Kraft pulp and paper mills have several advantages for serving the emerging biorefinery industry as a source of raw materials. This review examines technologies for producing liquid biofuels, chemicals, and advanced materials from woody feedstocks to generate new sources of revenue. Market pull comes in part from government policies that drive substitution of petroleum-based products with biobased equivalents. Kraft mills have ample networks to supply feedstocks, whether these are forest residues or byproduct side streams. Pulp mills are well suited to expand sufficiently to accommodate production of value added platform chemicals that are in demand because of brand owner sustainability commitments.
Integrating a Biorefinery into an Operating Kraft Mill
Mark A. Johnson and Peter W. Hart *
Kraft pulp and paper mills have several advantages for serving the emerging biorefinery industry as a source of raw materials. This review examines technologies for producing liquid biofuels, chemicals, and advanced materials from woody feedstocks to generate new sources of revenue. Market pull comes in part from government policies that drive substitution of petroleum-based products with biobased equivalents. Kraft mills have ample networks to supply feedstocks, whether these are forest residues or byproduct side streams. Pulp mills are well suited to expand sufficiently to accommodate production of value added platform chemicals that are in demand because of brand owner sustainability commitments.
Keywords: Kraft pulping; Biorefinery; Biofuels; Biochemicals; Pyrolysis; Hydrothermal treatment; Enzymatic hydrolysis; Platform Chemicals
Contact information: WestRock Company, 501 South 5th Street, Richmond, VA 23219 USA;
* Corresponding author: firstname.lastname@example.org
Integrated biorefineries are potentially attractive options for enhancing the long-term viability of the pulp and paper industry as a balanced source of value-added products. Traditional kraft paper mill biorefineries have long produced methanol, lignin, tall oil fatty acids, rosins, and turpentine as byproducts that go into a wide range of chemical platforms and internal use (Ragauskas et al.2006; Thorp et al. 2011; Bruycker et al. 2014; Jobes 2015). Government sponsored research and subsidies for biofuels stimulated efforts in the pulp and paper industry to explore a wider range of options for producing chemicals. The scale and maturity of the kraft pulp industry in biomass logistics and operations can be used to leverage a biorefinery industry (Van Heiningen 2006; Amidon and Liu 2009; Zhang et al. 2011; Zhu et al. 2011; Christopher 2012; Lundberg et al.2013; Wertz and Bédué 2013; Alen 2014; Hakovirta 2014; Lundberg et al. 2014).
A growing demand for energy, scarcity of materials, and volatility in commodity markets are seen as opportunities for growth in the pulp and paper industry through a biorefinery strategy (Hämäläinen et al. 2011; Pätäri et al. 2011, 2016; Hansen and Coenen 2015; Hansen 2016; Panwar et al. 2016). Key challenges come from the risk associated with early stages of development and the need to engage in collaborative efforts across unfamiliar industries. The history of using forest products to create chemical and transportation fuel supply chains has been reviewed by several authors (Luque et al. 2008; Manzer et al. 2013; Guo et al. 2015; Klein-Marcuschamer and Blanch 2015). The last few years have seen a new wave of biorefining (Runge 2013; Vasara 2013).
Several projects have demonstrated paths to value from biomass, creating a need to sort out those where an integrated biorefinery at a kraft mill has some advantages. Value-added products from marginal side streams that replace petroleum-based feedstocks meet the aims and objectives of sustainability and economic development (Bugge et al. 2016). Fostering niche markets that arise out of underutilized or damaged forest resources will call for strategies of close collaboration and innovation across the value chain (McCormick and Kautto 2013; Lamers et al. 2014; Hansen 2016; Van Lancker et al. 2016).
RESEARCH AND COMMERCIAL DEVELOPMENT CENTERS
US and European initiatives focusing on biorefinery platforms support several well-funded centers of research and consortia. Early reviews of the founding years of these research center initiatives can be found in a US Department of Agriculture (USDA) publication (Rudie 2009) and the European Joint Biorefinery Vision for 2030 (Annevelink and van den Oever 2010).
Progress by the three US Department of Energy (DOE) Bioenergy Research Centers over the last 7 years (Joint BioEnergy Institute (JBEI Berkeley), Great Lakes Bioenergy Research Center (GLBRC Madison), and Bioenergy Science Center (BESC Oak Ridge)) has been reviewed recently (Peters 2014; Klein-Marcuschamer and Blanch 2015; Papoutsakis 2015; Slater et al.2015). Key research areas addressed were biomass supply, crop optimization, deconstruction of biomass, and conversion of biomass to fuels. Further research will focus on combining biochemical processes to produce intermediates that can be catalytically upgraded to biofuels and platform chemicals. Fermentation technology is emerging to yield a commercial path to platform chemicals and the biobased polymers (Papoutsakis 2015; Shen et al. 2015).
The USDA National Institute of Food and Agriculture (NIFA) invested $156 MM in seven regional advanced biofuel centers across the US (Sustainable Advanced Biofuels across the United States 2015). The Northwest Advanced Renewables Alliance (NARA) developed a process for converting wood residues to jet fuel while taking into consideration the sustainability of the entire supply chain (Northwest Advanced Renewables Alliance (NARA). 3rd cumulative report 2015). Reviews of biomass conversion projects for advanced biofuel development by the USDA Agricultural Research Service focused on residues and energy crops (Orts and McMahan 2016; Steiner and Buford 2016). A survey by the USDA Forest Service reviewed their research on pretreatment technologies for conversion of wood to ethanol, biomass gasification, and fuel pellet technology (Rudie et al. 2016).
Integrated biorefinery platforms applicable to kraft mills can be broadly divided into two categories: (1) combined heat and power and (2) chemicals and materials (Jansson et al. 2015). Products, processes, and feedstocks overlap between these categories. Future kraft mill biorefineries are expected to serve markets in composites that use nanocellulose or lignin-based carbon fiber, synthetic transportation fuels (synfuels), biobased polymers from sugar or syngas carbon, and value-added chemicals.
Biomass gasification to produce a synthetic gas (H2 + CO syngas) has been used to power lime kilns (Manning and Tran 2015). Fischer-Tropsch catalytic processes have been used to reform syngas into a broad range of hydrocarbons and yield excess heat that can be used to power an integrated pulp mill (Haikonen et al. 2011; Ljungstedt et al. 2013; Isaksson et al. 2014). Cleaned syngas can also be used as a carbon source in fermentation to give platform chemicals and biofuels (Nanda et al. 2013; Karatzos 2014; Shen et al. 2015).
Chemical platforms fall into several categories: sugars from hemicellulose and cellulose, phenolics from lignin, biogas from waste treatment, tall oil and turpentine byproducts, and pyrolytic liquids and gasses. Pyrolytic gasses and liquids can be formed by either fast pyrolysis in a dry state or hydrothermal liquefaction in water (Amidon et al. 2008; Thorp et al. 2011; Lundberg et al. 2013; Hu et al. 2016; Isikgor and Remzi Becer 2015; Taylor et al. 2015; Thorp et al. 2015; Wikberg et al. 2015; Matsakas et al. 2016; Wilson and Lee 2016).
Material platforms are based on upgrading hemicellulose, cellulose, and lignin to higher value materials. Xylans have shown oxygen and mineral oil barrier performance in packaging materials (Johansson et al. 2012; Mikkonen and Tenkanen 2012; Laine et al. 2013; Le Normand et al.2014). Nanocellulose has broad applications in packaging materials for surface smoothness, bending stiffness, and barrier performance (Lavoine et al. 2012; Li et al. 2015a; Osong et al.2015). Reports have shown active development of new pilot facilities for producing microfibrillated cellulose and nanocrystalline cellulose for exploratory development in the paper industry (Miller 2015; Nelson et al. 2016). A recent review covered a wide range of uses for cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) in advanced material applications such as biosensors, optoelectronics, and organic solar cells (Zhu et al. 2016). The optical and mechanical properties of CNF and CNC combined with biodegradability, biocompatibility, and ease of functionalization provide a unique path to sustainable materials. Nanocellulose has broad potential in biomedical applications (Lin and Dufresne 2014). Conversion of lignin to carbon fiber is active area of research (Gellerstedt et al. 2010; Strassberger et al. 2014; Chatterjee and Saito 2015; Beckham et al. 2016).
BIOREFINERIES IN THE PULP AND PAPER INDUSTRY
The pulp and paper industry explored several technologies for producing transportation fuels and sugar feedstocks over the last 10 years with limited success, mostly from upgrading traditional byproducts or focusing on sulfite mill (dissolving pulp) sugars from spent liquor (Magdzinski 2006; Mendell et al. 2011; Lai and Bura 2012; Rødsrud et al. 2012; Anon. 2014; Rueda et al.2015; Zhu et al. 2015; Rueda et al. 2016). Production of ethanol from sugars from sulfite liquors in the US was reported at 11,000 gallons per day in 1987 (Zerbe 1991). The Tembec Témiscaming sulfite mill in Canada had a capacity of 15 to 18 million liters of ethanol per year, roughly the equivalent of US production in 1987 (Magdzinski 2006; Williamson 2013).
Early work in kraft mill biorefineries focused on an indirect thermal process that transforms black liquor to gasses that can be recombined to transportation fuels using Fischer-Tropsch (FT) catalysis (Larson et al. 2006; Haikonen et al. 2011; Ljungstedt et al. 2013; Bajpai 2014; Isakssonet al. 2014; Mesfun et al. 2014; Mesfun and Toffolo 2015) . FT catalysis has been long established in the petroleum industry on a large scale, but only recently has it been considered viable on the small scale of a typical biorefinery through the invention of micro-channel reactors and fluidized bed steam reforming (Connor 2007a,b; LeViness et al. 2013). These technologies have been used for non-kraft pulp mills without adequate chemical recovery systems. Micro-channel FT reactors are now in development for Red Rock’s wood chip to jet fuel facility in Oregon (LeViness et al. 2014).
Selection of a pulp mill biorefinery design depends on analysis of pathways that factor in the supply chain, process integration technologies, and product and market access (Hytönen and Stuart 2012; Dansereau et al. 2014; Cambero et al. 2015; Kim and Dale 2015; Kokossis et al.2015). While the drivers for change toward a biorefinery solution in the forest products industry have been recognized, paths to commercial products are not well developed (Hänninen et al.2014; Marinova et al. 2014; Novotny and Laestadius 2014; Pätäri et al. 2016). There is a large array of potential technical and commercial paths without clear agreement on an optimum (Nanda et al. 2013; de Jong et al. 2015; Jungmeier et al. 2015; Maronese et al. 2015; Zhao et al. 2015). Analysis of potential forest biorefineries have been done based on SWOT analysis (strengths, weaknesses, opportunities, and threats) for several feedstock and process pathways (Chambost and Stuart 2007; Wagemann 2012; Kretschmer 2014). SWOT analyses are recommended as a method for identifying a path to value by showing unique strengths and the competitive environment (Chambost et al. 2007).
A SWOT analysis shown in Table 1 highlights the general benefits and challenges of having a biorefinery integrated with a kraft pulp mill. Integration offers a cost saving in shared energy resources, biomass supply lines, creating value from underutilized waste streams and manufacturing expertise. A more specific SWOT analysis is needed for each type of feedstock, process technology, and product combination, producing an array of SWOT matrices that define platforms and success factors (Kretschmer 2014).
Table 1. SWOT Analysis of a Biorefinery Integrated with a Kraft Pulp Mill
Several reviews give a detailed view of how biorefineries may be deployed in a kraft mill (Ragauskas et al. 2006; Hamaguchi et al. 2012, 2013; Hakovirta 2014; Mariano 2015). Detailed descriptions of biorefinery plans and early commercial development by location and technology are available (Pytlar 2010; Mendell et al. 2011; Cellulosic Biofuels – Industry Progress Report 2012-2013 2012; Tuuttila and Joelsson 2012; Bacovsky et al. 2013; Bergström and Matisons 2014; Laqua 2015). An updated summary of current biorefinery activities in the forest products industry is provided in Table 2. Dissolving pulp mills are not included.
Table 2. Biorefinery Efforts in the Chemical Pulping and Recycled Fiber Industry
Figure 1 shows some of the multiple options for extracting value from the process flow of a biorefinery integrated with a kraft mill (Hamaguchi et al. 2012). The main paths to fuels and chemicals are through wood residue, bark, pins, fines, or hog fuel that can be de-ashed, dried, and ground. Ground wood residues can be converted to bio-oil through pyrolysis or hydrothermal liquefaction. Bio-oil made from sawmill residues by Ensyn’s pyrolysis technology has been developed for industrial heating oil applications and partial substitution of petroleum (up to 5%) at a refinery. Ensyn calls this product Renewable Fuel Oil (RFO). Pyrolysis oils made from wood or lignin are beginning to find commercial applications as biofuels (Anon. 2014b). Recent reviews have covered pyrolysis technology development by sponsor, commercialization stage, feedstocks, and type of unit (Meier et al. 2013; Nanda et al. 2013).
Fig. 1. Process flow of a kraft mill with an integrated biorefinery (source: Hamaguchi et al. 2012)
Using high temperature pyrolysis or hydrothermal gasification, wood is converted to a syngas consisting mostly of carbon monoxide and hydrogen (Brown et al. 2014; Li et al. 2015c). Prior to upgrading, gases are cleaned of sulfur and nitrogen contaminants that could poison the catalyst in the next stage. Catalytic upgrading of syngas through Fischer-Tropsch (FT) or steam reforming can produce a range of biofuels. One of the products, di-methyl ether (DME) can be used in diesel applications (Wetterlund et al. 2011; Ljungstedt et al. 2013; Isaksson et al. 2014; Ail and Dasappa 2016). Red Rock Biofuels is one of three projects selected by the DOE for producing jet and diesel fuels. A plant capable of producing 12 MM gallons per year is in the planning stage using Velocys small scale micro-channelled FT reactor technology (LeViness et al. 2013; Becker et al.2015a; Güttel and Turek 2016).
Gasification of black liquor produces a syngas that can be upgraded to diesel fuels. Black liquor gasification has been studied in great detail and implemented at the Weyerhaeuser mill in New Bern, NC (Landälv et al. 2010). Challenges in chemical recovery and sulfur poisoning of the catalysts employed have been responsible for abandoning this technology at kraft mills (Landälv et al. 2010). Research on black liquor gasification is continuing in Scandinavia (Naqvi et al.2010; Andersson et al. 2015, 2016; Jafri et al. 2016).
Hot water extraction (HWE) of wood chips has long been considered as a route to hemicellulose that can be converted to useful polymers or hydrolyzed to fermentable C5 sugars. Under a short burst of high pressure and slightly acidic conditions hemicellulose and cellulose can be selectively hydrolyzed out of the lignocellulose complex to produce separate streams of fermentable sugars in two steps (Colakyan 2012; Silveira et al. 2015). Extraction of lignocellulose with sub-critical water has been developed by Renmatix in partnership with UPM and others to yield low-cost sugars and clean lignin.
Autohydrolysis is a process in which hot water extraction can be used to obtain hemicellulose and sugars prior to pulping. Acids removed from hemicellulose and extractive esters catalyze the removal of sugars (Amidon and Liu 2009). Extraction results in wood chips that are better suited for making fluff pulp, specialty papers or dissolving pulp than softwood based kraft pulp for packaging grades due to strength loss (Goyal 2015).
Chemical demand in pulping and bleaching decreases after extraction by autohydrolysis (Chirat et al. 2013; Goyal 2015). Increasing hot water extraction of Eucalyptus chips measured by a severity factor (p) showed that furan degradation products and lignin deposits can accumulate to the point where fermentation of the resulting sugars would not be cost effective (Liu et al. 2015). Extraction of Eucalyptus chips at low severity factor resulted in removal of the 35% of the hemicellulose and gave handsheets with acceptable paper properties.
Other products such as wood fiber composites, fuel pellets, dissolving pulp, and nanocellulose could be made from hot water extracted wood chips (Hasan et al. 2010; Pu et al. 2011; Bach and Skreiberg 2016; Zhu and Yadama 2016). Another use for kraft pulp made from hot water extracted chips may be in wood fiber composite pulps such as Södra’s DuraPulp that can be used for making formable products (Hasan et al. 2010; Melin 2015). Nanocellulose added back to a paperboard furnish made from hot water extracted chips could restore some of the strength properties lost during extraction (Nelson et al. 2016).
Utilization of wood sugars to make fermentation products could bring forest products into the mainstream of industrial biotechnology. Surveys of major development efforts in cellulosic biofuels made from 2012 to 2013 by the Advanced Ethanol Council (AEC), the DOE, and others showed more than a dozen significant investments in wood-based sugars and biofuels (Cellulosic Biofuels – Industry Progress Report 2012 – 2013 2012; Bacovsky et al. 2013; Balan et al. 2013; Brown and Brown 2013). Almost all of these companies are now out of business, drifted back to lower cost feedstocks (MSW), or have reverted to early stage R&D.
Pyrolysis-based technology leaders like Ensyn and BTG-Empyro remain with a focus on heating oil made from wood. Recent work has shown that pretreatments and process adjustments can give pyrolysis oils with a high content of levoglucosan, which can be hydrolyzed to glucose, potentially a viable path to wood sugars (Bennett et al. 2009; Sukhbaatar et al. 2014; Jiang et al.2015, 2016; Wang et al. 2016a). Fermentation using sugars from mild sulfite-based pulping technology continues to be developed with potential for repurposed kraft mills to dissolving pulp (Rakkolainen et al. 2010; Gao et al. 2013; Cheng et al. 2015; Zhu et al. 2015; Dou et al. 2016).
NICHE MARKETS FOR KRAFT MILL BIOREFINERY PRODUCTS
Niche products offer biorefinery operations an opportunity to improve economic feasibility by growing in markets where bio-based feedstocks are valued (Chambost and Stuart 2007; Scott 2016b). Fractionation processes like hot water, cold caustic, solvent, or ionic liquid extractions enable separation of the valuable components of wood (Kenealy et al. 2007). Hot water extraction of unbleached birch kraft pulp could separate out enough of the lignin and xylan to allow the pulp to be used in rayon grades (Borrega and Sixta 2013). Use of pH control during hot water extraction can optimize the yield and molecular weight of extracted hemicellulose (Krogell et al.2016). High molecular weight xylans are useful for packaging films that provide oxygen and mineral oil barrier properties (Grondahl and Bindgard 2013). Cold caustic extraction with polyethylene glycol helped preserve the yield, polydispersity, and molecular weight of xylans (Li et al. 2015b).
Ionic liquids are typically molten salts at temperatures less than 100 oC. The salts are generally composed of an organic cation and inorganic anion. Ionic liquids can be tailored to dissolve the components of wood selectively (Xie et al. 2009; Li et al. 2010). Ionic liquids can be used to produce regenerated cellulose fiber at higher yield and better strength than conventional Lyocell fiber due to less polymer degradation (Sixta et al. 2015). Ionic liquid pretreatments proved useful in dissolving hemicellulose to give a higher yield in saccharification (Viell et al. 2013). Hemicellulose films obtained from ionic liquid pretreatment gave better oxygen barrier properties than those prepared from cold caustic extraction (Laine et al. 2016). Reductive amination of aldehydes obtained from degradation products of lignin and hemicellulose could be used to make tertiary amines that form the cationic component of low cost ionic liquids (Socha et al. 2014). Finding effective low-cost ionic liquids and recovering them in high yield are major challenges in commercializing their use in biomass fractionation (Baral and Shah 2016).
Material substitutions of petroleum-based bulk chemicals such as adhesives, solvents, and surfactants can be seen as greener alternatives where sustainable sources have reduced impacts on the environment (Smith et al. 2014; Diorazio et al. 2016). The Australian company Circa Group developed a process to convert wood waste and other lignocellulosic materials to levoglucosenone. The latter compound then can be hydrogenated to dihydrolevoglucosenone (CyreneTM), a polar aprotic solvent similar to n-methylpyrrolidone (NMP) and sulfolane (Clark et al. 2015; Duncan 2015).
Another trend in green solvent development is a move toward reactions in aqueous media rather than petroleum based solvents. To facilitate these reactions, bio-based surfactants are needed. Effective xylose-based surfactants can be made by glycosylation with long chain alcohols using p-toluenesulfonic acid as a catalyst (Klai et al. 2015). Sugar-based surfactants are expected to have a significant role in commercial processes due to their improved biodegradability and reduced ecotoxicity (Rojas et al. 2009; Spence et al. 2009).
Commercial lignin production for uses other than generation of heat and power represents 2% of the total lignin produced. Commercial lignin is fragmented into several niche markets (Zakzeski et al. 2010; Strassberger et al. 2014; Upton and Kasko 2016). The largest fraction of lignin sold comes from sulfite mills as lignosulfonate. Borregaard LignoTech, TEMBEC, and Domjso Fabiker are suppliers of sulfite mill lignin. Ingevity, formerly MeadWestvaco’s Specialty Chemicals division, has long been a supplier of sulfonated and unmodified kraft lignin under the trade name INDULINTM (Holliday et al. 2007; Lake and Blackburn 2014). Newer sources of kraft lignin coming online are from the Lignoboost and LignoForce processes developed by Innventia and FP Innovations, respectively (Table 2) (Tomani 2010; Kouisni et al. 2012; Benali et al. 2014).
The Lignoboost process has been implemented at the Domtar mill in NC and the Stora Enso pulp mill in Sunila, Finland. Domtar mill lignin is marketed as BioChoiceTM. The LignoForce process is running at the West Fraser pulp mill in Hinton, Canada. Kraft lignins originating from cooking processes to produce low or high kappa pulp are expected to have different properties. Chemical differences in pine lignin between a bleachable-grade pulp (BioChoice) and a high kappa linerboard-grade pulp (INDULIN) have been analyzed (Hu et al. 2016). These two sources of lignin are similar, with slightly higher phenolic hydroxyl, enol ether, and stilbene contents in the BioChoice sample.
Kraft lignins have been extensively studied for commercial applications. Examples include renewable aromatics, substitutes for phenol formaldehyde in particle board, asphalt emulsifiers, carbon fiber, reinforced polyurethanes, activated carbon, and cement dispersions (Suhas et al.2007; Homma et al. 2010; Li and Ragauskas 2012; Aso et al. 2013; Zhao and Yan 2014; Graglia et al. 2015; Taverna et al. 2015; Sadeghifar et al. 2016). In the future, lignin will serve as a feedstock for a wide array of advanced materials (Kai et al. 2016; Upton and Kasko 2016).
The Billion Ton study was published by the DOE and USDA in 2005 and updated in 2011 and 2016. The study examined the feasibility of displacing 30% of the US consumption of petroleum by conversion of sustainable and affordable biomass (ORNL 2011). More than one billion tons of biomass would be commercially used to reach this goal, primarily by using agricultural residues, forest resources, energy crops, and municipal solid waste. This is a significant move away from currently available biofuels, which are dependent on food crops such as corn, sugarcane, and vegetable oils. Ultimately, dedicated energy crops consisting of grasses and short rotation woody plants such as willow and poplar will have a major role once these sources have been developed. The feasibility of utilizing resources at this scale is largely dependent on local availability, cost, and prospects for supply over decades (Kim and Dale 2015).
Mills producing lumber, plywood, and pulp generate about 87 million tons of lignocellulosic residues in the form of bark, sawdust, fines, and shavings. Most of these residues are utilized in fiber products, combusted for energy, or as used as mulch. Under-utilized material from primary and secondary mill systems that could be diverted to petroleum replacements are estimated at 7 million tons in the US (ORNL 2011). This does not include black liquor, which is needed to recover pulping chemicals and provide energy for the mill. Outside the mill system, logging residues are expected to contribute 4 to 12 million tons and urban wood waste is expected to be 12 to 20 million tons at less than $60/ton.
Overall, the widely dispersed nature of these materials and relative low availability, make widespread use for conversion to transportation fuels unlikely. By comparison, conventional wood chips from pulpwood resources are not generally available below $80/ton, making conversion to products that can compete with fossil fuels even less likely (Quadrennial Technology Review 2015: Biomass Feedstocks and Logistics 2015). Rather, low-cost crop residues supplying integrated biorefineries in the food industry are expected to serve the bulk of the next generation of biofuels and come from non-food feedstocks.
In an effort to overcome many of the economic challenges from sharing wood resources with pellet, pulp, paper, and sawmills, studies have looked at the economic and environmental impact of forest plantations dedicated to biofuel production (Hall and Jack 2009; Jack and Hall 2010). Minimal impact on food production was predicted using marginal land for new forest plantations. These areas would be too hilly to cultivate and may be suitable only for grazing. Using the assumption that one ton of green wood could be used to produce a biofuel equivalent to 100 liters of petroleum, forest plantations on marginal land could be profitable sources of biofuel when the price of oil exceeds $180 per barrel. This amount is within range of the 2008 peak at $147 per barrel. In the long run, dedication of vast areas of new forest land to biofuel production would need to support multiple products other than biofuel to reduce the risk from fluctuations in the price of oil (Tomei and Helliwell 2016).
Fractionation of wood or pulp into useful chemicals has been categorized by the types of processes employed, primarily thermal or chemical. In the thermal process, the whole feedstock is liquefied together to produce water-soluble hydroxy acids, phenolics, and insoluble bio-oil containing a wide array of ethers and alcohols. The main thermal processes are fast pyrolysis in the absence of oxygen or hydrothermal liquefaction in hot compressed water at sub-critical conditions.
Pyrolysis is non-specific and gives a complex mixture of products that can be used as fuels or further purified to value added chemicals. Use of catalysts, acid pre-treatments, and a hydrogen atmosphere help improve the value of the product mix as fuels (Pittman and Steele 2006; Meier et al. 2013; Brown et al. 2014; Onarheim et al. 2015; Pedersen and Rosendahl 2015; Ramirez et al.2015). Fast pyrolysis methods require drying and grinding wood to particles that can be efficiently fluidized in a gas stream.
Hydrothermal liquefaction favors wet feedstocks, for which drying would be cost-prohibitive and there is less of a need for fine particles (Xu and Lancaster 2008; Huang and Yuan 2015; Knez et al. 2015; Wikberg et al. 2015). Hydrothermal liquefaction can be used to hydrolyze lignocellulose to C5 and C6 sugars and lignin sequentially (Pandey and Kim 2011; Colakyan 2012). Papermill sludge and black liquor can be readily converted to bio-oil for fuel or chemical platforms by hydrothermal treatment (Xu and Lancaster 2008; Knez et al. 2015; Huet et al. 2016).
CHEMICAL AND ENZYMATIC TREATMENTS
Fractionation of wood or pulp by chemical and mechanical processes can be used to selectively process major polymeric components separately, usually in the sequence of hemicellulose, cellulose, and lignin. Once separated, each polymer can be degraded to monomeric units to yield cleaner and higher value platform chemicals as compared to thermal routes alone. Kraft mills already separate lignin from fiber by a chemical process, so these mills should be well suited to separate the three main components of wood to useful feedstocks. The challenge has been to keep making quality pulp and paper while producing chemicals from wood feedstocks (Yoon and Van Heiningen 2008; Hamaguchi et al. 2013a). It may be necessary to find new markets for the type of pulp produced when supporting a biorefinery (Lundberg et al. 2013a).
Chemical pretreatments of wood chips that can be used to fractionate wood components prior to kraft pulping have been reviewed extensively (Lehto and Alén 2015; Liu 2015; Kim et al. 2016). Three types of cost-effective pretreatments were examined with two goals: to obtain fermentable sugars and to preserve the quality of the kraft pulp. Pretreatments include hot water, dilute acid, and alkaline extractions. In general, hot water or dilute acid produce sugar monomers while degrading pulp quality (Liu et al. 2009; Saukkonen et al. 2012). Recovery of hemicellulose from hardwoods is favored by alkaline extraction. Softwood hemicellulose rapidly degrades under alkaline conditions due to peeling reactions. Green liquor pretreatment to obtain fermentable sugars from hemicellulose has been studied and modeled as a natural biorefinery opportunity for kraft mills (Mao et al. 2008, 2010; Lundberg et al. 2012; Phillips et al. 2013; Andrew et al.2014). Prehydrolysis and extraction of hemicellulose under the right conditions may improve the bleachability of pulp and reduce loading on the recovery evaporators.
Severity of chemical pretreatment determines the level of fermentation inhibitors that are formed with sugars. Inhibitors include phenolics, lignin complexes, acetic acid, furans, and aldehydes (Boucher et al. 2014; Ko et al. 2015; Mechmech et al. 2015). Enzymatic hydrolysis after chemical pretreatment is inhibited by lignin complexes that compete for cellulase binding sites. Strategies are needed to produce sufficiently refined sugars from wood that are competitive with corn dextrose as a feedstock for fermentation to platform chemicals. Cost-effective removal of inhibitors will be a key part of developing commercial processes for wood sugars (Ajao et al.2015; Mechmech et al. 2015; Nwaneshiudu and Schwartz 2015). Simple processes such as over-liming have been effective in detoxifying acid hydrolysates of wood chips for ethanol production (Mendes et al. 2011).
Pretreatment technologies for converting lignocellulose to useful chemical intermediates such as C5 sugars, C6 sugars, and lignin have been the subject of a few books (Bajpai 2013; Wyman 2013; Mussatto 2016). Biorefinery plants using wood may compete for resources with kraft mills in the same way pellet mills do today. The kraft pulping and bleaching processes could be used as a pretreatment process if the end products, delignified fiber, and lignin are intended as a source of sugars and bio-aromatics (Yu et al. 2011; Buzała et al. 2015a,b; Pinto et al. 2016). Lower-cost sources of wood such as forest residues could be used if pulp mill capacity allowed. Modifications of normal pulping operations to accommodate pretreatment technologies would be more of a natural fit for pulp mills than a greenfield biorefinery (Stoklosa and Hodge 2015).
A range of mechanical and chemi-mechanical pretreatments for converting biomass to particle sizes amenable to fractionation of wood polymers has been reviewed (Balan 2014; Barakat et al.2014). Methods to couple pulverization with enzymatic hydrolysis in a continuous stream at high solids was proposed to improve cost and streamline the process. The use of conventional mechanical refining was examined as an alternative to chemical pretreatments for hydrolysis of wood to sugars with lower production of fermentation inhibitors (Jones et al. 2013; Dou et al.2016; Park et al. 2016). Refining coupled with mild pretreatment (steam or dilute acid) reduced overall conversion costs and the level of fermentation inhibitors at equal sugar yield. Mechanical pulping tools are part of the technology Leaf Resources developed for producing sugars from wood by acidic pretreatment and glycerol-based organic extraction (Sabourin 2015; Alex and Alan 2016). A related mechanical alkaline glycerol pulping process called AlkaPolp was developed to give lignin free pulp that can be readily hydrolyzed by enzymes to fermentable sugars (Hundt et al. 2015).
BIO-ADVANTAGED PLATFORM CHEMICALS FROM WOOD
Platform bulk chemicals that can be made from woody substrates fall into broad categories based on the number of carbons, origin (from polysaccharides or lignin), and can play a role as drop-in biobased equivalents or intermediates. Sugars are preferred feedstock for platform chemicals made through fermentation. A study on technical risk for sugar platforms in a kraft mill biorefinery focused on the challenges of generating added waste water and contamination issues in fermentation (Mariano 2014). Carbon monoxide from synthesis gas (syngas), methane, and carbon dioxide are also potential carbon sources for the fermentation processes that can be obtained from kraft mill waste streams (Shen et al. 2015; Drzyzga et al. 2015; Bomgardner 2016; Marcellin et al. 2016). A large market potential for biobased platform chemicals from sugars exists in fermentation intermediates generated for manufacturing polymers such as bio-PET, bio-PE, and bio-nylon (Collias et al. 2014; Becker et al. 2015b).
The DOE issued reports on the top value added chemicals that could be made from biomass using sugars, synthesis gas, or lignin as starting materials in 2004 and 2007 (Werpy and Petersen 2004; Holladay et al. 2007). An updated market assessment and potential of these chemicals was published in 2016 (Biddy et al. 2016).
A review of the most promising opportunities from a chemical and competitive market point of view highlighted multifunctional hydroxy acids that could not be readily made from petroleum products (Dusselier et al. 2014). Figure 2 shows a representation of platform chemicals that could be made from biomass, relating to a normalized functional index (F:C) versus carbon number. Higher functional numbers represent more highly reactive compounds that are suitable for obtaining biochemical from feedstocks. This guide is useful in sorting out target compounds that can have a niche market that will not be easily served by crude oil feedstocks. These chemicals are considered to be bio-advantaged.
Enzymatic saccharification and fermentation are dependent on pretreatment processes that generate little or no inhibitors during either step. Since woody biomass tends to be more recalcitrant than non-wood plant sources, leading to higher severity of pretreatment, crop residues are often preferred (McCann and Carpita 2015; Taylor et al. 2015). Hemicellulose is higher in non-wood residues and is easier to utilize than cellulose as a source of fermentable sugars and furanic chemicals (Cai et al. 2014). Waste streams from dissolving pulp mills are an exception, where hemicellulose has been commercially utilized to produce the sweetener xylitol (XiviaTMXylitol White Paper 2012). Enzymatic saccharification and fermentation technologies are being customized for crop residues to give optimal performance and cost on a commercial scale using some processes that can be found in a pulp mill (Schwab et al. 2016).
Wood feedstocks have sourcing advantages over crop residues due to the scale and maturity of forest product industries. Kraft mills are well suited to provide a wide range of low cost feedstocks to an integrated biorefinery for production of certain bulk chemicals.
Fig 2. Platform chemicals from biomass based on functional index and carbon number (source: Dusselier et al. 2014)
Table 3 lists key platform bulk chemicals that can be generated from lignocellulosic materials (WP 8.1. Determination of market potential for selected platform chemicals 2013; Choi et al.2015; Taylor et al. 2015). For processes that can utilize commodity sugars such as corn dextrose, the use of lignocellulose as a source of sugars may not currently be cost competitive.
Recent developments in commercializing cellulosic ethanol will offer technologies needed to make non-food sources of highly refined sugars more feasible. Virtually all the commercially explored lignocellulosic sugar examples come from agricultural residues. Anellotech uses wood as a feedstock in catalytic pyrolysis to give bio-PET precursors (Tullo 2016). Xylitol comes from xylose in hardwood extract of dissolving pulp pre-hydrolysis liquors.
Sugar production from woody feedstocks as a source of carbon for conversion to platform chemicals is in early stages of commercial exploration (Kobayashi and Fukuoka 2013). Fermentation to chemical intermediates is often more demanding in terms of yield, titer, and contamination than processes to generate ethanol (Papoutsakis 2015).
Table 3. Platform Chemicals with Potential for Sourcing from Lignocellulose
A few examples of companies developing a path to sugars from woody substrates can be listed:
- Sweetwater Energy: two-stage hemicellulose and cellulose hydrolysis followed by purification and clarification (Parekh 2015)
- Renmatix PlantroseTM: process for sub-critical water hydrolysis (Colakyan 2012; Colakyan and Jara-Moreno 2015)
- American Process: SO2-water-ethanol fractionation of wood to sugars (Iakovlev et al.2013; Retsina et al. 2014)
- Leaf Resources: acidic glycerol-water fractionation of wood to sugars and lignin (Sabourin 2015; Alex and Alan 2016)
- Arbiom: low temperature phosphoric acid saccharification (Amsallem 2016; Fouache 2016; Scott 2016a)
Biorefinery platforms available to the pulp and paper industry fall into three categories, thermochemical, biochemical, and materials. Thermochemical platforms are better suited to utilizing the whole tree without the need for fractionating into hemicellulose, cellulose, and lignin. Pyrolysis can be used to convert wood to a bio-oil that can be upgraded to be used in a petroleum refinery or used directly as a heating oil. Wood feedstocks for pyrolysis should be ground and dried. Pyrolysis technology may be adjusted to give a high yield of levoglucosan, which can go into bulk chemical synthetic pathways. Hydrothermal liquefaction of wood gives a bio-oil with a higher heating value than pyrolysis oils, but at lower yield. Pre-drying the feedstock is not needed. Hydrothermal bio-oils are better suited to upgrading to fuels in a petroleum refinery than most pyrolysis oils. Gasification of wood to syngas (H2 + CO) can be reformed to petroleum substitutes or fermented to platform chemicals.
Biochemical platforms call for fractionation of wood into polysaccharides and lignin. Further fractionation of polysaccharides into cellulose and hemicellulose is needed where downstream fermentation is not efficient with mixed C5 and C6 sugars. Wood is generally more recalcitrant than non-woody sources of lignocellulose, resulting in higher levels of enzyme and fermentation inhibitors arising from the severity of the fractionation process. Unbleached and bleached kraft pulp have an advantage over wood in ease of conversion to fermentable sugars. The low to negative cost of the fiber content in municipal solid waste (MSW) makes this source particularly attractive.
Material platforms can be developed from the polymeric components of wood. Chemically modified hemicellulose or cellulose can be made into films with thermoplastic and barrier properties suitable for packaging applications. Bleached pulp can be highly refined into nanofibrillar cellulose for packaging material reinforcement or advanced materials. Lignin can be chemically modified and converted to carbon fiber or nanotubes.
Several kraft pulp and paper mills are in early stages of planning, piloting, and implementing a biorefinery strategy. Kraft lignin production is expanding with the development of Lignoboost and Lignoforce black liquor separation technologies. Sulfite mills have a long history of producing valuable chemicals from the sugars and lignin remaining in spent liquors. Selection of an appropriate biorefinery strategy can be addressed through a SWOT analysis of available resources, technology readiness, market environment, and customer engagement.
Biopolymer equivalents of petroleum-based polymers have a large market potential for wood based sugars and lignin. Cellulosic ethanol from kraft mill residues is at a cost disadvantage versus ethanol from corn starch or sugar cane. Technology to obtain refined sugars from wood for commodity fermentation platforms needs more development. Promising leads are in pre-commercial and pilot stages. Economic viability will depend on the direction of oil prices and sustainability of government subsidies.
New pulping and fractionation systems will be developed for the kraft mill system that take advantage of opportunities for better utilization of wood components and their byproducts. Pyrolysis or hydrothermal bio-oils will be upgraded on site to prepare drop-in substitutes for petroleum derivatives using advanced catalysis technologies. Logistic networks will solve the supply chain optimization challenge of collecting forest residues over large areas and converting them to fuel and polymer precursors. Portable thermochemical conversion units show promise for addressing this issue. Fractionation technologies combined with new fermentation technologies will address the issue of inhibitor formation and sugar purity. Advanced materials developed from lignin or nanocellulose will find markets ready for commercialization.
Ail, S. S., and Dasappa, S. (2016). “Biomass to liquid transportation fuel via Fischer Tropsch synthesis – Technology review and current scenario,” Renewable and Sustainable Energy Reviews 58, 267–286. DOI: 10.1016/j.rser.2015.12.143
Ajao, O., Hir, M. L., Rahni, M., Marinova, M., Chadjaa, H., and Savadogo, O. (2015). “Concentration and detoxification of kraft prehydrolysate by combining nanofiltration with flocculation,” Industrial and Engineering Chemistry Research 54(3), 1113-1122. DOI: 10.1021/ie504271w
Alen, R. (2014). “Integrated possibilities of producing biofuels in chemical pulping,” in: Materials for Biofuels, A. J. Ragauskas (ed.), World Scientific Publishing Company, Singapore, pp. 317-338.
Alex, B., and Alan, E. L. (2016). “Methods for treating lignocellulosic material,” World Patent 2016004481.
Amidon, T. E., and Liu, S. (2009). “Water-based woody biorefinery,” Biotechnology Advances27(5), 542-550. DOI: 10.1016/j.biotechadv.2009.04.012
Amidon, T. E., Wood, C. D., Shupe, A. M., Wang, Y., Graves, M., and Liu, S. (2008). “Biorefinery: Conversion of woody biomass to chemicals, energy and materials,” Journal of Biobased Materials and Bioenergy 2(2), 100-120. DOI: 10.1166/jbmb.2008.302
Amsallem, G. (2016). “Changing the second-generation paradigm: Mitigating development risk through product diversification,” in: World Congress of Industrial Biotechnology, Program eBook, 17.
Andersson, J., Furusjö, E., Wetterlund, E., Lundgren, J., and Landälv, I. (2016). “Co-gasification of black liquor and pyrolysis oil: Evaluation of blend ratios and methanol production capacities,” Energy Conversion and Management 110, 240-248. DOI: 10.1016/j.enconman.2015.12.027
Andersson, J., Lundgren, J., Furusjö, E., and Landälv, I. (2015). “Co-gasification of pyrolysis oil and black liquor for methanol production,” Fuel 158, 451-459. DOI: 10.1016/j.fuel.2015.05.044
Andrew, J. E., Johakimu, J., and Sithole, B. B. (2014). “Bleaching of kraft pulps produced from green liquor pre-hydrolyzed South African Eucalyptus grandis wood chips,” Nordic Pulp and Paper Research Journal 29(03), 383-391. DOI: 10.3183/NPPRJ-2014-29-03-p383-391
Annevelink, E., and van den Oever, M. (2010). “Collection of information on biorefinery research funding and research organizations,” Strategic Targets for 2020 – Collaboration Initiative on Biorefineries, Star-COLIBRI .
Anon. (2014a). “Wood based biofuel is slashing emissions,” biofibre Magazine (11), 14–16.
Anon. (2014b). “Cellulosic game changer,” Bioenergy Insight 5(6), 58-59.
Aso, T., Koda, K., Kubo, S., Yamada, T., Nakajima, I., and Uraki, Y. (2013). “Preparation of novel lignin-based cement dispersants from isolated lignins,” Journal of Wood Chemistry and Technology 33(4), 286-298. DOI: 10.1080/02773813.2013.794841
Bach, Q.-V., and Skreiberg, Ø. (2016). “Upgrading biomass fuels via wet torrefaction: A review and comparison with dry torrefaction,” Renewable and Sustainable Energy Reviews 54, 665–677. DOI: 10.1016/j.rser.2015.10.014
Bacovsky, D., Ludwiczek, N., Ognissanto, M., and Wörgetter, M. (2013). Status of Advanced Biofuels Demonstration Facilities in 2012, IEA Bioenergy Task 39.
Bajpai, P. (2013). Biorefinery in the Pulp and Paper Industry, Elsevier, Amsterdam, NL.
Bajpai, P. (2014). Black Liquor Gasification, 1st Ed., Elsevier, Amsterdam, NL.
Balan, V. (2014). “Current challenges in commercially producing biofuels from lignocellulosic biomass,” ISRN Biotechnology 2014, 463074. DOI: 10.1155/2014/463074
Balan, V., Chiaramonti, D., and Kumar, S. (2013). “Review of US and EU initiatives toward development, demonstration, and commercialization of lignocellulosic biofuels,” Biofuels, Bioproducts and Biorefining7(6), 732-759. DOI: 10.1002/bbb.1436
Barakat, A., Mayer-Laigle, C., Solhy, A., Arancon, R. A. D., de Vries, H., and Luque, R. (2014). “Mechanical pretreatments of lignocellulosic biomass: Towards facile and environmentally sound technologies for biofuels production,” RSC Advances 4(89), 48109-48127. DOI: 10.1039/C4RA07568D
Baral, N. R., and Shah, A. (2016). “Techno-economic analysis of cellulose dissolving ionic liquid pretreatment of lignocellulosic biomass for fermentable sugars production,” Biofuels, Bioproducts & Biorefining 10(1), 70-88. DOI: 10.1002/bbb.1622
Becker, H., Güttel, R., and Turek, T. (2015a). “Enhancing internal mass transport in Fischer–Tropsch catalyst layers utilizing transport pores,” Catalysis Science and Technology 6(1), 275–287. DOI: 10.1039/C5CY00957J
Becker, J., Lange, A., Fabarius, J., and Wittmann, C. (2015b). “Top value platform chemicals: Bio-based production of organic acids,” Current Opinion in Biotechnology 36, 168-175. DOI: 10.1016/j.copbio.2015.08.022
Beckham, G. T., Johnson, C. W., Karp, E. M., Salvachúa, D., and Vardon, D. R. (2016). “Opportunities and challenges in biological lignin valorization,” Current Opinion in Biotechnology 42, 40-53. DOI: 10.1016/j.copbio.2016.02.030
Benali, M., Périn-Levasseur, Z., Savulescu, L., Kouisni, L., Jemaa, N., Kudra, T., and Paleologou, M. (2014). “Implementation of lignin-based biorefinery into a Canadian softwood kraft pulp mill: Optimal resources integration and economic viability assessment,” Biomass and Bioenergy 67, 473-482. DOI: 10.1016/j.biombioe.2013.08.022
Bennett, N. M., Helle, S. S., and Duff, S. J. B. (2009). “Extraction and hydrolysis of levoglucosan from pyrolysis oil,” Bioresource Technology 100(23), 6059-6063. DOI: 10.1016/j.biortech.2009.06.067
Bergström, D., and Matisons, M. (2014). Forest Refine, 2012-2014. Efficient forest biomass supply chain management for biorefineries. Swedish University of Agricultural Sciences.
Biddy, M. J., Scarlata, C., and Kinchin, C. (2016). Chemicals from Biomass: A Market Assessment of Bioproducts with Near-Term Potential, National Renewable Energy Laboratory (NREL). DOI: 10.2172/1244312
Bomgardner, M. M. (2016). “Rethinking biobased chemicals,” Chemical and Engineering News94(18), 26.
Borrega, M., and Sixta, H. (2013). “Purification of cellulosic pulp by hot water extraction,” Cellulose 20(6), 2803-2812. DOI: 10.1007/s10570-013-0086-1
Boucher, J., Chirat, C., and Lachenal, D. (2014). “Extraction of hemicelluloses from wood in a pulp biorefinery, and subsequent fermentation into ethanol,” Energy Conversion and Management88, 1120-1126. DOI: 10.1016/j.enconman.2014.05.104
Brown, D., Rowe, A., and Wild, P. (2014). “Techno-economic comparisons of hydrogen and synthetic fuel production using forest residue feedstock,” International Journal of Hydrogen Energy 39(24), 12551-12562. DOI: 10.1016/j.ijhydene.2014.06.100
Brown, T. R., and Brown, R. C. (2013). “A review of cellulosic biofuel commercial-scale projects in the United States,” Biofuels, Bioproducts and Biorefining 7(3), 235-245. DOI: 10.1002/bbb.1387
Bruycker, R. D., Anthonykutty, J. M., Linnekoski, J., Harlin, A., Lehtonen, J., Geem, K. M. V., Räsänen, J., and Marin, G. B. (2014). “Assessing the potential of crude tall oil for the production of green-base chemicals: An experimental and kinetic modeling study,” Industrial and Engineering Chemistry Research 53(48), 18430-18442. DOI: 10.1021/ie503505f
Bugge, M., Hansen, T., and Klitkou, A. (2016). “What is the bioeconomy? A review of the literature,” Sustainability: Science Practice and Policy 8(7), 691. DOI: 10.3390/su8070691
Buzała, K. P., Przybysz, P., Kalinowska, H., Przybysz, K., Kucner, M., and Dubowik, M. (2015a). “Evaluation of pine kraft cellulosic pulps and fines from papermaking as potential feedstocks for biofuel production” Cellulose 23(1), 649-659. DOI: 10.1007/s10570-015-0808-7
Buzała, K., Przybysz, P., Rosicka-Kaczmarek, J., and Kalinowska, H. (2015b). “Comparison of digestibility of wood pulps produced by the sulfate and TMP methods and woodchips of various botanical origins and sizes,” Cellulose 22(4), 2737-2747. DOI: 10.1007/s10570-015-0644-9
Cai, C. M., Zhang, T., Kumar, R., and Wyman, C. E. (2014). “Integrated furfural production as a renewable fuel and chemical platform from lignocellulosic biomass,” Journal of Chemical Technology and Biotechnology 89(1), 2-10. DOI: 10.1002/jctb.4168
Cambero, C., Sowlati, T., Marinescu, M., and Röser, D. (2015). “Strategic optimization of forest residues to bioenergy and biofuel supply chain,” International Journal of Energy Research 39(4), 439-452. DOI: 10.1002/er.3233
Cellulosic Biofuels – Industry Progress Report 2012 – 2013. (2012). Advanced Ethanol Council.
Chambost, V., Eamer, R., and Stuart, P. R. (2007). “Systematic methodology for identifying promising forest biorefinery products,” Pulp and Paper Canada 108(6), 30-35.
Chambost, V., and Stuart, P. R. (2007). “Selecting the most appropriate products for the forest biorefinery,” Industrial Biotechnology 3(2), 112-119. DOI: 10.1089/ind.2007.3.112
Chatterjee, S., and Saito, T. (2015). “Lignin-derived advanced carbon materials,” ChemSusChem8(23), 3941-3958. DOI: 10.1002/cssc.201500692
Chirat, C., Boiron, L., and Lachenal, D. (2013). “Bleaching ability of pre-hydrolyzed pulps in the context of a biorefinery mill,” Tappi Journal 12(11), 49-53.
Cheng, J., Leu, S.-Y., Zhu, J., and Gleisner, R. (2015). “High titer and yield ethanol production from undetoxified whole slurry of Douglas-fir forest residue using pH profiling in SPORL,” Biotechnology for Biofuels 8, 22. DOI: 10.1186/s13068-015-0205-3
Choi, S., Song, C. W., Shin, J. H., and Lee, S. Y. (2015). “Biorefineries for the production of top building block chemicals and their derivatives,” Metabolic Engineering 28, 223-239. DOI: 10.1016/j.ymben.2014.12.007
Christopher, L. (Ed.). (2012). Integrated Forest Biorefineries, RSC Green Chemistry Series. DOI: 10.1039/9781849735063
Clark, J. H., Farmer, T. J., Hunt, A. J., and Sherwood, J. (2015). “Opportunities for bio-based solvents created as petrochemical and fuel products transition towards renewable resources,” International Journal of Molecular Sciences 16(8), 17101-17159. DOI: 10.3390/ijms160817101
Colakyan, M. (2012). “The role of supercritical hydrolysis,” Bioenergy Insight 3(5), 51-52.
Colakyan, M., and Jara-Moreno, R. H. (2015). “Method for mixed biomass hydrolysis,” US Patent 9200337.
Collias, D. I., Harris, A. M., Nagpal, V., Cottrell, I. W., and Schultheis, M. W. (2014). “Biobased terephthalic acid technologies: A literature review,” Industrial Biotechnology 10(2), 91-105. DOI: 10.1089/ind.2014.0002
Connor, E. (2007a). “The integrated forest biorefinery: The pathway to our bio-future,” in: International Chemical Recovery Conference: Efficiency and Energy Management, 323-327.
Connor, E. J. (2007b). “The pathway to our bio-future,” PaperAge (March/April), 40-43.
Dansereau, L. P., El-Halwagi, M., Chambost, V., and Stuart, P. (2014). “Methodology for biorefinery portfolio assessment using supply-chain fundamentals of bioproducts,” Biofuels, Bioproducts and Biorefining 8(5), 716-727. DOI: 10.1002/bbb.1490
Diorazio, L. J., Hose, D. R. J., and Adlington, N. K. (2016). “Toward a more holistic framework for solvent selection,” Organic Process Research & Development 20(4), 760-773. DOI: 10.1021/acs.oprd.6b00015
Dou, C., Ewanick, S., Bura, R., and Gustafson, R. (2016). “Post-treatment mechanical refining as a method to improve overall sugar recovery of steam pretreated hybrid poplar,” Bioresource Technology 207, 157-165. DOI: 10.1016/j.biortech.2016.01.076
Drzyzga, O., Revelles, O., Durante-Rodríguez, G., Díaz, E., García, J. L., and Prieto, A. (2015). “New challenges for syngas fermentation: Towards production of biopolymers,” Journal of Chemical Technology and Biotechnology 90(10), 1735-1751. DOI: 10.1002/jctb.4721
Duncan, T. (2015). “Beyond timber, pulp and paper – New opportunities for home grown chemicals,” Appita Journal 68(2), 95.
Dusselier, M., Mascal, M., and Sels, B. F. (2014). “Top chemical opportunities from carbohydrate biomass: A chemist’s view of the biorefinery,” Topics in Current Chemistry 353, 1-40. DOI: 10.1007/128_2014_544
Fouache, R. (2016). “Reducing industrialization risk of bio-refineries through integration within the woody biomass value chain,” in: World Congress of Industrial Biotechnology, Program eBook, 20.
Gao, J., Anderson, D., and Levie, B. (2013). “Saccharification of recalcitrant biomass and integration options for lignocellulosic sugars from Catchlight Energy’s sugar process (CLE Sugar),” Biotechnology for Biofuels 6(1), 10. DOI: 10.1186/1754-6834-6-10
Gellerstedt, G., Sjöholm, E., and Brodin, I. (2010). “The wood-based biorefinery: A source of carbon fiber?” The Open Agriculture Journal 4(1), 119-124. DOI: 10.2174/1874331501004010119
Goyal, G. (2015). “Value prior to pulping (VPP) – A techno-economic analysis,” in: 7th International Colloquium on Eucalyptus Pulp.
Graglia, M., Kanna, N., and Esposito, D. (2015). “Lignin refinery: Towards the preparation of renewable aromatic building blocks,” ChemBioEng Reviews 2(6), 377-392. DOI: 10.1002/cben.201500019
Grondahl, M., and Bindgard, L. (2013). “High performance from waste, Renewable barrier layer material for paper and board packaging,” European Coatings Journal (11), 28-31.
Guo, M., Song, W., and Buhain, J. (2015). “Bioenergy and biofuels: History, status, and perspective,” Renewable and Sustainable Energy Reviews 42, 712-725. DOI: 10.1016/j.rser.2014.10.013
Güttel, R., and Turek, T. (2016). “Improvement of Fischer–Tropsch synthesis through structuring on different scales,” Energy Technology 4(1), 44-54. DOI: 10.1002/ente.201500257
Haikonen, T., Tuomaala, M., Holmberg, H., and Ahtila, P. (2011). “Energy efficiency in biorefineries—a case study of Fischer-Tropsch diesel production in connection with a pulp and paper mill,” J-For, Journal of Science and Technology for Forest Products and Processes 1(3), 71-75.
Hakovirta, M. (2014). “Incorporation of biofuels technology into a pulp mill,” in: Materials for Biofuels, A. J. Ragauskas (ed.), World Scientific Publishing Company, Singapore, 295-316.
Hall, P., and Jack, M. (2009). Bioenergy options for New Zealand, Analysis of large-scale bioenergy from forestry, Scion, Energy Project.
Hamaguchi, M., Cardoso, M., and Vakkilainen, E. (2012). “Alternative technologies for biofuels production in kraft pulp mills—Potential and prospects,” Energies 5(7), 2288-2309. DOI: 10.3390/en5072288
Hamaguchi, M., Kautto, J., and Vakkilainen, E. (2013a). “Effects of hemicellulose extraction on the kraft pulp mill operation and energy use: Review and case study with lignin removal,” Chemical Engineering Research and Design 91(7), 1284-1291. DOI: 10.1016/j.cherd.2013.02.006
Hamaguchi, M., Saari, J., and Vakkilainen, E. (2013b). “Bio-oil and biochar as additional revenue streams in South American kraft pulp mills,” BioResources 8(3), 3399-3413. DOI: 10.15376/biores.8.3.3399-3413
Hämäläinen, S., Näyhä, A., and Pesonen, H.-L. (2011). “Forest biorefineries – A business opportunity for the Finnish forest cluster,” Journal of Cleaner Production 19(16), 1884-1891. DOI: 10.1016/j.jclepro.2011.01.011
Hänninen, R., Hetemäki, L., Hurmekoski, E., Mutanen, A., Näyhä, A., Forsström, J., Viitanen, J., Koljonen, T. (2014). European forest industry and forest bioenergy outlook up to 2050: A synthesis, Research Report No D 1.1.1, Cleen Oy.
Hansen, E. (2016). “Responding to the bioeconomy: Business model innovation in the forest sector,” in: Environmental Impacts of Traditional and Innovative Forest-Based Bioproducts, A. Kutnar and S. S. Muthu (eds.), Springer Science+Business Media, Singapore, pp. 227-248. DOI: 10.1007/978-981-10-0655-5_7
Hansen, T., and Coenen, L. (2015). “Unpacking investment decisions in biorefineries,” Lund University, CIRCLE-Center for Innovation, Research and Competences in the Learning Economy.
Hasan, A., Bujanovic, B., and Amidon, T. (2010). “Strength properties of kraft pulp produced from hot-water extracted woodchips within the biorefinery,” Journal of Biobased Materials and Bioenergy 4(1), 46-52. DOI: 10.1166/jbmb.2010.1064
Holladay, J. E., White, J. F., Bozell, J. J., and Johnson, D. (2007). “Top value-added chemicals from biomass – Volume II—Results of screening for potential candidates from biorefinery lignin,” Pacific Northwest National Laboratory. DOI: 10.2172/921839
Homma, H., Kubo, S., Yamada, T., Koda, K., Matsushita, Y., and Uraki, Y. (2010). “Conversion of technical lignins to amphiphilic derivatives with high surface activity,” Journal of Wood Chemistry and Technology 30(2), 164-174. DOI: 10.1080/02773810903349713
Hu, Z., Du, X., Liu, J., Chang, H.-M., and Jameel, H. (2016). “Structural characterization of pine kraft lignin: BioChoice lignin vs Indulin AT,” Journal of Wood Chemistry and Technology 36(6), 432-446. DOI: 10.1080/02773813.2016.1214732
Huang, H.-J., and Yuan, X.-Z. (2015). “Recent progress in the direct liquefaction of typical biomass,” Progress in Energy and Combustion Science 49, 59-80. DOI: 10.1016/j.pecs.2015.01.003
Huet, M., Roubaud, A., Chirat, C., and Lachenal, D. (2016). “Hydrothermal treatment of black liquor for energy and phenolic platform molecules recovery in a pulp mill,” Biomass and Bioenergy 89, 105-112. DOI: 10.1016/j.biombioe.2016.03.023
Hundt, M., Engel, N., Schnitzlein, K., and Schnitzlein, M. G. (2015). “The AlkaPolP process: Fractionation of various lignocelluloses and continuous pulping within an integrated biorefinery concept,” Chemical Engineering Research and Design 107, 13-23. DOI: 10.1016/j.cherd.2015.10.013
Hu, W., Dang, Q., Rover, M., Brown, R. C., and Wright, M. M. (2016). “Comparative techno-economic analysis of advanced biofuels, biochemicals, and hydrocarbon chemicals via the fast pyrolysis platform,” Biofuels 7(1), 87-103. DOI: 10.1080/17597269.2015.1118780
Hytönen, E., and Stuart, P. R. (2012). “Early-stage design methodology for biorefinery capital appropriation,” Tappi J 11(4), 9-23.
Iakovlev, M., You, X., van Heiningen, A., and Sixta, H. (2013). “SO2–ethanol–water (SEW) fractionation of spruce: Kinetics and conditions for paper and viscose-grade dissolving pulps,” RSC Advances 4(4), 1938-1950. DOI: 10.1039/C3RA45573D
Isaksson, J., Åsblad, A., and Berntsson, T. (2014). “Pretreatment methods for gasification of biomass and Fischer–Tropsch crude production integrated with a pulp and paper mill,” Clean Technologies and Environmental Policy 16(7), 1393–1402. DOI: 10.1007/s10098-014-0815-7
Isikgor, F. H., and Remzi Becer, C. (2015). “Lignocellulosic biomass: A sustainable platform for the production of bio-based chemicals and polymers,” Polymer Chemistry 6(25), 4497-4559. DOI: 10.1039/C5PY00263J
Jack, M., and Hall, P. (2010). “Large-scale forests for bioenergy: Land-use, economic and environmental implications,” Unasylva 61(234/235), 23-27.
Jafri, Y., Furusjö, E., Kirtania, K., and Gebart, R. (2016). “Performance of a pilot-scale entrained-flow black liquor gasifier,” Energy and Fuels 30(4), 3175-3185. DOI: 10.1021/acs.energyfuels.6b00349
Jansson, M., Backlund, B., Fornell, R., and Kohnke, T. (2015). The pulp mill biorefinery roadmap 2015 – 2025, RISE Research Institutes of Sweden.
Jiang, L., Zheng, A., Zhao, Z., He, F., Li, H., and Liu, W. (2015). “Obtaining fermentable sugars by dilute acid hydrolysis of hemicellulose and fast pyrolysis of cellulose,” Bioresource Technology 182, 364-367. DOI: 10.1016/j.biortech.2015.01.032
Jiang, L., Zheng, A., Zhao, Z., He, F., Li, H., and Wu, N. (2016). “The comparison of obtaining fermentable sugars from cellulose by enzymatic hydrolysis and fast pyrolysis,” Bioresource Technology 200, 8-13. DOI:10.1016/j.biortech.2015.09.096
Jobes, O. (2015). “At Ingevity we’re out to make a splash,” Tribology and Lubrication Technology 71(11), 70-72.
Johansson, C., Bras, J., Mondragon, I., Nechita, P., Plackett, D., Simon, P., Svetec, D. G., Virtanen, S., Baschetti, M. G., Breen, C., and Aucejo, S. (2012). “Renewable fibers and bio-based materials for packaging applications – A review of recent developments,” BioResources 7(2), 2506-2552. DOI: 10.15376/biores.7.2.2506-2552
Jones, B. W., Venditti, R., Park, S., Jameel, H., and Koo, B. (2013). “Enhancement in enzymatic hydrolysis by mechanical refining for pretreated hardwood lignocellulosics,” Bioresource Technology 147, 353-360. DOI: 10.1016/j.biortech.2013.08.030
de Jong, S., Hoefnagels, R., Faaij, A., Slade, R., Mawhood, R., and Junginger, M. (2015). “The feasibility of short-term production strategies for renewable jet fuels – A comprehensive techno-economic comparison,” Biofuels, Bioproducts & Biorefining 9(6), 778-800. DOI: 10.1002/bbb.1613
Jungmeier, G., Van Ree, R., de Jong, E., Stichnothe, H., de Bari, I., Jørgensen, H., Wellisch, M., Bell, G., Spaeth, J., Torr, K., and Kimura, S. (2015). “The biorefinery fact sheet and its application to wood based biorefining,” in: NWBC 2015 Nordic Wood Biorefinery Conference.
Kai, D., Tan, M. J., Chee, P. L., Chua, Y. K., Yap, Y. L., and Loh, X. J. (2016). “Towards lignin-based functional materials in a sustainable world,” Green Chemistry 18(5), 1175-1200. DOI: 10.1039/C5GC02616D
Karatzos, S. (2014). “The potential and challenges of drop-in biofuels,” IEA Bioenergy Task Force 39.
Kenealy, W. R., Houtman, C. J., Laplaza, J., Jeffries, T. W., and Horn, E. G. (2007). “Pretreatments for converting wood into paper and chemicals,” in: Materials, Chemicals, and Energy from Forest Biomass, Argyropoulos, DS, (ed.), American Chemical Society, Washington, pp. 392-408.
Kim, J. S., Lee, Y. Y., and Kim, T. H. (2016). “A review on alkaline pretreatment technology for bioconversion of lignocellulosic biomass,” Bioresource Technology 199, 42-48. DOI: 10.1016/j.biortech.2015.08.085
Kim, S., and Dale, B. E. (2015). “All biomass is local: The cost, volume produced, and global warming impact of cellulosic biofuels depend strongly on logistics and local conditions,” Biofuels, Bioproducts and Biorefining 9(4), 422-434. DOI: 10.1002/bbb.1554
Klai, N., Bidjou-Haiour, C., and Bouquillon, S. (2015). “d-Xylose-based surfactants: Synthesis, characterization and molecular modeling studies,” Comptes Rendus Chimie 18(6), 599-606. DOI: 10.1016/j.crci.2014.11.007
Klein-Marcuschamer, D., and Blanch, H. W. (2015). “Renewable fuels from biomass: Technical hurdles and economic assessment of biological routes,” AIChE J 61(9), 2689-2701. DOI: 10.1002/aic.14755
Knez, Ž., Markočič, E., Hrnčič, M. K., Ravber, M., and Škerget, M. (2015). “High pressure water reforming of biomass for energy and chemicals: A short review,” Journal of Supercritical Fluids96, 46-52. DOI: 10.1016/j.supflu.2014.06.008
Kobayashi, H., and Fukuoka, A. (2013). “Synthesis and utilisation of sugar compounds derived from lignocellulosic biomass,” Green Chemistry 15(7), 1740. DOI: 10.1039/c3gc00060e
Ko, J. K., Um, Y., Park, Y.-C., Seo, J.-H., and Kim, K. H. (2015). “Compounds inhibiting the bioconversion of hydrothermally pretreated lignocellulose,” Applied Microbiology and Biotechnology 99(10), 4201-4212. DOI: 10.1007/s00253-015-6595-0
Kokossis, A. C., Tsakalova, M., and Pyrgakis, K. (2015). “Design of integrated biorefineries,” Computers and Chemical Engineering 81, 40-56. DOI: 10.1016/j.compchemeng.2015.05.021
Kouisni, L., Holt-Hindle, P., Maki, K., and Paleologou, M. (2012). “The Lignoforce SystemTM: A new process for the production of high-quality lignin from black liquor,” J-FOR Journal of Science & Technology for Forest Products and Processes 2(4), 6–10.
Kretschmer, W. (2014). “SWOT analysis and biomass competition analysis for SUPRABIO biorefineries,” IUS Institute for Environmental Studies.
Krogell, J., Eränen, K., Pranovich, A., and Willför, S. (2016). “Utilizing active pH control for enhanced hot-water extraction of wood,” Nordic Pulp & Paper Research Journal 31(1), 4-13. DOI: 10.3183/NPPRJ-2016-31-01-p004-013
Lake, M. A., and Blackburn, J. C. (2014). “SLRPTM – An innovative lignin-recovery technology,” Cellulose Chemistry and Technology 48(9-10), 799-804.
Lai, L. X., and Bura, R. (2012). “The sulfite mill as a sugar-flexible future biorefinery,” Tappi J11(8), 27-35.
Laine, C., Asikainen, S., Talja, R., Stépán, A., Sixta, H., and Harlin, A. (2016). “Simultaneous bench scale production of dissolving grade pulp and valuable hemicelluloses from softwood kraft pulp by ionic liquid extraction,” Carbohydrate Polymers, 136, 402-408. DOI: 10.1016/j.carbpol.2015.09.039
Laine, C., Harlin, A., Hartman, J., Hyvärinen, S., Kammiovirta, K., Krogerus, B., Pajari, H., Rautkoski, H., Setälä, H., Sievänen, J., Uotila, J., and Vähä-Nissi, M. (2013). “Hydroxyalkylated xylans – Their synthesis and application in coatings for packaging and paper,” Industrial Crops and Products 44, 692-704. DOI: 10.1016/j.indcrop.2012.08.033
Landälv, I., Stare, R., and Barry, D. (2010). “Operating experience and evolution of the world’s first commercial black liquor gasification plant,” in: Tappi Peers 2010, 1-8.
Laqua, M. (2015). “Paving the way for an arboreal comeback,” European Biotechnology14(Autumn), 40-45.
Larson, E. D., Consonni, S., Katofsky, R. E., Iisa, K., and James Frederick, W., Jr. (2006). “A cost-benefit assessment of gasification-based biorefining in the kraft pulp and paper industry,” US Department of Energy and the American Paper and Forest Association.
Lamers, P., Junginger, M., Dymond, C. C., and Faaij, A. (2014). “Damaged forests provide an opportunity to mitigate climate change,” GCB Bioenergy 6(1), 44-60. DOI: 10.1111/gcbb.12055
Lavoine, N., Desloges, I., Dufresne, A., and Bras, J. (2012). “Microfibrillated cellulose – Its barrier properties and applications in cellulosic materials: A review,” Carbohydrate Polymers90(2), 735-764. DOI: 10.1016/j.carbpol.2012.05.026
Lehto, J. T., and Alen, R. J. (2015). “Chemical pretreatments of wood chips prior to alkaline pulping – A review of pretreatment alternatives, chemical aspects of the resulting liquors, and pulping outcomes,” BioResources 10(4), 8604-8656. DOI: 10.15376/biores.10.4.Lehto
Le Normand, M., Moriana, R., and Ek, M. (2014). “The bark biorefinery: A side-stream of the forest industry converted into nanocomposites with high oxygen-barrier properties,” Cellulose21(6), 4583-4594. DOI: 10.1007/s10570-014-0423-z
LeViness, S., Deshmukh, S. R., Richard, L. A., and Robota, H. J. (2013). “Velocys Fischer–Tropsch synthesis technology, New advances on state-of-the-art,” Topics in Catalysis 57(6-9), 518-525. DOI: 10.1007/s11244-013-0208-x
LeViness, S. C., Robota, H. J., Deshmukh, S. R., Miller, A., Yuschak, T., and Davis, M. (2014). “Commercializing an advanced Fischer-Tropsch synthesis technology,” Preprints – American Chemical Society, Division of Energy and Fuels 59(2), 809-812.
Li, B., Asikkala, J., Filpponen, I., and Argyropoulos, D. S. (2010). “Factors affecting wood dissolution and regeneration of ionic liquids,” Industrial & Engineering Chemistry Research49(5), 2477-2484. DOI: 10.1021/ie901560p
Li, F., Mascheroni, E., and Piergiovanni, L. (2015a). “The potential of nanocellulose in the packaging field: A review,” Packaging Technology and Science 28(6), 475-508. DOI: 10.1002/pts.2121
Li, J., Ma, X., Duan, C., Liu, Y., Zhang, H., and Ni, Y. (2015b). “Enhanced removal of hemicelluloses from cellulosic fibers by poly(ethylene glycol) during alkali treatment,” Cellulose23(1), 231-238. DOI: 10.1007/s10570-015-0800-2
Li, Y., Chen, L., Wang, T., Ma, L., Ding, M., Zhang, X., and Yin, X. (2015c). “Demonstration of pilot-scale bio-dimethyl ether synthesis via oxygen- and steam- enriched gasification of wood chips,” Energy Procedia 75, 202-207. DOI: 10.1016/j.egypro.2015.07.303
Li, Y., and Ragauskas, A. J. (2012). “Kraft lignin-based rigid polyurethane foam,” Journal of Wood Chemistry and Technology 32(3), 210-224. DOI: 10.1080/02773813.2011.652795
Lin, N., and Dufresne, A. (2014). “Nanocellulose in biomedicine: Current status and future prospect,” European Polymer Journal 59, 302-325. DOI: 10.1016/j.eurpolymj.2014.07.025
Liu, J., Li, M., Luo, X., Chen, L., and Huang, L. (2015). “Effect of hot-water extraction (HWE) severity on bleached pulp based biorefinery performance of eucalyptus during the HWE–Kraft–ECF bleaching process,” Bioresource Technology 181, 183-190. DOI: 10.1016/j.biortech.2015.01.055
Liu, J., Lin, L., Pang, C., Zhuang, J., Luo, X., Shi, Y., Ouyang, P., Li, J., and Liu, S. (2009). “Poplar woodchip as a biorefinery feedstock—Prehydrolysis with formic/acetic acid/water system, xylitol production from hydrolysate and kraft pulping of residual woodchips,” Journal of Biobased Materials and Bioenergy 3(1), 37-45. DOI: 10.1166/jbmb.2009.1005
Liu, S. (2015). “A synergetic pretreatment technology for woody biomass conversion,” Applied Energy 144, 114-128. DOI: 10.1016/j.apenergy.2015.02.021
Ljungstedt, H., Pettersson, K., and Harvey, S. (2013). “Evaluation of opportunities for heat integration of biomass-based Fischer–Tropsch crude production at Scandinavian kraft pulp and paper mill sites,” Energy 62, 349-361. DOI: 10.1016/j.energy.2013.09.048
Lundberg, V., Axelsson, E., Mahmoudkhani, M., and Berntsson, T. (2012). “Process integration of near-neutral hemicellulose extraction in a Scandinavian kraft pulp mill – Consequences for the steam and Na/S balances,” Applied Thermal Engineering 43, 42-50. DOI: 10.1016/j.applthermaleng.2012.03.037
Lundberg, V., Bood, J., Nilsson, L., Axelsson, E., Berntsson, T., and Svensson, E. (2014). “Converting a kraft pulp mill into a multi-product biorefinery: Techno-economic analysis of a case mill,” Clean Technologies and Environmental Policy 16(7), 1411-1422. DOI: 10.1007/s10098-014-0741-8
Lundberg, V., Bood, J., Nilsson, L., Mahmoudkhani, M., Axelsson, E., and Berntsson, T. (2013a). “Enlarging the product portfolio of a kraft pulp mill via hemicellulose and lignin separation — Process integration studies in a case mill,” Chemical Engineering Transactions 35, 127-132. DOI: 10.3303/CET1335021
Lundberg, V., Svensson, E., Axelsson, E., and Mahmoudkhani, M. (2013b). “Converting a kraft pulp mill into a multi-product biorefinery – Part 2: Economic aspects,” Nordic Pulp and Paper Research Journal 28(4), 489-497. DOI: 10.3183/NPPRJ-2013-28-04-p489-497
Luque, R., Herrero-Davila, L., Campelo, J. M., Clark, J. H., Hidalgo, J. M., Luna, D., Marinas, J. M., and Romero, A. A. (2008). “Biofuels: A technological perspective,” Energy and Environmental Science 1(5), 542. DOI: 10.1039/b807094f
Magdzinski, L. (2006). “Tembec Temiscaming integrated biorefinery,” Pulp and Paper Canada107(6), 44-46.
Manning, R., and Tran, H. (2015). “Impact of cofiring biofuels and fossil fuels on lime kiln operation,” Tappi J 14(7), 474-480.
Manzer, L. E., van der Waal, J. C., and Imhof, P. (2013). “The industrial playing field for the conversion of biomass to renewable fuels and chemicals,” in: Catalytic Process Development for Renewable Materials, First Edition, Pieter Imhof and Jan Cornelis van der Waal (eds.), Wiley-VCH Verlag GmbH & Co. KGaA, Berlin, DE. DOI: 10.1002/9783527656639.ch1
Mao, H., Genco, J. M., van Heiningen, A., and Pendse, H. (2010). “Kraft mill biorefinery to produce acetic acid and ethanol: Technical economic analysis,” BioResources 5(2), 525-544.DOI: 10.15376/biores.5.2.525-544
Mao, H., Genco, J. M., Yoon, S.-H., van Heiningen, A., and Pendse, H. (2008). “Technical economic evaluation of a hardwood biorefinery using the “near-neutral’’ hemicellulose pre-extraction process,” Journal of Biobased Materials and Bioenergy 2(2), 177-185. DOI: 10.1166/jbmb.2008.309
Marcellin, E., Behrendorff, J. B., Nagaraju, S., DeTissera, S., Segovia, S., Palfreyman, R. W., Daniell, J., Licona-Cassani, C., Quek, L.-E., Speight, R., Hodson, M. P., Simpson, S. D., Mitchell, W. P., Köpke, M., and Nielsen, L. K. (2016). “Low carbon fuels and commodity chemicals from waste gases – systematic approach to understand energy metabolism in a model acetogen,” Green Chemistry 18, 3020-3028. DOI: 10.1039/C5GC02708J
Mariano, A. P. (2014). “Due diligence for sugar platform biorefinery projects: Technology risk,” J-For Journal of Science & Technology for Forest Products and Processes 4(5), 12-19.
Mariano, A. P. (2015). “How Brazilian pulp mills will look like in the future?,” O Papel 76(6), 55-61.
Marinova, M., Perrier, M., and Paris, J. (2014). “Implementation of a forest biomass-based biofuel industry: A Canadian experience,” Journal of Energy and Power Engineering 8(10), 1680-1686.
Maronese, S., Ensinas, A. V., Mian, A., Lazzaretto, A., and Maréchal, F. (2015). “Optimum biorefinery pathways selection using the integer-cuts constraint method applied to a MILP problem,” Industrial and Engineering Chemistry Research 54(28), 7038-7046. DOI: 10.1021/acs.iecr.5b01439
Matsakas, L., Rova, U., and Christakopoulos, P. (2016). “Strategies for enhanced biogas generation through anaerobic digestion of forest material – An overview,” BioResources 11(2). DOI: 10.15376/biores.11.2.
McCann, M. C., and Carpita, N. C. (2015). “Biomass recalcitrance: A multi-scale, multi-factor, and conversion-specific property,” Journal of Experimental Botany 66(14), 4109–4118. DOI: 10.1093/jxb/erv267
McCormick, K., and Kautto, N. (2013). “The bioeconomy in Europe: An overview,” Sustainability: Science Practice and Policy 5(6), 2589-2608. DOI: 10.3390/su5062589
Mechmech, F., Chadjaa, H., Rahni, M., Marinova, M., Ben Akacha, N., and Gargouri, M. (2015). “Improvement of butanol production from a hardwood hemicelluloses hydrolysate by combined sugar concentration and phenols removal,” Bioresource Technology 192, 287-295. DOI: 10.1016/j.biortech.2015.05.012
Meier, D., van de Beld, B., Bridgwater, A. V., Elliott, D. C., Oasmaa, A., and Preto, F. (2013). “State-of-the-art of fast pyrolysis in IEA bioenergy member countries,” Renewable and Sustainable Energy Reviews 20, 619-641. DOI: 10.1016/j.rser.2012.11.061
Melin, L. (2015). “Development of a DuraPulp packaging demonstrator,” Master Thesis, Lund University, Lund, SE.
Mendell, B., Lang, A. H., and Schiamberg, B. (2011). Transportation fuels from wood – Investment and market implications, Forisk Consulting.
Mendes, C. V. T., Rocha, J. M. S., Sousa, G. D. A., and Carvalho, G. (2011). “Extraction of hemicelluloses prior to kraft cooking: A step for an integrated biorefinery in the pulp mill,” O Papel 72(9), 79–83.
Mesfun, S., Lundgren, J., Grip, C.-E., Toffolo, A., Nilsson, R. L. K., and Rova, U. (2014). “Black liquor fractionation for biofuels production – A techno-economic assessment,” Bioresource Technology 166, 508-517. DOI: 10.1016/j.biortech.2014.05.062
Mesfun, S., and Toffolo, A. (2015). “Integrating the processes of a kraft pulp and paper mill and its supply chain,” Energy Conversion and Management 103, 300-310. DOI: 10.1016/j.enconman.2015.06.063
Mikkonen, K. S., and Tenkanen, M. (2012). “Sustainable food-packaging materials based on future biorefinery products: Xylans and mannans,” Trends in Food Science and Technology 28(2), 90-102. DOI: 10.1016/j.tifs.2012.06.012
Miller, J. (2015). Nanocellulose – state of the industry, December 2015, Market-Intell LLC.
Mussatto, S. I. (2016). Biomass Fractionation Technologies for a Lignocellulosic Feedstock Based Biorefinery, Elsevier.
Nanda, S., Mohammad, J., Reddy, S. N., Kozinski, J. A., and Dalai, A. K. (2013). “Pathways of lignocellulosic biomass conversion to renewable fuels,” Biomass Conversion and Biorefinery4(2), 157-191. DOI: 10.1007/s13399-013-0097-z
Naqvi, M., Yan, J., and Dahlquist, E. (2010). “Black liquor gasification integrated in pulp and paper mills: A critical review,” Bioresource Technology 101(21), 8001-8015. DOI: 10.1016/j.biortech.2010.05.013
Nelson, K., Retsina, T., Iakovlev, M., van Heiningen, A., Deng, Y., Shatkin, J. A., and Mulyadi, A. (2016). “American Process: Production of low cost nanocellulose for renewable, advanced materials applications,” in: Materials Research for Manufacturing, L. D. Madsen, and E. B. Svedberg (eds.), 267-302. DOI: 10.1007/978-3-319-23419-9_9
Northwest Advanced Renewables Alliance (NARA). 2015. 3rd Cumulative Report. (2015). NARA.
Novotny, M., and Laestadius, S. (2014). “Beyond papermaking: Technology and market shifts for wood-based biomass industries–Management implications for large-scale industries,” Analysis and Strategic Management 26(8), 875-891. DOI: 10.1080/09537325.2014.912789
Nwaneshiudu, I. C., and Schwartz, D. T. (2015). “Rational design of polymer-based absorbents: application to the fermentation inhibitor furfural,” Biotechnology for Biofuels 8(72), 1-8. DOI: 10.1186/s13068-015-0254-7
Onarheim, K., Lehto, J., and Solantausta, Y. (2015). “Technoeconomic assessment of a fast pyrolysis bio-oil production process integrated to a fluidized bed boiler,” Energy and Fuels 29(9), 5885-5893. DOI: 10.1021/acs.energyfuels.5b01329
ORNL. (2011). U.S. Billion-ton Update, DOE.
Orts, W. J., and McMahan, C. M. (2016). “Biorefinery developments for advanced biofuels from a sustainable array of biomass feedstocks: Survey of recent biomass conversion research from agricultural research service,” Bioenergy Research 9(2), 430-446. DOI: 10.1007/s12155-016-9732-4
Osong, S. H., Norgren, S., and Engstrand, P. (2015). “Processing of wood-based microfibrillated cellulose and nanofibrillated cellulose, and applications relating to papermaking: a review,” Cellulose 23(1), 93-123. DOI: 10.1007/s10570-015-0798-5
Pandey, M. P., and Kim, C. S. (2011). “Lignin depolymerization and conversion: A review of thermochemical methods,” Chemical Engineering and Technology 34(1), 29-41. DOI: 10.1002/ceat.201000270
Panwar, R., Kozak, R., and Hansen, E. (2016). Forests, Business and Sustainability, Routledge, New York, NY.
Papoutsakis, E. T. (2015). “Reassessing the progress in the production of advanced biofuels in the current competitive environment and beyond: What are the successes and where progress eludes us and why,” Industrial and Engineering Chemistry Research 54(42), 10170-10182. DOI: 10.1021/acs.iecr.5b01695
Parekh, S. (2015). “Sugar separation and purification through filtration,” US Patent 20150329927.
Park, J., Jones, B., Koo, B., Chen, X., Tucker, M., Yu, J.-H., Pschorn, T., Venditti, R., and Park, S. (2016). “Use of mechanical refining to improve the production of low-cost sugars from lignocellulosic biomass,” Bioresource Technology 199, 59-67. DOI: 10.1016/j.biortech.2015.08.059
Pätäri, S., Kyläheiko, K., and Sandström, J. (2011). “Opening up new strategic options in the pulp and paper industry: Case biorefineries,” Forest Policy and Economics 13(6), 456-464. DOI: 10.1016/j.forpol.2011.06.003
Pätäri, S., Tuppura, A., Toppinen, A., and Korhonen, J. (2016). “Global sustainability megaforces in shaping the future of the European pulp and paper industry towards a bioeconomy,” Forest Policy and Economics 66, 38-46. DOI: 10.1016/j.forpol.2015.10.009
Pedersen, T. H., and Rosendahl, L. A. (2015). “Production of fuel range oxygenates by supercritical hydrothermal liquefaction of lignocellulosic model systems,” Biomass and Bioenergy 83(C), 206-215. DOI: 10.1016/j.biombioe.2015.09.014
Peters, N. K. (2014). DOE Bioenergy Research Centers, DOE SC-0162.
Phillips, R. B., Jameel, H., and Chang, H. M. (2013). “Integration of pulp and paper technology with bioethanol production,” Biotechnology for Biofuels 6(1), 13. DOI: 10.1186/1754-6834-6-13
Pinto, P. C. R., Oliveira, C., Costa, C. A. E., and Rodrigues, A. E. (2016). “Performance of side-streams from eucalyptus processing as sources of polysaccharides and lignins by kraft delignification,” Industrial and Engineering Chemistry Research 55(2), 516-526. DOI: 10.1021/acs.iecr.5b03712
Pittman, C. U., Jr., and Steele, P. H. (2006). “Pyrolysis of wood/biomass for bio-oil: A critical review,” Energy and Fuels 20(3), 848-889. DOI: 10.1021/ef0502397
Pu, Y., Treasure, T., Gonzalez, R. W., Venditti, R., and Jameel, H. (2011). “Autohydrolysis pretreatment of mixed hardwoods to extract value prior to combustion,” BioResources 6(4), 4856-4870. DOI: 10.15376/biores.6.4.4856-4870
Pytlar, T. S. (2010). “Status of existing biomass gasification and pyrolysis facilities in North America,” in: 18th Annual North American Waste-to-Energy Conference, 141-154. DOI: 10.1115/NAWTEC18-3521
Quadrennial Technology Review 2015: Biomass Feedstocks and Logistics. (2015). DOE.
Ragauskas, A. J., Nagy, M., Kim, D. H., Eckert, C. A., Hallett, J. P., and Liotta, C. L. (2006). “From wood to fuels: Integrating biofuels and pulp production,” Industrial Biotechnology 2(1), 55-65. DOI: 10.1089/ind.2006.2.55
Rakkolainen, M., Iakovlev, M., Teräsvuori, A.-L., Sklavounos, E., Jurgens, G., Granström, T. B., and Van Heiningen, A. (2010). “SO2-ethanol-water fractionation of forest biomass and implications for biofuel production by ABE fermentation,” Cellulose Chemistry and Technology44(4-6), 139-145.
Ramirez, J., Brown, R., and Rainey, T. (2015). “A review of hydrothermal liquefaction bio-crude properties and prospects for upgrading to transportation fuels,” Energies 8(7), 6765-6794. DOI: 10.3390/en8076765
Retsina, T., Pylkkanen, V., and O’Connor, R. P. (2014). “Integrated biorefineries for production of sugars, fermentation products, and coproducts,” US Patent 20140356915.
Rødsrud, G., Lersch, M., and Sjöde, A. (2012). “History and future of world’s most advanced biorefinery in operation,” Biomass and Bioenergy 46, 46-59. DOI: 10.1016/j.biombioe.2012.03.028
Rojas, O. J., Stubenrauch, C., Lucia, L. A. and Habibi, Y. (2009). “Interfacial properties of sugar based surfactants,” in: Hayes, D. G., Kitamoto, D., Solaiman, D. K. Y., and Ashby, R. D., (eds.), Bio-Based Surfactants and Detergents: Synthesis, Properties and Applications, AOCS Press, Urbana, 457-480.
Rudie, A. (2009). State of the Art in Biorefinery in Finland and the United States, 2008, USDA.
Rudie, A. W., Houtman, C. J., Groom, L. H., Nicholls, D. L., and Zhu, J. Y. (2016). “A survey of bioenergy research in forest service research and development,” Bioenergy Research 9(2), 534-547. DOI: 10.1007/s12155-016-9731-5
Rueda, C., Calvo, P. A., Moncalián, G., Ruiz, G., and Coz, A. (2015). “Biorefinery options to valorize the spent liquor from sulfite pulping,” Journal of Chemical Technology and Biotechnology 90(12), 2218-2226. DOI: 10.1002/jctb.4536
Rueda, C., Marinova, M., Paris, J., Ruiz, G., and Coz, A. (2016). “Technoeconomic assessment of different biorefinery approaches for a spent sulfite liquor,” Journal of Chemical Technology and Biotechnology DOI: 10.1002/jctb.4868
Runge, W. (2013). Technology Entrepreneurship: A Treatise on Entrepreneurs and Entrepreneurship for and in Technology Ventures. Band 2, KIT Scientific Publishing. DOI: 10.5445/KSP/1000036460
Sabourin, M. (2015). “Hybrid opportunities for bio projects in the pulp & paper industry,” in: IBBC – International Bioenergy and Bioproducts Conference, TAPPI.
Sadeghifar, H., Sen, S., Patil, S. V., and Argyropoulos, D. S. (2016). “Toward carbon fibers from single component kraft lignin systems: Optimization of chain extension chemistry,” ACS Sustainable Chemistry & Engineering Articles ASAP. DOI: 10.1021/acssuschemeng.6b00848
Saukkonen, E., Kautto, J., Rauvanto, I., and Backfolk, K. (2012). “Characteristics of prehydrolysis-kraft pulp fibers from Scots pine,” Holzforschung 66(7), 801-808. DOI: 10.1515/hf-2011-0158
Schwab, A., Warner, E., and Lewis, J. (2016). “2015 survey of non-starch ethanol and renewable hydrocarbon biofuels producers,” NREL.
Scott, A. (2016a). “Deinove and Arbiom target forestry waste,” Chemical & Engineering News94(12), 16.
Scott, A. (2016b). “Biobased chemical start-ups seek niche in Europe,” Chemical & Engineering News 94(19), 25-26.
Shen, Y., Jarboe, L., Brown, R., and Wen, Z. (2015). “A thermochemical–biochemical hybrid processing of lignocellulosic biomass for producing fuels and chemicals,” Biotechnology Advances 33(8), 1799-1813. DOI: 10.1016/j.biotechadv.2015.10.006
Silveira, M. H. L., Morais, A. R. C., da Costa Lopes, A. M., Olekszyszen, D. N., Bogel-Łukasik, R., Andreaus, J., and Pereira Ramos, L. (2015). “Current pretreatment technologies for the development of cellulosic ethanol and biorefineries,” ChemSusChem 8(20), 3366-3390. DOI: 10.1002/cssc.201500282
Sixta, H., Michud, A., Hauru, L., Asaadi, S., Ma, Y., King, A. W. T., Kilpelainen, I., and Hummel, M. (2015). “Ioncell-F: A high-strength regenerated cellulose fibre,” Nordic Pulp & Paper Research Journal 30(1), 43-57. DOI: 10.3183/NPPRJ-2015-30-01-p043-057
Slater, S. C., Simmons, B. A., Rogers, T. S., Phillips, M. F., Nordahl, K., and Davison, B. H. (2015). “The DOE bioenergy research centers: History, operations, and scientific output,” Bioenergy Research 8(3), 881-896. DOI: 10.1007/s12155-015-9660-8
Smith, E. L., Abbott, A. P., and Ryder, K. S. (2014). “Deep eutectic solvents (DESs) and their applications,” Chemical Reviews 114(21), 11060-11082. DOI: 10.1021/cr300162p
Socha, A. M., Parthasarathi, R., Shi, J., Pattathil, S., Whyte, D., Bergeron, M., George, A., Tran, K., Stavila, V., Venkatachalam, S., Hahn, M. G., Simmons, B. A., and Singh, S. (2014). “Efficient biomass pretreatment using ionic liquids derived from lignin and hemicellulose,” Proceedings of the National Academy of Sciences of the United States of America 111(35), E3587–95. DOI: 10.1073/pnas.1405685111
Spence, K., Venditti, R., and Rojas, O. J. (2009). “Sugar surfactants in paper recycling,” Nordic Pulp & Paper Research Journal 24(1), 107-111. DOI: 10.3183/NPPRJ-2009-24-01-p107-111
Steiner, J. J., and Buford, M. A. (2016). “The origin of the USDA regional biomass research centers,” Bioenergy Research 9(2), 379-383. DOI: 10.1007/s12155-016-9736-0
Stoklosa, R. J., and Hodge, D. B. (2015). “Fractionation and improved enzymatic deconstruction of hardwoods with alkaline delignification,” Bioenergy Research 8(3), 1224-1234. DOI: 10.1007/s12155-015-9579-0
Strassberger, Z., Tanase, S., and Rothenberg, G. (2014). “The pros and cons of lignin valorization in an integrated biorefinery,” RSC Advances 4(48), 25310-25318. DOI: 10.1039/C4RA04747H
Suhas, Carrott, P. J. M., and Ribeiro Carrott, M. M. L. (2007). “Lignin – from natural adsorbent to activated carbon: A review,” Bioresource Technology 98(12), 2301-2312. DOI: 10.1016/j.biortech.2006.08.008
Sukhbaatar, B., Li, Q., Wan, C., Yu, F., Hassan, E.-B., and Steele, P. (2014). “Inhibitors removal from bio-oil aqueous fraction for increased ethanol production,” Bioresource Technology 161, 379-384. DOI: 10.1016/j.biortech.2014.03.051
Sustainable Advanced Biofuels Across the United States. (2015). USDA.
Taverna, M. E., Ollearo, R., Moran, J., Nicolau, V., Estenoz, D., and Frontini, P. (2015). “Mechanical evaluation of laminates based on phenolic resins using lignins as partial substitutes for phenol,” BioResources 10(4), 8325-8338. DOI: 10.15376/biores.10.4.8325-8338
Taylor, R., Nattrass, L., Albert, G., Paul Robson, Chudziak, C., Bauen, A., Libelli, I. M., Lotti, G., Prussi, M., Nistri, R., Chiaramonti, D., Contreras, A. L., Harriette Bos, G. E., Jan Springer, R. B., and van Ree, R. (2015). “From the sugar platform to biofuels and biochemicals,” European Commission.
Thorp, B. A., Seamans, H., and Akhtar, M. (2011). “Major cellulosic biofuels – Biochemical activities in the U.S,” Cellulose Chemistry and Technology 45(7-8), 467-474.
Thorp, B. A., Seamans, H., Cullinan, H., and Akhtar, M. (2015). “Review of currently available technology for the conversion of woody biomass to value-added products,” Tappi J 14(3), 159-164.
Tomani, P. (2010). “The Lignoboost process,” Cellulose Chemistry and Technology 44(1-3), 53-58.
Tomei, J., and Helliwell, R. (2016). “Food versus fuel? Going beyond biofuels,” Land Use Policy56, 320-326. DOI: 10.1016/j.landusepol.2015.11.015
Tullo, A. (2016). “Catalyzing aromatics,” Chemical and Engineering News 94(6), 20.
Tuuttila, T., and Joelsson, J. (2012). Current Development of Forest Biorefineries in Finland and Sweden. Forest Refine.
Upton, B. M., and Kasko, A. M. (2016). “Strategies for the conversion of lignin to high-value polymeric materials: Review and perspective,” Chemical Reviews 116(4), 2275-2306. DOI: 10.1021/acs.chemrev.5b00345
Van Heiningen, A. (2006). “Converting a kraft pulp mill into an integrated forest biorefinery,” Pulp and Paper Canada 107(6), 38-43.
Van Lancker, J., Wauters, E., and Van Huylenbroeck, G. (2016). “Managing innovation in the bioeconomy: An open innovation perspective,” Biomass and Bioenergy 90, 60-69. DOI: 10.1016/j.biombioe.2016.03.017
Vasara, P. (2013). “The four waves of biorefining,” Results Pulp and Paper 31(2), 7. DOI: 10.1086/640175
Viell, J., Wulfhorst, H., Schmidt, T., Commandeur, U., Fischer, R., Spiess, A., and Marquardt, W. (2013). “An efficient process for the saccharification of wood chips by combined ionic liquid pretreatment and enzymatic hydrolysis,” Bioresource Technology 146, 144-151. DOI: 10.1016/j.biortech.2013.07.059
Wagemann, K. (2012). Biorefineries Roadmap, German Federal Government.
Wang, S., Wang, Y., Leng, F., and Chen, J. (2016a). “Stepwise enrichment of sugars from the heavy fraction of bio-oil,” Energy and Fuels 30(3), 2233-2239. DOI: 10.1021/acs.energyfuels.6b00039
Wang, S., Wang, Y., Leng, F., Chen, J., Qiu, K., and Zhou, J. (2016b). “Separation and enrichment of catechol and sugars from bio-oil aqueous phase,” BioResources 11(1), 1707–1720. DOI: 10.15376/biores.11.1.1707-1720
Werpy, T., and Petersen, G. (2004). “Top value added chemicals from biomass: Volume I – results of screening for potential candidates from sugars and synthesis gas,” National Renewable Energy Lab. DOI: 10.2172/15008859
Wertz, J.-L., and Bédué, O. (2013). Lignocellulosic Biorefineries, Taylor & Francis Group, Boca Raton, FL.
Wetterlund, E., Pettersson, K., and Harvey, S. (2011). “Systems analysis of integrating biomass gasification with pulp and paper production – Effects on economic performance, CO2 emissions and energy use,” Energy 36(2), 932-941. DOI: 10.1016/j.energy.2010.12.017
Wikberg, H., Gronberg, V., Jermakka, J., Kemppainen, K., Kleen, M., Laine, C., Paasikallio, V., and Oasmaa, A. (2015). “Hydrothermal refining of biomass-an overview and future perspectives,” Tappi J 14(3), 195-207.
Williamson, M. (2013). “A biorefiner ahead of its time,” Internationale Papierwirtschaft (4), 19-21.
Wilson, K., and Lee, A. F. (2016). “Catalyst design for biorefining,” Philosophical Transactions. Series A 374, 20150081. DOI: 10.1098/rsta.2015.0081
WP 8.1. Determination of market potential for selected platform chemicals. (2013). Weastra.
Wyman, C. E. (2013). Aqueous Pretreatment of Plant Biomass for Biological and Chemical Conversion to Fuels and Chemicals, John Wiley & Sons, Chichester, UK.
Xie, H., Kilpelainen, I., King, A., Leskinen, T., Jarvi, P., and Argyropoulos, D. S. (2009). “Opportunities with wood dissolved in ionic liquids,” in: Cellulose Solvents: for Analysis, Shaping and Chemical Modification, Liebert, T. F., Heinze, T. J., and Edgar, K. J., (eds.), American Chemical Society, Washington, 343-363.
XIVIATM Xylitol White Paper. (2012). DuPont Danisco.
Xu, C., and Lancaster, J. (2008). “Conversion of secondary pulp/paper sludge powder to liquid oil products for energy recovery by direct liquefaction in hot-compressed water,” Water Research42(6-7), 1571-1582. DOI: 10.1016/j.watres.2007.11.007
Yoon, S.-H., and Van Heiningen, A. (2008). “Kraft pulping and papermaking properties of hot-water pre-extracted loblolly pine in an integrated forest products biorefinery,” Tappi J 7(7), 22-27.
Yu, Z., Jameel, H., Chang, H.-M., and Park, S. (2011). “The effect of delignification of forest biomass on enzymatic hydrolysis,” Bioresource Technology 102, 9083-9089. DOI: 10.1016/j.biortech.2011.07.001
Zakzeski, J., Bruijnincx, P. C. A., Jongerius, A. L., and Weckhuysen, B. M. (2010). “The catalytic valorization of lignin for the production of renewable chemicals,” Chemical Reviews 110(6), 3552-3599. DOI: 10.1021/cr900354u
Zerbe, J. (1991). “Liquid fuels from wood – ethanol, methanol, diesel,” World Resource Review3(4), 406-414.
Zhang, X., Paice, M. G., and Deng, J. (2011). “Modify existing pulp and paper mills for biorefinery operations,” in: Sustainable Production of Fuels, Chemicals, and Fibers from Forest Biomass, J. Zhu, X. Zhang, and X. Pan (eds.), pp. 395-408. DOI: 10.1021/bk-2011-1067.ch015
Zhao, X., Brown, T. R., and Tyner, W. E. (2015). “Stochastic techno-economic evaluation of cellulosic biofuel pathways,” Bioresource Technology 198, 755-763. DOI: 10.1016/j.biortech.2015.09.056
Zhao, Y., and Yan, N. (2014). “Recent development in forest biomass derived phenol formaldehyde (PF) resol resin for wood adhesives application,” Journal of Biobased Materials and Bioenergy 8(5), 465-480. DOI: 10.1166/jbmb.2014.1463
Zhu, H., Luo, W., Ciesielski, P. N., Fang, Z., Zhu, J. Y., Henriksson, G., Himmel, M. E., and Hu, L. (2016). “Wood-derived materials for green electronics, biological devices, and energy applications,” Chemical Reviews. Article ASAP. DOI: 10.1021/acs.chemrev.6b00225
Zhu, J., Zhang, X., and Pan, X. (2011). Sustainable Production of Fuels, Chemicals, and Fibers from Forest Biomass, American Chemical Society, Washington, DC. DOI: 10.1021/bk-2011-1067
Zhu, J. Y., Chandra, M. S., Gleisner, R., Gilles, W. T., Gao, J., Marrs, G., Anderson, D., and Sessions, J. (2015a). “Case studies on sugar production from underutilized woody biomass using sulfite chemistry,” Tappi J 14(9), 577-583.
Zhu, J. Y., Chandra, M. S., Gu, F., Gleisner, R., Reiner, R., Sessions, J., Marrs, G., Gao, J., and Anderson, D. (2015b). “Using sulfite chemistry for robust bioconversion of Douglas-fir forest residue to bioethanol at high titer and lignosulfonate: A pilot-scale evaluation,” Bioresource Technology 179, 390-397. DOI: 10.1016/j.biortech.2014.12.052
Zhu, R., and Yadama, V. (2016). “Effects of hot water extraction pretreatment on physicochemical changes of Douglas fir,” Biomass and Bioenergy 90, 78-89. DOI: 10.1016/j.biombioe.2016.03.028
Article submitted: June 18, 2016; Peer review completed: August 7, 2016; Revised version received and accepted: September 9, 2016; Published: September 13, 2016.