Extractable liquid,its energy and hydrocarbon content in the green alga Botryococcus braunii

Due to sparse sampling across races, studies on various strains of Botryococcus braunii have effectively been indiscriminate, and so the target strains for energy production have not come clearly into focus. This study compares extractable liquid biofuel content, bioenergy content and hydrocarbon content across 16 strains B. braunii (A, B and L races) by direct combustion of algal biomass using thermogravimetric analysis (TGA), pressure differential scanning calorimetry (PDSC) and gas chromatography/mass spectrometry (GC/MS). All B. braunii strains were cultured in the same environmental conditions in 250 ml flasks, and were harvested for analysis when algae reached the exponential growth phase. Significant differences were detected within and between races A, B and L. The ranges of variation in extractable liquid, biofuel energy and hydrocarbon contents in algal dry biomass were 10–40%, 10–60% and 4–25%, respectively. The race B strains (Ayame 1, Kossou 4, Overjuyo 3 and Paquemar) had more than 21% of dry weight comprising C₃₁-C₃₆ hydrocarbons, which are suitable for biofuel and bioenergy production. The Overjuyo 7 and CCAP 807/2 strains in race A and the Madras 3 and Yamoussoukro 4 strains in race L also showed high biofuel production with extractable liquid biofuel accounting for >30% of dry weight. This study identified particular B. braunii strains that are suitable for biofuel production. The application of TGA and PDSC provides a useful analytical approach for assessing the biodiesel production potential of microalgae.     

Emission analysis of Botryococcus braunii algal biofuel using Ni-Doped ZnO nano additives for IC engines

Microalgae biodiesel has been considered ?as a clean renewable fuel for diesel marine engines. This is due to its optimistic characterizations such as ?rapid growth rate, high productivity, and its ability to convert CO₂ into fuel. In this study, the use of microalgae biodiesel, obtained from Botryococcus braunii, as an alternative fuel for diesel marine engines has been investigated. The diesel engine is verified experimentally using Ni-Doped ZnO nano additive blends with algae biodiesel and neat diesel fuel. The results showed that doped nano additive blends? produce less emission compared to B20.     

Effects of culture medium salinity on the hydrocarbon extractability,growth and morphology of Botryococcus braunii

Here, we investigated the effects of culture medium salinity on the hydrocarbon extractability, growth and morphology of Botryococcus braunii strain Showa. At all tested salinities, the hydrocarbon recovery rate increased during the first or second cell division, which occurred within 7 days. Algal growth in modified Chu13 medium did not differ significantly from that in medium with 0.3% seawater salinity (0.3%SM) to which seawater (3.6%, salinity was 36 g L⁻¹) was diluted. In contrast, culturing in 0.3% seawater salinity improved hydrocarbon extractability and shortened the time required for hydrocarbon extraction. This change supposed to be due to the decrease in the production of polysaccharides which prevent non-polar solvent from contacting hydrocarbons. Additionally, there was an increase in the colony sizes and flotation of the alga when cultured in 0.3% seawater salinity. The results of our experiments suggest that culturing B. braunii in a medium with the appropriate salinity can reduce the input energy and the costs incurred from harvest to hydrocarbon extraction without decreasing biomass production.     

纤维藻培养及制备生物柴油的研究

探讨了纤维藻(Ankistudesmus sp)的低成本培养模式,考察了氮源和碳源以及反应器形式对纤维藻生物量、油脂积累以及油脂组成的影响。户外培养纤维藻在氮饥饿条件下油脂产率较高;通过槽式反应器和管式反应器的比较发现:槽式反应器更适合微藻的大规模培养;混养培养时能显著增加纤维藻的生物量和油脂含量,最佳添加条件下藻的生物量和油脂含量分别高达1.64 g/L和15.9%,1.41 g/L和11.9%。藻油经酸催化甲酯化制备生物柴油,经气相色谱分析,藻油主要成分为棕榈酸、油酸和亚油酸。氮缺陷、流加葡萄糖培养得到的纤维藻油含有25.32%的棕榈酸、44.74%的油酸,其制备得到的生物柴油具有更好的氧化稳定性和低温流动性。     

Energetic optimization of microalgal cultivation in photobioreactors for biodiesel production

Traditionally, algal cultivation in sparged photobioreactors has been optimized to maximize biomass productivity. In this study, an energy-based methodology is presented to maximize the net energy gain of the cultivation process by minimizing the energy input for sparging and by maximizing the energy output. Options for minimizing energy input through optimal gas-to-culture volume ratio and CO₂-air ratio and options for maximizing lipid production through optimal levels of nutrition and CO₂ are presented and validated with results from 900-mL bubble column reactors. In contrast to the traditional practice, the proposed energy-based optimization resulted in positive net energy gains. In single stage approach under optimal conditions (CO₂ enrichment of 0.5%, gas-to-culture volume ratio of 0.18 min⁻¹, and nitrate level of 1 mM), tests with Nannochloropsis salina resulted in positive net energy gain of 20 W/m³. In a test under nitrate starvation, the net energy gain in a reactor sparged with CO₂ enrichment of 0.5% was double that in the reactor sparged with ambient air (8 vs. 19 W/m³).     

Energetic and economic evaluation of a poplar cultivation for the biomass production in Italy

The cultivation of crops for biomass production on good soils allows to reduce surplus production of food crops and increase the sustainability of energy production from the environmental point of view. The short rotation forestry (SRF), is only at a preliminary study level in Italy but, is already a reality in North Europe where was already developed an high planting density (6000–8000 cuttings ha^-1) technique and a whole mechanization of plantation and biomass harvest.On the basis of this cultivation technique, it was realized as an energetic and economic evaluation of a poplar SRF in Northern Italy. In detail, they were considered data of poplar growth in a plantation for the production of two-year whips in Western Po Valley considering SRF duration of 8 years and a biomass (20 t ha⁻¹ D.M.) harvest every 2 years. Indeed it was assumed to operate on a plantation in production (12.5% of the surface replanted every year) with a spacing 3.00 × 0.4 m (6700 cutting per hectare) that allows the use of conventional tractors.In this computing system it was pointed out a ratio between output and input energy of 13 and a cost of 80 € t⁻¹ of D.M. Nevertheless a positive energetic balance, the economic sustainability of poplar SRF depends, due to the present monopolistic energy management in the same countries, on political choices of chip price or public subventions to the producers.     

Rapeseed for energy production: Environmental impacts and cultivation methods

This study involves an environmental impact analysis of rapeseed production in Italy to identify the highest and lowest impact of the method of cultivation. The environmental analysis included five farming units, which were extracted from a sample of 251 rapeseed farm units (2751 ha) using cluster analysis. Using the Life Cycle Assessment (LCA) method, we evaluated the environmental performance of the five units, showing how the cultivation practises and the type/quantity of input can cause environmental impact. Practises of intensive farming with high fertilization and mechanization (machinery and fertilizers production and application) are responsible for the greatest environmental impact. When the level of productivity is low, the impact is still higher. The most damaged environmental category is “human health”, even if the impact on “ecosystem” and “resource depletion” is critical. The potential feasibility to integrate economic cost with the environmental results was just approached.     

High-temperature reactor for hydrogen production by partial oxidation of hydrocarbons

Today, conversion of hydrocarbons is one of the most common hydrogen production technologies. This paper presents a design of a high-temperature reactor — the main component of a hydrogen production unit using partial oxidation of hydrocarbons — as well as a physical model of gas generation. It also presents a schematic diagram of an experimental setup as well as results of experimental studies on steady-state modes of partial oxidation in the combustion chamber of a high-temperature reactor for various hydrocarbon feed/oxidant combinations. In the course of the study, we identified patterns that describe how the excess oxidant ratio affects the composition of products of incomplete combustion of hydrocarbons to obtain hydrogen-containing gas of the required composition and parameters for hydrogen production. We propose a method to calculate nominal geometric dimensions of a high-temperature reactor, which makes it possible to estimate its weight and size at the design stage. The paper presents results of experimental studies confirming the adequacy of the proposed method.     

A comprehensive model for production data analysis in unconventional reservoirs of hydrocarbons

Because of the large amount of energy-rich organic compound, shale gas reservoirs can be good sources of hydrogen energy. To ensure high yield of hydrogen energy, the production data analysis in those shale gas reservoirs is of great significance. However, due to geological and engineering factors, there exist complex mechanisms including stress-sensitivity effect of permeability, gas desorption, complex gas flows, multiple finite-conductivity fractures, and wellbore hydraulics. Unfortunately, little work has been done to focus on these complex mechanisms simultaneously. To comprehensively address this issue, this paper presents a comprehensive model by using a semi-analytical method, and those complex mechanisms are all considered by introducing adsorption index, Knudson diffusion coefficient, reservoir-wellbore constant, and Reynolds number. Both model verification and field application are performed. This study further narrows the gap between theory and practice of production data analysis in shale gas reservoirs, which helps to parameter evaluation, performance forecast, and productivity enhancement in the unconventional reservoirs of hydrocarbons.     

Influences of carbon sources on the biomass,production and compositions of exopolysaccharides from Paecilomyces hepiali HN1

The parasitic fungus, Paecilomyces hepiali, is used to produce Cordyceps materials as succedaneum of natural Cordyceps sinensis in China. The purpose of this research was to investigate the effects of glucose, mannose, sucrose, lactose as solo carbon source and sucrose + lactose or mannose + sucrose as synthetic carbon source on the growth of mycelium and production, chemical composition, molecular weight distribution and monosaccharide composition of exopolysaccharides from P. hepiali HN1 (PHEPS). The maximum mycelium biomass of 12.16 kg m⁻³ and PHEPS yield of 4.57 kg m⁻³ were achieved from the culture with sucrose (50 kg m⁻³) as carbon source. The resulting PHEPS was characterized by analyses of chemical composition, size-exclusion chromatography and high performance liquid chromatography with 1-phenyl-3-methyl-5-pyrazolone pre-column derivatization. It was found that the chemical compositions and monosaccharide ratios in PHEPS were significantly affected by the carbon sources used. Glucose or mannose as carbon source enhanced the biosynthesis of PHEPS with higher-molecular weight (>1000 kD), but solo carbon source of lactose or synthetic carbon source of mannose + lactose did not increase the ratio of galactose in PHEPS. The metabolism kinetics of carbon sources demonstrated the correlation between PHEPS synthesis and the utilization of carbon sources. These findings will be useful for further works on the production, structure and function of PHEPS.     

Experimental verification of various methods for biological hydrogen production

The aim of the work was to compare two different biological methods for hydrogen production: fermentative and photosynthetic based upon the modality of batch cultures. For testing of fermentative bio-hydrogen production four mixed cultures representing anaerobic microorganisms (dominant strain Clostridium) were selected. The kinetic parameters on the intensity of bio-hydrogen production were established. The efficiency coefficient of transformation ranged from 1.65 mol H₂/mol glucose in the pectin culture up to 2.45 in the mixed culture. The bio-hydrogen concentration never exceeded 30%. The carbon dioxide was produced in a ratio of CO₂ to H₂ (0.5–0.67)/1. The testing of green algae proved that the most effective was the algae species Scenedesmus. High bio-hydrogen purity was analytically verified. The fermentative method of H₂ production is more efficient; it does not need light, has a longer efficiency of one charge and enables effective use of different biological wastes.     

Optimization of media composition for the production of biohydrogen from waste glycerol

Enterobacter aerogenes has a known ability to convert glycerol during a fermentative process to yield hydrogen and ethanol as the main products. A Box-Behnken design and response surface methodology were used to determine the optimal concentration of some media constituents and oxygen to maximize the yield of biohydrogen. Results indicated that the concentration of the salts studied: NH₄NO₃, FeSO₄, and Na₂HPO₄ and; the presence of oxygen in the pre-culture significantly influence the production of biohydrogen. Optimal conditions were determined to be 7.5% O₂ in the inoculum transfer step, ratio of inocula 18%, 8 g/L of Na₂HPO₄, 0.00625 g/L of FeSO₄ and 1.5 g/L of NH₄NO₃. These optimal conditions resulted in a measured yield of 0.85 mol H₂/mol glycerol at a substrate concentration of 15 g/L and a maximum predicted yield of 0.95 mol H₂/mol glycerol at a substrate concentration of 21 g/L. These results were obtained using lower concentrations of salts than in previous studies, corresponding to a 76% cost savings. These experimental results also demonstrated the importance of optimizing the amount of oxygen present in the biological system rather than maintaining complete anaerobic conditions.     

Comparison of dairy wastewater and synthetic medium for biofuels production by microalgae cultivation

This study is concerned with comparing raw dairy wastewater (DWW) with blue-green medium (BG11 medium) for biofuel production. Three microalgae strains (Chlorella sp., Scenedesmus sp., and Chlorella zofingiensis) were cultured in tubular bubble column photobioreactors with two media separately. After 8 days of cultivation, DWW was demonstrated to be more suitable medium for microalgae biomass and lipid production than BG11 medium. The biomass and lipid produced within wastewater provided suitable feedstocks for anaerobic digestion and biodiesel conversion. Nutrients in wastewater were efficiently removed (>90% total nitrogen removal, approximately 100% ammonia removal, and >85% total phosphorus removal) during this process.     

Characterization of kilowatt-scale autothermal reformer for production of hydrogen from heavy hydrocarbons

Catalytic autothermal reforming is considered one of the most effective methods of producing hydrogen from heavy hydrocarbon fuels, such as diesel fuel, for fuel cell or emissions reduction applications. This article describes an investigation of the reactor characteristics and catalytic efficiency of a kilowatt-scale catalytic autothermal reformer currently being developed at Argonne National Laboratory. Dodecane and hexadecane were used individually as surrogates for diesel fuels to simply the reaction study and the interpretation of the test results. The reforming of these hydrocarbon fuels was examined at a variety of oxygen-to-carbon and steam-to-carbon ratios at gas hourly space velocities ranging from 10,000 to 100,000 h⁻¹. At steady state, the product composition correlated well with that calculated from thermodynamic equilibrium at a representative equivalent temperature. The oxygen-to-carbon ratio was determined to be the most significant operating parameter that influenced the reforming efficiency; the reforming efficiency (and the selectivity to CO_x) increased with increasing oxygen-to-carbon ratio up to about 0.42, at which value the maximum efficiency was attained.     

Mixotrophic cultivation,a preferable microalgae cultivation mode for biomass/bioenergy production,and bioremediation,advances and prospect

Microalgae have received much attention in recent years as a feedstock for producing renewable fuels. Microalgae cultivation technology is one of the main factors restricting biomass production as well as energy fuel production and bioremediation. There are four types of cultivation conditions for microalgae: photoautotrophic, heterotrophic, mixotrophic and photoheterotrophic cultivation. Though photoautotrophic and heterotrophic cultivation are two common growth modes of microalgae, some microalgae can also grow better under mixotrophic condition, which may combine the advantages of autotrophic and heterotrophic and overcome the disadvantages. This review compared these growth modes of microalgae and discussed the advantages of mixotrophic mode in bioenergy production by considering the difference in growth, photosynthesis characteristic and bioenergy production. Also, the influence factors of mixotrophic cultivation and the application of mixotrophic microalgae in bioremediation are discussed, laying theoretical foundation for large scale microalgae cultivating for biomass production, bioenergy production and environmental protection.     

Comparison of open-air and semi-enclosed cultivation system for massive microalgae production in sub-tropical and temperate latitudes

This study compared open-air and semi-enclosed production system of the marine microalgae Nannochloropsis oculata in a sub-tropical region (32°S; 52°W) under uncontrolled environmental conditions. The semi-enclosed system was composed of 1.2 m³ circular tanks installed inside of a greenhouse. Water temperature was 4 °C higher in the indoor treatment than in the outdoor, mainly in winter although no difference was observed in warmer seasons. Moreover, variation in salinity was observed in the outdoor treatment due to rainfall (winter) and evaporation (spring), whereas indoor treatment experienced an increase (up to 100 PSU) due to evaporation only in warmer seasons. Light transmission was approximately 20% lower in the indoor treatment although cell densities and biomass yields were higher indoor during winter. As the temperature increased (spring) no differences were observed among treatments. In summary, partial control of temperature and salinity in the semi-enclosed system, especially during the colder and rainy season, allowed higher microalgae biomass production. Further experiments must be conducted with CO₂ addition, larger pH range and salinity control.     

Nickel-cobalt-oxide cathodes for hydrogen production by water electrolysis in acidic and alkaline media

Mixed NiCo-oxide cathodes of various compositions were fabricated by a thermal-decomposition method and used as electrocatalysts for hydrogen production by water electrolysis in acidic and alkaline media. The oxide electrodes were found to be of a semi-crystalline structure, yielding the surface morphology characterized by a surface roughness factor going up to 25. Linear potentiodynamic and potentiostatic electrochemical measurements revealed that the Volmer reaction step controlled the kinetics of the hydrogen evolution on all the NiCo-oxide cathodes, and also on the pure metal Ni electrode (control). The Ni_0.2Co_0.8-oxide was identified as the best electrode material candidate among the investigated metal oxides, which was linked to the surface-area effect. However, its intrinsic activity was found to be lower than that of pure metallic Ni. Nevertheless, the Ni_0.2Co_0.8-oxide electrode showed a significantly higher electrocatalytic stability (fouling/deactivation tolerance) in comparison to metallic Ni.     

甲烷在多孔介质中过滤燃烧制氢的数值模拟

对燃料极富条件下(φ>2.0)甲烷在多孔介质中的部分氧化重整制取氢气的工艺过程进行了数值模拟.建立了一维定常双温度模型,采用详细化学反应机理GRI1.2,着重研究燃烧区峰值温度、主要化学组分的分布规律和氢气的转化效率.讨论了混合气体流速、当量比等参数对甲烷转化特性的影响.数值模拟结果与文献[4]的实验结果基本吻合.     

Energy consumption in barley and turnip rape cultivation for bioethanol and biodiesel (RME) production

The energy consumption for six spring barley (Hordeum vulgare L.) production chains and five spring turnip rape (Brassica rapa ssp. oleifera (DC) Metsg.) production chains were compared with each other and in relation to the energy content of the seed yield. Two cultivation intensities, standard and intensive production, were used for barley. Fertiliser production and grain drying were the most energy consuming phases of the chains. The production of nitrogen fertiliser alone accounted for 1/3-1/2 of the total energy consumption of the production chains. If barley were direct drilled and the yield stored in airtight silos, instead of drying, the energy consumption would decrease by 30-34%. Use of wood-chips instead of oil for grain drying would decrease the use of fossil fuel to the same extent. The input-output ratios for the intensive barley production chains were 0.18-0.25. They were somewhat lower than the ratios for the standard production intensity. The intensive production was more energy efficient despite higher input rates. The input-output ratios for turnip rape production were 0.32-0.34. The energy consumption for manufacturing, repair and maintenance of machines and buildings requires more research because it is a significant factor but the data available are largely old and few studies have been conducted.