic and environmental features, is also calculated. The centralized configuration offers better economic performance for small-scale biorefineries, while the distributed configuration is economically superior for large-scale biorefineries. The MESP of the centralized configuration declines with increased biorefinery size up to a point and then rises due to the cost of trucking biomass to the biorefinery. In contrast, the MESP in the distributed configuration continuously declines with increasing biorefinery size due to the lower costs of railroad transportation and the greater economies of scale achieved at much larger biorefinery sizes, including biorefineries that reach the size of an average oil refinery—about 30,000 tons per day of feedstock. The centralized system yields lower environmental impacts for most impact categories than does the distributed system regardless of the biorefinery size. Eco-efficiency analysis shows that the centralized configuration is more sustainable for small-scale biorefineries, while the distributed configuration with railroad transport is more sustainable for large-scale biorefineries. Compared with gasoline from petroleum, cellulosic ethanol fuel offers sustainability advantages for the following environmental impact categories: fossil energy consumption, global warming, human health impacts by particulate matter, ozone layer depletion, ecotoxicity, human health cancer, and human health non-cancer, depending somewhat on the biorefinery sizes and the system configurations.

Stabilization of Cobalt Catalysts by Embedment for Efficient Production of Valeric Biofuel

We herein report, for the first time, a bifunctional base-metal catalyst (Co@HZSM-5) that acts as an efficient alternative to noble-metal catalysts (e.g., Pt, Ru) for the conversion of levulinic acid into valeric biofuel under batch and fixed-bed reactor conditions. The cobalt nanoparticles were embedded in HZSM-5 crystals and catalyzed the sequential hydrogenations of the ketone and alkene functional groups; meanwhile, the acidic zeolite catalyzed the ring opening of the γ-valerolactone intermediate. Although base metals (e.g., Co) are abundant and inexpensive, their sintering and/or leaching under liquid-phase conditions always lead to the irreversible deactivation of the catalyst. In this system, the embedment structure stabilizes the nanoparticles, and Co@HZSM-5 could be used up to eight times. This work provides a practical clue toward the stabilization of base-metal catalysts and will inspire the development of large-scale biorefinery.

Biorefinery product potentials using tree biomass as feedstock – A survey on opportunities and threats to the new wood products industry

A questionnaire survey on the potential of biorefinery products was carried out along with an analysis of energy prices and wood assortments. Electricity production was considered to have the potential for the highest investment return over ten years, followed by solid wood products, bioenergy assortments and textiles. Only pulp and paper were perceived as returning lower potential investment values over the next ten years than over the next five. Of the survey respondents, 95% believed that the value of woody biomass will increase over the next ten years, mainly through its replacement of oil-based products, although there will be problems due to lack of suitable raw material. A wide range of chemical products were described but a greater confidence in more traditional solid fuel products still prevails. Stemwood is the most favored part of the tree with only a few respondents saying that they wanted specific chemicals extracted. The electricity price and wood fuel price were found to be strongly correlated and 91% of respondents said their products would be affected by the electricity price. Electricity prices within OECD countries are expected to increase by 15% from 2011 to 2035, with wood fuel prices increasing by roughly 10% during the same period. Therefore, the electricity price could become a decisive factor in the future use of biomass in biorefineries. Our results suggest that large-scale commercial biorefinery production will soon be possible but new wood assortment classifications are needed that include both fiber properties and chemical properties such as extractive content.

Optimization of sugar release from sweet sorghum bagasse following solvation of cellulose and enzymatic hydrolysis using response surface methodology

To release sugars effectively from sweet sorghum bagasse (SSB), a cellulose solvent and organic solvent-based lignocellulose fractionation pretreatment approach was studied using response surface methodology (RSM). Based on RSM's central composite design, a batch experimental matrix was set up to determine the effects of reaction time (20-60 min) and temperature (40-60 °C) on delignification, total reducing sugar yield, glucan digestibility, and overall glucose yields following a pretreatment-hydrolysis process. The optimum pretreatment conditions of 50 °C and 40 min led to 51.4% delignification, 86% overall glucose yield, and 61% overall xylose yield. An effort has also been made to obtain predictive models to illustrate the correlation between independent and dependent variables using RSM. The significance of the correlations and adequacy of these models were statistically tested for the selected objective functions. The optimum pretreatment condition predicted by the model was 49.1 °C and 39.2 min which matched the experimental data well. Results from this study can be applied to large scale biorefineries using sugars released from SSB for producing various biofuels.

On the Use of Seawater as Reaction Media for Large‐Scale Applications in Biorefineries

AbstractBiorefineries are expected to take over the production of chemicals and biofuels in the coming decades, in parallel to the depletion of fossil resources. Considerable research efforts have been made to develop efficient (bio)catalytic systems for the production of bio‐based solvents and novel products with improved ecological footprints and “smart” properties. Among other challenges, water consumption will be an important aspect to assess in the full sustainability of biorefineries, which are envisaged for large‐scale operations. The already existing fresh water shortage in many regions of our overpopulated planet has brought more pressure and uncertainties to these aims. Thus, over the past years, a number of enzymatic, fermentative, and chemocatalytic applications using seawater as a reaction medium for large‐scale biorefineries have been reported by several research groups, which emphasize the use of nonpotable water resources for coastal regions and for locally available biomass (e.g., algae). This article contextualizes in detail these seawater‐based applications for biorefineries. Overall, the use of such nonpotable water resources is promising, provided that applied catalytic systems can lead to straightforwardly treatable waste(sea)water effluents. Opportunities at the interface between biology, chemistry, and chemical engineering are foreseeable for (holistic) innovation and further research.

Optimal configuration and combination of multiple lignocellulosic biomass feedstocks delivery to a biorefinery

Biomass availability and transportation are major challenges in establishing a large-scale biorefinery. The objective of this study was to assess the delivery cost of different combinations of multiple forms of lignocellulosic feedstocks including agricultural and woody biomass. Three types of biomass i.e., wheat straw, corn stover and forest biomass were considered in different forms such as loose biomass, bales/bundles, chopped/chipped and pellets. It was found that the delivery cost of a combination of woody and agricultural biomass feedstocks is lower than that for a single type of biomass. The delivery of agricultural residues as bales and woody biomass as chips is an economically attractive option with optimal combination of 30% bales and 70% wood chips to a biorefinery of capacity 5000 dry tonnes per day. The anticipated traffic congestions resulting from biomass supply to a large facility could be significantly reduced by increasing the density of biomass.

New Biofuels Industry: Biomass Availability and Supply Chain

Biomass Availability This was addressed through both oral presentations and posters. An update was given on the Billion-Ton Resource Assessment report by Bob Perlack. The original report was published in 2005 and estimated the current and potential availability of biomass feedstocks. The potential was projected as approximately 1.3 billion tons and was what might be reasonably available around midcentury when large-scale biorefineries are likely to exist. The report emphasized primary sources of forestand agriculture-derived biomass such as logging residues, fuel treatment thinnings, crop residues, and perennially grown grasses and woody crops. These primary sources have the greatest potential to supply large sustainable quantities of biomass. Since publication of the Billion-Ton Resource Assessment, follow-up efforts have focused on updating the results, disaggregating the resource potential to counties and fine spatial scales, examining how the resource potential is affected by environmental sustainability, and answering questions involving what feedstocks will be used, when will they be used, what will be the costs, and what will be the economic impacts. Answers to these latter questions are focused on nearer-term time periods coincident with implementation of the Energy Independence and Security Act. Michael Blaylock highlighted corn stover as a potential biomass feedstock for cellulosic ethanol. Currently grown on more than 93 million acres in the USA and annually yielding 300 million tons of biomass that could produce up to about 25 billion gallons of cellulosic ethanol, its planting, cultivation, and harvesting costs can be shared with a popular cash Appl Biochem Biotechnol (2009) 154:268–270 DOI 10.1007/s12010-009-8612-1

Identification of optimal poultry litter biorefinery location in Alabama through minimization of feedstock transportation cost

AbstractThe estimated amount of poultry litter produced annually in Alabama is more than 1,250,000 tons. This large amount results in significant litter management challenges. Currently, poultry producers are facing many regulatory issues and challenges with respect to environmental impacts of litter management. Commercialization and implementation of environmentally benign biorefinery technologies have the potential to generate electric power (including on‐site power) and heat as well as transportation fuels, hydrogen, valuable chemicals, and fertilizer from poultry litter economically while addressing environmental problems caused by traditional disposal practices.In this study, poultry litter generated annually in northern and southern Alabama was documented on the basis of published literature, and transportation cost of poultry litter is minimized for both north and south Alabama by the selection of the best large‐scale biorefining facility location and optimal feedstock allocation using mathematical optimization techniques. The available portion of the existing poultry litter feedstock for a large scale biorefinery is found to be an important factor in determining transportation cost. Transportation cost increases several fold as the local feedstock availability for biorefining reduces from 100 to 50%. Optimum facility locations for both north and south Alabama were found within a 10 mile radius for three different poultry litter feedstock availabilities. © 2008 American Institute of Chemical Engineers Environ Prog, 2008