Influence of inoculum cell density and carbon dioxide concentration on fed-batch cultivation of Nannochloropsis oculata

The marine microalgae Nannochloropsis oculata is a promising source of biofuel because of its high lipid content. For achieving high productivity of oil from microalgae, a high cell concentration before harvesting is beneficial. The present study investigated fed-batch cultures of N. oculata fed with vitamins and nutrient solutions and found that the biomass yield of N. oculata in the fed-batch culture was 1.25 times higher than that in batch culture. Fed-batch cultivation, especially at high illumination, decreased the inhibitory effect of high carbon dioxide (CO₂) concentration on the microalgal growth. The specific growth rate was directly proportional to the light intensity in the CO₂ environment. A light intensity of 40,000 Lux was able to achieve high specific growth rates in fed-batch cultivation at a CO₂ volume fraction of 2%–15%. The tolerance of N. oculata to CO₂ was enhanced by the daily feeding of nutrients in the fed-batch cultivation. At 2% CO₂, a final cell density of about OD₆₈₂ = 11.4 was achieved in the fed-batch culture in 30 days. Furthermore, a cell density of 14.4 g L⁻¹ was obtained by outdoor fed-batch cultivation in 27 days.     

Techno-economic analysis of a bio-refinery process for producing Hydro-processed Renewable Jet fuel from Jatropha

HRJ (Hydro-processed Renewable Jet) conversion technology has been recently used to produce renewable jet fuel for commercial or military flights. In this study, a techno-economic analysis is carried out for evaluating the production of jatropha-derived HRJ fuel through a bio-refinery process. Each component of the chosen feedstock jatropha can be converted into valuable products. The bio-refinery process is split into 6 parts: (1) Fruit Dehulling; (2) Shell Combustion; (3) Oil Extraction; (4) Press Cake Pyrolysis; (5) Oil Upgrading; (6) Product Separation. The minimum jet fuel selling price (MJSP) from this fruit scenario is calculated to be $5.42/gal based on the plant capacity of 2400 metric tonne of feedstock per day. The co-products obtained from the process not only significantly deduct the production cost but make the entire process energy self-sustainable. We also discuss the oil scenario, which oil is the starting material and the process begins from Oil Upgrading section. The oil scenario offers the MJSP of $5.74/gal with lower capital but higher operating costs. The differences of MJSPs for fruit and oil scenarios are due to feedstock cost, refinery capital cost, co-product credits and energy cost. Based on the sensitivity analysis, the feedstock price, oil content, plant capacity, reactor construction and catalyst usage are important parameters that control the price of the produced fuel.     

Price dynamics in Wisconsin woody biomass markets

This study quantifies the potential impact of biofuel/bioenergy development on the pulpwood market in Wisconsin. Important demand and supply factors to take into account when quantifying the potential spillover effects include: (i) availability of regional forest residues, (ii) forest biomass demand of the Renewable Portfolio Standard (RPS) mandated by the state, and (iii) the slack pulpwood supply due to the recent economic recession. The results indicate that given the limited amount of regional forest residues, demand for primary forest resources over 2.29 million dry Mg will likely spill over into local pulpwood market and have a pronounced impact on pulpwood prices. The price effect could be more substantial if the pulp and paper industry expands production capacity significantly over the same period.     

Development of a bifunctional Ni/HZSM-5 catalyst for converting prairie cordgrass to hydrocarbon biofuel

Ni/HZSM-5 catalysts were prepared using the impregnation method. The HZSM-5 and impregnated Ni/HZSM-5 catalysts were characterized by Brunauer–Emmett–Teller and X-ray diffraction. The HZSM-5 and Ni/HZSM-5 catalysts were used for prairie cordgrass (PCG) thermal conversion in a two-stage catalytic pyrolysis system. The products contained gas, bio-oil, and bio-char. The gas and bio-oil were analyzed by gas chromatography and gas chromatography–mass spectrometry separately. Higher heating values and elemental composition of bio-char were determined. The results indicated that 12% Ni/HZSM-5 treatment yielded the highest amount of gasoline fraction for hydrocarbons and showed a robust ability to upgrade bio-oil vapor.     

Interactions of mixing and reaction kinetics of depolymerization of cellulose to renewable fuels

As the biofuel industry is heavily depend on technological advancement to remain competent, creation of new process techniques becomes inevitable to replace the existing under-performed operations. Mixing in the reactor requires enormous amount of energy to achieve required homogeneity. Reduction in the energy consumption and ultimately the cost of the product is possible by devising smart mixing strategies. In this review, interactions of mixing and reaction kinetics of enzymatic hydrolysis, fermentation, and cellulosic depolymerization in ionic solvents are discussed. When the processes are operated under various mixing conditions, changes in the reaction kinetics and dynamics of the processes occur. Therefore, analyzing the mixing effects at various levels (micro to macro) is crucial to decide best operating mixing conditions that drive the reaction kinetics toward the increased product yield. The review is helpful to identify a suitable mixing strategy that maximizes the production of biofuels—ethanol, 5-hydroxymethylfurfural, etc.     

Three routes forward for biofuels: Incremental,leapfrog, and transitional

This paper examines three technology routes for lowering the carbon intensity of biofuels: (1) a leapfrog route that focuses on major technological breakthroughs in lignocellulosic pathways at new, stand-alone biorefineries; (2) an incremental route in which improvements are made to existing U.S. corn ethanol and soybean biodiesel biorefineries; and (3) a transitional route in which biotechnology firms gain experience growing, handling, or chemically converting lignocellulosic biomass in a lower-risk fashion than leapfrog biorefineries by leveraging existing capital stock. We find the incremental route is likely to involve the largest production volumes and greenhouse gas benefits until at least the mid-2020s, but transitional and leapfrog biofuels together have far greater long-term potential. We estimate that the Renewable Fuel Standard, California's Low Carbon Fuel Standard, and federal tax credits provided an incentive of roughly $1.5–2.5 per gallon of leapfrog biofuel between 2012 and 2015, but that regulatory elements in these policies mostly incentivize lower-risk incremental investments. Adjustments in policy may be necessary to bring a greater focus on transitional technologies that provide targeted learning and cost reduction opportunities for leapfrog biofuels.     

Microwave-promoted conversion of concentrated fructose into 5-hydroxymethylfurfural in ionic liquids in the absence of catalysts

Under microwave irradiation, concentrated fructose (33-92 wt%) in ionic liquids afforded 5-hydroxymethylfurfural in ca. 97-57% yields without addition of catalysts, within 3 min. In-situ¹³C NMR and ¹H NMR spectra suggest that the transformation of fructose in ionic liquid is a highly selective reaction that proceeds predominantly via the cyclic fructofuransyl intermediate. This method is expected to be valuable in facilitating cost-effective conversion of carbohydrates into biofuels and platform chemicals.     

Effect of TiO2 and nozzle geometry on diesel emissions fuelled with biodiesel blends

In this present study, the compression ignition engine was designed to run on CIME (Calophyllum inophyllum methyl ester) biodiesel with nanoparticles. The TiO₂ nanoparticle is added to the biodiesel in the form of nanofluid at concentration levels of 100?ppm whereas ethanox is added at levels of 100, 200 and 500?ppm. The nanoparticle and the ethanox are dispersed by the ultrasonication process. The addition of nanofluid reduces the particulate emission like nitrogen oxide (NO_x) at 100% load. The efficiency is better and emission is reduced owing to the influence of explosion of water molecules present in the biodiesel. We found ethanox to be a superlative nanofluid to reduce the emission of toxic gas at appreciable levels. We have witnessed a 20% reduction in emission of NO_x and 10% reduction of other particulate emission. In addition, the exit geometry of exhaust is modified from a circular shape to an elliptical one and the consequence of the geometry is calculated.     

The use of (green field) biomass pretreatment liquor for fermentative butanol production and the catalytic oxidation of biobutanol

In this study, pretreatment liquor of acid-stored green and yellowish barley silage was used for fermentative acetone–butanol–ethanol (ABE) production. Further, the catalytic oxidation of biobutanol over Pt catalysts was studied to investigate the behaviour of butanol as a fuel in the combustion engine. After the hydrothermal treatment of green and yellowish barley silage followed by enzymatic hydrolysis, approximately 88% and 100% of the available sugars were recovered, respectively. Batch fermentations of pretreatment barley silage liquor, supplemented with gelatinised barley grain, showed good fermentability with total ABE concentrations of 9.0 g/L and 10.9 g/L. Butanol yields of 0.20, 0.17 and ABE yields of 0.28, 0.26 (g/g monosaccharide) were obtained, respectively. In catalytic activity measurements, the conversion of biobutanol became appreciable in the 120–140 °C range, whereas conversions greater than 95% were obtained over 200 °C. Selectivities were also high, although formation of by-products, such as butyraldehyde, was observed.     

Storage stability of poultry fat and diesel fuel mixtures: Part II - Chemical properties

This publication continues previously published work from the authors which evaluates the storage potential of poultry fat for its use as an unmodified biofuel in heat and steam generating systems [1]. The previous work examined the physical properties of these fats while this study is concerned with chemical properties. In this study poultry fat (biofuel) and its 20%, 40%, 60% and 80% mixtures with #2 pump diesel fuel were stored for 1 year at bench scale (1L) under controlled laboratory conditions at 4, 38, 54.4 °C and at 22 °C. One hundred percent of poultry fat was studied under these same conditions with and without an antioxidant additive. Twenty and eighty percent of poultry fat mixtures were also stored at pilot scale (250 gallons) under outdoor, ambient conditions. Chemical properties relevant to the use of these mixtures as a biofuel for industrial boilers were studied and tracked. These properties include Energy Values (BTU), Ultimate Analysis (carbon, hydrogen, oxygen, ash, nitrogen, and sulfur), moisture, impurities, unsaponafiables (MIU), and Free Fatty Acid Content. Energy content of the biofuel samples dropped over the course of the study with untreated biofuel losing 18.9% of its BTU value over the course of a year. Ultimate analyses showed an overall increase in carbon composition and a decrease in oxygen content. Hydrogen levels increased in most treatments as did overall ash and sulfur percent composition. MIU values increased, this overall increase was attributable to variable increases in insolubles and unsaponifiables. Free fatty acid levels increased in all treatments. Most of the chemical changes observed in this study were reduced by the addition of antioxidant to 100% biofuel.