Economics of Biobutanol: A Review

ABSTRACT Due to rapid depletion of fossil fuels and fluctuating market prices of crude oil, extensive research is going on worldwide to find out alternative renewable fuels that can either completely replace the fossil fuels or that can be blended in certain proportions with the fossil fuels without having major modifications in the engines. The most popular alternative liquid fuels are biodiesel and ethanol. However, both of these have limitations that they can be blended with petro-diesel and gasoline only up to 20%. They also suffer from other limitations such as separation from petrol at low temperature and low heat content that reduces economy of blended fuel. A new alternative fuel that has emerged in recent past is biobutanol, which overcomes the problems faced with biodiesel and bioethanol. Biobutanol is manufactured through the process of ABE (acetone-butanol-ethanol) fermentation using various substrates. In this review, we have compared various processes and the substrates used by them from viewpoint of unit price of the butanol. This analysis is based on published literature, but still gives a view into the niche areas for improving economy of the ABE fermentation process and the biobutanol fuel

Homologous overexpression of hydrogenase and glycerol dehydrogenase in Clostridium pasteurianum to enhance hydrogen production from crude glycerol

This study reports engineering of a hypertransformable variant of C. pasteurianum for bioconversion of glycerol into hydrogen (H2). A functional glycerol-triggered hydrogen pathway was engineered based on two approaches: (1) increasing product yield by overexpression of immediate enzyme catalyzing H2 production, (2) increasing substrate uptake by overexpression of enzymes involved in glycerol utilization. The first strategy aimed at overexpression of hydA gene encoding hydrogenase, and the second one, through combination of overexpression of dhaD1 and dhaK genes encoding glycerol dehydrogenase and dihydroxyacetone kinase. These genetic manipulations resulted in two recombinant strains (hydA ++ /dhaD1K ++) capable of producing 97% H2 (v/v), with yields of 1.1 mol H2/mol glycerol in hydA overexpressed strain, and 0.93 mol H2/mol glycerol in dhaD1K overexpressed strain, which was 1.5 fold higher than wild type. Among two strains, dhaD1K ++ consumed more glycerol than hydA ++ which proves that overexpression of glycerol enzymes has enhanced glycerol intake rate

Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides) that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques

Numerical Simulation and Investigation of System Parameters of Sonochemical Process

This paper presents the effects of various parameters that significantly affect the cavitation. In this study, three types of liquid mediums with different physicochemical properties were considered as the cavitation medium. The effects of various operating parameters such as temperature, pressure, initial bubble radius, dissolved gas content and so forth, were investigated in detail. The simulation results of cavitation bubble dynamics model showed a very interesting link among these parameters for production of oxidizing species. The formation of •OH radical and H2O2 is considered as the results of main effects of sonochemical process. Simulation results of radial motion of cavitation bubble dynamics revealed that bubble with small initial radius gives higher sonochemical effects. This is due to the bubble with small radius can undergo many acoustic cycles before reaching its critical radius when it collapses and produces higher temperature and pressure inside the bubble. On the other hand, due to the low surface tension and high vapor pressure, organic solvents are not suitable for sonochemical reactions

Integrated approach to optimization of an ultrasonic processor

In an ultrasonic processor, the input electrical energy undergoes many transformations before getting converted into the cavitation energy, which is dissipated in the medium to bring out the physical/chemical change. An investigation of the influence of free and dissolved gas content of the system on the efficiency of this energy transformation chain is attempted. The results of the experiments reveal that the cavitation intensity produced in the medium varies significantly with the gas content of the system. A unified physical model, which combines basic theories of acoustics and bubble dynamics, has been used to explain the experimental results. An attempt has been made to establish the mechanism of the steps in the energy transformation chain, the involved physical parameters, and interrelations between them. It has been found that the influence of free and dissolved gas content of the medium on the overall energy transformation occurs through a complex inter-dependence of several parameters. Thus, simultaneous optimization of individual steps in the energy transformation chain, with an integrated approach, is necessary for the optimization of an ultrasonic processor. The present study puts forth a simple methodology, with the gas content of the system as manipulation parameter, for this purpose

Acoustical characteristics of textile materials

An attempt is made to identify the acoustical characteristics of textile materials using precision woven monofilament fabrics as model textiles. The experiments try to eliminate the effect of entrapped air pockets in the fabric on an ultrasound wave field. The results of the experiment reveal that the power consumption of the ultrasound horn remains practically constant after introducing the textile at different positions in the standing wave field. Measurements of transmitted acoustic pressure amplitude through the textile reveal that fabrics form an almost transparent boundary for acoustic waves. A simple model involving the structural and hydrodynamic characteristics of the textiles is proposed to determine their acoustic impedance, and the results of the experiments are explained on the basis of this model. The overall conclusion of the study is that in the absence of entrapped air, textiles do not have any individual impact on the ultrasound wave field. \ud \u

Bubble behavior in hydrodynamic cavitation: effect of turbulence

This article does not have an abstract

Biomass gasification for decentralized power generation: The Indian perspective

This article attempts to highlight the technical and economical issues related to decentralized power generation in India using biomass gasification. Biomass-based energy has several distinct advantages such as wide availability and uniform distribution that puts it ahead among the renewable energy options for India. The estimated potential of power generation through renewable sources in India is 85 GW with biomass power contributing approximately 20 GW. Especially, in the remote areas and hilly terrains of India, biomass gasification-based power generation offers a highly viable solution for meeting energy demands of small villages and hamlets, which would not only make them independent but will also reduce burden on state electricity boards. This paper reviews various technical options for biomass gasification-based low-, medium- and large-scale power generation. We essentially discuss the merits and demerits (operational and other problems) of different systems. Further, we also deal with economics of these systems and discuss principal factors influencing the viability of the biomass-based power generation. Finally, we review some case studies of biomass-based power generation for meeting energy needs, both thermal and electrical.Biomass gasification Biomass gasifiers Rural electrification Decentralized power generation

Mapping the cavitation intensity in an ultrasonic bath using the acoustic emission

A new method for separate identification and determination of the spatial distribution of the two components of the energy intensity in an ultrasound bath (due to the ultrasound waves and cavitation activity) uses two media - cavitating (water) and noncavitating (silicon oil) - under the conditions of the acoustic field in the ultrasound bath. The variation of cavitation intensity in the frequency domain was obtained by subtracting the acoustic emission spectrum of silicon oil from that of water. Measurements at various locations in the bath revealed significant spatial variations in the cavitation intensity in the bath. The local cavitation phenomena in the bath (stable or transient cavitation) were explained based on the spectral characteristics of acoustic emission. The radial dynamics of the bubbles at the location of cavitation intensity measurements was determined using the Gilmore model of bubble dynamics. The bubbles in the region of highest cavitation intensity underwent a transient motion, while the bubbles in the region of lowest cavitation intensity underwent stable/oscillatory motion. The transient collapse of the bubbles that gives rise to local temperature and pressure maxima is at the root of the observed effects of ultrasound on chemical systems. The more violent the collapse of the bubbles, the higher the local cavitation intensity. It was verified using the spectral characteristics of the acoustic emission and simulation of the radial motion of the bubbles

Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides) that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques