Climate Change and Green Chemistry of CO2 Sequestration

At the COP-21 UNFCCC Summit, India has made a challenging and significant commitment (INDC) to the goal of confining global warming to no more than 1.5 °C. This is particularly remarkable because India’s economic growth trajectory requires a substantial increase in energy access to underpin the development and ensure the widespread benefits of such growth to all strata of society. At the same time, India depends significantly on fossil fuels imports and is projected to be primarily fossil-fuel-dependent for at least two decades going forward. This indicates that both demand-side interventions, i.e., improved energy efficiencies as well as reduced carbon-derived energy, and supply-side interventions involving greater use of renewable carbon energy and lower footprint of deployed non-renewable carbon energy are critical to achieving simultaneous targets of energy access, energy security, and GHG mitigation. In this chapter, an innovative approach to analyzing the implications of these elements at a level of carbon atoms in the supply chain, their energy conversion, implications on GHG emissions, and potential long-term strategies including carbon capture, sequestration, and utilization is presented.

Carbon management from the energy sector is a key challenge before the nations. India as a nation is undergoing rapid economic and social transitions requiring diversified energy resources to meet basic energy needs of the people. India is having a 7% share in the world coal resources, and coal has been the dominant fuel for energy. Several policies that work toward climate change control by reducing or avoiding greenhouse gas emissions, exist. This chapter describes India’s energy scene, trends in coal consumption, and India’s renewable energy targets. To assess the potential of CO₂ sequestration—carbon capture, utilization, and storage, in mitigating emissions from the Indian industry—CO₂ emission scenarios need to be generated. Using basic assumptions from Coal Vision 2030, the CO₂ emission projections in three scenarios of high coal, business-as-usual, and high renewable energy, without and with CO₂ sequestration are calculated for 2017–2030. The current national and international CO₂ sequestration research is highlighted.

The subject of integration of renewable sources of energy, namely wind and solar (mainly) into the grid, has assumed significance in view of the fact that the renewable sources of power are now being adopted on a large scale to bring down the generation of huge quantities of CO₂ from fossil-fired power plants. Govt. of India has set grand targets of renewable energy source capacity additions. More proportion of renewable energy in the grid creates the problem of grid security and reliability issues. To avoid any load shedding into system due to variable nature of the RE sources, the higher ramping up and ramping down rates per minutes are required to be incorporated in the existing and new coal-/gas-fired conventional power plants. Further, the standards of minimum loading of the thermal power plants without oil support need to be brought down from the present value of 55% to further lower values to save on the import of huge quantities of diesel and crude oil and consequent drains of foreign exchange. The new technologies to ignite the coal directly are now commercially available internationally. These would need to be seriously considered. All these aspects have been discussed in the paper in detail so that there could be smooth change over from the present scenario of low renewable to high renewable and consequently prepare a solid ground for accepting without problem areas a higher share of renewable energy into our system.

Soaring of average temperature and change in climate pattern is posing challenge to find out a reliable and economical solution of reducing carbon dioxide percentage from the atmosphere. Out of various methods of capturing carbon dioxide, chemical looping combustion (CLC) is proving to be the most efficient and economical method. Although many researchers did experimental investigation of CLC, prior to experimentation, it is necessary to perform numerical simulation to determine the optimum working parameters. The literature on CFD simulation of CLC is very limited. This paper reviews the recent work done by researchers on CFD simulation of CLC with different qualities of coal including Indian coal.

In the recent years, due to the rapid escalation in the vehicle population and deforestation, the CO₂ level in the atmospheric has been increased drastically. Since CO₂ is formed due to complete combustion of fuel, which is desirable for getting more millage, the abnormally increased CO₂ level causes climate change problems. To mitigate the CO₂ level in the atmosphere, different approaches like absorption, adsorption and membrane separation can be adopted in the automobile sector. This chapter provides the information about the CO₂ emissions worldwide and nationwide. The experimental results show that the phase change fluids like amine solutions have better absorption characteristics up to 90%, as compared with activated carbon and zeolites. The regeneration of amines after absorption is, however, a big challenge, especially when it is used in vehicles. Possible technologies to alleviate the CO₂ emission from the automotive sector are also discussed.

CO₂ sequestration is the process of capturing, transporting and storing CO₂ from major emission sources. Alarming levels of CO₂ in atmosphere are responsible for creating huge climate change and risks like global warming. To reduce CO₂ and other greenhouse levels, world should shift to renewable resources. The Paris Agreement sets goal of reducing increase in temperature of earth which could be achieved by capturing and storage of CO₂ in parallel of reducing use of fossil fuels for industries. The CO₂ capturing methods are pre-combustion, post-combustion, etc., and storage sites are geological, ocean storage, industrial uses, etc. This chapter presents patent landscape analysis of CO₂ capture technologies. Analysis includes patents filed in the field of carbon capture technologies worldwide and their geographical distribution, top countries, top assignees and top inventors in the world and India. It further discusses categorization of patents based on technology domain, commercialized products worldwide and Indian scenario.

India has come up with many policies and programs to take action toward mitigation of carbon dioxide from the energy sector through rapid augmentation of renewable energy growth and energy efficiency improvement. However, there is also need to unify abatement and recycling measures like amplification of low-carbon technologies. Emissions from various industries can be captured and reused for the production of various value-added chemicals and fuels. This chapter briefly discusses all the chemical reactions which require carbon dioxide as a primary product, giving a brief detail of electrocatalytic and photocatalytic pathways in which the anthropogenic carbon dioxide can be activated and subsequently converted into value-added chemicals/fuels. Apart from that, certain issues related to scaling up the technology have been highlighted. The author concludes by putting light on various problems related to the technologies, which need efforts and research so as to achieve practically viable catalysts for CO₂ conversion to chemicals and fuel.

Global warming due to emission of greenhouse gases, especially carbon dioxide (CO₂), has a major impact on climate change. A large number of absorbents were tested for CO₂ capturing, and the literature reports suggested that ionic liquids (ILs) showed better performance than conventional absorbents. In recent years, several researchers studied experimental and theoretical methods to understand the role of ILs in CO₂ capture, regeneration and conversion. ILs have potential to replace conventional absorbents for CO₂ capture due to the combination of unique properties and good solvating capability. The physical and chemical properties of ILs could be modified by tuning their ionic mobilities to achieve specific application requirements. Further, CO₂ solubility in ILs can be attributed to free volume effect and Lewis acid–base interactions. The significant enhancement in viscosity of IL after CO₂ absorption can be controlled by the addition of water as co-solvent, and the presence of water has the potential to compete with the CO₂ for absorption. After CO₂ absorption, the recycling of ILs is important, which can be performed by heating. From the viewpoint of thermodynamics, the enthalpy change is the main driving force for CO₂ absorption for ILs, and other thermodynamic parameters can be derived for this absorption process.

One of the major constituents of greenhouse gases is carbon dioxide whose concentration in the atmosphere is increasing at an alarming rate due to the disorganized human activities. Therefore, capturing CO₂ and utilizing it to make various value-added chemicals is regarded as a green transformation, which thereby balances the carbon footprint. In this chapter, the advances in CO₂ as the C₁ source by utilizing it as a carbonylating agent for important organic transformations for the synthesis of cyclic carbonate, substituted urea, cyclic urea, carbamates, glycerol carbonate and dimethyl carbonate are discussed. These products have a wide range of applications as specialty solvents, starting materials/intermediates for polymer, paint, agrochemicals, pesticides, herbicides and pharmaceutical industries. Also, a few products like dimethyl carbonate have potential applications as fuel additives. Although CO₂ is thermodynamically and kinetically stable molecule, it can be activated by basic sites in the catalyst due to the electron deficiency of the carbonyl carbon at appropriate reaction condition. Various catalyst systems such as metal oxides, mixed metal oxides, supported metal oxides, metal-organic framework, bifunctional catalysts and importance of solvent have been highlighted and discussed in detail for the efficient production of these commercially important chemicals from CO₂.

Present scenario global warming is a major concern worldwide, due to the continuous increment of CO₂ level in the environment. The power plants, chemicals, manufacturing industries, and automobiles applications are the major cause for the same. Nowadays, various protocols and norms have been in the implementation stage to either reduce the CO₂ level or to capture the CO₂ produced during the process. In this chapter, one of the utilization of captured CO₂ has been explored as a natural refrigerant, which has favourable thermophysical properties and having the lowest global warming potential (GWP). Many research is going on worldwide for different application in the HVAC sector, like automobile air conditioning, supermarket, cold chain, industrial application, etc. The cold chain is one of the major sectors where the use of CO₂ as refrigerant can be appreciated, especially for the referred vehicles and cold storage for NH3 charge reduction. This chapter summarizes the recent development of the CO₂ refrigeration system based on the available literature, for the supermarket and cold chain applications followed by advantages of CO₂ as refrigerant, its technical challenges, and opportunities over the existing systems.

Economic growth, due to increased consumerism, extravagance and human greed, necessitates higher energy demand. Fossil fuels burning, which generates carbon dioxide, a greenhouse gas, provides this energy resulting in a quantum jump in carbon dioxide emission and accumulation. Carbon cycle and other natural processes like mineralization of carbon dioxide through weathering of rocks rich in magnesium or calcium are inadequate to remove excess greenhouse gases. This has caused global climate change, threatening the existence of living beings including Homo sapiens. Removing carbon dioxide from atmosphere, either at the sites of carbon dioxide generation like power plants, called point capture of carbon dioxide (PCC) or in ambient air popularly known as direct air capture (DAC), therefore has become a necessity. In this chapter, DAC techniques like biosequestration, absorption and adsorption are discussed along with the challenges in their implementation. The DAC machines offer a greater flexibility of usage, as they are not tethered to the generation plants and can be placed at the site of subsequent usage of carbon dioxide or sequestration. Challenges in DAC are requirement of high energy, high water consumption and economic viability. Few companies have incorporated these techniques in their startups, and these have been deliberated along with the financial costs. It is concluded that initiating direct air capture as research and development projects on larger scale will help in developing viable options for carbon dioxide reduction as a future strategy.

Industrial Revolution has led to an unprecedented rise in carbon dioxide concentrations in the atmosphere. Among various methods available for carbon capture from the industrial emissions such as flue gas, carbonic anhydrase (CA)-based carbon capture techniques have been evolved and gained immense attention in the recent years. Carbonic anhydrase (CA) is a zinc metalloenzyme, which is an essential biocatalyst for all living beings. It plays a role in accelerating the hydration and dehydration of carbon dioxide. This enzyme can be utilized in vitro for capturing carbon from industrial emissions. Thermo-alkali stable CAs from prokaryotes are the most promising candidates for biomimetic carbon sequestration owing to the high temperature of flue gas and alkaline condition needed for precipitation of calcium carbonate formed in the reaction. These CAs can be essentially immobilized on various solid supports and matrices for developing bioreactors and their continuous operation. This chapter reviews developments in utilizing CAs of prokaryotes in carbon capture technologies.

Numerous types of adsorbents have been studied and used in industrial scale during upgradation of biogas by employing pressure swing adsorption. This chapter provides an insight into the working principle, efficiency, and energy consumption of this method in comparison with other processes. The most recent advancement includes the addition of subsequent units, omissions of additional stages, and the use of novel adsorbents in the process that determine the productivity, separation efficiency, and cost of the technology. Based on the literature review, research gaps were identified concerning the biogas upgradation to deliver renewable natural gas to the combined heat and power industries or to the natural gas pipelines as a vehicular fuel. The main setbacks for this sustainable sector are initially due to the digester conditions that lower the biomass conversion to methane, inadequate pre-treatment of biogas for removal of other contaminants, followed by production and selection of appropriate low-cost adsorbent in the final upgradation stage to maximize carbon dioxide elimination. In recent years, biowastes have been found to have the potential of transforming into mesoporous and nanoporous adsorbents upon carbonization and activation techniques which would enhance the adsorption activity. Also, reformation of the simple biochemical and thermochemical methods has intensified the methane yield at digester and reactor levels, respectively. Nonetheless, analyzing the effects of the process parameters for upgradation of biogas and production of adsorbents will lead to further investigation and innovative outcomes. Conclusions are drawn to augment the recent developments and sustainable technologies for broader adoption of renewable natural gas.

Concentration of carbon dioxide in the Earth’s atmosphere reached high, according to the World Meteorological Organization (WMO) Report and became parts per million in December 2018. The main causes of global warming are emission of CO₂ and other Green House Gases (GHG), and it is due to anthropogenic activities. To reduce the impact, sequestrating CO₂ through photosynthetic process is more effective. This process known as phytoremediation has been used to clean up greenhouse gases, heavy metals, pesticides, xenobiotics, organic compounds, and toxic aromatic pollutants. It is a cost-effective technique to mitigate global warming. Plants capture atmospheric CO₂ and convert it into organic compounds. The CO₂ sequestration of plants through the leaf and extensive root systems is useful for reduction of CO₂ by the potential assimilating capacity plants. Different plant species have different capacity of carbon sequestration potential. Plants that are identified and grown in and around the urban and industrial areas can reduce the air pollutants. They act as a wind breaker to minimize the transportation of air pollutants; the article has emphasis on the development of greenbelt model in urban forestry by planting more CO₂ assimilating plants. The benefits of developing this model will not only sequester CO₂, but also improve micro-climate of the urban area and increase urban biodiversity as best practices for sustainable environment and urban development. Three case studies are presented.

The aim of the present study is to study the effect of anthropogenic activities, i.e. burning and logging on the rate of soil CO₂ flux and its relationship with the abiotic and the biotic factor in the Dipterocarpus forest of Northeast India. Rates of soil CO₂ flux were found to be the highest in burnt and the lowest in logged forest site. Seasonally soil CO₂ flux rate was found to be maximum in rainy season and minimum in winter season in all the study sites. Simple linear regression shows there is a strong positive relationship between soil CO₂ flux and soil moisture, temperature, and soil organic carbon. Soil CO₂ flux rate can be altered through different forest management practices such as harvesting, thinning, and burning to mitigate climate change.

The rates of exchange of carbon dioxide between atmosphere, land and ocean is a key component of the global carbon budget. It is extremely important to quantify these both on a spatial and temporal basis as it can identify sources and sinks of anthropogenic carbon which are important in setting goals for country-wise emissions and uptake. This chapter presents results from a 4D variational assimilation scheme of ingesting carbon dioxide data between 2006 and 2011 into the adjoint of the LMDZ transport model to obtain fluxes between land, ocean and atmosphere. Carbon dioxide data from three stations from India (Hanle, Pondicherry and Port Blair) along with one hundred global stations have been assimilated into the model, and this is expected to increase the confidence in the results for the tropical and temperate Asian regions. The grid point-wise results are aggregated into larger regions representing India, China, USA, Western Europe and the Rest of the World to reflect the quantification of sources and sinks in these regions. In addition, aggregation in terms of Transcom regions is also presented.