Fossil fuels have been the main energy resource for economic and human development. However, this conventional energy will not prevail longer due to the ever-increasing demand and it being nonrecyclable. Now we are in search of alternative energy sources, renewable resources. Biofuel is one of the most suitable energy resources primarily for its productivity, availability, and low cost. The technologies for the production of biofuel has been changed and modernized depending on the generation of the fuel. First-generation biofuel production by utilizing the feedstock has now been restricted due to fuel versus food and competitive economies. This chapter provides a comparative aspect of biofuel production using modern technologies upon their transformation from the second generation to third generation, that is, biofuel productions from lignocellulosic wastes and algae, respectively. The review process includes extensive database searches, metadata analyses of the electronically available materials, and SWOT analysis.

The second- and third-generation biofuel technologies: comparative perspectives

Rapid depletion of fossil fuels worldwide presents a dire situation demanding a potential replacement to surmount the current energy crisis. Lignocellulose presents a logical candidate to be exploited at industrial scale owing to its vast availability, inexpensive and renewable nature. Microbial degradation of lignocellulosic biomass is a lucrative, sustainable, and promising approach to obtain valuable commercial commodities at gigantic scale. The enzymatic hydrolysis involving cellulases is fundamental to all the technologies needed to transform lignocellulosic biomass to valuable industry relevant products. Cellulases have enormous potential to utilize cellulosic biomass, thus reducing environmental stress in addition to production of commodity chemicals resolving the current challenge to meet the energy needs globally. The substitution of petroleum-based fuels with bio-based fuels is the subject of thorough research establishing biofuel production as the future technology to achieve a sustainable, eco-friendly society with a zero waste approach.

Cellulases: Role in Lignocellulosic Biomass Utilization.

I am very pleased to summarize accomplishments and activities of the Sustainable Futures Institute (SFI) faculty, staff, and students for the year 2014–2015 (July 2014-June 2015). In the following pages you will find information on new and ongoing projects in the various thrust areas of the Institute as well as core education and outreach activities. Included also is a list of scholarly output from the faculty and students affiliated with the SFI. At the very end can be found information on the financial status and other aspects of SFI operations.

Director's Letter

Algae oil is an intriguing supportable feedstock for biodiesel producing. Green algae have risen as a standout amongst the most encouraging hotspots for biodiesel creation. It can be construed that green growth developed in CO2-enhanced air can be changed over to sleek substances. This study was embraced to know the proper transesterification, measure of biodiesel production (ester) and characterization. Glycerol as a By-product which is used for many other products.

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Production and Characterization of Biodiesel from Algae

The apparent Henry’s Law constant ( ), which quantifies the concentration partition of a gas-liquid equilibrium of carbon dioxide (CO2), is used to optimize the absorption of carbon dioxide in algae liquors. The values of were examined under various conditions: in water at different temperatures (27 and 37°C), in alkaline buffering chemicals (sodium hydroxide (NaOH) and sodium carbonate (Na2CO3)), and in aquatic algae plants (Egeria densa and Anubias barteri nana). The optimal conditions for CO2 absorption can be obtained by controlling the aqueous pH values (around weak alkalinity with pH 9-10) using sodium carbonate as an alkaline buffering chemical at 27°C, yielding exact values of around 16.3–21.3 atm/M, which were obtained from the mean gaseous CO2 concentration of 803 ppm and the total aqueous carbonate concentration of 4.085 mg/L. The experimental results reveal that an alkaline buffering compound, sodium carbonate, can be added to water to maintain a constant aqueous alkalinity enough for the fixation of carbon dioxide by the photosynthesis of green algae in a photobioreactor.

https://downloads.hindawi.com/journals/ijp/2016/2562638.pdf

Optimization of Gas-Water Absorption Equilibrium of Carbon Dioxide for Algae Liquors: Selection of Alkaline Buffering Chemicals

Depleting fossil fuel reserves and growing demand for energy have necessitated the renewed search for alternative energy resources such as plants and algae. The first generation biofuels were produced from starch and sugars (bioethanol) and from seed oils (biodiesel). These, however, soon became negatively associated with issues such as competition with food supply, significant land-use changes and many other ethical issues. The production of second generation biofuels from lignocellulosic materials from grasses and trees requires high-input technologies involving extensive pre-treatments and expensive cellulolytic enzymes, adding to the high costs of second generation bioethanol. Recently, third generation biofuels derived from microalgae have attracted the attention of plant biologists and industrialists due to fast growth rate, high CO2 fixation ability and high production capacity of microalgae. Now, there also exists a promising fourth generation of biofuels on the horizon which involves metabolically-engineering of plants and algae possessing traits such as high biomass yield, improved feedstock quality and high CO2 fixation. Various novel processes such as gasification, pyrolysis and torrefaction are also being pursued for improving the total energy yield from plant biomass. Recent investigations in biofuels area are aimed at developing plants with improved feedstock quality, developing recombinant enzymes for rapid cell wall degradation, improving capacity of microorganisms for efficient fermentation, and discovering novel methods for efficient utilization of plants and algae for producing biofuels.

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New Avenues of Bioenergy Production from Plants: Green Alternatives to Petroleum

Multipactor mitigation is of relevance to microwave applications, and external magnetic fields, surface modifications, and materials engineering have previously been utilized for this purpose. In this contribution, geometric modifications made to rectangular waveguide surfaces in the form of nested grooves are investigated for the suppression of multipactor growth. A time-dependent kinetic scheme is used to simulate electron dynamics that folds in electron trapping at the nested groove structures, with inclusion of the electric field perturbations arising from the presence of various grooved geometries. The charge growth in the system is modeled based on an empirical approach that includes both energy and angular dependencies of secondary electron emission from all the different surfaces. A varying number of grooves, their widths, and their placement (either one sided or dual-sided) within the rectangular waveguide structure are included for a more complete analysis. The results demonstrate that nested grooves can lead to reductions in charge growth by over a factor of 280 when compared with a simple waveguide over the same time period. Furthermore, wider nested grooves are shown to have an advantage, with multiple aligned grooves across two parallel surfaces being especially useful at high external fields. Determining optimal combinations for an arbitrary field, operating frequency, and physical dimensions would require further work.

Numerical analysis for suppression of charge growth using nested grooves in rectangular waveguides

A distributed circuit approach is used to simulate the development of electric potentials across a cell membrane and the resulting poration dynamics for ∼700 ns duration voltage pulses. Besides electric field effects, temperature increases from a pulse train are included on an equal footing to probe heating effects. The results show (i) strong heating and power dissipation at the membrane in keeping with previous simpler models, (ii) an initial spike in the membrane temperature within 100 ns timescales, (iii) a monotonic increase in membrane temperature with successive pulses to about 8 K over twelve pulses within roughly 10  μs, and (iv) large temperature gradients in excess of 2 × 107 K/m at the polar membrane region indicative of a strong source for thermo-diffusive transport. Our results suggest that inherent heating during repeated pulse application may be used to tailor excitation sequences for maximal cellular transport, broaden the permeabilization beyond the polar regions for greater transmembrane conduction, and lower the electric field thresholds for greater efficiency in longer duration irreversible electroporation protocols. More generally, the present analysis represents an initial step toward a comprehensive analysis-based optimization for tumor treatment that could select waveforms for tissues, factor in heating effects (whether for synergistic action or to ascertain safe operating limits), and engineer temporal manipulation of wavetrains to synchronize with timescales of selective bio-processes of interest for desired transient responses.

Modeling coupled single cell electroporation and thermal effects from nanosecond electric pulse trains

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Author Correction: Importance of surface morphology on secondary electron emission: a case study of Cu covered with carbon, carbon pairs, or graphitic-like layers

Self-consistent evaluations of membrane electroporation along with local heating in single spherical cells arising from external AC radiofrequency electrical stimulation have been carried out. The present numerical study seeks to determine whether healthy and malignant cells exhibit separate electroporative responses with regards to operating frequency. It is shown that cells of Burkitt's lymphoma would respond to frequencies >4.5 MHz, while normal B-cells would have negligible porative effects in that higher frequency range. Similarly, a frequency separation between the response of healthy T-cells and malignant species is predicted with a threshold of about 4 MHz for cancer cells. The present simulation technique is general and so would be able to ascertain the beneficial frequency range for different cell types. The demonstration of higher frequencies to induce poration in malignant cells, while having minimal affecting healthy ones, suggests the possibility of selective electrical targeting for tumor treatments and protocols. It also opens the doorway for tabulating selectivity enhancement regimes as a guide for parameter selection towards more effective treatments while minimizing deleterious effects on healthy cells and tissues.

rashekhar P. Joshi

Papers

New Avenues of Bioenergy Production from Plants: Green Alternatives to Petroleum

Numerical analysis for suppression of charge growth using nested grooves in rectangular waveguides

Modeling coupled single cell electroporation and thermal effects from nanosecond electric pulse trains

Author Correction: Importance of surface morphology on secondary electron emission: a case study of Cu covered with carbon, carbon pairs, or graphitic-like layers

Selective Electroporation of Tumor Cells Under AC Radiofrequency Stimulation - A Numerical Study.