Sequestration Technologies Research Articles

3D structural and stratigraphic characterization of X field Niger Delta: implications for CO2 sequestration

Carbon capture and sequestration technology has been a ground-breaking tool in tackling carbon dioxide (CO2) emissions worldwide but has limitedly been researched and practised in Africa at present. Considering the vast growth and developmental level in the continent, there is a need to consider this option of mitigating global climate change. In this study, a systematic and process-based incorporation of seismic and well logs datasets was used to characterize the structural and stratigraphic framework of sandstone reservoirs within the field in order to determine their capacities for effective CO2 sequestration. Petrophysical analysis, fault modelling as well as geostatistical techniques were used to build facies and property models which enabled a qualitative assessment of the sealing potential of faults associated with the reservoirs based on prediction of key properties such as shale gouge ratio, lithological juxtaposition, fault permeability and fault transmissibility across the fault faces. Nine water-bearing sandstone reservoirs (reservoirs A–J) with varying reservoir quality were identified in the field. The dominance of high SGR, low permeability, higher fault throws and low fault transmissibility values at the lower parts of the faults indicates the deeper structural traps of the field are low-risk zones and might serve as good storage areas for CO2.

CO2 sequestration by propagation of the fast-growing Azolla spp.

Azolla is a group of aquatic floating plants that can achieve very high growth rates compared to other aquatic macrophytes, with a doubling time of 2–5 days under optimal growing conditions. The ability of Azolla to grow at such rapid rates allows for the opportunity of utilizing it as a method to sequester a significant amount of atmospheric CO2 in the form of biomass, which can be locked away to completely remove the carbon from the active carbon cycle, or which can be used in various applications such as animal feeds, biofertilizers, and biofuel production, which in turn will contribute to reduction in the fossil CO2 emissions. In this desktop study, the potential use of Azolla for mitigating the annual increase in the atmospheric CO2 levels was addressed, which were estimated at 18.9 billion tons of CO2 per year. A theoretical setup of 1-ha ponds was assessed to estimate the total Azolla growing area required for counterbalancing the annual atmospheric CO2 increase. Each 1-ha pond was found capable of capturing 21,266 kg of CO2 (C) per year. The calculated required total area to mitigate the total annual increase was estimated to be 1,018,023 km2 (equivalent to around a fifth of the Amazon forest area). Sensitivity analysis, which was based on the variations in the productivity of Azolla due to growing conditions, indicated that the required area would range between 763,518 and 1,527,036 km2. This study provides a novel natural method for CO2 sequestration that has lower environmental impacts compared to conventional sequestration technologies as an alternative green approach for mitigating the effects of fossil fuels.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-16986-6.

CO2 Sequestration

Starting with an overview of Science, Engineering, Technology and Management. An application of Science is called Engineering; an application of Engineering is called Technology; and applying the Knowledge of Science, Engineering & Technology in Management. Globally, due to the realization that, from last three decades, carbon dioxide sequestration gaining interest to reduce the concentration of CO2. CO2 Sequestration terms as CO2 capture. In the atmosphere capture carbon dioxide through chemical process and physical process. This process is not new and used by petroleum, petrochemical, chemical and power industries. Carbon dioxide Sequestration Technology involves the process of extracting, separating, transporting and storage. Carbon dioxide emissions can be preventing before release into the atmosphere. By this, global warming can be defer and dangerous climate change can be stop. The most important challenges that should be considered are regulatory, political, technical and economical

Pathway toward carbon-neutral electrical systems in China by mid-century with negative CO2 abatement costs informed by high-resolution modeling

<h2>Summary</h2> China, the largest global CO₂ emitter, recently announced ambitious targets for carbon neutrality by 2060. Its technical and economic feasibility is unclear given severe renewable integration barriers. Here, we developed a cross-sector, high-resolution assessment model to quantify optimal energy structures on provincial bases for different years. Hourly power system simulations for all provinces for a full year are incorporated on the basis of comprehensive grid data to quantify the renewable balancing costs. Results indicate that the conventional strategy of employing local wind, solar, and storage to realize 80% renewable penetration by 2050 would incur a formidable decarbonization cost of $27/ton despite lower levelized costs for renewables. Coordinated deployment of renewables, ultra-high-voltage transmissions, storages, Power-to-gas and slow-charging electric vehicles can reduce this carbon abatement cost to as low as $−25/ton. Were remaining emissions removed by carbon capture and sequestration technologies, achieving carbon neutrality could be not only feasible but also cost-competitive post 2050.

Mineral carbonation as a design project for green chemical engineering education

Accelerated mineral carbonation is a promising CO2 sequestration technology that is strongly linked to concepts of sustainability and Green Chemistry, and its process requirements apply principles of reaction kinetics, transport phenomena, and materials characterization. The present work aimed to develop educational tools for including accelerated mineral carbonation in chemical engineering curricula. To this end, an experimental investigation laboratory procedure and a design project outline have been conceived. As a way to further engage students in this learning experience, the process conditions for the laboratory work are varied between groups of students, and the experimental data obtained are pooled to be used by every group for the subsequent design exercise. This is meant to give students motivation to generate accurate data that they knew would be useful for the entire class and, at the same time, provide students with the opportunity to use data generated by colleagues, much in the same way the design work is done in the industry. In the design project, students use the experimental data obtained by themselves and classmates on the accelerated mineral carbonation of wollastonite, to determine if this is a feasible process for industry to sequester carbon dioxide, in view of mitigating climate change. Also, they use the experimental data, acquired using a range of process conditions, to study the effect of the process variables (CO2 pressure and mixing rate) on the carbonation kinetics and mass transfer rate. The focus of our previously published article was on the experimental investigation, while the focus of this conference paper is on the design project.

High-pressure water and gas alternating sequestration technology for low permeability coal seams with high adsorption capacity

Traditional ECBM techniques, which cannot extract methane adsorbed in coal pores effectively, is still difficult to greatly improve coalbed methane recovery rate until now. Waterflooding or CO2-ECBM can displace methane adsorbed in nanopores but increases the risk of coal and gas outbursts. We proposed a novel coalbed methane recovery technique, e.g. high-pressure water and gas alternating sequestration technique (H–P-WGAS), which can displace adsorbed methane in coal pores without introducing other gases with high adsorption capacity. Additionally, the injected H–P gas can eliminate the water lock and be easily extracted during methane drainage. Numerical simulation and field test were conducted to verify effectiveness of the H–P-WGAS technique. The numerical results show that the H–P-WGAS technique can enhance methane migration in coal seam by changing pore pressure distribution and increase influence radius to 70 m at 20 MPa in 48 h. For water and air co-injection, methane content can decrease by up to 37.6%, which is much more effective comparing with that under single water injection or gas injection. Meanwhile, field tests show that the reduction of methane content by percentage lies between 25.14% and 80.62% with an average of 53.17%. Meanwhile, the influence radius of field test reached ∼48 m. The average methane drainage flow rate of single borehole increased by 2.65 times. Average methane drainage concentration increased from 31.3% to 47.6%. The methane drainage flow rate and concentration of the whole coal mine increased by 50.2% and 32.4%, respectively. The above results indicate that the proposed H–P-WGAS has best effectiveness comparing with single water injection or air injection.

A Combined Chemical-Electrochemical Process to Capture CO2 and Produce Hydrogen and Electricity

Several carbon sequestration technologies have been proposed to utilize carbon dioxide (CO2) to produce energy and chemical compounds. However, feasible technologies have not been adopted due to the low efficiency conversion rate and high-energy requirements. Process intensification increases the process productivity and efficiency by combining chemical reactions and separation operations. In this work, we present a model of a chemical-electrochemical cyclical process that can capture carbon dioxide as a bicarbonate salt. The proposed process also produces hydrogen and electrical energy. Carbon capture is enhanced by the reaction at the cathode that displaces the equilibrium into bicarbonate production. Literature data show that the cyclic process can produce stable operation for long times by preserving ionic balance using a suitable ionic membrane that regulates ionic flows between the two half-cells. Numerical simulations have validated the proof of concept. The proposed process could serve as a novel CO2 sequestration technology while producing electrical energy and hydrogen.

Some challenges and opportunities for Russia and regions in terms of the global decarbonization trend

This article discusses a possible scenario of energy transition in Russia, taking into account the economic structure, presence of huge oil and gas infrastructure and unique natural resources. All this allows to consider global trends of energy and economic decarbonization not only as a challenge, but also as a new opportunity for the country. Considering developed oil and gas production, transportation, refining and petrochemical infrastructure, as well as the vast territory, forest, water and soil resources, our country has unique opportunities for carbon sequestration using both biological systems and the existing oil and gas infrastructure. It is proposed to use the existing oil and gas production facilities for hydrogen generation in the processes of hydrocarbon catalytic transformation inside the reservoir. It is suggested to create and use large-scale technologies for CO2 sequestration using existing oil and gas production infrastructure. Considering high potential of the Russian Federation for carbon sequestration by biological systems, a network of Russian carbon testing areas is being developed, including one at Kazan Federal University (KFU), – the “Carbon-Povolzhye” testing area. The creation of carbon farms based on the applications at such testing areas could become a high-demand high-tech business. A detailed description of the KFU carbon testing area and its planned objectives are given.

Thermodynamic analysis of 350 MWe coal power plant based on calcium looping gasification with combined cycle

Carbon capture and sequestration (CCS) technology is needed for fossil fuels (FFs) based power generation, in order to make it sustainable in future. Calcium looping gasification (CLG) is a novel energy technology that fulfils CCS, unlike IGCC post combustion, CO2 capture is not required, making it less energy demanding and saving capital cost, moreover CaO-CaCO3 is an exothermic reaction, hence the generated heat is adequate to perform CLG. In this study, both experiments and simulations of CLGCC, with CaO as a CO2 sorbent, were performed at varying gasifier temperatures and pressures using Aspen Plus, while results were compared to maximize the overall efficiency. Here, we propose calcium looping gasification with combined cycle (CLGCC) simulation using Aspen Plus with CaO as CO2 sorbent, and results are validated against experimental data in terms of gasifier temperature and pressure. The IGCC without CCS system along with CLGCC are simulated simultaneously for comparison. The CLGCC system achieved an efficiency as high as 54.93%, while IGCC's system without CCS efficiency was calculated as 53.22% and corresponding exergetic efficiencies are 51.67% and 50.03%, respectively. The carbon capture efficiency of CLGCC is 83.5 % with 94.4 vol% of CO2 achieved after steam condensation for carbon capture system. On the basis of results, we demonstrate the applicability of CLGCC against the conventional power plants and it has a great window for adaptation in the future in advanced power plants.

Assessment of the Redox Characteristics of Iron Ore by Introducing Biomass Ash in the Chemical Looping Combustion Process: Biomass Ash Type, Constituent, and Operating Parameters.

Chemical looping combustion (CLC) is a potential CO2 capture and sequestration (CCS) technology that can easily separate CO2 and H2O without energy loss and greatly improve the efficiency of carbon capture. Due to the inherent defects of natural iron ore, such as low reactivity and poor oxygen carrying capacity, four kinds of biomass ashes (rape stalk ash, rice stalk ash, platane wood ash, and U. lactuca ash) that have different constituents of K, Na, Ca, and Si were applied to modify the redox performance of natural iron ore. The effects of biomass ash type, constituent, reaction temperature, H2O vapor flow rate, and redox cycle on the CLC process were assessed experimentally in a batch fluidized bed reactor system. Oxygen carrier physicochemical characteristics were determined by several analytical techniques. The results showed that rape stalk ash, platane wood ash, and U. lactuca ash with a high K content and high K/Si ratio significantly improved the reactivity and cycle stability of iron ore, even after 10 redox cycles, while rice straw ash with a low K/Si ratio showed an inhibitory effect due to the formation of bridge eutectics, which enhanced agglomeration. In a range from 800 to 950 °C, higher temperatures led to a much better ability to promote the CLC process than lower temperatures. A higher flow rate of H2O had little effect on the further promotion of the CLC process due to hydrogen inhibition. It is believed that the application of BA-modified iron ore oxygen carriers is an effective strategy to improve the CLC process.

Transition pathways towards a deep decarbonization energy system—A case study in Sichuan, China

China has set ambitious carbon emission reduction targets to combat climate change, however, there has been little scientific focus on the achievement of deep decarbonization at the provincial level. The contradiction between rapid economic development and increasing energy utilization exacerbates the difficulty of achieving this goal. Here, we explored the feasibility of fulfilling deep decarbonization in the energy system by 2050 in Sichuan, one of the leading provinces in economic growth in China. Three transition pathways sustained by imported electricity, biomass, and natural gas were developed and simulated using the EnergyPLAN model. All the pathways utilized local hydropower, wind power, and solar photovoltaic resources. These pathways were evaluated using multi-dimensional analysis considering energy self-sufficiency, environmental sustainability, and economic affordability. We found that the energy self-sufficiency rate of the 100% electricity pathway was less than 68%, whereas those of the other pathways were nearly 100%. The CO2 emission reduction differed by pathway, with 100% electricity achieving 91.52%, biomass achieving 90.48%, and natural gas achieving 58.17%. Moreover, all the pathways achieved zero direct CO2 emissions with carbon capture and sequestration (CCS) technology. From an economic perspective, the highest system cost, i.e. 1.3 times that of the reference system, appeared in the 100% electricity pathway after introducing CCS technology, and was comparable to the energy system costs of other provinces in 2050. The methods and results of this study can serve as a basis for facilitating decarbonization in any provincial energy system in the long term.

An intelligent platform for evaluating investment in low-emissions technology for clean power production under ETS policy

This study develops an investment decision making platform for carbon capture and sequestration (CCS) technology using an artificial intelligent (AI) algorithm featuring an optimization via a mixed integer non-linear programming (MINLP) formulation. This computational strategy offers a smart rapid investment decision evaluation of CCS technology through several economic-environmental-technical-policy (EETP) uncertainties. This is applied to a coal-fired power plant (PP) in Shenzhen, China. Historical (2019) and forecast (2030) operations are evaluated under dynamic and static carbon price regimes. Scenario 1 under dynamic carbon pricing exhibits a positive (sustainable) investment decision for CCS deployment at 28% net revenue gain of selling electricity. Scenarios 2–4 feature negative (unsustainable) investments for CCS technology at 44%, 7% and 66% net revenue loss, respectively. Carbon price is identified to be the dominant variable/uncertainty in recognizing the sustainability outcome of CCS investment followed by the combined market trends of coal and electricity prices. This current work demonstrates a computation approach for dealing with all the uncertainties at hand and is therefore necessary and critical for rational future investment decisions and operations in clean power production (as demonstrated in this PP + CCS context), suggesting the EETP objectives cannot be met without intelligent algorithmic operations. The present analysis exemplifies the trade-offs mainly between the cost of CO2 emission and the cost of PP operation with CCS. It can be used as an indicator on the energy transformation readiness based on current and forecast global conditions. This algorithmic approach can be generalized and extended to other cleaner power production processes and to alternative energy-based industrial symbiosis (IS), which collectively aims to mitigate the use of traditional fuel (i.e. coal) and subsequently stimulating a circular economy energy transition.

Cold plasma-Metal Organic Framework (MOF)-177 breathable system for atmospheric remediation

The direct capture of CO2 and CH4 from the atmosphere to stabilize the concentrations in the air to control global warming is accelerating. There are continued efforts to develop and optimize different technologies for capture and sequestration of these greenhouse gases from industrial emission sites. In this work we employed MOF-177 as an efficient CO2 and CH4 adsorbent at standard temperature and pressure conditions. We demonstrated the possibility of desorbing the gases under study when employing gentle plasma pulses of He. Moreover, we performed the synthesis of methanol from CH4 using O2 and CO2 as oxidants respectively in the presence of MOF-177. We observed the highest conversion for the CH4 + O2 system when employing the MOF-177 at (5:1) (CH4: O2) flow ratio of 23.5 % and methanol selectivity of 17.65 %. While the best performance for the CH4 + CO2 system at the same conditions i.e., (5:1) (CH4: O2) flow ratio was 18.4 % for the methane conversion and 11.68 % for the selectivity towards methanol. We expect this preliminary understanding of the adsorption-reaction system under non-thermal plasma environment can lead to future atmospheric remediation technologies.

Climate Change Adaptation in the British Columbia Wine Industry Can Carbon Sequestration Technology Lower the BC Wine Industry’s Greenhouse Gas Emissions?

This paper measures the benefits and costs of using biochar, a carbon sequestration technology in the British Columbia (BC) wine industry. It was found that the use of biochar, produced from wine industry waste, can reduce greenhouse gas emissions, and make a significant economic contribution to the BC wine industry. An economic model was developed to calculate the value-added from each of the three sectors that comprise the BC Wine industry value chain. The model uses biochar, produced from grape prunings and pomace, as a soil amendment in the vineyards. Grapes produced from these vineyards are used to produce wine. The assumptions for each variable used in this study are drawn from the literature and prior research by the authors. In addition to achieving the industry’s sustainability goals, each sector of the wine value chain is potentially profitable, however producing biochar as a profitable independent business is likely minimal compared to what could be achieved along the value chain with increased yields of the same quality. Biochar as a soil amendment is a long-term investment for farmers with results best assessed after multiple years. Future research is needed to better understand the biochar production process as an integral part of the BC wine industry, the carbon sequestration benefits, the specific increases in long-term grape yields and wine production. Also, the industry willingness to re-evaluate and change present industry practices, and other important benefits that can be derived from marketing climate friendly wine to BC consumers needs to be understood.

Formation of mechanisms for creating innovative national polygons

Currently, the issues of environmental protection and conservation are becoming very acute. The development strategy of the world community is determined by the UN Sustainable Development Goals. According to this document, one of the priorities is to eliminate the harmful effects of carbon fuel emissions. In the world, about 80% of the energy produced is produced by burning carbon, which leads to the release of greenhouse gases into the atmosphere. Annual CO2 emissions reach 33.1 billion tons, causing irreparable damage to the environment. Our nature will continue to develop and evolve under these conditions, but the drastic climate change, global warming, and the mutation of flora and fauna are tasks that require immediate solutions. As a solution to these problems, we can offer the use of alternative energy sources. They represent promising ways to obtain, transfer and use energy from renewable sources, reducing the risk of harm to the environment. Also, to reduce harmful CO2 emissions into the atmosphere, methods for reducing greenhouse gas emissions are proposed, including carbon dioxide sequestration technologies, which are implemented in the form of CC (U) S (carbon capture, utilization and storage) projects. Another solution to the tasks set can be the creation of carbon landfills and farms that will allow us to develop technologies for monitoring carbon emissions and runoff.

A review on application of activated carbons for carbon dioxide capture: present performance, preparation, and surface modification for further improvement

The atmosphere security and regulation of climate change are being continuously highlighted as a pressing issue. The crisis of climate change owing to the anthropogenic carbon dioxide emission has led many governments at federal and provincial levels to promulgate policies to address this concern. Among them is regulating the carbon dioxide emission from major industrial sources such as power plants, petrochemical industries, cement plants, and other industries that depend on the combustion of fossil fuels for energy to operate. In view of this, various CO2 capture and sequestration technologies have been investigated and presented. From this review, adsorption of CO2 on porous solid materials has been gaining increasing attention due to its cost-effectiveness, ease of application, and comparably low energy demand. Despite the myriad of advanced materials such as zeolites, carbons-based, metal-organic frameworks, mesoporous silicas, and polymers being researched, research on activated carbons (ACs) continue to be in the mainstream. Therefore, this review is endeavored to elucidate the adsorption properties of CO2 on activated carbons derived from different sources. Selective adsorption based on pore size/shape and surface chemistry is investigated. Accordingly, the effect of surface modifications of the ACs with NH3, amines, and metal oxides on adsorption performance toward CO2 is evaluated. The adsorption performance of the activated carbons under humid conditions is also reviewed. Finally, activated carbon-based composite has been surveyed and recommended as a feasible strategy to improve AC adsorption properties toward CO2. The activated carbon surface in the graphical abstract is nitrogen rich modified using ammonia through thermal treatment. The values of CO2 emissions by sources are taken from (Yoro and Daramola 2020).

Research progress of CO2 resource utilization based on biological carbon sequestration technology

Research progress of CO2 resource utilization based on biological carbon sequestration technology

A study of CO2 injection well selection in the naturally fractured undulating formation in the Jurong Oilfield, China

Oilfields are major sites for the implementation of carbon dioxide capture, utilization, and sequestration technology. The Jurong oilfield is located in the Subei Basin, which is an important petroleum exploration region in southern China. This study focused on evaluating the CO2 leakage risks and injection capacities of the exploration wells in the Jurong oilfield. A three-dimensional geological model was established to depict the naturally fractured undulating formation. The burial depth of selected wells N3, N10, Rong3, and Jubei1 decreases in order. Wells N3 and Jubei1 located in the greatest stratigraphic fluctuation. The results indicate that ScCO2 do not migrate into the fracture zones for a 30 years injection period, and they are conducive to pressure diffusion. The larger fluctuation causes a larger migration of CO2 in vertical, which is more obvious in the synclinal structure than in the anticlinal structure. The injection volume is proportional to the burial depth of wells. The 30 years’ injection volume of well N3 is 2.57 × 106 t which would not reduce more than 5% if there are other injection wells nearby. According to the analysis of the leakage risk and injection capacity conducted in this study, well N3 is the optimal injection well. We defined an effective injection coefficient J to represent the injection capacity of well, and we concluded that the injection capacity of ScCO2 and dissolved CO2 for study area are 8.96 × 108 t and 4.69 × 107 t, respectively.

Effects of Direct Air Capture Technology Availability on Stranded Assets and Committed Emissions in the Power Sector

We examine the effects of negative emission technologies availability on fossil fuel-based electricity generating assets under deep decarbonization trajectories. Our study focuses on potential premature retirements (stranding) and committed emissions of existing power plants globally and the effects of deploying direct air carbon capture and biomass-based carbon capture and sequestration technologies. We use the Global Change Analysis Model (GCAM), an integrated assessment model, to simulate the global supply of electricity under a climate mitigation scenario that limits global warming to 1.5–2°C temperature increase over the century. Our results show that the availability of direct air capture (DAC) technologies reduces the stranding of existing coal and gas based conventional power plants and delays any stranding further into the future. DAC deployment under the climate mitigation goal of limiting the end-of-century warming to 1.5–2°C would reduce the stranding of power generation from 250 to 350 GW peaking during 2035-2040 to 130-150 GW in years 2050-2060. With the availability of direct air capture and carbon storage technologies, the carbon budget to meet the climate goal of limiting end-of-century warming to 1.5–2°C would require abating 28–33% of 564 Gt CO2 -the total committed CO2 emissions from the existing power plants vs. a 46–57% reduction in the scenario without direct air capture and carbon storage technologies.

Study of Copper and Copper Supported on N-Doped Graphene Nanoparticles for Enhanced Electrochemical Reduction of CO2 to Ethanol

Excessive carbon dioxide (CO2) emissions due to combustion of fossil fuels create serious impact on our atmosphere and will result in unwanted climate change and species extinction. In addition to the recent attempts to establish environmentally sustainable energy sources and to advance CO2 capture and sequestration technology, the conversion of CO2 into useful chemicals is a pragmatic approach for reducing its concentration in the atmosphere [1]. In this respect, sustainable electricity-powered electrochemical CO2 reduction (ECR) offers an exciting way because it not only transforms CO2 into useful fuels and chemicals, but also provides a solution for the long-term storage of volatile renewable energy [2,3]. Therefore, the design of efficient electrocatalysts with high selectivity (Faradaic efficiency (FE)), low overpotential, and good stability/reusability is key consideration for the development of ECR [4]. To date, copper is the only electrocatalyst that can reduce CO2 into hydrocarbons and alcohols which can be further used as fuel [1,4].For this, we have prepared metallic copper nanoparticles (Cu NPs) with and without N-doped graphene support and characterized by Scanning Electron Microscopy (SEM), High-resolution Transmission Electron Microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS) and X-ray Diffraction (XRD). The electrochemical experiments were performed in a customized H-type cell using 0.1 M KHCO3 electrolyte solution. Proton nuclear magnetic resonance (1H NMR) and High performance liquid chromatography (HPLC) was employed to analyze and quantify the liquid products. In the case of Cu NPs, we found ~46 % Faradaic efficiency (FE) and ~2.3 mA cm-2 current density (CD) towards Formic acid at -0.8 V vs. RHE, which would suggest that these particular Cu NPs are an ineffective catalyst for multicarbon production. While, Cu/NGN exhibit the highest selectivity for multicarbon products in the studied potential range. It gives a total 26 % FE and ~7.5 mA cm-2 CD at -1.0 V (vs. RHE) for the ethanol products. The study reveals that the structural and electronic properties of the electrode were enhanced by the addition of Cu NPs on NGN surface. In addition, reusability and long term stability is also studied. Acknowledgements The authors would like to thank Prof. P. K. Bajpai for his comments. This work was supported by Science and Engineering Research Board (SERB), Department of Science and Technology (DST), India (Grant No. EMR/2016/007437, dated March 13, 2018).