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Abstract Hydrogen is considered a potential game changer for world energy systems and a solution to climate change concerns, as it generates zero waste and it is suited for power generation and transportation. Despite its several advantages, there are significant technical challenges in deploying a stable hydrogen economy including improving its process efficiencies, lowering production costs, maintaining cost-effective transmission and distribution, and exploiting inexpensive and sustainable feedstocks. In this context, a detailed study was conducted to analyze the production sources, technologies, storage and transport systems, and global potential exportable feedstocks to produce hydrogen. A comprehensive analysis of current hydrogen production technologies with their energy efficiencies and hydrogen selling prices was reported in this study. Various hydrogen production technologies with their capital investments and CO2 emissions were also presented. Potential feedstocks for hydrogen production were identified and analyzed through a product space model, which characterizes a network of global exportable products based on their similarities and productive knowledge. It was established that the hydrogen production feedstocks and sources currently used are primarily available in six countries: the United States of America, France, Russia, Sweden, the Netherlands, and Spain. Broadly, the results revealed that the United States of America and Russia shared the highest hydrogen feedstock exports, indicating a higher probability of hydrogen production in these countries. Except for Russia, all the studied countries fell in the most desired quadrant, indicating that they can move in all product space directions to exploit unexplored hydrogen feedstocks for better sustainable economic growth.

Energy conservation potential of the evaporative roof cooling technique for a cinema house in a composite climate (characterized by Delhi) has been evaluated. Thermal loads due to heat conduction through the building envelope, the required ventilation and the occupants have been taken into account. Life-cycle-cost analysis has been employed to evaluate the cost effectiveness of this energy conservation technique. It is seen that evaporative cooling on the roof leads to a net saving of 14% in the initial investment and 17% in the annual cost.

Abstract Due to the various restrictions on the energy performance of public office buildings, it is essential to obtain occupancy information for not only evaluating but also regulating the building energy performance. There is still a lack of information and standard, however, for occupancy density due to the limitations on data collection and the lack of reliable data. Therefore, this study aimed to determine the optimal occupancy density for reducing the energy consumption in public office buildings. Towards this end, this study used various statistical methods, such as correlation analysis, decision tree, and Mann-Whitney U test, based on the actual occupancy data from public office buildings in South Korea. This study was conducted in three steps: (i) establishment of the database; (ii) determination of the optimal occupancy density using the statistical approach; and (iii) application of the proposed occupancy density using building energy policies. As a result, it was shown that buildings with an occupancy density above 31.41 m2/person could save up to 50.3% energy on average compared to those with an occupancy density below 31.41 m2/person. The analysis results showed that the proposed occupancy density could help in deciding the appropriate occupancy density for reducing the energy consumption of public office buildings.

Abstract Small hydropower projects (SHPs), though generally considered more environmentally benign and socially acceptable as compared to large projects, yet their overall sustainability is under suspicion in the Himalayan regions. Almost all SHPs in this region are being developed as run of the river mode which generally causes less/no submergence and quite less displacement of people as compared to large reservoir based hydropower production mode. However, in the absence of proper planning and monitoring mechanism, these projects are causing implacable tunnelling of hills, choking of streams, conversion of streams into dry ditches and long term socio-environmental impacts. This paper presents a SHP development study from hydro rich Beas river basin of Himachal Pradesh, a state nestled in western Himalayan region of India. In depth field studies, focus group discussions with the project affected people and interaction with project proponents of five SHPs in this region suggest that sustainability issues with respect to SHPs are not small vis-a-vis size of their installed capacity. There is an urgent need to take steps to include SHPs having an installed capacity of above 10 MW into the ambit of environment clearance process which is absent in many countries of the world at present.

Abstract The diesel engine is being widely used in day to day life in both mobile and stationary applications. The main drawback is the release of harmful gasses like HC, CO, NOx and particulate matter into the atmosphere. This affects both human beings and environment to a great extent and should be controlled effectively. This paper reviews the works on the control of diesel particulate matter in both pre-combustion and post-combustion techniques employed in the past few decades. The initial part of this review will discuss particulate matter composition and its structure. Then the various physical processes involved in the formation of particulate matter are discussed. Effects of fuel composition and its structure on soot formation are reported. Hazardous effects of particulate matter on both human beings and the environment are reviewed. Use of biodiesel water emulsified fuel as a fuel to control soot formation is highlighted. This review also highlights control of particulate matter by varying injection parameters like injection pressure, injection timing and auxiliary air injection. Multiple fuel injections within the same cycle to control NOx and particulate matter are also discussed. The conventional control technique of particulate matter by using Diesel particulate filter and its types are also compared with the new technologies. Various regeneration concepts to burn the collected soot are also highlighted. The major part of this review focuses on pre-combustion techniques to control particulate matter. This review paper, it is hoped, will be very useful for the researchers working on the control of diesel particulate matter.

Abstract Plastics have been reported as one of the major pollutants among various pollutants that are disposed of in the environment. They play a pivotal part in human life as they are cost-effective and are versatile. Plastics are known to have a mixture of many chemical components and are used for various domestic applications. Despite various useful applications, plastics take a long time to degrade. The burning of plastics releases chemicals such as phosgene and dioxides that are considered a hazard to the ecosystem. The toxic debris that is released from the plastics enters the food chain and water bodies in the form of microplastics. Microplastic-polluted foods and the presence of meager amounts of phthalates in toys lead to serious health consequences such as congenital diseases and malignant cancers. The dioxins released from the plastic polymers are lethally persistent organic pollutants which cause tumor and neurological damage in humans. Inadequate waste management practices have led to significant plastic pollution of water bodies. Plastics tend to settle on beaches, which decreases esthetic and recreation values. In this article, we have discussed ways for resource recovery from plastic wastes and the possible effects of plastics on the environment and available safety regulations for the use of plastics. This article also discusses scientific literature about the remediation of plastics using various methods, which can help to promote further improvement of the existing system by competent authorities and researchers.

Abstract Rice husk (RH), an agricultural waste, is abundantly available in rice producing countries like China, India, Bangladesh, Brazil, US, Cambodia, Vietnam, Myanmar, and South East Asia. Despite the massive amount of annual production worldwide, so far RHs have been recycled only for low-value applications. In recent years, many rice mills in rice producing countries have started using RH for the energy production for mill operations as well as household lighting in rural regions. Burning of RHs produces the rice husk ash (RHA). The disposal in landfills or open fields can be problematic and may cause a serious environmental and human health related problems due to the low bulk density of RHA. Several ways are being thought of for disposing RHA by making its commercial use. The amorphous silica forms the main component (83–90%) of RHA. The amorphous silica rich RHA has wide range of applications. High-value applications and current research investigations such as the use of RHA in manufacturing of silica gels, silicon chip, synthesis of activated carbon and silica, production of light weight construction materials and insulation, catalysts, zeolites, ingredients for lithium ion batteries, graphene, energy storage/capacitor, carbon capture, and in drug delivery vehicles are presented. Use of RHA in potential future applications is also discussed. It is suggested that the amorphous silica rich RHA could become a potential resource of low cost precursor for the production of value-added silica based materials for practical applications.

Abstract Anaerobic digestion (AD) technology has piqued scientists’ interest in light of the growing demand for renewable energy and environmental preservation. This paper discusses the analysis of national biogas producing capacity, energy demand, and methods for meeting that demand. Also, public health and environmental issue, biogas technology and their utilization, current national scenario, and future in the biogas field have been discussed. The Government of India (GOI) has been providing subsidies or financial support through various programs. They support the rural area for generating biogas and also announced the Sustainable Alternative Towards Affordable Transportation (SATAT) initiative for the generation of compressed biogas (CBG) for the installation of 5000 plants up to 2023-24. These plants are expected to produce 15 million metric tonnes (MMT) of CBG per annum, which is about 40% of the current compressed natural gas (CNG) consumption of 44 MMT per annum in the region.

Abstract Characterization of the effects of cruise ship emissions on local air quality is scarce. Our objective was to investigate community level concentrations of fine particulate matter (PM2.5), nitrogen dioxide (NO2) and sulphur dioxide (SO2) associated with cruise ships in James Bay, Victoria, British Columbia (BC), Canada. Data obtained over four years (2005–2008) at the nearest air quality network site located 3.5 km from the study area, a CALPUFF modeling exercise (2007), and continuous measurements taken in the James Bay community over a three-month period during the 2009 cruise ship season were examined. Concentrations of PM2.5 and nitrogen oxide (NO) were elevated on weekends with ships present with winds from the direction of the terminal to the monitoring station. SO2 displayed the greatest impact from the presence of cruise ships in the area. Network data showed peaks in hourly SO2 when ships were in port during all years. The CALPUFF modeling analysis found predicted 24-hour SO2 levels to exceed World Health Organization (WHO) guidelines of 20 μg m−3 for approximately 3% of 24-hour periods, with a maximum 24-hour concentration in the community of 41 μg m−3; however, the CALPUFF model underestimated concentrations when predicted and measured concentrations were compared at the network site. Continuous monitoring at the location in the community predicted to experience highest SO2 concentrations measured a maximum 24-hour concentration of 122 μg m−3 and 16% of 24-hour periods were above the WHO standard. The 10-minute concentrations of SO2 reached up to 599 μg m−3 and exceeded the WHO 10-minute SO2 guideline (500 μg m−3) for 0.03% of 10-minute periods. No exceedences of BC Provincial or Canadian guidelines or standards were observed.