Carbon Utilization

Carbon dioxide and other greenhouse gas emissions are potential global warming threats and are accepted physical manifestations of increasing anthropogenic and development activities around the globe. Carbon dioxide (CO₂) having the highest contribution in it, understanding of its mitigation pathways is important for combating global warming and climate change. This paper on CO₂ sequestration and utilization for energy security in six sections is divided in two parts. We begin with natural carbon cycle, increasing carbon dioxide emissions from the energy sector, and the need for removal of excess carbon dioxide in the atmosphere. Among various geo-engineering approaches, carbon capture, storage and utilization comprises of  carbon dioxide removal (CDR) - a land engineering technique for climate control and carbon dioxide utilization (CDU) through direct and indirect routes - a move for closing the carbon cycle toward a low carbon growth strategy. Several CO₂ reuse applications have come up for the energy industry. In part 2 of the paper, we present an overview of the existing initiatives by international and national agencies towards capability development. To address the challenges of capacity building in the emerging energy technology, a series of awareness workshops for researchers in academia and industry were organized in India. The contents of present book as an outcome of an awareness and capacity building workshop held in 2015 are covered. This chapter oversees latest developments, serves as Introduction to the book as well as  presents the case for strengthening CO₂ utilization research in India and makes policy advocacy recommendations. The need for a CCU-Net India is highlighted.

The paper highlights and traces the history of development of the power sector in India with special reference to the unit sizes of thermal turbo-generators which gradually increase from about 30 MW in 1947 to 660 and 800 MW at present. The initial focus has been on capacity addition to meet the demand increase. However, in the last two decades the greater stress was laid on the efficiency aspects of power generation to reduce the specific fuel consumption and consequently the CO₂ reduction. Reference has been made for adoption of CCS technology in our power stations and the pros and cons of the same have been discussed. Recommendations have been made towards the best practices for operation of the supercritical units in most optimal manner. Constructive criticism of the existing philosophical policies of the load dispatch centres has been made. Suggestions are also made to improve the situation. The action plan for climate change is referred to in connection with the strategy to adopt the supercritical technology in the overall improvement of the sector.

Despite the fact that India has taken a giant leap forward in increasing the installed capacity from a mere 1367 MW in beginning of Independence era to over 303,100 MWe in June 2016, the renewable energy sources however contribute merely 14.1% with total capacity of over 42,800 MW. But this contribution has a major social and economic impact on rural and remote area population. The growth of clean energy technologies for mega Power generation, such as the Solar Mega Power under Jawaharlal Nehru Solar Mission, both Solar Thermal and PV, clean coal technologies, CCTs, i.e., supercritical power plants, integrated gasification combined cycle (IGCC), and fluidized bed combustion (FBC) are key to the success of Green Power Mission for India. Carbon capture and sequestration (CCS) is considered as the frontier Green Energy technology. CCS technology is still in the demonstration phase, and it is important that India is not left behind in this area. While there is a considerable amount of work already underway domestically, there may still be a need for research collaborations and knowledge sharing and transfer. Areas of research in CCS include development of new adsorbents, better process integration of capture equipment, and conversion of CO₂ to useful products, among others. The important challenge of energy penalty in CCS being faced worldwide can be met through the use of Concentrated Solar Power (CSP) for supplementing steam for regeneration in a solvent-based post-combustion CO₂ capture in thermal power plants. Low Carbon Technologies (LCT) and carbon capture and sequestration (CCS) are key factors for energy security and environmental sustainability, and the same are put forward in this chapter leading to an opportunity for course-correction in our thinking in Green Power.

Soils act as a major sink and source of atmospheric CO₂ and therefore have a huge role to play in the carbon capture and storage (CCS) activity. The soils capture and store both organic (through photosynthesis of plants and then top soils as decomposed plant materials and roots) and inorganic carbon (through the formation of pedogenic calcium carbonates). The sequestration of organic and inorganic carbon in soils and its follow-up require basic information of CCS in the soils and their appropriate management techniques. The most prudent approach to estimate the role of soils as source and sink for carbon should require information on the spatial distribution of soil type, soil carbon (soil organic carbon, SOC and soil inorganic carbon, SIC) and the bulk density (BD). To estimate the CCS of soils in spatial domains, we have used the agroclimatic zones (ACZs), bioclimatic systems (BCS) of India and the agro-ecosubregions (AESRs) maps as base maps. These three approaches of land area delineations have been used for various purposes at the national and regional-level planning. We have shown the utility of these maps for prioritizing areas for C sequestration in soils through a set of thematic maps on carbon stock. It will make a dataset for developmental programmes at regional as well as national levels, to address the role of soils in capturing and storing elevated atmospheric CO₂ due to global climate change.

Soil carbon stock and soil CO₂ flux are the major components of carbon budget and carbon cycle in the different terrestrial ecosystems of the world. Soils are the largest carbon reservoirs of the terrestrial carbon cycle. About three times more carbon is contained in soils than in the world’s vegetation and soils hold double the amount of carbon that is present in the atmosphere. Soil can be source or sink of greenhouse gases depending on land use and management. The detailed information on soil carbon stock and soil CO₂ flux and its controlling factors is critical for constraining the ecosystem C-budget and for understanding the response of soils to changing land use and global climate change. Therefore, we examined the soil carbon stock and CO₂ flux in the different terrestrial ecosystems, i.e. forest, bamboo and grasslands of north-east India and its controlling of biotic and abiotic factors. Soil organic carbon was found to be highest in bamboo and followed by grassland and forests whereas reverse trend was observed in rate of soil CO₂ flux which was in the order of forest > grassland > bamboo forest and were influenced by biotic and abiotic factors.

Forest plays a significant role in storage of atmospheric carbon dioxide in plants as well as soil. This paper provides an assessment of the potential of tree growth in different altitudes and its contribution in carbon dioxide sequestration in Pachamalai reserve forest in India. The Pachamalai reserve forest is a part of Eastern Ghats in Tamil Nadu. The amount of biomass and carbon stock was estimated by allometric equation at different altitudes. The results revealed that height and diameter of trees are increasing from lower to higher altitudes. Higher altitude trees attained more height and diameter, especially the trees Tamarindus indica, Ficus benghalensis, Artocarpus heterophyllus, Lepisanthus tetraphyllus, Terminalia paniculata, and Tectona grandis. The presence of total biomass in 15 (10 m × 10 m) quadrats at different altitudes of Pachamalai forest is 1679 tons and it stores 839 tons of carbon. 3081 tCO₂ intake by trees in 15 quadrats, thus indicating that Pachamalai reserved forest had sequestered significant level of carbon dioxide. This study is useful for sustainable management of the Pachamalai reserve forest and can help in reducing the pressure on forest resource while sequestering carbon dioxide from the atmosphere.

Carbon capture storage and utilization (CCSU) can be a probable and efficient solution for mitigating global warming. It refers to the conversion and storage of CO₂ in stable and usable forms. Carbon sequestration using carbonic anhydrase (CA) has attracted much attention in the recent years. Due to high temperature and CO₂ content in flue gas emitted from coal-based thermal plants, the enzyme for CO₂ sequestration must have thermostability, tolerance to high CO₂ and heavy metals, and alkalistability for mineralization. The extremophilic microbial CAs with these attributes would be useful in sequestering CO₂. The production of large quantities of native carbonic anhydrase from wild microbial strains for carbon capture becomes costly because they possess low levels of CA. The cloning CA-encoding genes from extremophiles and their overexpression in heterologous hosts such as E. coli would bring down the cost of enzyme production. Further improvement in the desirable properties of CAs can be achieved through protein engineering approaches. In this chapter, an attempt has been made to review developments in the production of recombinant CAs, their characteristics and applicability in carbon sequestration. Other biotechnological applications of CAs are also briefly discussed.

Carbon dioxide is a waste product in many industries, especially from thermal power plants and is a major contributor to global warming. The large scale solution to the problem of CO₂ emissions currently being considered is carbon capture and storage (CCS). In CCS, the CO₂ is first separated from the flue gas by capture techniques and then later stored underground. This method does not eliminate CO₂; it just stores it. Environmental threats of escape are spurring re-evaluation of CCS to eliminate CO₂ rather than move and store it. A more attractive solution would be carbon capture and utilization (CCU) in which the waste CO₂ is not dumped, but converted into a commercially valuable product. The growing re-evaluation of carbon capture strategies emphasizes transforming CO₂ to valuable chemical rather than storing it. This chapter gives an overview to cover the work carried out on CO₂ from flue gas, and how it could be converted into a valuable chemical for which there is a demand. This article first covers briefly the CO₂ separation or capture from flue gas and storage and then the technologies to convert the separated CO₂ into usable chemicals employing methods, such as chemical, photochemical, electro-chemical and bio-process. The proper use of CO₂ from waste flue gas is expected to provide both environmental and economic benefits.

A promising biological solution for the utilization and conversion of CO₂ from a power plant into viable economic products has been discussed in this study. Algae grow well on a high concentration of carbon dioxide and nitrogen dioxide. These pollutants which are released by automobiles, cement plants, breweries, fertilizer plants, steel plant scan serve as nutrients for the algae growth. The biotechnology of microalgae production can be divided into the following different types as cultivation systems, ponds and Photobioreactorsas closed system with associated harvesting and processing equipment and the wetware as the specific algae species and strains are being cultivated. Algae when used for reducing the carbon dioxide concentration in the atmosphere are known as algae-based Capture technology. The algae-growing facilities when fed with the exhaust gases from these plants to significantly increase the algal productivity and reduce the pollutants from atmosphere. Additionally the oil found in algae can be processed into a biodiesel or green fuel. Additional products from algae includes ethanol and livestock feed. This technology offers a safe and sustainable solution to the problems associated with global warming. The value-added products that can be produced from these four main technologies are biomass with both low and high grade, biomass derived products as pharmaceutical, chemical or nutritional, synthesis gas as methanol, fuel and chemical production, speciality products as extracted using supercritical technology, organic carbonates as linear, cyclic or polycarbonates, carboxylates as formic acid, oxalic acid, etc. along with salicylic acid and urea.

Adsorbents like zeolites, metal-organic materials (MOM), porous polymers, metal oxides, carbonaceous materials (CM) and porous silica, etc. are being investigated for CO₂ capture/storage. Contemporary literature reports highest CO₂ adsorption capacity in MOMs, e.g. MOF-200 and MOF-177 as 54.5 mmol g⁻¹ (at 5 MPa and 298 K) and 33.5 mmol g⁻¹ (at 3.5 MPa and 298 K), respectively; and it is 46.9 mmol g⁻¹ for CM. Noticeable drawbacks, however, are hard to synthesise and expensive; sensitive to moisture; issues with activation, regeneration and recycling of sorbent materials, etc. Ideal material for CCS should be cheaper, robust for recycling, good thermal and structural stability towards moisture. Although the other materials can fulfil some conditions, e.g. recyclable, thermal and structural stability, etc. but their CO₂ adsorption capacity is significantly low. The gas hydrates on the other hand have proven to be useful and economical alternative for gas separation and storage/sequestration. In the present set of experiments, we demonstrate that the CO₂ storage capacity is 29.7 g⁻¹, in hydrates, formed from water trapped in the voids of SiO₂.

India has approximately 0.5% of world’s Oil and Gas reserves and fifth highest coal reserves in the world. Renewables like solar, hydropower and wind are in plenty but considering the state of the technology and commercial issues, renewables can only make a significant contribution to India’s energy basket in the mid- to long term. Most of our power plants are coal-based and power requirements are growing exponentially. Energy analysts believe that in spite of huge coal reserves, India may overtake China and be the world’s highest importer of coal. It is therefore imperative that we start adopting clean coal technology. Carbon dioxide sequestration is one such technology where carbon dioxide emitted in power plants is captured and reinjected into the subsurface either in depleted oil, gas fields or coal seams or even in plain saline aquifers so that it remains entrapped. Carbon dioxide sequestration is also used as a tertiary recovery process to enhance recovery factor in discovered oil fields, both for light and heavy oil. USA, Canada and Brazil are champions in enhanced oil recovery projects through carbon sequestration with more than hundreds of projects worldwide. Sequestration in saline aquifers is relatively new and besides USA and Canada, South Africa has commenced a pilot project. Algeria is also exploring feasibility of using depleted gas fields for sequestration. Porosity, permeability, volume of reservoir and seal are the critical parameters for success of sequestration in a saline reservoir. China is the first country in Asia to take up sequestration in saline aquifers and is carrying out research and modelling work in a large scale to ensure technical feasibility. Enhanced coal-based methane production through carbon dioxide sequestration is an area of active global research. Coal rocks have higher affinity for carbon dioxide; hence methane is displaced increasing its mobility. Coal-based methane production is however low at present. This paper describes carbon dioxide utilization challenges for enhanced oil recovery, sequestration in saline aquifers and the success in Iceland on storing carbon dioxide within basalts. Reservoir modelling and simulation studies on the specific host reservoir rock have to be carried out before large volumes of carbon dioxide can be reinjected and stored in the subsurface.

Enhancing coalbed methane recovery through injection of CO₂ in depleted low pressure coal reservoir is a potential, economic and environmentally suitable solution to reduce greenhouse gas emissions. In India, commercial coalbed methane (CBM) production has been started since 2007 at Raniganj and Sohagpur basins and subsequently to Jharia and Bokaro coalfields. CBM reservoirs are at low pressure, and after some years of production through primary reduction of hydrostatic pressure, rate of recovery declines and harms the well economics. In a secondary drive, the CO₂ or CO₂ + N₂ or other mixture of gases can be injected to enhance the methane recovery and to maintain reservoir pressure. Studies conducted so far support stronger affinity of CO₂ to the coal molecule, displacing each methane molecule by 2–3 molecules of CO₂. Coal may adsorb more carbon dioxide than methane and that carbon dioxide is preferentially adsorbed onto the coal structure over methane (with 2:1 ratio). High-pressure methane and CO₂ sorption measurements were carried out for various coal seams in India. On the basis of CO₂ sorption capacity, seam thickness and extension, the suitable sites and their storage capacities estimated to be 4459 Mt for CO₂. It is assumed that this quantity of storage is sufficient to store over 20% of total gas emission from the present power plants over their lifetime. The sites close to the operating thermal power units may be the most appropriate for CO₂ sequestration as the transportation cost of the gas will be minimum. The rate of CO₂ generation and total CO₂ generated within the life span of a thermal power station presuming 20 years more from the date will be helpful for enhanced coalbed methane (ECBM) process in the close vicinity of CBM blocks. It is also required that geologic data and experimentally determined mineralization reaction rates and kinetics should be incorporated into geochemical models to predict the permanent storage of CO₂ in unmineable deep coals after ECBM recovery.

In spite of aggressive development of renewable energy alternatives, the continued use of fossil fuels will remain essential to national economic development for India and other emerging economies. India is ideally positioned to provide a practical demonstration of a suite of technologies that allows the continued use of indigenous resources while substantially limiting conventional and greenhouse gas pollutants. This suite of technologies employs oxy-combustion-based carbon capture systems fitted to a coal-fired power plant coupled with the injection of by-product gases for enhanced coalbed methane recovery. India has coal resources that currently provide an attractive domestic source of methane through conventional coalbed methane recovery techniques. Recent research concludes that enhanced recovery techniques using CO₂ and N₂ injection can provide substantial additional methane production. Highly concentrated anthropogenic CO₂ is produced by carbon capture technologies based on oxy-combustion, while supplemental N₂ can be available from the associated oxygen plant. Selling the CO₂ and N₂ that is produced, helps to offset the additional costs of air separation and CO₂ compression and transportation. The CO₂ thus utilized remains permanently stored in the coalbed, reducing net atmospheric emissions of this problematic greenhouse gas. The Jupiter Oxygen integrated oxy-combustion technology is uniquely suited to reduce costs associated with conventional pollutant removal and carbon capture. Combined with enhanced coalbed methane recovery, it offers a pathway to advance the national development agendas of coal dependent countries.

Aluminium plays an important part in the development of a country as it has diverse range of applications and utilities. A global warming and greenhouse gases have become key issues for aluminium industry and the industry has committed itself to reduce emissions of greenhouse effect gases in coming years. The CO₂ equivalent per tonne of aluminium can be reduced by lowering the emission of perfluorocarbon (PFC) arising from anode effects and by reducing the energy consumption. Carbon footprint of aluminium industry has been illustrated and sources of carbon emissions have been explained in the paper. Carbon neutrality can be achieved by implementing several R&D measures and enhanced usage of aluminium in various sectors.

Microalgae with its numerous applications such as food, dietary supplement, fuels, and materials in environmental biotechnology are being regarded as a priority area for further investigations. National Aluminum Company (NALCO) in India uses coal as source of energy in aluminum production. A pilot project was undertaken by NALCO for carbon capture and storage by using microalgae in their captive power plant at Angul in Orissa. The production of microalgae using industrial emissions enhances the carbon sequestration in addition to the economic benefits of algal cultivation. The algal biomass while being processed for high-value extractives generates the residual biomass as the process waste and needs to be utilized effectively; preferably for renewable fuel or material applications. This paper provides an exclusive comparative evaluation of biomass generation of about 2 tons/year and application for possible types of bioenergy potentials with the carbon sequestered as carbon sink. The important criteria and factors reported are useful for further study on comparative lifecycle analysis.

Carbon dioxide is the major greenhouse gas in the environment. Its largest contributor is fossil fuel based industries and among them steel industry holds one of the vital positions. In view of global climate change agreements, there are efforts to reduce CO₂ emission by development of suitable technologies. In last decades, various technologies have been developed to separate CO₂ from the flue gas of power and industrial plants by using chemical or physical absorption, adsorption, cryogenic methods, membrane systems and biological fixation, etc. This paper elaborates on the aspects of different carbon capture processes and sequestration technologies developed and adopted by steel industries. In many cases, pilot scale studies have been completed successfully and are ready for implementation. Though, further development and fine tuning is required for commercialization of such processes.

Cement is a ubiquitous building material in the developing and the developed world due to its flexibility of production and use. Despite being a relatively sustainable material, the large quantities of cement produced make it one of the biggest contributors to CO₂ emissions. The cement industry has been tackling this issue through the improvement of production technologies and higher replacements using supplementary cementitious materials. New cements that have lower specific emissions and those that consume CO₂ are also being developed. Still, the projections of the growth of the cement industry indicate that carbon capture and storage will be important for meeting the emission reduction targets set by the industry.

Carbon dioxide (CO₂) emission from stationary point sources connected to combustion facilities using fossil fuels in addition to other industrial sources is adversely affecting the climate on earth. Thus capturing CO₂ from the combustion sources followed by its safe stabilization or storage constitutes an important target. Legion of researches have so far been undertaken to develop absorbents, adsorbents, and membranes to remove CO₂ from combustion facilities. Capturing CO₂ from the post-combustion flue gas by the chemical absorption method using aqueous ammonia (NH₃) has been given serious attention by the researchers considering the advantages of high CO₂ capture efficiency, ease of operation, and lower investment cost. Life cycle CO₂ emission analysis revealed that capturing CO₂ from the exhaust of flue gas of a coal-fired thermal power plant (TPP) using aqueous NH₃ could be a plausible option. The possible solid reaction products of aqueous NH₃ based multipollutant capture of the flue gas from the TPP targeting for CO₂ capture would be ammonium sulfate [(NH₄)₂SO₄], ammonium nitrate [NH₄NO₃], and ammonium bicarbonate [NH₄HCO₃]. These products have the potential to serve as N-fertilizer. In this communication, the present status of investigations on the aqueous NH₃ based CO₂ capture process is analyzed gathering information from the existing literatures. Given the tremendous scope of research in India, the current national research potential could be gainfully utilized for envisaging the CO₂ capture by aqueous NH₃ in coal-fired TPP. In this regard, multisectoral research programs could be proposed in a planned manner for making use of the available resources in the country with the coordinated approach of few important streams such as academia, thermal power, fertilizer, agriculture, environment, and climate change. Recommendations are made for development of suitable CO₂ capture technology in Indian coal-fired TPPs.