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Fast-paced industrialization, accompanied by the indiscriminate burning of fossil fuels, has led to excessive emission of greenhouse gases over the past two centuries, resulting in the  global warming being witnessed today[1]. According to the U.S. Environmental Protection Agency (USEPA), the total emission of greenhouse gases in the US alone during the year 2017 was 6,457 Million Metric Tons of Carbon di oxide (CO2) equivalent, as shown in Figure 1.  As per the Intergovernmental Panel on Climate Change (IPCC), such emissions have to be reduced by 50 to 80% by the year 2050[2].

Overview of Green House Gas emissions in 2019

Figure 1. Overview of Green House Gas emissions in 2019(Source)

Carbon emissions can be controlled by using Carbon Capture and Storage (CCS) technologies, which involve capturing and transporting the CO2, and securely storing it underground in depleted oil and gas fields or deep saline aquifer formations. According to the American Bureau of Shipping (ABS), carbon capture utilization and storage (CCUS) is a process wherein CO2 can be captured, cleaned, dehydrated, liquefied, transported and stored at a final location or utilised[3]. The capture technologies selectively pull CO2 gas, either before the fuel is burnt (Pre-combustion) or from the flue gas after fuel combustion (post-combustion), or from oxyfuel combustion systems, and store it underground[4] for reuse in industry, agriculture or energy production. In order to isolate the CO2 from the fuel/flue gas stream prior to transportation, a number of technologies such as absorption using monoethanolamine (MEA), diethanolamine (DEA) and potassium carbonate, adsorption on molecular sieves, activated carbon, zeolites, calcium oxides, hydrotalcites and lithium zirconate, chemical looping combustion, membrane separation, hydrate-based separation and cryogenic distillation have been explored[5]. Recently, the U.S. Department of Energy’s Office of Fossil Energy announced a funding of  $131 million for the research and development of CCUS projects [6].


CCS is the process of capturing almost 90% of the CO2 emitted during the burning of fossil fuels for electricity generation or industrial processes, followed by transporting it by pipeline or ship for safe and permanent storage several kilometres below the earth’s surface. CCU differs from CCS in that in CCU, instead of permanent geological storage, the captured CO2 is converted into valuable commercial products ranging from plastics and concrete to reactants for various chemical synthesis. CO2 utilization technologies such as enhanced oil recovery (EOR) are already successfully commercialized and others are at various stages of development[7].

comparison between sequestration and utilization of captured co2

Figure 2. Comparison between sequestration and utilization of captured CO2 (Source)


The main utilization of captured carbon has been demonstrated in enhanced oil/gas recovery, chemical conversion, electricity generation, and in desalination as shown in Figure 3[8].

various carbon-utilization pathways

Figure 3. Various carbon-utilization pathways (Source)

Enhanced oil recovery (EOR): CO2-based EOR was first employed in the early 1970s in the US, and it is expected that in future, EOR will increase oil recovery from approximately 30% to 60% [9].

co2 enhanced oil recovery

Figure 4.  CO2 Enhanced Oil Recovery (Source)

Gas injection offers advantages such as reduction of oil viscosity and addition of pressure in the reservoir, which facilitates oil production. Until 2019, there were approximately 30 EOR projects in the Asia-Pacific region, with China leading the chemical injection segment, which was expected to reduce crude oil import by 202210. Vicki Hollub, President and CEO of Occidental Petroleum Corporation, recently cajoled the big banks for more investment in EOR technology11. Abu Dhabi National Oil Company, in association with Japan’s largest upstream company Inpex, the largest power generation company JERA, and Japan Oil, Gas and Metals National Corporation, has planned to explore the feasibility of producing NH3 with a reduced carbon footprint from natural gas-derived H2. Most of the CO2 emitted from the production of NH3 is to be sequestered and utilized in EOR operations at Abu Dhabi onshore oil fields[12]. Japanese power producer J-Power and US oil services provider Schlumberger have planned to jointly improve EOR technique by using CO2 coming out from their joint coal gasification process with an aim of reducing CO2 from power plants by 20% before 2030 and net-zero emissions by 2050[13]. Norway’s €1.7 billion project named “Project Longship” aims to sequester 1.25 billion tonnes of CO2 and bury the same under the North Sea[14]. In a joint venture, Hyundai Oil Bank Co. of Korea signed an agreement with Saudi Aramco, whereby it will take liquefied petroleum gas cargoes from Saudi Aramco and convert it into hydrogen (H2) and send the CO2 gas, a by-product of hydrogen making process to Saudi, which will be used to pump more oil out of the ground[15]. Having seen the success of utilizing captured CO2 in EOR, investment in this area is rising. Denbury, a US oil producer, and Kinder Morgan, an energy infrastructure company that operates pipelines and terminals, have invested in CCUS; whereas new players such as EnLink Midstream (ENLC) are reported to be entering this market[16]. Some companies like Gas Liquids Engineering Ltd have also come up with new carbon capture engineering processes to be utilised in EOR[17].

Chemical Conversion of CO2: Studies show that use of CO2 in mineral carbonation can reduce global warming potential (GWP) by 4–48%. Using CO2 for production of dimethylcarbonate (DMC) reduces the GWP by 4.3 times and ozone layer depletion by 13 times as compared to conventional processes[18]. Encouraged by the cost-effective conversion of flue gas CO2 into carbonate-based building aggregates, Chevron has planned to invest in Blue Planet Systems Corporation, a start-up that manufactures coarse and fine carbonate aggregate from sequestered CO2[19]. It has been predicted that CO2 utilization in building materials through the production of aggregates that can be mixed with cement or injected directly into wet concrete for curing, will reach 86% of the total market value by 2040[20]. Carbon8 Systems, a UK-based company is about to run its first Energy from Waste (EfW) pilot project in the Netherlands, which will produce high value, lightweight construction aggregates suitable for concrete applications, by combining industrial waste residues with captured CO2 emissions[21]. Carbon8 Systems is part of The South Wales Industrial Cluster (SWIC); which is a partnership between industry, energy suppliers, infrastructure providers, academia, legal sector, service providers and public sector organisations; and has been awarded GBP 1.5M from UKRI’s (UK Research and Innovation) Industrial Decarbonisation Programme to map what is needed to support South Wales in becoming a net-zero carbon region by 205022. Australia’s Mineral Carbonation International (MCi) has planned to lock away 1 billion tonnes of CO2 by 2040 through the transformation of CO2 into building materials and other value-added industrial products. When dissolved CO2 reacts with the minerals in rocks, it produces carbonates that are stable over a long period of time and is therefore suitable for construction. Using this technology, cement bricks and plaster boards are being built every day at MCi’s pilot plant in Newcastle, Australia23. Attempts have been made to synthesize cyclic carbonates from atmospheric CO2 by the scientists of Tomsk Polytechnic University (TPU) in collaboration with scientists from Czech Republic, wherein the researchers could produce carbonates at room temperature with the help of sunlight, for use as electrolytes in lithium-ion batteries, and green solvents for pharmaceutical drug manufacturing[24]. The steel industry is one of the biggest producers of  CO2 and it was found that every ton of steel produced in 2018 emitted on average 1.85 tons of CO2, which is equivalent to about 8% of global CO2 emissions. The steel industry is facing a decarbonization challenge across the globe, especially in Europe[25]. Cyclic utilization of emitted CO2 in “basic oxygen furnace (BOF)–Rheinsahl Heraeus (RH) steelmaking process” was found to reduce dust generation and endpoint nitrogen content, increase dephosphorization rate and remove inclusions, thus benefitting the process of dehydrogenation[26]. Eni, the Italian oil and gas company, tried to produce polymers, particularly polycarbonates, using CO2 as a reactant or convert it to methane for use in the chemical industry as an intermediary or directly as a fuel[27]. In order to reduce the emissions of CO2, the University of Illinois at Chicago (UIC) has developed a technology for producing ethylene using captured CO2, to make polyethylene, which Braskem, the largest polyolefin producer in the Americas, will assist in scaling-up[28]. Electrochemical reduction of CO2 to form ethylene has been introduced by Dr. Yun-Jeong Hwang and her team at the Clean Energy Research Centre of the Korea Institute of Science and Technology (KIST). Using infrared spectroscopy, ethylene intermediate (OCCO) has been synthesized from CO2 on the surface of copper-based catalysts, resulting in the production of methane and ethylene,[29] as shown in Figure 5.

real-time analysis of catalytic surface in the process of electrochemical carbon

Figure 5. Real-time analysis of catalytic surface in the process of electrochemical carbon (Source)

Conversion of CO2 to formic acid has been accomplished either enzymatically, by using the Formate Hydrogenlyase (FHL) enzyme produced by Escherichia coli, or by using an organic catalyst developed by researchers in Japan.[30], [31]  Formic acid, a feedstock for the synthesis of various chemicals, is also used as a H2 carrier in fuel cells.  Researchers from the Tata Institute of Fundamental Research (TIFR), India, have revealed that Magnesium (Mg) can be used to convert CO2 into methane, methanol, and formic acid. In this case, CO2 reacts with water at room temperature and atmospheric pressure in the presence of Mg[32]. Japan’s Sumitomo Chemical has undertaken a joint research project with Shimane University to synthesize methanol by combining propane dehydrogenation (PDH) technology with another technology that efficiently synthesizes methanol using H2 and CO2. Since this synthesis process requires H2, which is a by-product of PDH technology, the company is considering a possible application of these two technologies wherein both H2 and CO2 can be effectively used, as shown in Figure 6[33].

synthesis of methanol from co2

Figure 6. Synthesis of methanol from CO2 (Source)

Swiss company Proman recently signed an agreement with Global Energy Group, an international energy company, to develop a green methanol production plant at Nigg Oil Terminal at North Sea. The two companies will source CO2 from local industries to power the industrial-scale green methanol plant[34].

CO2 utilization in electrical and electronics arena: A liquid metal catalyst, made up of a gallium alloy and cerium, has been developed to convert CO2 into solid flakes of carbon/coal, which can be buried or utilised for electronic components[35]. Electricity and H2 generation have been accomplished by utilizing the acidity formed by the spontaneous dissolution of CO2 in an aqueous zinc–aluminium–CO2 system36. CO2 sequestration has been done successfully by researchers at the Ulsan National Institute of Science and Technology (UNIST), South Korea. The research team designed a membrane-free (MF) Mg-CO2 battery, as an advanced approach to sequester CO2 emissions for generating electricity and synthesizing value-added chemicals without any harmful by-products. It has also been found that the new battery exhibits high faradaic efficiency of 92% [37]. MIT researchers are working on the electrochemical conversion of CO2 and development of Lithium-CO2 battery. Very high-capacity batteries with significant discharge voltages have been produced by developing a novel electrolyte where amine is incorporated into the DMSO-based electrolyte along with the lithium salt and CO2 [38]. Researchers from Northwestern University have also attempted to develop a method wherein long range vehicles such as ships and cargos can store concentrated CO2 on board by using CO2-capturing solid oxide fuel cells, and the concentrated CO2 can be sequestered and recycled into renewable hydrocarbon fuel[39].

Algal cultivation: The prospect of algal cultivation using CO2 captured from coal fired power plants, the extraction of algal oil by solvent extraction process for pharmaceutical sector, and the conversion of residual oil to biodiesel have been studied[40]. Keeping in mind the same, the US Department of Energy (DOE) Office of Fossil Energy (FE) recently announced $8 million in federal funding to utilize CO2 from power systems or other industrial sources by algal systems to create valuable products and services[41]. Although Shell, Chevron and Exxonmobil had initially started working on algal biofuel, considering its bright future as a renewable source of energy, Chevron and Shell dropped out later due to its higher production cost. Currently, only Exxonmobil is actively pursuing its dream on algal biofuel[42].

Making Fuel and other additives: Gas-Switching Reforming (GSR) with integrated CO2 capture has been designed for pure H2 and syngas production[43], [44]. Solar power can convert CO2 into chemicals that can be used as fuel. In this technology from Linköping University, Sweden, a photoelectrode covered with a layer of graphene captures solar energy and creates charge carriers that can convert CO2 and water into methane, carbon monoxide, and formic acid[45]. Currently, CO2 conversion into fuels, for the most part, requires H2, which is expensive and highly energy-intensive. Scientists are trying to develop alternate routes of developing chemicals from CO2. One such example is Ethyl levulinate, an alternative biofuel and biofuel additive, that has been produced by the reaction of CO2 with 1, 4 butanediol[46].

Electrolysis and Desalination: Chemical engineers at the University of Illinois have developed a new electrolysis technology wherein a stream of CO2 gas moves through the electrolysis cell and breaks down into molecules such as ethylene. This process reduces the energy consumption of the waste-to-value process by 53% [47]. Another approach was to develop an ion exchange desalination (HAIX-Desal) process where CO2 at 10 atm pressure acts as the sole source of energy and chemical regenerant as shown in Figure 7. The desalination process does not require any semipermeable membrane and can desalinate lean brackish water (TDS ≤ 1500 mg/L)[48].

hybrid ion exchange desalination (hix-desal) using pressurized co2

Figure 7. Hybrid Ion Exchange Desalination (HIX-Desal) using pressurized CO2 (Source)

Another utilization of captured CO2 is the production of  chemicals such as  NaHCO3 when CO2 reacts with concentrated brine wastes after desalination. It is a feasible way of reducing environmental pollution caused by the disposal of concentrated brine into surface water bodies, particularly in places dependent on desalination for potable water49, as shown in Figure 8.

co2 utilization combined with desalinated reject brine

Figure 8. CO2 utilization combined with desalinated reject brine (Source)

Although research on the best posible ways of utilization of captured carbon is very much in progress, CCU is still considered a poorly explored area. The costs incurred in capture and utilization steps are still high50.


saudi aramcoIn 2019, Saudi Aramco developed the Converge Polyol technology to produce high-performance polyols wherein waste CO2 combines with hydrocarbon feedstock. Propylene oxide, on polymerization in the presence of a proprietary catalyst, produces 100% polypropylene carbonate (PPC), and the resultant polyols are found to have perfect repeating units. The applications of the Converge polyol technology include coatings, adhesives, sealants and elastomers. Converge polyols impart improved abrasion and environmental resistance on coatings, improve bond strength in adhesives, enhance tensile and tear properties when added to elastomers, produce nontoxic by-products in electronic and ceramic industries, and improve both durability and compressive strength in composites51.

heidelbergIn partnership with Calix, an Australian technology company, and a European consortium, Heidelberg cement has planned to build an extension of their LEILAC 1 (Low Emissions Intensity Lime and Cement) technology, named LEILAC 2, for carbon capture at its cement plant in Hanover, Germany. The project is based on Calix’s “calciner technology” and is expected to cost €25 million ($34.2 million U.S.). The goal is to capture 20% of the cement plant’s capacity, or 100,000 tons of CO2 per year. The project is expected to be in operation by 202552.

lotteLotte Chemical of South Korea has started using CCU technology for converting CO2 to polycarbonate, a raw material for the production of dry ice and semiconductor cleaning liquid. The company uses Airrane’s gas separation membranes, which are very fine hollow fibers through which different mixtures of gases are fed in a process called selective permeation. It is an asymmetric filter made of various types of polymer53. Lotte Chemical aims to utilize more than 200,000 tons of CO2 annually by expanding related facilities.

pinonPiñon Midstream has launched its Greenfield Dark Horse Sour Gas Treating and Carbon Capture Facility with an acid gas sequestration well, which will remove both CO2 and hydrogen sulfide (H2S) from the incoming natural gas stream. The pipeline construction is under progress in Lea County, New Mexico. The project has the capability of treating up to 400 million cubic feet of sour gas per day54.

exonmobilExxonmobil has planned to invest $3 billion further on some of its new ventures on carbon capture, or on the expansion of existing CCS projects, upto 2025. Some of the projects include installation of a CCS hub in Singapore, expansion of its La Barge CCS facilities in Wyoming, agreement on a joint project in Porthos (Port of Rotterdam CO2 Transportation Hub) for caputring industrial CO2 and transporting it to North Sea offshore gas fields etc55.


  • Advantage Oil & Gas Ltd. and Allardyce Bower Consulting Ltd. have recently developed CCS technology capable of keeping commercial price of carbon below $50/tonne. This Modular Carbon Capture and Storage (MCCS) technology can be retrofitted to most point-source industrial emissions, including sectors that are difficult to decarbonize such as power generation, blue hydrogen, LNG, oil and gas processing, and manufacture of cement and steel. The modular technology is extremely versatile, applicable to projects as small as 8,000 T CO2/year, allowing decarbonisation to occur in easy financed increments. There is no upper limit to the scalability for larger projects. MCCS recovers approximately 90% of carbon emissions. The first demonstration of the technology will occur at Advantage’s Glacier Gas Plant near Grande Prairie, Alberta, and is expected to enter into service by March 202256.
  • An MOU was signed between China Huaneng Group Clean Energy Research Institute and Carbon Capture Transport and Storage Company of Glencore on CCUS technology, at the 6th China International Conference on CO2 Capture Utilization and Storage57. With the CTSCo Project in Millmerran power station in Australia, the collaboration will be implemented.
  • With the aim of utilization of carbon for concrete production in the U.S. Gulf Coast, CarbonCure Technologies Inc. announced a collaboration with Airgas, an Air Liquide company. In CarbonCure’s technology, CO₂ is injected into concrete from the refineries of industrial emitters when the CO₂ becomes mineralized, enhancing the strength of the concrete. Airgas will supply CO₂ to concrete producers and will preserve the environment by reducing atmospheric CO₂ emissions58.
  • Chevron has invested in Blue Planet Systems, a start-up manufacturing carbonate-based building aggregates from captured CO2, with the goal of reducing the carbon impact of industrial operations. Blue Planet uses Direct Air Capture (DAC) technologies to concentrate and remove CO2 from the air. The company then creates a chemical reaction to convert the COinto limestone, which is a building block of concrete. Subsequently, Blue Planet sells the aggregate to be used in concrete mixes, which is used in a number of projects. One such project is the San Francisco International Airport interim boarding area B. Blue Planet Systems has also partnered with Sulzer Chemtech on the venture59,60.
  • Carbon Free, a company specializing in SkyCycle technology in which carbon is mineralized using calcium and magnesium salts to produce precipitated calcium carbonate and synthetic limestone, signed a memorandum of understanding with Tetra Technologies Inc. under which it plans to use each other’s technical expertise, chemistry knowledge and production facilities to jointly improve the commercialization of SkyCycle™61


climeworksClimeworks is a Swiss Company specializing in CO2 capture technology. Climework’s machines consist of modular CO₂ collectors that can be stacked to build machines of any size. The machines are powered solely with renewable energy or energy-from-waste. First, air is drawn into the collector with a fan. CO₂ is captured on the surface of a highly selective filter material that sits inside the collectors. Once the filter material is filled with CO₂, the collector is closed. The temperature is then increased between 80 and 100°C to release the CO₂. Finally, the high-purity, high-concentration CO₂ is collected. The filter can be reused many times and may last for several thousand cycles62.

solidiaSolidia is a cement and concrete company having concrete curing technology with CO2 instead of water. The CO2 reacts with cement to make calcium carbonate and silica, which harden the structure to form concrete. Solidia’s technology has been found to be efficient for the removal of 1.5 gigatonnes of CO2 from atmosphere; which saves 3 trillion litres of fresh water, reduces energy consumption by 260 million oil barrels, and eliminates 100 million tonnes of concrete landfill 63, 64.

LanzaTech‘s carbon recycling technology helps make new products from CO₂ in industrial off-gases, syngas, reformed biogas etc. Lanzatech is hopeful that from the emissions of a steel plant, it could make aviation fuel as well as chemicals such as synthetic fibers, plastics and rubbers called CarbonSmart™ products needed for the body and cabin of the aircraft. The company has been able to generate ethanol from the waste gases of factories using rabbit-gut bacteria. The customised Clostridium microbes would capture carbon monoxide, converting it into ethanol that can be used to run cars and aeroplanes. More recently, in partnership with the Energy Department’s Argonne National Laboratory (ANL), LanzaTech has been selected to build and operate a pre-pilot facility to produce sustainable aviation fuel (SAF), made from biogenic waste carbon dioxide (CO2) such as is emitted from corn refining, and renewable H265, 66.


Figure 9. LanzaTech’s innovation in recycling carbon waste (Source)

lactrolystThe goal of Lectrolyst is to convet CO2 and make valuable chemicals and fuels. With the help of tandem electro-chemical reactors, the scientists carried out a two-step process of transforming  CO2 as shown in Figure 10 67, 68.


Figure 10. Greenhouse gases to products (Lectrolyst) (Source)

The CO2 electroreduction process is divided into separate processes to improve the selectivity towards more complex high-value products.


  • LanzaTech’s patent EP3058080B1 titled Process of carbon capture in gas fermentation discloses that in presence of a bacterial culture consisting of carboxydotrophic Clostridium autoethanogenum or Clostridium ljungdahlii, gaseous substrate comprising CO, H2 and CO2 gets fermented and a portion of the CO2 is converted into products such as ethanol, acetic acid or acetate, 2,3-butanediol, butanol, isopropanol, lactate, succinate, methyl ethyl ketone (MEK) etc.
  • Saudi Aramco’s membrane based approach on CO2 capture and utilization has been disclosed in US20170191173A1. An apparatus has been developed that comprises of an anode chamber and a cathode chamber, separated by a cation exchange membrane; an aqueous solution containing an alkali metal salt or an alkaline earth metal salt is supplied to the anode chamber; CO2 and a capturing solution such as NH3 solution in the cathode chamber; a voltage of 2 V to 10 V is applied such that the cations get separated from the aqueous solution containing the alkali metal or alkaline earth metal salt and move toward the cathode chamber through the cation exchange membrane resulting in the formation of Carbonate salt.
  • Saudi Arabian Oil Company’s patent US20190168417A1 describes a vehicle comprising a concrete mixer vehicle and a vehicle exhaust capture system onboard the concrete mixer vehicle. The mixer tank in the concrete mixer vehicle containing an uncured cementitious material mixes with a portion of CO2 emission generated by the concrete mixer vehicle, carbonizing the uncured cementitious material into CaCO3. The vehicle exhaust capture system uses carbon capturing structures such as amines, carbonate, ammonia, hydroxide, activated carbons, zeolites, metal organic frameworks, mesoporous structures, carbon capture filters, fibers, microporous structures etc.


While carbon that is captured is only 0.1% of total emissions, it needs to be increased 100 times to meet the global goals set for 2050. CCU being a more sustainable solution, wherein CO2 is being recycled to create valuable products such as fuels, building materials, value-added chemicals etc., huge investments are being made by companies across the globe to make fuels or value-added chemicals from CO2. Compact modular CCU units are being built to facilitate easy transportation and simple installation. Governments are committed to reduce global warming and are supporting the initiatives of industries. While Australia is the current leader in CCUS technology, with the highest production of zero or low-carbon building materials, other countries too are expected to join the race.







































































  • This document has been created for educational and instructional purposes only
  • Copyrighted materials used have been specifically acknowledged
  • We claim the right of fair use as ascertained by the author


Dr. Baisali Sarkar
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