This study focuses on developing a novel UiO-66-NH2/ZnO/TiO2 nano-catalyst for efficient biodiesel generation from dairy waste scum oil (DWSO). UiO-66-NH2, UiO-66-NH2/TiO2, and UiO-66-NH2/ZnO/TiO2 nano-catalysts were prepared via the sol-gel approach and their structural features were analyzed by XRD, FT-IR, BET, ED/Map, SEM, TEM, and CO2-TPD approaches. The UiO-66-NH2/ZnO/TiO2 nano-catalyst demonstrated a mesoporous surface with a specific surface area and an average particle size of 568.1 m2/g and 28.35 nm, respectively. The central composite design (CCD) was also utilized to optimize crucial variables. Biodiesel conversion of 98.7 % was achieved under the optimized process circumstances such as the methanol to DWSO ratio of 9.8:1, reaction temperature of 61 degrees C, and nano-catalyst concentration of 2 wt%. As a novelty, biodiesel conversion is the highest methyl ester achieved from DWSO so far. The survey of the reaction kinetics employing UiO-66-NH2/ZnO/TiO2 indicated that the rate constant, activation energy and Arrhenius factor are 0.1325 min-1, 48.73 kJ mol-1, and 39.6 x 105 min- 1 , respectively. Besides, the thermodynamic scrutiny implicates that the process is non-spontaneous (Delta G = 88.94 kJ/mol at 338 K) and endothermic (Delta H = 46.01 kJ/mol). Moreover, the impact of adding DWSO-derived biodiesel to diesel on the diesel engine parameters and viscosity alterations was scruti-nized. Fuel rheological behaviour appraisal exhibited that biodiesel follows the Newtonian model. The stability of the UiO-66-NH2/ZnO/TiO2 nano-catalyst was assessed in transesterification successive processes. The nano-catalyst could be reused multiple times, and a conversion of 90.14 % was obtained during the 7th consecutive run. It can be concluded that UiO-66-NH2/ZnO/TiO2 nanoparticles can be employed as a highly retrievable nano-catalyst for efficient transesterification of DWSO.

The current study explores a sustainable process involving enhanced production of biomass in association with wastewater treatment. In this study, a mixed culture of a new microalga strain named, Scenedesmus sp. DDVG I and indigenous bacteria that were readily available in rubber wastewater (RWW) were cultivated for concomitant bioremediation of RWW and enhanced lipid production of the biomass. Initially, individual cultures of Scenedesmus DDVG I and indigenous bacteria, viz. Bacillus sp. 0S26, Bacillus Cereus 0S36, Lysinibacillus macroides ST13, Burkholderia cepacia DF12, were cultivated in RWW diluted with distilled water (DI) in varying concentrations ranging from 5 to 100%. The diluted RWW, which showed superior growth of all the strains, was further used for the cultivation of consortium. The species were co-cultivated autotrophically under the inoculation ratios of 1:1, 1:2, 2:1 (Scenedesmus sp. / bacteria) based on cell density for 16 days cultivation period. The consortium's lipid content and productivity of the biomass were analyzed on every 4th day. The maximum biomass productivity of 1.15 g/L.d and having lipid content of 41% were achieved by the microbial consortium of Scenedesmus sp., Bacillus sp. 0S26 and Bacillus cereus 0S36 in RWW. The consortium exhibited maximum biomass harvesting efficiency of 100% compared to the individual cultures. Significant removal of COD, BOD, phosphate, ammonium, and nitrate concentration by the microalga-bacteria consortium from the RWW was observed during the growth. The study results suggested that the consortium cultivation strategy has the potential for sustainable improvement in the environment as well as the generation of oil-rich feedstock.

Climate change is a worldwide concern due to unfavorable consequences on human health and ecosystem quality. Accordingly, the world is looking for strategies to stop this destructive phenomenon. Biodiesel production is one of the promising strategies to decrease diesel consumption as one of the most important contributors to climate change. The carbon contained in biodiesel is derived from biogenic carbon dioxide, and therefore, it has a lower contribution to the atmospheric carbon pool and global warming. However, biodiesel suffers from poor stability due to the radical-mediated oxidative degradation of the fuel. The susceptibility of biodiesel towards oxidative degradation, attributed to the presence of points of unsaturation in the form of mono and polyunsaturated fatty acids, can be addressed by antioxidants. However, the presence of antioxidants in biodiesel might also change fuel behavior in diesel engines. Accordingly, the present study reviews and critically discusses biodiesel stability in the presence of antioxidants and, subsequently, the behavior of biodiesel doped with antioxidants in diesel engines. This review shows that antioxidants are highly effective in quenching the free radicals involved in oxidative chain reactions. Biodiesel treatment with synthetic antioxidants is a promising approach to increase biodiesel stability, but they may be toxic to humans and other organisms. Antioxidants extracted from plants and agri-food residues can help overcome this challenge and even lead to sustainable antioxidants production within circular bioeconomy frameworks. In addition to the stability problem, biodiesel suffers from higher nitrogen oxides emissions vs diesel. Antioxidants are also an effective solution to mitigate this emission by quenching free radicals. However, the quenching of radicals is accompanied by a setback in the oxidation process in the combustion engine, leading to higher smoke, unburned hydrocarbons, and carbon monoxide. Due to the impacts of these gases on human health, future studies should move towards the introduction of antioxidant compounds whose negative aspects are discounted.

Polarization and Depolarization Current measurement technique is a popular technique used for the condition assessment of Power Transformer insulation system. The assessment is usually done by identifying Debye model parameters from the measured polarization current data. However, obtaining the Debye model parameters involves complex computation and the model parameters are also dependent upon the number of branches in the model. Hence, in the present work, a Detrended Fluctuation Analysis (DFA) based method is proposed for the estimation of insulation condition sensitive parameters of the oil-paper insulation system. It was observed that one of the DFA coefficients maintain well-defined relationships with the Insulation condition sensitive parameters: dissipation factor, paper moisture content, polarization index and dielectric absorption ratio, which shows the applicability of the proposed technique.

Amid the COVID-19 pandemic, there has been an unprecedented cessation of outdoor anthropogenic activities leading to a significant improvement of the environment across the world. However, the positive impacts on the environment are not expected to last long as countries have started to gradually come out of lockdown and engage in aggressive measures to regain the pre-COVID-19 levels of economic activity. The present study provides for an assessment of air quality changes during the period of lockdown and unlocking across 9 major cities in the Indian state of Uttar Pradesh, including three cities (Ghaziabad, Noida, and Greater Noida) in the national capital region, which have frequently been included among the most polluted cities in the world. The pollutant load in a vertical column of air during March-July 2020 has been analyzed and compared with the corresponding period's pollution load in 2019. In addition, a detailed analysis of the ground-level changes in pollution load for Ghaziabad, Noida, and Greater Noida is also presented, along with the changes in local meteorology. A significant reduction in the total column density of NO2, CO and ground-level pollution load of PM10, PM2.5, NO2, and SO2 have been observed. In contrast, an increase in total column density of SO2 across all the cities (except Kanpur) and ground-level concentration of CO (in Noida and Greater Noida) and O3 (in Noida) was evident. The improvement in air quality (with respect to particulate matter) can primarily be attributed to the restrictions on construction and demolition activities, reduced re-suspension of roadside dust, and the restrictions on the movement of vehicles. A significant decline in the average summer temperature was recorded, and it can plausibly be attributed to lower radiative forcing due to reduced pollutant load in the atmosphere.

The attractiveness of renewable alternative transportation fuels has substantially increased over time. Biofuel mandates, energy insecurity, environmental pollution, and commitments to mitigate climate change are the prominent drivers of the biofuel industry. Biodiesel and bioethanol remain the most popular choices for the transportation sector. The conventional approach of catalyzed biodiesel production suffers from several strategic, environmental, and techno-economic challenges. To circumvent such challenges, utilization of lipase is being advocated as enzymatic transesterification has several remarkable advantages over conventional approaches. These primarily include lower capital investment, straightforward operation, ability to process both virgin and recycled feedstocks, and environment friendliness. However, the cost of lipase remains to be a significant deterrent in the process scale-up. Using lipase sourced from two or more sources, genetic engineering, lipase immobilization, and improving the recyclability of lipase hold promise in improving the cost-competitiveness of the process. Likewise, the scale-up potential of bioethanol production has been limited by the recalcitrant nature of lignocellulosic biomass, but significant advancements have been made in past few years which could aid the techno-economic viability of mass-scale bioethanol production. Thermostable enzymes are promising options for increasing the efficiency and cost effectiveness of the bioethanol process from lignocellulosic material as approximately 50% of the process cost is related to the efficiency of the enzyme activity.

Poor stability is among the most significant challenges faced by the biodiesel industry. Although the oxidation of the fuel is inevitable, it can be substantially delayed by antioxidant additives. The attractive attributes of plant phenolics as potential radical scavengers, among others, are renewability, non-toxicity, and activity similar to that of synthetic antioxidants. The present work explores the efficacy and antiradical activity of Bael leaf extract (BLE) in delaying the onset of (soybean) biodiesel oxidation during accelerated tests. A three-factor (each at two levels) experimental design was used to enrich the content of phenolics in BLE. At optimum conditions, the BLE contained 74.66 mg GAE g−1of phenolics, and the extract could scavenge over 73

One of the primary concerns in the use of biodiesel is its susceptibility towards radical-mediated oxidative reactions. The presence of unsaturated methyl esters renders biodiesel vulnerable to oxidation. It necessitates strategic interventions, which among a few others, includes the use of antioxidant additives. Natural antioxidants have multiple significant advantages over their synthetic counterparts. In the present study, the activity of methanolic passion fruit seed (PFS) extract as an antioxidant additive for waste cooking oil (soybean) biodiesel has been evaluated. The PFS extract contained a high proportion of phenolic compounds and exhibited excellent antiradical activity against model radical DPPH, which encouraged us to explore the case of unstable biodiesel further. At a concentration of 200 ppm, the PFS extract augmented the fuel's resistance towards oxidation to levels where it could comply with European and the Indian specifications for blend-stock biodiesel. The performance of PFS extract was comparable to that of synthetic antioxidants, including butylated hydroxyanisole and butylated hydroxytoluene. The present study substantiates the utility of plant extracts rich in phenolics as an antioxidant additive for biodiesel.

In this paper, an optimal linear quadratic regulator (LQR)-based integral controller (i.e., linear quadratic integral [LQI]) has been designed with an innovative approach for the tracking problems of a wind-driven doubly-fed induction generator (DFIG) system. The main objective of this controller is to reject the deviations that occurred in the DFIG powers together with the DC-link voltage due to the perturbations in the stator voltage. The purpose of the inclusion of integral action with the well-known modern optimal controller LQR is to guarantee zero steady-state error for disturbance rejection/set-point tracking. Further, the genetic algorithm (GA) technique is included for the optimal design of the LQI weighting matrices, which rapidly, as well as effectively rejects the disturbances from the system by regulating the augmented state variables. Therefore, to overcome these issues we have chosen the appropriate control model, which controls as a whole, that is, a multi-input-multi-output (MIMO) system. The DFIG system is a MIMO system, which has been modeled in a state-space approach in the d-q axes rotating frame of reference. To examine the effectiveness and robustness of the suggested control strategy, small-signal stability has been done by eigen values and participation factors method on digital simulations in the MATLAB/Simulink environment. Furthermore, the optimal control solutions have been tested under the various larger perturbations in the stator voltage and the mechanical torque. The comparative simulation results among the different controllers show that the proposed controller greatly enhances the dynamic performances and the robustness of the DFIG-based wind energy systems (WES).

The conventional approaches in transesterification have several techno-economic and sustainability challenges. To this end, the utilization of waste resources and renewably sourced energy has tremendous appeal. The present study reports the findings on the transesterification of waste cooking oil (WCO) catalyzed by CaO (sourced from waste chicken eggshells) using solar irradiation based thermal energy. A co-solvent (ethyl acetate) was used to enhance the miscibility of transesterification reactants. The process variables (alcohol to oil molar ratio, catalyst concentration, reaction time, and reaction temperature) were optimized using response surface methodology based Box-Behnken design. During the experiments, the intensity of solar radiation varied, and the reactor temperature ranged between 40 and 46 degrees C. At the predicted optima, a conversion of 90.14% was attained, which was in reasonable agreement with the predicted response (93.64%). A gradual loss of catalytic activity was observed over consecutive batch transesterification runs, and at the end of a 3rd run, 73.13% conversion of WCO was attained. The solar radiation available at the ground level during the experimental period was approximate to 5.15 kW m(-2) d(-1), while the conventional approach (hot-plate based heating) led to an energy input of 2.5 kWh per run at the optimized reaction condition. With process intensification strategies, solar irradiation is poised to become an increasingly sustainable alternative to the conventional approach. The findings of the study present an economical and environmentally benign approach to biodiesel production.

This study analyses the dynamic behaviour of a doubly fed induction generator (DFIG)-based wind integrated power system (WIPS) resulting from a major disturbance. The effects of transient disturbance on WIPS are examined without and with a controller in terms of performance and stability of the system. To enhance the performance of WIPS after a sudden disturbance, an optimally designed linear quadratic regulator (LQR) controller is applied to the system. The wind energy system is described in state-space representation, whose states and outputs are taken as feedback to the controller for improving their dynamic response. An artificial bee colony (ABC)-based swarm optimisation technique is used to evaluate the optimal weighting matrices of the LQR controller in parallel with minimising the performance index and dynamic response characteristics of the system. The effectiveness of the proposed ABC–LQR controller in WIPS is verified by comparing their simulation and numerical results with standard proportional–integral and LQR controllers. It indicates that the proposed controller provides better enhancement of dynamic response as compared with other controllers in terms of performance index and dynamic response characteristics. Moreover, the robustness and stability of various system configurations are tested by the eigenvalue analysis.

Polyhydroxyalkanoates (PHAs) have emerged as one of the most promising substitutes of conventional plastics owing to their biological origin, renewability, environment friendliness, biodegradability, biocompatibility, and tunable properties. The PHA accumulation trait is ubiquitous, and a diverse culture collection is available for exploitation. Despite the attractiveness of PHA over conventional plastics, further advancements in the fields of synthetic biology, genetic engineering, and biosynthetic pathways are required to make PHA production economical and environmentally appealing. The major thrust areas include the screening and identification of an ideal strain possessing a desirable combination of traits and process improvements that aid in the industrial-scale production of PHA in an eco-friendly and economical manner. A reliable supply of growth substrate/feedstock is critical for any biomass supply chain, and given their abundance and other attractive attributes, the lignocellulosic/agroindustrial residues are expected to serve as an important substrate. This would improve not only the attractiveness of the process but also provide a means to dispose of/valorize such wastes/resources. This work is a compilation of important research investigations on the techno-economic analysis of microbial PHA production and aims to highlight the major challenges and opportunities in the successful scale-up of the process.

Perovskite BaZrO3 was synthesised via a relatively mild solid-state reaction route by using nitrate precursors. Thermal behaviour, the presence of crystalline phases and functional groups, specific surface area, microstructural characteristics, elemental composition, and basic strength of the synthesised material was examined. Further, the partial ionic exchange of Ba ions in BaZrO3 was attempted to synthesise Cs modified BaZrO3. Characterisation results revealed the synthesis of phase pure and strongly basic materials. BaZrO3 was tested as a transesterification catalyst for the synthesis of biodiesel. Transesterification reaction variables for BaZrO3 catalysed transesterification were optimised using response surface methodology based Box-Behnken designing approach. Under the suggested optimal conditions the predicted conversion was 94.12%, and the experimentally determined conversion of 93.2 +/- 0.3% confirmed the validity of the generated quadratic model. Cs modification of BaZrO3 enhanced its basic strength. Under the optimised conditions for pristine BaZrO3, the effect of Cs modification on BaZrO3 was assessed, and it led to a conversion of 97.27 +/- 0.4%. Both the materials were effective in catalysing the transesterification of M. pinnata oil, however; only Cs-BaZrO3 catalysed oil met the EN 14214:2003 specification for minimum ester content in biodiesel. (C) 2018 Elsevier Ltd. All rights reserved.

Numerous studies on the techno-economic and life cycle assessment of microalgal biodiesel production are available in the literature, and an overwhelming majority of such studies suggest that the standalone production of biodiesel is currently unviable. The production of microalgal biomass using the currently available technologies costs approximately $4.92 kg(-1), which is unacceptably high for biodiesel production. The challenges lie in high biomass production cost and unfavorable energetic balance and significant process, and engineering advancements are desirable before mass-scale production of algal oil and biodiesel at a cost-competitive price is realized. On the other hand, various high-value products sourced from microalgae are already commercialized. The biomass production cost of $4.92 kg(-1) is more than acceptable if such products are also derived which, according to some estimates, may command a price as high as $123 kg(-1) biomass. It is expected that with process modifications and engineering advancements, the biomass production cost can be brought down to as low as $0.50 kg(-1). Moreover, coupling phycoremediation of pollution loads in waste streams to microalgal biomass production offers economic (up to $170 t(-1) biomass produced) and environmental gains (90% reduction in water footprint, improved GHG balance, and a substantial reduction in external input of fertilizers). Such approaches are more likely to translate into an economically appealing and environmentally desirable business model. The current study is an attempt to analyze some of the recent research investigations addressing the concept of a microalgal biorefinery for the production of biodiesel.

Poor stability and low-temperature operability are among the major hurdles in the commercialization of biodiesel. The presence of polyunsaturated fatty acid esters renders the fuel susceptible to oxidative attack while the long-chain saturated components limit its utility under low-temperature conditions. In this study, an attempt was made to improve these properties of Karanja biodiesel. Karanja biodiesel synthesized via a two-step alkali-catalyzed process exhibited poor stability and cold-flow properties. Karanja biodiesel was winterized to limit the content of long-chain saturates, and it had a favorable effect on the cloud and pour point of the fuel. Removal of long-chain saturated components led to an enrichment of the fuel in unsaturated fractions, and as a result, the stability of the fuel further deteriorated. For improving, the stability of the fuel T. cordifolia stem extract rich in phenolic constituents was added to winterized biodiesel. The combined treatment of winterization and phenolic-rich extract (1000 ppm) had a pronounced effect on fuel quality as it led to a reduction in the cloud (by 7 degrees C) and pour point (by 6 degrees C) and substantially improved the stability of the fuel under accelerated oxidative test conditions. The ASTM D6751, IS 15607, and EN 14214 specifications for the minimum induction period for blendstock biodiesel were satisfied. Thus, coupling the use of winterization and natural antioxidants offers novel opportunities in improving the fuel properties and acceptability of biodiesel in an efficient, economical, and environment-friendly manner.

Construction and demolition waste materials such as concrete and mortar have limited reuse and recycling, and as a result, are accumulating in landfills. In this work, the utility of concrete and mortar waste materials as transesterification catalysts for the production of biodiesel from non-edible Karanja oil has been investigated. Locally collected concrete and mortar were washed thoroughly, dried, ground, sieved and calcined at 850 degrees C for 3 h before their use as transesterification catalysts. These materials were characterised by using X-ray diffraction, Fourier transform infrared spectroscopy and Hammett basicity indicator methods. The basic strength of the calcined materials (15.0 >H _>= 10.1) was found to be higher than the uncalcined materials. The catalytic activity of cementitious waste materials has been compared with that of cement and commercial grade CaO. Among all cementitious materials tested, cement was found to be the most efficient (76 +/- 0.3%) in the transesterification of Karanja oil to biodiesel. The experimental results were used to conduct an economic analysis of a 50 kt biodiesel production facility using cement as a heterogeneous catalyst. The final manufacturing cost of biodiesel was estimated to be $1.23 kg(-1). (C) 2018 Elsevier Ltd. All rights reserved.

The frequency deviation and power fluctuation need to be controlled in a wind-integrated power system (WIPS) for keeping the balance between system power generation and demand, which support the quality and stability of overall power system. The present paper addresses this problem while concerning the integration of intermittent wind power and load disturbance into the WIPS. With this intent, it proposes the compensated superconducting magnetic energy storage (CSMES) system with proportional integral derivative (PID) controller for improving the frequency and power deviation profile. A novel swarm intelligence-based artificial bee colony (ABC) algorithm is used for optimal design of PID-CSMES system. Robustness of the proposed ABC-based PID-CSMES control strategy is tested in WIPS under various disturbance patterns of load and wind power. To demonstrate the improved dynamic response, their simulation results are compared with particle swarm optimization-based PID-CSMES, PID with SMES, and only PID controller technique. The performance indices and transient response characteristics of frequency and power deviation are used to evaluate and compare the accuracy and efficiency of each controller. Stability of various system configurations is analyzed using eigenvalue location. Comparing the results of different controller in WIPS indicates a substantial improvement in the dynamic response of system frequency and power deviations by utilizing the proposed control strategy.