Nanotechnology: A tool for Improving Efficiency of Bio-Energy

Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________

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Nanotechnology: A tool for Improving Efficiency of Bio-Energy Parth Malik, Research Scholar, Center for Nanosciences, Central University of Gujarat, Gandhinagar. Anurag Sangwan, Assistant Professor, Deptt. of Biotechnology; Maharishi Markandeshwar University, Mullana (Ambala)

ABSTRACT Energy crisis has been a key problem affecting overall economic progress in different countries of the world. The problem is far more acute in the perspective of developing economies like India where there is significant pressure on the available natural sources of energy. To meet this severity of daily life requirement, we must shift our focus towards alternative sources of energy which possess tremendous hidden energetic potential and can suitably address the pressurizing economic concerns of the countries. Bioenergy is one branch of such nonconventional energy resources. It includes energy derived from life forms, howsoever small or tiniest they may be. Biomass, chiefly from microbial source can be a gift in disguise. Moreover, all these sources are ecofriendly and pose no serious environmental risks. Nanotechnology is the new dimension of material sciences aimed at miniaturization of entities to achieve enhanced performance by enhancement of their functionalities. This has its roots emanating from different overlapping fields of natural sciences and is therefore multidisciplinary in nature. This paper highlights the application of nanotechnology for the optimized harnessing of energy from different biological sources. Key breakthroughs in terms of efficient material utilization, energy output, quicker and reliable results and yields have been highlighted. Keywords: Energy, economic concerns, bioenergy, nanotechnology, biomass, multidisciplinary, miniaturization, functionalities, natural sciences, optimized, breakthroughs.

Introduction With the ever dwindling population of the world, energy requirements have soon become an area of prime concern for most of the nations in the world. This burning issue of energy requirement and fulfillment has not spared even the most developed economies of the world. The need for the exploration of alternate sources of energy has thus reached its prime stage and particularly in the developing economies like India, it is the first agenda in terms of investment issues. This is primarily because of too much dependence on the conventional energy sources, derived directly or indirectly from fossil fuels such as coal and petroleum. Moreover, this has not only resulted in the rapid depletion of coal and petroleum reserves in the nature but has also affected the environmental quality to a great extent. The air we breathe today and the water we drink today are certainly not as pure as they used to be three decades back. To address these correlated issues, bioenergy presents an extremely rich eco-friendly remedy. This is primarily because bioresources do not need to be created, they are self-prevalent, ubiquitous and most importantly, do not pose any harm to the environment and leave no toxic end products or residues on being processed. This is an

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everlasting source like that of biomass, cow-dung, dead parts of plants and animals and so on. Despite of so much potential, the utilization of biomass for energetic application is highly limited. The main problem behind this issue is the unavailability of efficient biochemical modification techniques through which biomass can be harvested in a profitable manner. So, the present situation requires specification, optimization and highly focused progressive development of biochemical modification agents. Nanotechnology has proved to be just like that of a blessing in this regard for its unique domains and extraordinary potential towards the improvement in the efficiency of conventional methods. Nanotechnology is that branch of physical science which deals with the study and analysis of matter on an atomic or molecular scale to yield new structures, devices, materials, systems and catalysts with unique and extraordinary properties [1]. This technology can provide us quicker, faster and more reliable methods to optimize the energy generation from the biological sources. Products based on nanotechnology that are available today have an extremely diverse background, ranging from industrial measuring and sensing devices, therapeutic systems and consumer friendly goods such as wrinkle

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ resistant clothes, tubeless tires and so on. Research is underway to achieve continuous betterment in daily life requirements like that of transport, energy, agriculture, medicine, computers and electronics [2]. The present paper summarizes the nanotechnology based advances and significant breakthroughs which have improved the efficiency of bioresources as an energy source. Nanoscale Materials These are the materials which are made through nanotechnological principles and procedures. A nanometer is typically one-billionth of a meter (10-9of a meter). These materials are developed basically two main types of methodologies. One is the top-down technique, involving creation of smaller and smaller entities from the larger ones while the other is bottom-up approach, involving the creation of larger structures from the smaller scale objects. Nanoscale materials typically include all those materials which have at least one dimension ranging within (1-100) nm. Likewise, there can be one dimensional, two dimensional and three dimensional on the basis of their dimensions lying within the nanometer range. There are several methods to design nanomaterials. In a broader sense, they can be categorized as being physical, chemical and biological. Nanoparticles can play crucial roles in bringing about the biotransformation of microbial species so as to maximize the production of bio products which enlist biofuel as a chief ingredient. The specific choice of the method critically influences the net effect of the biotransformation and hence the yield of the biofuels. This process can be a big relief for meeting the problem of energy crisis. It is not only cost effective but it is easier and more reliable [3]. Nanoparticles of metals have been, particularly, of special interest with respect to energy requirements. They have been employed as nanocatalysts, nanoclusters and nanostructured amorphous alloys, metals and metal oxides to improve the efficiency of energy yielding chemical reactions. The text ahead discusses the various advantageous prospects bestowed by the use of nanotechnological inputs for the best extraction of bioenergy. Nanobiocatalysis: The means for efficient and economic biomass processing There has been a growing interest of industries in the oxidation of saturated hydrocarbons like those of cyclohexane in order to meet their energy requirements. The available industrial methods for this purpose are not energetically favorable as they require a high temperature and pressure. The problem gets further multiplied if we use living systems as it requires room temperature. The oxidation of cyclohexanol by direct attack of oxygen is an endothermic process. The real motive is to search for alternative oxidizers which can help overcoming the endorgenicity of the reaction and can save substantial amount of energy. This has resulted in the

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incorporation of several alternative oxidizers for this process. Nanocatalysts, in this regard have provided a significant breakthrough. In a significant study, Murahashi et al have successfully employed the iron powder for this process that has enabled to carry out the oxidation of cyclohexane in a very easily controllable manner and that too at ambient room temperature and pressure conditions. They have obtained a conversion of 11% and a selectivity of 70% for the formation of cyclohexanol and cyclohexanone. In order to improve the selectivity, the reaction can also be performed at 70oC and a pressure of 8atm of oxygen in the presence of a solvent [4]. This provides a great insight and scope to use nanophased catalysts for efficient bioconversions as they have larger surface areas. In an extension to the previous study, Kesavan et al have reported a conversion of 40% and a selectivity of 80% using nanophased catalytic particles of iron and nickel from the catalytic mixtures of iron carbonyl, Fe(CO)5 and nickel carbonyl, Ni(CO)4. They have also compared their experimental results with those of the control models where there are no nanophased catalysts involved and found the results with the use of nanocatalysts significantly better. Further, they have demonstrated that with the use of cobalt nanoparticles as catalysts at 70oC and under 40 atm. of oxygen for about 8 hrs., the conversion extent of cyclohexane goes upto 67% but the relative ratios of the obtained alcohol and ketone changes [5].These findings successfully demonstrated that nanophased catalyst particles are very potent energy savers in terms of their excellent product yields.

Fig.1. Potential features and benefits of nanocatalysts. [6] Fig. 1 presents the chief benefits and possible controllable characteristics which can be exercised upon by the use of nanophased catalysts. The remarkable control over the surface can help us catalyze the highly diverse and non-uniform natured biosources such as animal fats, plant biomass and cellular remains, chemical modification of pre-

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ processed compounds such as alcohols. The process of surface engineering in these catalysts helps in modifying biochemical features of their active sites which makes them more and more robust. The development of sustainable and reliable utilization of biomass for energy requirements requires many complex and interrelated issues to be fulfilled on a large scale. The foremost of these requirements centers on the use of efficient pre-processing techniques and development of degrading enzymes in an efficient and readily available manner. To meet this dire essential pre-processing requirement, there is an urgent need of enzyme such as those of degrading hydrolases[7]accompanied by strong processing conditions which in turn require the use of strong acid treatments and that too at a higher temperature [8]along with the organic solvents such as acetone or ethanol [9] so that conversion of complex feedstock compounds into readily accessible and energetically useful intermediates by intervention of microorganisms can be carried out in a relatively easy manner [10]. The cost requirements to procure strong and efficient biocatalysis each time are a hot area of concern affecting this technology. To mitigate this problem, the process of enzyme immobilization has been explored and adapted to a great extent. Nanotechnology has been an airlifter in this regard as nanoparticles, with their high surface areas to volume ratios, have been just like revolutionary interventions by bringing about better and better enzyme immobilization. This breakthrough has multifold advantages. Firstly, the overall process becomes very easy and far less time consuming and secondly, there is the benefit of reusability of so much expensive enzymes by their recovery. Additionally, the benefit of exploring an everlasting and crisis-mediating energy source is always there. As an instance, the enzyme free cellulose is used for catalytic conversion of complex carbohydrate cellulose. It suffers from several drawbacks in its native form, the vital factors being its low specific activity, susceptibility to inactivation and difficulty in recovery is very high [11]. So, it has been immobilized in order to optimize its performance under extreme temperature and pH conditions required for cellulose conversion [12, 13]. Unfortunately, immobilization through most of the conventional means, has resulted in a significant loss of the specific activity of the enzyme concerned. Nanotechnology has proved to be just like a potent weapon in this regard. Immobilization can be significantly bettered upon by the incorporation of nanoparticles that possess high surface area to volume ratios. The use of nanoparticles [14], nanotubes [15] and nanoporous materials [16] which possess high aspect ratios has really made this process a lot much simpler and economically feasible. This technique has wonderfully addressed the issue of enhanced enzyme loading, biocatalyst recovery and reusability [17] but also has provided a

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much needed impetus for ensuring continuous operation [18]. With the recent intervention of enzyme aggregate coatings, the problem of enzyme loading that was due to inability to overcome the monolayer adsorption upon the nanostructured matrix, has been resolved. This technique involves the covalent binding of enzymes with nanostructured supports before they are crosslinked with the additional enzymes by treatment with surfactant like glutaraldehyde. This approach has not only resulted in increased enzyme loading as well as the activity but it has also assured long term enzyme stability [19,20].

Biofuel: The Energetic Potential and Harnessing Problems Biofuel refers to the entire living material which has an energetic potential. It includes a number of highly variable sources ranging from animal fats, agricultural crops, feedstock materials, microbial biomass, both in living as well as dead forms. With the problem of energy crisis looming at large, the developed as well as developing nations have been focused at harnessing this source of energy with utmost expertise. The evidence stems well from the fact that European union has targeted the increase in biofuel consumption as an energy source to 5.75% by 2010 and 20% by 2020. & chemically complex

Biomass (Renewable)

• Agricultural,Micro bial and Animal biomasseven usable in dead form, otherwise a wsate lessens the technical hurdles • involved

Texturally nonuniform & chemically complex

• Complex materials such as lignocellulose, ethanol etc. need to be converted into simpler forms

Nanoscale engineering of conventional catalysis

Fig.2. The problems and nanotechnological potentials for Biofuel harvesting. The current bioresources are complex and need to be converted or chemically modified so as to be accessible as biofuels. This is the inherent problem in all the biosources as the available energy is tough to be harnessed and this presents one of the toughest challenges to the modern day scientists. The issue has been tried of by biochemists, but unfortunately

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• Nanocatalysts quicker, accurate and highly specific. • Nanoengineered systems : selfdriven and more capable.

Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ without any substantial breakthrough. In this regard, material scientists have thrown their hats in the field and have touched the first success story by the use of nanostructured materials.. As an instance, to make biodiesel, the complex biomass from agricultural sources and animals needs to be chemically modified into simpler forms. The starting materials are high oil yielding crop plants such as rape and lignocellulose based woody crops. They possess vegetable oils in a high yield. These fatty acid chains are present as triglycerides, with three fatty acid chains joined together by glycerine units. The direct usage of this form is energetically not feasible as it leads to clogging of diesel engines by glycerine. To resolve this difficulty, triglycerides need to be reduced into singular free fatty acids. Each triglyceride molecule gives three molecules of fatty acid methyl ester. This is what all biodiesel is chemically composed of. This process is termed as transesterification (FAME). The most significant problem of this potential not being tapped on deals with the tedious chemical processing of triglycerides which can be greatly minimized with the incorporation of nanophased catalyst particles [21]. Considering the case of retreivance of biofuels from lignocellulosic biomass, the same problem of efficient conversion of biomass into biofuels has not been well addressed. Lignocellulose, chemically a mixture of cellulose and lignin, is difficult to be degraded into simpler forms. Nanotechnology enabled control of chemistry at the molecular scale enables the extremely specific and targeted modification of the biocatalysts which can achieve the tough bioconversion of bioproducts into biofuels in a much better manner. Nanotechnology provides reliable answers to the potential problem of design of materials, engineering of processes and minimization of hazards and wastes. Although in infancy but still nanotechnology presents very exciting interventions for energetic harvesting of the biomass which are conventionally very cumbersome [22]. Nanotechnology for Biofuel production from Butchery Waste In many countries, after animal rearing has been carried out, a large amount of animal fats are just discarded and thrown as garbage. These animal fats can be chemically reduced via transestrification into energetically useful materials such as biofuels. This is a very important and useful considering the increased use of petroleum and its derivatives that has put a serious risk on their depletion in the countries throughout the world and this has therefore made the shifting towards the alternate and renewable biodiesel a more serious topic. Biodiesel is the most acceptable and feasible fuel as a substitute in diesel engines due to its technical, environmental and user friendly nature [23]. Biodiesel is chemically obtained from trans esterification of vegetable oils, animal fats

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and other waste materials which possess a texture of animal fats in nature. Trans esterification is the most commonly used strategy because it is the most appropriate way to bring down the viscosity of animal oils. In a comprehensive study, Hussain et al have used nickel and cobalt based nanoparticles as catalysts for biofuel production and they have also shown excellent improvement in terms of the biofuel yield from the process [24]. As the properties of nanoparticles vary with their size, the nickel nano particles when employed in combination with cobalt particles result in the better catalysis [25]. Not only this, Ni nanoparticles have also been a big boost to carry out the catalytic reduction of complex aromatic and carbonyl compounds present in animal fats [24, 26-27]. Kidwai et al have further elaborated the use of nickel nanoparticles by proving their selective potential to act as green catalysts and capitalizing their unique ability to selectively reduce the aldehydic functional groups in the presence of other functional groups such as cyanides and alkenes to produce corresponding alcohols in excellent yields. These alcohols then react with fatty acids to produce esters. This is only accomplished through the high temperature and higher activities of nickel and cobalt particles due to their nanosize range. All the nanosized preparations were analyzed and optimized by their characterization before being employed for the exact process. The process also employed the involvement of TiO2 in the nanophased form as photo catalysts. The use of the photocatalysts stems from the fact that they act as very strong oxidizing agents, which is an important requirement of the overall process. They help to induce electron-hole pair generation when incident by the ultra-violet light, which further helps in cracking of organic matter into carbon dioxide and water via the formation of reactive free radical species. The use of TiO2 particles, in particular, as nanocatalysts in the process stems from the corresponding unique and extraordinary characteristics of performance, low cost, no toxicity, stability, wide energy band gap and availability [26]. Nanoscale materials have the extraordinary ability to trap the solar energy, their higher activity, smaller size and easily tunable energetic features are very potent in terms of the oxidation of carbon based biomass into carbondioxide. The moisture content in the process helped control the preparation of methane, methanol and ethanol of requisite chemical texture. Methane, being a rich source of combustible energy and possessing a high calorific value was a big boost in the process involved. Photocatalysis using nanoparticles produced small chain fatty acids along with minute quantities of n-heptane and n-octane. Both n-heptane and and n-octane are energy savvy in terms of their inherent qualities and usage potential, the latter plays an immensely important role in determining the quality of petroleum products. This example of

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ harnessing biofuels in extraordinary quantities with the help of nanoscaled catalyst particles highlights the hidden potential of nanotechnology to bring a revolutionary change to the lifestyle and meet the ever-pressurizing energy requirements in a far more convincing manner. Further, the technology is hugely significant with regard to cheaper and easily available raw material and inputs and delivers no toxicity or chemical risks to the environment.

Application of Nanotechnology Biofuel Production from Spent Tea

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Spent tea is a type of solid waste. It is chiefly composed of milk and sugar. By the intervention of fungus Aspergillus Niger, the solid biomass of spent tea can be biologically reduced to give a mixture of liquid extracts, solid charcoal and gaseous compounds [28]. The conventional process for this biological transformation involves gasification and catalysis to be carried out in well-distinguished manner at a temperature of 650-800 K and a pressure of 1-5 bars in the absence of air. The conventional methods provide nearly 60% yield, which is dependent critically on the type of tea and the relative extents of milk and sugar in it. To improvise the current method, there is a strong requirement for development of an efficient green catalyst that involves an easy work-up and can provide better yields in shorter reaction times. In this regard, He et al have extensively studied the influence of catalyst and temperature on the yield and nature of products during gasification. They have evaluated the performance of cobalt as a catalyst in the typical temperature range of 750-950oC but unfortunately, the catalysis by cobalt is slow in terms of the speed owing to the low surface area. The potential solution of this problem has been proposed using the nanoparticles of cobalt. This is so as nanoparticles have greater surface areas. In addition, the activity of cobalt nanoparticles has also been found to be sharply dependent on their shape and size in addition to the presence of additional components such as Si, Mg or Ni [29]. Several other studies have also established the use of cobalt or cobalt oxide nanostructures as effective catalysts [30-32]. In addition, for their cheapness, cobalt nanoparticles require mild reaction conditions and give higher product yields in shorter reaction times as compared to the performance of traditional catalysts. Alongwith this, the benefit of reusability is always there in case of nanoparticles. In a related attempt, Reddy and Tucker (1983) have achieved the accomplishment of gasification of the liquid extract involved by using the energetic potential of water hyacinth plant. Due to the involvement of Co nanoparticles as catalysts, the temperature required was only 800oC in this process [33]. Studies on nanocatalysts have reported the

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extensive and exhaustive use of cobalt nanoparticles for the purpose of gasification of biomass. The chief factors responsible for regulation of nature of product in terms of its percentage yield and the corresponding reaction rate are temperature, particle size, particle morphology, pressure, surface area, nature of nanocatalytical particles and the nature of biomass involved [29, 34-38]. Biodiesel formation is achieved through trans esterification in the presence of ethyl alcohol and sodium hydroxide. The characterization confirming the formation of biodiesel has been achieved via FTIR screening, XRD and SEM analysis. Lestari et al (2008) have confirmed an active participation of cobalt nanoparticles which they recovered as residues in the tea extract in their attempt to make biodiesel as esters [39]. In another significant attempt, Kondamudi et al (2008) have accessed the biodiesel formation and efficiency of the biofuel obtainable from tea as well as coffee. They have postulated that biodiesel derived from spent tea is far better in terms of its energetic potential and source dependent yield [40]. The chief advantages of incorporating cobalt nanoparticles as catalysts in this bioconversion stems from high reactivity and high surface areas which resulted in the decrease of the reaction temperature and the corresponding activation energy requirement. As a concrete study to explore the potential advantages of the biodiesel obtained via gasification over the petroleum diesel, Suarez et al (2009) have comprehensively analyzed the prepared biodiesel and successfully concluded that the biodiesel is low in terms of its sulphur and nitrogen content, which ultimately proves to be a big boost towards the environmental damage. During their analysis, they have also analyzed energetic potential of the biodiesel by Gas Chromatography techniques and have found it to be better than that of the petroleum diesel conventionally used. They have also obtained better lubrication potential in case of the biodiesel [41]. All these qualities and features underline the upcoming potential of the magical nanoscience by virtue of which energy generation through alternative resources can achieve a much needed impetus.

Nanostructured Materials Bioelectrochemical Systems

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Microbial systems have also been exploited for the generation of electrical energy via intervention of nanomaterials. Nanomaterials have been employed both in their natural as well as in engineered forms to mitigate the problem of energy crisis and tap the unlimited potential of the bioenergy residing within microorganisms. They have made possible the generation of electric current in microbial bioelectrochemical systems (BES’s). These systems are analogous to the conventional fuel cells and are of two main types, viz. microbial fuel cells (MFCs) and

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ microbial electrolysis cells (MECs). The former produce electricity while the latter generates hydrogen through electrolysis [42]. Significantly, in both the cases, the source of energy is the oxidative metabolism of electrochemically active bacterial species which catalyzes the generation of electrons from inorganic sources such as those of acetate, glucose, starch or even waste water [43] and utilizes this generated for energy generation via completion of the electrical circuit. Although the conventional design of microbial fuel cells promises a power density as high a 75W/m3 but their architehture for this energetic yield has proved to be a too costly affair. Nanoporous membranes, for instance, have shown significant promise in being utilized as low cost selective proton transfer membranes as compared to the currently employed costly ones [44]. In the above mentioned bioelectrochemical interventions, bacterial species have been used as anodic material, with a range of bacterial species being optimized to work as nanowires and aid in the extracellular transport of the electrons [45]. There has been an intriguing interest for exploring the precise and exact genetic traits responsible for imparting the extraordinary electromechanical features to the microbial genomes, significant efforts have reported an active role played by the electron transfer proteins making up the cytochromes at the membrane surface. They have been found to be actively involved in nanowire synthesis and also assisting the electron transfer in several microbial species [45,46]. These traits of bio electromagnetism have been further improved to a better scale by the incorporation of genetically modified viruses as assemblers of the participating nanowires. Cloning of viruses into M13 phage which has a high copy number has been exploited to make nanowires. This has been made possible by the inclusion of metal engineered nucleating peptide [47]. Upon being incorporated into the coat of the genetically modified viruses, this has facilitated the synthesis of metallic intermediates such as cobalt oxide, zinc sulfide, cadmium sulfide, iron platinum and cobalt platinum, which are key inputs in the synthesis of single crystal nanowires. Figure 5 illustrates one such strategy which

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Fig.5: A Nano-Bio fuel cell. The diagram shows the working of enzymes glucosidaze and laccase, this innovation involves the current flow through a nanoconductor which is a nanowire here [46]. uses the biocatalysts glucosidaze and laccase to carry out the oxidation reduction reactions via the electrolysis of biological fluids. The enzyme glucosidaze oxidizes glucose and the enzyme laccase brings about the biological reduction of blood. Figure 5 shows a NBFC immersed into a biofuel solution, two chemical reactions occur in the anode and cathode regions, creating a corresponding chemical potential drop along the nanowire, which derives the flow of protons in the nanowire and electrons in the external load [48].This energy if channelized properly used can be used to drive a cardiac pacemaker and can be a wonderful biomedical innovation. This approach is a very versatile step considering the readily available nature of the source and well-managed overall economy of the process and is one of the classical illustrations of the nanotechnological advances for scaling up of bioenergy.

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ Bioelectromagnetism is another hidden source for tapping the unharnessed biological energy. Microbial species have ATP releasing cellular pathways in their bodies which require proper activity of different metallic cofactors and coenzymes that are composed of charged metallic intermediates. The concentration gradient of several metallic ions in the living systems, across the membranes serves as a source of electrical potential. This can further be more useful in the species of microorganisms which can metabolize iron and metals similar to iron in their bodies [49]. This generates electromagnetism. All these delicate and sensitive energetic in vitro events can be capitalized upon by their coupling with external magnetic and electrical fields. Coupling the external stimuli with these internal biochemical features can optimize the performance of living microbial species for particular applications. In this case nanodevices such as nanosized voltmeters have been utilized to optimize the living systems for the better yield of their bioproducts which are then used as efficient means of meeting energy requirements. The incorporation of nanostructured materials for this application has really proved to be very vital lead in this process as a whole due to their rich attributes of high specific surface area, facilitating higher electron fluxes, which has commutatively resulted in significantly reducing the overall cost and reposing scientific faith to evolve this relatively unexplored source of energy.

Nanofarming Technology for Obtaining Biofuel from Algal Biomass Budding research on microbial energy usage has underlined the importance of biological organisms for their energetic potential. The current focus of bioenergy industries all over the world is revolving around the biofuels based on alcohol. The products of natural and synthetic fermentations, chiefly ethanol, n-butanol, isobutanol and pentanol are currently the most favored and optimized sources of bioenergy in the form of biofuels [50-52]. A key factor influencing the harnessing of biofuels in this method is the processing of short-chained aliphatic alcohols, which is complex due to their inherent cytotoxicity. Due to this the biocatalyst activity is also affected at lower concentrations of the fermentation broth [53-55]. As a result, whatever processes are in use, remain confined to small scale fermentations [56] which in turn have a significant bearing on the expenses and overall economy of the extraction and purification processes during the downstream processing leading to the economic non-feasibility of the process [57]. Algal biomass has soon been started to be widely anticipated as the next energy storehouse for meeting the world’s energy needs. Unfortunately, the current technology for extraction of biofuels from algae suffers from some tedious bottlenecks. The foremost of these hurdles concerns with the fact that algae are

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killed after the process of obtaining biofuels from them is over. Nanotechnology has provided a worthwhile solution to meet this problem. Scientists at U.S. Ames Laboratory have developed nanoparticles as catalysts which not only optimize the process of biofuel extraction from algal biomass but also enable the organism survival even after the process has been completed. This significant inroad has not only reduced the production cost to synthesize the biofuel but has also bypassed some cumbersome procedural steps involved in the conventional method. In this intervention, pores of the spheres are lined with chemicals which extract algal oil without breaking the cell membrane [58]. More recently, a series of biocompatible, mesoporous nanoparticles with a propensity to absorb hydrophobic molecules have been developed and investigated as a novel mechanism to harvest fatty acids from algal cultures [59]. A breakthrough study at the U.S. Department of Energy's Ames Laboratory has described the development of nanoparticles capable of drawing oils from living algae without killing them [60]. This is made feasible by the entrapping of lipid molecules produced by the specifically selected algal strain between the cell wall and the cell membrane. Then sponge like mesoporous nanoparticles are employed in a highly careful manner so that there is no disturbance to the cell membrane and the oils produced by lipid processing within the rigid space are absorbed from the cells into the pores of the sponge structure. In a further advancement, catalysts such as oxides of strontium and calcium [61] can be introduced into the pore structure of the nanoparticles which enable transesterification of the entrapped lipids to occur in vitro. Nanofarming technology has thus proved to be very effective by enabling the synthesis of biofuels without the disruption of biocatalysts. In this way, it can be a big breakthrough for biodiesel production.

Algal Biomassexcellent biofuel carrier.

Conventio nal Processrigid, forces killing of algae in extraction of lipids

Lack of specific biocatalysts and yield is low. Economic complications.

Fig.6. Conventional method of algal biofuel extraction.

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ Nanotechnological InterventionsMaking process energy as well as eco friendly

Highly efficient catalytic nanoparticles of Co, Ni, Fe are used, highly efficient biocompatible mesoporous nanoparticles

Entrapping of lipid molecules located between cell wall and cell membrane without killing organisms.

Fig.7. Nanotechnological improvements in the method. Nanoporous carbons and a variety of other inorganic derivatives are currently on the verge of being established and developed as adsorbents for biofuel separation [62]. Fig. 6 highlights the conventional procedure for biofuel extraction from algal species. It mentions the drawbacks of selective extraction of membrane lipids of algal species trapped between the cell wall and cell membrane and the problem of organism getting killed after extraction. Fig. 7 predicts the benefits incorporated by the implementation of the nanotechnology. The efficient biocatalysts, highly selective mesoporous membranes supplemented with nanoparticle adsorption are excellent in terms of yield and also eliminate the problem of algal biomass getting killed after the extraction process is over. A very popular method of harnessing the biofuels deals with the removal of water from fractional distillation products of ethanol. In general, water is present in the distilled product and disturbs the ethanol extraction by formation of azeotropic mixtures. In this regard, nanoparticles have been used for the specialized zeolites synthesis which are hydrophilic in nature and have improved the water removal extent to a very high degree [6367]. The zeolites involved have a precise and highly sensitive pore size configuration and also have an additional variability in terms of charge specific activity [68] which ensures a clean, smooth and more effective removal of the undesired particles interfering with biofuel extraction.

Nanowires and Nanosieves Improvement of Biofuel Generation

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Nanotechnology has also provided the researchers throughout the world with a strong quest for inventing self-performing nano devices and nanoscale systems that are very efficient towards the

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extraction and powerful utilization of plentiful energy from the surroundings. Nanowire based fuel cell (NBFC) is a device optimized for the conversion of chemical energy from biofluids into electrical energy, employing glucose oxidase and laccase as catalysts [46]. The system involves a single proton conductive polymer nanowire which converts the chemical energy into a usable form. This device is pH sensitive and works as a Nano biosensor. The active functioning starts when it senses the glucose. One nanowire based fuel cell can produce a power of the order of 0.5µW in biomaterials such as human blood, glucose and melon juice. Integrated set of nanaowires is thus commonly preferred and it can function as self-performed sensor. Naflon nanowires made by electrospinning method further aid in this process by improving the proton conductivity through the nanowires. These interventions can significantly increase the power output of a biofuel cell and make the nanowire based biofuel cell strong enough to power the nanodevices requiring power in nano watt range. Studies have reported that an improved biofuel cell can power a cardiac heart pacemaker by generating power from human blood [69]. Nanotechnology provides us with stronger, multifunctional and efficient materials, processes and enables a great reduction in terms of hazards and wastage. Another potential field where nanotechnology drives energy conservation involves the utilization of lignocellulosic based agricultural inputs. Advanced biotechniques and analytical procedures can significantly help in the economical production of lignocellulosic based biomass. The problem behind using lignocellulosic based biomass for biofuel production is the lack of an efficient technology which can provide a good output for efficient conversion of biomass into liquid fuel. Advances in nanotechnology have made it possible to control molecular scale chemistry which in turn has enabled to have a better control over the conversion of biomass into biofuel production. Significant improvements have been obtained in terms of optimizing the output and enzyme yield by the incorporation of nanofiltration technology. Nanofiltration in combination with ultrafiltration has been employed for recycling of cellulose enzyme and recovery of glucose from lignocellulosic waste. The use of nanofilters has been so effective that it has made the output of ultrafiltration technology quadrupled. The incorporation of this technology not only reduces the cost of hydrolysis of the lignocellulosic waste but it also improves the efficiency of fermentation carried out with the intention to tap the energetic potential of the lignocellulose. In this way, the involvement of nanotechnology can revolutionize the yield of biofuels and that too using the agricultural waste [70].

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________

Nanotechnology Advances Optimizing Biogas Production

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In most general terms, biogas refers to the gas produced by the biological breakdown of organic matter in the anaerobic conditions. Organic wastes such as dead plants and animals, animal excretion products and kitchen wastes are the chief ingredients of the biogas. Since the source of this material is biological in nature and texture, it is very smooth from the environmental point of view and that forms the basis as to why biogas is referred to as a type of biofuel. The pilot scale process for the biogas production involves anaerobic digestion or fermentation of dead biomass including manures, sewage materials, dead crops, municipal waste [71]. Nanotechnology can pave the way for betterment of biogas production through the use of nanocatalysts which ensure more efficient bioconversion strategies, better breakdown of substrates and more optimized output delivery. Nanomaterials such as nanoparticles, nanotubes, nanofibres, and nanoporous catalysts provide significant breakthroughs to achieve powerful and more easily controllable ways for feedstock processing, genetic engineering, and biofuel harvesting. A significant factor involved in the biogas generation is the material of which the inner surroundings of the anaerobic digestor are made up of. The problems like corrosion, wear and tear resistance significantly limit the energy output from biogas as a biofuel. The nanotechnology based materials which include everything from nanocatalysts to nanoparticles as construction agents of the plant design can really prove to be a big asset for harnessing this renewable energy resource. Through the application of nanomaterials incorporated in the form of photovoltaics, we can achieve excellent absorption of sunlight in the biogas plants which will make the process quicker, efficient and more reliable. Several studies have reported the use of iron and iron oxide nanoparticles for the biochemical reduction of the wastewater streams so that their anaerobic treatment can be carried out more effectively and the resultant biogas production can be improved as compared to the traditional processes employed till date [72]. In a significant attempt, Lo HM et al have studied the effect of micro-nano municipal solid waste incinerator fly ash and bottom ash on the biogas production and have concluded that the bioreactors incorporated with micro-nano fly ash and bottom ash ingredients are excitingly much better in terms of biogas production as compared to those which are not having these nano scaled inputs [73]. Nanomaterials have been employed for the designing of specialized membranes having fillers in the form of zeolites and metal nanoparticles that are particularly designed with a view to maximize the performance and selective movement of the biofluids

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and biomaterials involved. They also aid in the recycling of the potential costs and thus have a big impact on the overall economic aspects of the procedure. Nanomaterials incorporated into filters and membranes have improved their performance to a very high degree. In conventional operation of a biogas plant, carbon dioxide gas needs to be removed as the residual product. Traditional methods to capture carbon dioxide suffer from efficient functioning in terms of yield potential. Moreover, the devices involved get corroded too frequently and are very complex in design and functioning. Nanotechnology has provided a significant breakthrough in this dimension. Nanomembranes have been the solution to this problem; their multifunctional nature has provided efficient means to remove residual gases from the biogas plants. This has served the dual purpose, one being the improvement of biogas plant operation and the other being the utilization of the trapped gaseous mass. These nanomembranes can separate different substances at the molecular level. Pentair et al have developed one such nanomembrane that can eliminate carbon dioxide from nitrogen at a selection rate of 75: 1 at 873 K. This membrane possesses a thickness of 5-25nanometres and is chiefly made up of silica [74]. The use of nanocatalysts in the form of nanoparticles with an increased surface area has proved to be very economical as it has substituted the precious and costly metals normally employed for this purpose [75].With so many versatile functionalities, the efforts are on with a viewpoint to control and manipulate the structure of nanomaterials which can deliver more powerful performance in fuel cells and to devices that enable more efficient energy extraction in fossil fuels. These new and advanced nanomaterials can be used in making electrodes that has enabled more efficient and direct utilization of natural gas or biogas via fuel cells [76].

Conclusion Nanotechnology has therefore solved some very crucial problems of the world ranging from energy crisis, manpower requirement, quicker, faster and more reliable productivity. It has been the backbone of energy mitigation in the past two decades. No doubt, the distribution of the developmental and application reforms remain abruptly distributed throughout the world but still the technology is almost on the verge of rapid acceptance and application by the most developed nations also. It has provided a much needed boon to the everyday problems of mankind which are dependent on the sheer requirement of energy. The solutions provided by the successful intervention of nanotechnology are highly significant and that’s why projects on nanotechnology mediated improved energy harnessing are receiving a very surprising increase

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Journal of Engineering, Computers & Applied Sciences (JEC&AS) ISSN No: 2319-5606 Volume 1, No.1, October 2012 _________________________________________________________________________________ throughout the world. This is in particular a big relief for developing economies like India, China and so on with reference to their large populations and ever dwindling energy requirements. The inherent wonders of the nanosystems are so great that the devices at nanoscale are highly specific and energetically useful. Moreover, these devices are significantly better than their bulk scale counterparts due to the complexity of handling and operation in the latter. However, no doubt the problem of energy has found a very benign solution but there are some crucial concerns ahead of the commercial application of the nanotechnological interventions in the daily life. Nanomaterials, due to their novel properties and extremely small size can pose some serious risks to the environment and individuals. They can escape easily and gain rapid entry into the living systems as well as the water bodies. This manifests itself as a crucial ecosystem risk and thus demands an immediate urgent introspection. Considerable efforts should be put in to analyze the toxic effects of the use of nanoparticles and nanosystems for obtaining energy. Moreover, funding and awareness are two key issues which should be encouraged and stimulated as much as possible to bring the nanotechnological advantages in retereiving the energy of bioresources to the forefront. There are still many domains of bioresources which are untouched with reference to their energy potential. This is because of the tough optimization of the biochemical modifications involved. Nanotechnological inroads can prove to be revolutionary cascades in overcoming these technical hurdles as it ensures the modification in microscle properties and inter-molecular engineering advancements. The futuristic prospects of this technology are still in pendulum stage but there is immense technical inherent potential which makes it urgent to address the handling issues of nanomaterials and nanoparticles so that the technological advantage can traverse to as many doorsteps as possible.

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