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Nowadays, increasing population, widespread urbanization, rise in living standards together with versatile use of polymers have caused non-biodegradable polymeric wastes affecting the environment a chronic global problem, simultaneously, the existing high energy demand in our society is a matter of great concern. Hence forth, this review article provides an insight into the technological approach of pyrolysis emphasizing catalytic pyrolysis for conversion of polymeric wastes into energy products and presents an alternative waste management technique which is a leap towards developing sustainable environment. Pyrolysis of waste non-biodegradable polymer materials involves controlled thermal decomposition in the absence of oxygen, cracking their macromolecules into lower molecular weight ones, resulting into the formation of a wide range of products from hydrogen, hydrocarbons to coke. Nanocatalyzed pyrolysis is a recommended solution to the low thermal conductivity of polymers, promoting faster reactions in breaking the C-C bonds at lower temperatures, denoting less energy consumption and enabling enhancement in the process selectivity, whereby higher value added products are generated with increased yield. Nanotechnology plays an indispensable role in academic research as well as in industrial applications. Existing reviews illustrate that one of the oldest application field of nanotechnology is in the arena of nanocatalysis. Nanocatalysis closes the gap between homo and heterogeneous catalyses while combines their advantageous characteristics and positive aspects, reducing the respective drawbacks. During the current nanohype, nanostructured catalysts are esteemed materials and their exploration provide promising solutions for challenges from the perspective of cost and factors influencing catalytic activity, due to their featured high surface area to volume ratio which render enhanced properties with respect to the bulk catalyst.

With objective to design cyanobacterial biorefinery, taking Lyngbya as a model organism, a detail sequential protocol has been developed for production of UV protectant and lipids. This study addresses ultra violet radiations (UVR), exposure time of UVRT, nitrogen stress, salinity, oxidative stress to produce UV protectant and lipid in cyanobacteria. To evaluate these parameters a design of experiment (DOE; using a 2 k design) was performed. Based on chemical solubility property of UV protectant in form of mycosporine like amino acid (MAAs) and lipids were extracted. Quantitative and qualitative assay of UV protectant was confirmed by spectrophotometric scanning and Fourier-transform infrared spectroscopy and lipid through fatty acid methyl esters analysis. Nitrogen abundance and high oxidative stress is helpful in the synthesis of UV protectant. This study concluded, UV exposure is good strategy to induce synthesis of UV protectant and saturated lipid productivity. This biorefinery approach encourages economical and environmentally sustainable options.

AbstractIn Rajasthan, the received solar irradiation is high, however, dry and dusty atmosphere are issues for harnessing of solar energy. The high speed wind characteristic of Rajasthan can initiate the saltation process, which in turn removes and carries dust from ground and deposit on collecting surfaces, such as, heliostats. This in turn reduces the collection and therefore the overall efficiency of concentrating solar thermal system. Dust deposition on flat mirror plates depends on various factors like heliostat field density, soil composition, atmospheric condition, mirror orientation, wind speed, plate material, height and structure of heliostat etc.In this article, experiments on dust deposition by wind onto a mirror simulating a heliostat model in wind tunnel are presented. Further, the performed analyses of dust deposition on single and multiple heliostats are described. These clearly indicate the influence of flow and position of heliostat. Furthermore, the obtained observations indicate a possible way of mitigating cleaning effort with localized deposition.

Abstract A transient analysis of a double basin solar still has been presented. Explicit expressions have been derived for the temperatures of various components of the inverted absorber double basin solar still and it’s efficiency. The effect of water depth in the lower basin on the performance of the system has been investigated comprehensively. For enunciation of the analytical results, numerical calculations have been made using meteorological parameters for a typical winter day in Delhi. It has been observed that the daily yield of an inverted absorber double basin solar still increases with the increase of water depth in the lower basin for a given water mass in the upper basin.

In this review article, discuss the many ways utilized by the dairy sector to treat pollutants, emphasizing their influence on the quality and efficiency with which contamination is removed. It focuses on biotechnology possibilities for valorizing dairy waste in particular. The findings revealed that dairy waste may be treated using physicochemical, biological, and biotechnological techniques. Notably, this article highlighted the possibility of dairy waste being used as a feedstock not only for the generation of biogas, bioethanol, biohydrogen, microbial fuel cells, lactic acid, and fumaric acid via microbial technology but also for the production of biooil and biochar by pyrolysis. In addition, this article critically evaluates the many treatment techniques available for recovering energy and materials from dairy waste, their combinations, and implementation prospects. Valorization of dairy waste streams presents an opportunity to extend the dairy industry's presence in the fermented functional beverage sector.

The research work aims to estimate the bioenergy potential of pistachio shell and study its degradation kinetics which is necessary for the efficient design and optimization of thermochemical processes for bioenergy generation. Initial characterizations (proximate, ultimate, higher heating value, and compositional analysis), kinetic study, and thermodynamic analysis accompanied by reaction mechanism are investigated. Physicochemical characterization results confirmed high volatile matter (~ 79.8 wt%) and high heating value (16.85 MJ/kg) of pistachio shell. Thermogravimetric analysis (TGA) is performed at four different heating rates of 10, 20, 30, and 40 °C/min under nitrogen gas flow rate from ambient temperature to 900 °C. TGA results show the three-stage pyrolysis reaction which involves removal of moisture and light volatiles, degradation of cellulose and hemicellulose, and decomposition of lignin. The result also reveals that maximum degradation occurred in the temperature range of 200–400 °C. For calculating the kinetic (activation energy and pre-exponential factor) and thermodynamic parameters (enthalpy, entropy, and Gibbs free energy), different iso-conversional models, i.e. Flynn-wall-Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink, and Friedman, are employed which gives the average value of activation energy as 168.86, 165.80, 166.29, and 190.10 kJ/mol, respectively and the pre-exponential factor values lie in the range of 107-1021 s−1. The average values of Gibbs free energy calculated for FWO, KAS, Starink, and Friedman methods are 182.09, 182.15, 182.13, and 181.42 kJ/mol, respectively. Criado method and Z plot are showing complex reaction mechanism. The results of kinetics and thermodynamic study reveal pistachio shell is an efficient biomass for bioenergy production.

With the depletion of coal reserves all over the world, efforts are being made worldwide to utilize those deep underground coal seams, which are difficult to mine or are not feasible economically. Underground coal gasification (UCG) is a promising technology to achieve that objective and also to reduce the atmospheric pollution that is casued by surface gasification of the mined coal. Based on the previous research performed in this field, it is a well-known fact that the optimum quantity of water influx into coal seam can increase the hydrogen content of the product gas. In our earlier study, a novel method of utilizing humidified oxygen as the gasification agent was conducted for low ash coal gasification. The experimental results had shown the production of substantial quantity of hydrogen in the product gas. In the present study, the laboratory-scale experiments are extended to high-ash Indian coals with increases in the absolute humidity of the feed oxygen by preheating the water (humidifying medium)...

The challenges of providing electricity to rural households are manifold. Ever increasing demand–supply gap, crumbling electricity transmission and distribution infrastructure, high cost of delivered electricity are a few of these. Use of renewable energy technologies for meeting basic energy needs of rural communities has been promoted by the Governments world over for many decades. Photovoltaic (PV) technology is one of the first among several renewable energy technologies that was adopted globally as well as in India for meeting basic electricity needs of rural areas that are not connected to the grid. This paper attempts at reviewing and analyzing PV literature pertaining to decentralized rural electrification into two main categories—(1) experiences from rural electrification and technology demonstration programmes covering barriers and challenges in marketing and dissemination; institutional and financing approaches; and productive and economic applications, (2) techno-economic aspects including system design methodologies and approaches; performance evaluation and monitoring; techno-economic comparison of various systems; and environmental implications and life cycle analysis. The paper discusses the emerging trends in its concluding remarks.

The concept of reducing the cooling load of airconditioned building by maintaining a water film spray over the roof is a well known proposition in the literature and has been exploited both experimentally and theoretically by several workers. The conscious scientific application of air ventilation in summer has also been suggested for passive space airconditioning. Since the ventilation is controlled by opening windows/door and hence depends on ventilation timings or its duration, a periodic analysis for variable ventilation is also desirable if the window on south-facing wall is opened/closed on daily cycle. In this communication the authors have developed a periodic heat transfer model which incorporates the effects of furnishings (assumed isothermal mass), air ventilation through window/door (assumed time dependent) and the basement ground heat storage. Explicit expression for the indoor air temperature as a function of time in a building with a water film over the roof and controlled ventilation has been obtained. Numerical calculations for a typical hot summer day in Delhi using the relevant parameters have been made to study the feasibility of the proposed model. The effects of the presence/absence of water spray over the roof, continuous and intermittent ventilation rates and timings on the indoor air temperature have been examined. It is found that the maintenance of a water film spray over the roof and the ventilation control systems in a building in hot sunny climates significantly reduces the indoor air temperature.