• Energy Research

Lignocellulosic biomass is available in abundance as a renewable resource, but the major portion of it is often discarded as waste without utilizing its immense potential as an alternative renewable energy resource. To overcome recalcitrance of lignocellulosic biomass, various pretreatment methods are applied to it, so that the complex and rigid polymeric structure can be broken down into fractions susceptible for enzymatic hydrolysis. Effective and efficient biomass processing is the goal of pretreatment methods, but none of the explored pretreatment methods are versatile enough to fulfil the requirement of biomass processing with greater flexibility in terms of operational cost and desired output efficiency. Deployment of green solvents such as ionic liquids for the pretreatment of lignocellulosic biomass has been a topic of discussion amongst the scientific community in recent times. The presented work provides a detailed overview on the deployment of ionic liquid for the pretreatment of lignocellulosic biomass coupled with a brief discussion on other pretreatments methods. The recyclability and reusability along with other unique properties makes an ionic liquid pretreatment different from the other traditional pretreatment methods. Also, this study explores diverse critical parameters that governs the dissolution process of biomass. Hazardous properties of ionic liquids have also been explored. Future perspective and recommendations have been given for an efficient, effective, and eco-friendly deployment of ionic liquid in biomass pretreatment process.

Abstract Rising wastes due to all round development can emphatically be seen in today’s world. Cutting edge and innovative waste processing technologies such as integration of anaerobic digestion (AD) with thermochemical processes (pyrolysis, gasification and hydrothermal carbonization) are required to decrease the adverse effects of wastes on environment and health, and to enhance the resource efficiency. The coupling of two or more technologies can not only offset the limitations of each other but can also act as a driving force to encourage the circular economy. This paper delivers an evaluation on the viability of integrating AD with thermochemical processes. The versatility of pyrochar (biochar) is examined as a means to promote it for multiple applications. The concept of integrated process design is proposed to pave a way for future research. This article throws light on different areas of waste valorization via coupling of thermal and biological routes to boost it as a possibly sustainable and green technology.

Thermal plasma assisted treatment is a viable pathway to process difficult waste streams to generate useful product gas.

A solar still is an eco-friendly device that makes use of ample solar energy for the purification of water. The main objective of this research is to increase the yield output of a double-slope solar still (DSSS) by coupling the basin liner with copper tubes and parabolic fins. In this work, the experiments were supervised for nine days with three different cases. For these experiments, copper tubes with thickness of 2 mm, outer diameter of 32 mm, inner diameter of 28 mm, and parabolic fins with 30 mm diameter and 50 mm height were considered. In the first case, non-coated copper tubes (NCCTs) were used, in the second case, coated copper tubes (CCTs) were employed, and in the last case, coated copper tubes with a combination of parabolic fins (CCTPFs) were used. The MSS (case-III) demonstrated a substantial yearly productivity enhancement of 57.79%, establishing its superiority in terms of output because of its higher daily distillate yield of 1215 mL/day in contrast to CSS. When compared, case III—CCTPF—performed better than case II—CCT—by 35.75%. The CSS and MSS both contributed to a decrease in the pH of the saline water, which went from 8.18 to 7.64 and 7.23, respectively. In comparison to the MSS and CSS, which had 0.428 mg/L and 0.569 mg/L of fluoride ions, respectively, brine water had a fluoride ion level of 0.734 mg/L. Total dissolved solids (TDS) concentration before desalination was 440 ppm and it was minimized to 20 ppm with MSS and 55 ppm with CSS, respectively, post-desalination. The corresponding cost per liter (CPL) of MSS and CSS is USD 0.053 and USD 0.040, respectively.

Anthropogenic carbon dioxide emissions are the main cause of global climate change. The COVID-19 pandemic has been one of the worst of its kind in the last century with regard to global deaths and, in the absence of any effective treatment, it led to governments worldwide mandating lock-down measures, as well as citizens voluntarily reducing non-essential trips and activities. In this study, the influence of decreased activity on CO2 emissions and on the economy was assessed. The US, EU-28, China and India, representing almost 60% of anthropogenic carbon emissions, were considered as reference entities and the trends were extrapolated to estimate the global impact. This study aimed to deduce initial estimates of anthropogenic CO2 emissions based on the available economic and industrial outputs and activity data, as they could not be directly measured. Sector-wise variations in emissions were modeled by assuming proportionality of the outputs/activities and the resulting emissions. A decline in road traffic was seen up to March 2020 and then a steady growth was observed, with the exception of China where road traffic started to recover by the end of January. The vast majority of passenger flights were grounded and, therefore, global air traffic plummeted by 43.7% from January to May 2020. A considerable drop in coal power production and the annual industrial growth rate was also observed. The overall economic decline led to a drop of 4.9% in annual global gross domestic product (GDP) for Q2 2020. The total global CO2 emissions reduction for January through April 2020 compared to the year before was estimated to be 1749 Mt. CO2 (14.3%) with a maximum contribution from the transportation sector (58.3% among total emissions by sector). Like other previous crises, if the economy rebounds as expected the reductions will be temporary. Long-term impacts can be minimized considering the business as well as lifestyle changes for travel, utilizing virtual structures created during this crisis, and switching to sustainable transportation.

Abstract As the world races toward its urban future, the quantity of wastes, one of the vital by-products of an enhancement in the standards of living, is exponentially rising. The treatment of wastes employing plasma is an upcoming area of research and is globally used for the simultaneous processing of diverse wastes coupled with the recovery of energy and materials. Ground-breaking and cost-effective thermal plasma technologies with high efficiencies are a prerequisite for the growth of this technology. This paper delivers an evaluation of the fundamentals such as the generation and characteristics of the thermal plasma along with the various types of wastes treatable by thermal plasma and the related issues. Furthermore, the authors discuss different types of advanced technologies as well as the material and energy recovery techniques and their present status worldwide, at lab-scale and industrial scale. The application of different thermal plasma technologies is discussed as a means to promote this technology into alternative applications, which require higher flexibility and greater efficiency. Mathematical modeling studies are also assessed with an objective to derive ideal conditions and permissible limits for the reactors and to test a variety of waste materials. A strategy to improve the feasibility and sustainability of waste utilization is via technological advancement and the minimization of environmental effects and process economics. This paper sheds light on diverse areas of waste utilization via thermal plasma as a potentially sustainable and environmentally friendly technology.

The presented study addresses the threefold challenges namely, sustainable waste valorization of a difficult waste stream, climate change due to CO2 emissions and clean energy crisis and it is a small step forward to achieve SDG-7. A hybrid DC thermal plasma was employed in a pilot scale facility (∼150 kW) to treat sewage sludge in the presence of waste CO2 (according to the concept of CCUS, Carbon Capture Utilization and Storage) to produce syngas and assess the viability to retrieve phosphorus and other valuable materials from the generated ash. An equilibrium model was also developed to enhance the understanding about the dynamics of process. The H2 generation was around 0.5 m3/kg fuel whereas the amount of char produced was negligible (0–0.013 kg/kg fuel) realizing an efficient transformation of carbon. It was promising to find a high amount of P2O5 in the ash retained in the filter (30 wt %) and reactor (9 wt %) as evaluated by XRF. An average value of 97 % was obtained for CCE (carbon conversion efficiency) depicting almost complete carbon conversion. The results are encouraging to valorize sewage sludge under the CCUS scheme to produce clean energy and reclaim valuable nutrients.

The article reviews diverse areas of conventional and advanced biomass gasification discussing their feasibility and sustainability vis-à-vis technological and socio-environmental impacts.