A novel reforming method for hydrogen production from biomass steam gasification

In this work, an experimental study of biomass gasification in different operation conditions has been carried out in an updraft gasifier combined with a porous ceramic reformer. The effects of gasifier temperature, steam to biomass ratio (S/B), and reforming temperature on the gas characteristic parameters were investigated with and without porous ceramic filled in reformer. The results indicated that considerable synergistics effects were observed as the porous ceramic was filled in reformer leading to an increase in the hydrogen production. With the increasing gasifier temperature varying from 800 to 950 °C, hydrogen yield increased from 49.97 to 79.91 g H₂/kg biomass. Steam/biomass ratio of 2.05 seemed to be optimal in all steam-gasification runs. The effect of reforming temperature for water-soluble tar produced in porous ceramic reforming was also investigated, and it was found that the conversion ratio of total organic carbon (TOC) contents is between 71.08% and 75.74%.     

Cellulose nanowhiskers extracted from TEMPO-oxidized jute fibers

Cellulose nanowhiskers is a kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Here, for the first time, a novel controllable fabrication of cellulose nanowhiskers from jute fibers with a high yield (over 80%) via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization is reported. The versatile jute cellulose nanowhiskers with ultrathin diameters (3-10nm) and high crystallinity (69.72%), contains C6 carboxylate groups converted from C6 primary hydroxyls, which would be particularly useful for applications in the nanocomposites as reinforcing phase, as well as in tissue engineering, pharmaceutical and optical industries as additives.     

A novel biochemical route for fuels and chemicals production from cellulosic biomass

The conventional biochemical platform featuring enzymatic hydrolysis involves five key steps: pretreatment, cellulase production, enzymatic hydrolysis, fermentation, and product recovery. Sugars are produced as reactive intermediates for subsequent fermentation to fuels and chemicals. Herein, an alternative biochemical route is proposed. Pretreatment, enzymatic hydrolysis and cellulase production is consolidated into one single step, referred to as consolidated aerobic processing, and sugar aldonates are produced as the reactive intermediates for biofuels production by fermentation. In this study, we demonstrate the viability of consolidation of the enzymatic hydrolysis and cellulase production steps in the new route using Neurospora crassa as the model microorganism and the conversion of cellulose to ethanol as the model system. We intended to prove the two hypotheses: 1) cellulose can be directed to produce cellobionate by reducing β-glucosidase production and by enhancing cellobiose dehydrogenase production; and 2) both of the two hydrolysis products of cellobionate--glucose and gluconate--can be used as carbon sources for ethanol and other chemical production. Our results showed that knocking out multiple copies of β-glucosidase genes led to cellobionate production from cellulose, without jeopardizing the cellulose hydrolysis rate. Simulating cellobiose dehydrogenase over-expression by addition of exogenous cellobiose dehydrogenase led to more cellobionate production. Both of the two hydrolysis products of cellobionate: glucose and gluconate can be used by Escherichia coli KO 11 for efficient ethanol production. They were utilized simultaneously in glucose and gluconate co-fermentation. Gluconate was used even faster than glucose. The results support the viability of the two hypotheses that lay the foundation for the proposed new route.     

A novel nanocomposite film prepared from crosslinked cellulosic whiskers

Cellulose whiskers are increasingly being used as a reinforcing phase in polymer systems and their use is a growing area of importance in bionanocomposite research. Although the reinforcing effect of cellulose whiskers has been studied in various polymers, the impact of crosslinking cellulose whiskers has not been explored so far. This work deals with the development of novel cellulose nanocomposites, wherein the cellulose nanowhiskers are crosslinked with poly(methyl vinyl ether-co-maleic acid) and poly(ethylene glycol). The morphology of the nanocomposite was studied using atomic force microscopy (AFM), which revealed a network structure embedded in a continuous phase. The water sorption studies demonstrated that the crosslinked nanocomposites are capable of absorbing up to ～900% water and have potential to be used as hydrogels.     

Fermentative hydrogen production from pretreated biomass: A comparative study

The aim of this work was to evaluate the potential of employing biomass resources from different origin as feedstocks for fermentative hydrogen production. Mild-acid pretreated and hydrolysed barley straw (BS) and corn stalk (CS), hydrolysed barley grains (BG) and corn grains (CG), and sugar beet extract (SB) were comparatively evaluated for fermentative hydrogen production. Pretreatments and/or enzymatic hydrolysis led to 27, 37, 56, 74 and 45 g soluble sugars/100 g dry BS, CS, BG, CG and SB, respectively. A rapid test was applied to evaluate the fermentability of the hydrolysates and SB extract. The thermophilic bacterium Caldicellulosiruptor saccharolyticus showed high hydrogen production on hydrolysates of mild-acid pretreated BS, hydrolysates of BG and CG, and SB extract. Mild-acid pretreated CS showed limited fermentability, which was partially due to inhibitory products released in the hydrolysates, implying the need for the employment of a milder pretreatment method. The difference in the fermentability of BS and CS is in strong contrast to the similarity of the composition of these two feedstocks. The importance of performing fermentability tests to determine the suitability of a feedstock for hydrogen production was confirmed.     

Energy production from biomass (Part 1): Overview of biomass

The use of renewable energy sources is becoming increasingly necessary, if we are to achieve the changes required to address the impacts of global warming. Biomass is the most common form of renewable energy, widely used in the third world but until recently, less so in the Western world. Latterly much attention has been focused on identifying suitable biomass species, which can provide high-energy outputs, to replace conventional fossil fuel energy sources. The type of biomass required is largely determined by the energy conversion process and the form in which the energy is required. In the first of three papers, the background to biomass production (in a European climate) and plant properties is examined. In the second paper, energy conversion technologies are reviewed, with emphasis on the production of a gaseous fuel to supplement the gas derived from the landfilling of organic wastes (landfill gas) and used in gas engines to generate electricity. The potential of a restored landfill site to act as a biomass source, providing fuel to supplement landfill gas-fuelled power stations, is examined, together with a comparison of the economics of power production from purpose-grown biomass versus waste-biomass. The third paper considers particular gasification technologies and their potential for biomass gasification.     

Cellulose factories: advancing bioenergy production from forest trees

Fast-growing, short-rotation forest trees, such as Populus and Eucalyptus, produce large amounts of cellulose-rich biomass that could be utilized for bioenergy and biopolymer production. Major obstacles need to be overcome before the deployment of these genera as energy crops, including the effective removal of lignin and the subsequent liberation of carbohydrate constituents from wood cell walls. However, significant opportunities exist to both select for and engineer the structure and interaction of cell wall biopolymers, which could afford a means to improve processing and product development. The molecular underpinnings and regulation of cell wall carbohydrate biosynthesis are rapidly being elucidated, and are providing tools to strategically develop and guide the targeted modification required to adapt forest trees for the emerging bioeconomy. Much insight has already been gained from the perturbation of individual genes and pathways, but it is not known to what extent the natural variation in the sequence and expression of these same genes underlies the inherent variation in wood properties of field-grown trees. The integration of data from next-generation genomic technologies applied in natural and experimental populations will enable a systems genetics approach to study cell wall carbohydrate production in trees, and should advance the development of future woody bioenergy and biopolymer crops.     

Engineering photorespiration in chloroplasts: a novel strategy for increasing biomass production

Photosynthetic carbon metabolism is rate limiting in C3 plants because of a competing process: photorespiration. Photorespiration lowers the energy efficiency of photosynthesis by metabolizing glycolate produced by the oxygenate activity of Rubisco. The chloroplasts of Arabidopsis thaliana have recently been reported to contain a novel respiratory pathway that converts glycolate directly to glycerate and thus increases productivity by improving photosynthesis in transgenic plants. This pathway promises to widen the applicability of the approach to other C3 plants.     

Ethanol production from olive cake biomass substrate

The inexpensive production of sugars from lignocellulose is an essential step for the use of biomass to produce fuel ethanol. Olive cake is an abundant by-product of the olive oil industry and represents a potentially significant lignocellulosic source for bioethanol production in the Mediterranean basin. Furthermore, converting olive cake to ethanol could add further value to olive production. In the present study, olive cake was evaluated as a feedstock for ethanol production. To this end, the lignocellulosic component of the olive cake was dilute-acid pretreated at a 13.5% olive-cake loading with 1.75% (w/v) sulfuric acid and heating at 160°C for 10 min. This was followed by chemical elimination of fermentation inhibitors. Soluble sugars resulting from the pretreatment process were fermented using E. coli FBR5, a strain engineered to selectively produce ethanol. 8.1 g of ethanol/L was obtained from hydrolysates containing 18.1 g of soluble sugars. Increasing the pretreatment temperature to 180°C resulted in failed fermentations, presumably due to inhibitory by-products released during pretreatment.     

Two-stage biohumus production from inedible potato biomass

The feasibility of a two-stage bioconversion of inedible potato biomass into biohumus by oyster mushroom followed by worms was tested. As a raw material for biohumus production the inedible potato biomass in certain properties ranked below wheat straw. The most feasible method to convert the potato wastes into biohumus was to mix them with wheat straw at the mass ratio of 1:3 and then treat with mushrooms followed by worms. This gave a good yield of mushrooms. The biohumus produced from the mixture was suitable for use as a plant growth medium.     

Yeast biomass production from acid whey permeate

Summary The yield ofKluyveromyces marxianus Y-113 grown on sulphuric acid casein whey permeate was decreased at high lactose or ethanol concentrations and slightly increased with high agitation and supplementation of the permeate with nutrients. The maximum specific growth rate was most influenced by the stirrer speed, ethanol concentration and nutrient supplementation.     

Energy production from biomass (Part 2): Conversion technologies

The use of biomass to provide energy has been fundamental to the development of civilisation. In recent times pressures on the global environment have led to calls for an increased use of renewable energy sources, in lieu of fossil fuels. Biomass is one potential source of renewable energy and the conversion of plant material into a suitable form of energy, usually electricity or as a fuel for an internal combustion engine, can be achieved using a number of different routes, each with specific pros and cons. A brief review of the main conversion processes is presented, with specific regard to the production of a fuel suitable for spark ignition gas engines.     

Energy production from biomass (Part 3): Gasification technologies

The conversion of biomass by gasification into a fuel suitable for use in a gas engine increases greatly the potential usefulness of biomass as a renewable resource. Gasification is a robust proven technology that can be operated either as a simple, low technology system based on a fixed-bed gasifier, or as a more sophisticated system using fluidized-bed technology. The properties of the biomass feedstock and its preparation are key design parameters when selecting the gasifier system. Electricity generation using a gas engine operating on gas produced by the gasification of biomass is applicable equally to both the developed world (as a means of reducing greenhouse gas emissions by replacing fossil fuel) and to the developing world (by providing electricity in rural areas derived from traditional biomass).     

A multiple species approach to biomass production from native herbaceous perennial feedstocks

Due to the rapid rate of worldwide consumption of nonrenewable fossil fuels, production of biofuels from cellulosic sources is receiving increased research emphasis. Here, we review the feasibility to produce lignocellulosic biomass on marginal lands that are not well-suited for conventional crop production. Large areas of these marginal lands are located in the central prairies of North America once dominated by tallgrass species. In this article, we review the existing literature, current work, and potential of two native species of the tallgrass prairie, prairie cordgrass (Spartina pectinata), and little bluestem (Schizachyrium scoparium) as candidates for commercial production of biofuel. Based on the existing literature, we discuss the need to accelerate research in the areas of agronomy, breeding, genetics, and potential pathogens. Cropping systems based on maintaining biodiversity across landscapes are essential for a sustainable production and to mitigate impact of pathogens and pests.     

Ethanol production from lignocellulosic biomass of energy cane

Ethanol produced from lignocellulosic biomass is a renewable alternative to diminishing petroleum based liquid fuels. The release of many new sugarcane varieties by the United States Department of Agriculture to be used as energy crops is a promising feedstock alternative. Energy cane produces large amounts of biomass that can be easily transported, and production does not compete with food supply and prices because energy cane can be grown on marginal land instead of land for food crops. The purpose of this study was to evaluate energy cane for lignocellulosic ethanol production. Energy cane variety L 79-1002 was pretreated with weak sulfuric acid to remove lignin. In this study, 1.4 M sulfuric acid pretreated type II energy cane had a higher ethanol yield after fermentation by Klebsiella oxytoca without enzymatic saccharification than 0.8 M and 1.6 M sulfuric acid pretreated type II energy cane. Pretreated biomass was inoculated with K. oxytoca for cellulose fermentation and Pichia stipitis for hemicellulose fermentation under simultaneous saccahrification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) conditions. For enzymatic saccharification of cellulose, the cellulase and ??-glucanase cocktail significantly increased ethanol production compared to the ethanol production of fermented acid pretreated energy cane without enzymatic saccharification. The results revealed that energy cane variety L 79-1002 produced maximum cellulosic ethanol under SHF (6995 mg/L) and produced 3624 mg/L ethanol from fermentation of hemicellulosic sugars.     

Adsorption of methylene blue dye from aqueous solution by sugar extracted spent rice biomass

This study was aimed at using sugar extracted spent rice biomass (SRB) as a potential adsorbent to remove methylene blue (MB) dye from aqueous solution. The SRB was used without any modification. A three factor full factorial experimental design (2(3)) was employed to investigate the effect of factors (adsorbent dose, dye concentration, temperature) and their interaction on the adsorption capacity and color removal. Two levels for each factor were used; adsorbent dose (0.25-0.5g/100mL), dye concentration (25-50mg/L), and temperature (25-45°C). Initial dye concentration and adsorbent dosage were found as significant factors for the adsorption of MB dye. Langmuir isotherm (R(2)>0.998) best explained the equilibrium of MB adsorption on SRB with monolayer adsorption capacity of 8.13mg/g. The pseudo-second order model (R(2)>0.999) was best fitted to explain the adsorption kinetics. Thermodynamic investigation revealed that the adsorption process was spontaneous, endothermic, and was feasible to treat dyeing wastewater.     

Microalgal biomass production: challenges and realities

The maximum quantum yield (Φ _max), calculated from the maximum chlorophyll a specific photosynthetic rate divided by the quantum absorption per unit chlorophyll a, is 8 photons or 0.125 mol C per mol Quanta light energy. For the average solar radiation that reaches the earth’s surface this relates to a photosynthetic yield of 1.79 g(dw) m^?2 day^?1 per percentage photosynthetic efficiency and it could be doubled for sunny, dry and hot areas. Many factors determine volumetric yields of mass algal cultures and it is not simply a question of extrapolating controlled laboratory rates to large scale outdoor production systems. This is an obvious mistake many algal biotechnology start-up companies make. Closed photobioreactors should be able to outperform open raceway pond cultures because of the synergistic enhancement of a reduced boundary layer and short light/dark fluctuations at high turbulences. However, this has not been shown on any large scale and to date the industrial norm for very large production systems is open raceway production ponds. Microalgal biomass production offers real opportunities for addressing issues such as CO₂ sequestration, biofuel production and wastewater treatment, and it should be the preferred research emphasis.     

Effective production of fermentable sugars from brown macroalgae biomass

Brown macroalgae are renewable and sustainable biomass resources for the production of biofuels and chemicals, owing to their high levels of carbohydrates and low levels of lignin. To increase the biological usage of brown macroalgae, it is necessary to depolymerize the polysaccharides that generate macroalgal monomeric sugars or sugar derivatives and to convert them into fermentable sugars for the production of biofuels and chemicals. In this review, we discuss the chemical and enzymatic saccharification of the major carbohydrates found in brown macroalgae and the use of the resulting constituents in the production of biofuels and chemicals, as well as high-value health-benefiting functional oligosaccharides and sugars. We also discuss recently reported experimental results, novel enzymes, and technological breakthroughs that are related to polysaccharide depolymerization, fermentable sugar production, and the biological conversion of non-favorable sugars for fermentation using industrial microorganisms. This review provides a comprehensive perspective of the efficient utilization of brown macroalgae as renewable resources for the production of biofuels and chemicals.     

Biotechnological routes based on lactic acid production from biomass

Lactic acid, the most important hydroxycarboxylic acid, is now commercially produced by the fermentation of sugars present in biomass. In addition to its use in the synthesis of biodegradable polymers, lactic acid can be regarded as a feedstock for the green chemistry of the future. Different potentially useful chemicals such as pyruvic acid, acrylic acid, 1,2-propanediol, and lactate ester can be produced from lactic acid via chemical and biotechnological routes. Here, we reviewed the current status of the production of potentially valuable chemicals from lactic acid via biotechnological routes. Although some of the reactions described in this review article are still not applicable at current stage, due to their “greener” properties, biotechnological processes for the production of lactic acid derivatives might replace the chemical routes in the future.