Undeniably, ‘Carbon’ is there to stay. We cannot eliminate carbon footprint – it can be reduced. CCUS is one way to reduce the carbon footprint.
CCUS is one obvious way to address the world’s GHG issue and climate change. The required measures to meet climate goals are broadly energy efficiency, renewable energy and Carbon Capture, Utilisation and Storage (CCUS). With increase in CO2 concentration in the atmosphere, climate change poses threat to humanity. Average global temperature over the preindustrial era has already increased by 1.1 deg C. As per IEA estimates, CCUS has potential of reducing CO2 emission by approx. 9%.
CCUS is a group of technologies that prevent CO2 from reaching the atmosphere. The methods and technologies to remove the CO2 from the flue gas and from the atmosphere, is followed by recycling the CO2 for utilisation and determining safe and permanent storage options. With CCUS CO2 is separated from emissions (carbon capture) and can be logged into products (use) or transported and stored safely underground (storage).
CO2 capture technologies are covered 3 major processes such as Pre-Combustion, Oxy-Combustion and Post-Combustion CO2 capture. Pre combustion CO2 capture deals with removal of CO2 from the fuel before combustion such as gasification process, use of solvent. Oxy combustion CO2 captures deals with combustion of primary fuel in oxygen in place of air, producing few gases with high concentration of CO2. In post combustion CO2 capture, it is removed from the few gases resulting from combustion of fossil fuel and separation involves mostly use of solvent to capture CO2.
The various technologies for CO2 captures include Absorption, Adsorption (PSA/ VPSA), Chemical Looping Combustion, Membrane Separation and Cryogenic Process. Technology solution depends on the concentration of CO2, scale and proposed utilisation. Absorption based PCC is most practice option for large scale CCS. There are about 20 commercial CCUS operations worldwide with plans for another 30. Although the application do not have same cost, the cost vary by CO2 source in the range of USD15-25/ t CO2 for industrial processes producing pure CO2 stream and USD40-120/ t CO2 for processes with dilute gas stream.
The captured CO2 is stored with following options:
- Underground geological storage – storages possible in many different geological settings. Best areas are below caprocks, low permeability shale, or salt beds since they physically trap the CO2. It is also stored in oil fields, gas fields, coal seams, saline formation, depleted oil and gas reservoirs.
- Ocean storage – The captured CO2 is compressed and injected deep in the ocean so that it can dissolve in surrounding water and become part of ocean carbon cycle. Could lead to acidification and impact marine biology.
- CO2 utilisation such as EOR (Enhanced Oil Recovery), CO2 mineralisation and conversion to chemicals.
CO2 utilisation opens a window of possibility of recycling carbon through CO2 conversion. Any marketable product obtained from CO2 will have added value and could generate profit in a frame of availability of large volume of CO2. The major pathways are as under:
- Utilisation as feedstock for chemicals – The utilisation of CO2 (conversion to chemicals and other applications) ranges around 200 MT/year
- Conversion of CO2 into fuels – Commensurate with size of problem we intend to address
CO2 utilisation for industrial application includes EOR, Urea yield boosting, beverage carbonation, pharmaceutical processes, food processing, preservation & packaging, and other oil and gas applications. Carbon mineralisation is an emerging approach to remove CO2 from air and/ or store it in the form of carbonate minerals which are thermodynamically stable, environmentally benign and stored for long time. Such carbonates may prove valuable as substitute for raw material in various industries.
Sources: Minutes of COP Meetings, official websites of PSU oil companies (India), and The Ministry of Environment, Forest and Climate Change, Government of India
Citation: This Insight may be cited as InfEneTy ‘Carbon Capture, Utilization and Storage (CCUS)’ 05.09.2022
Tags: Carbon capture; Carbon utilization; Carbon storage; Carbon footprint; Climate change; Clean energy; Renewable energyAbout InfEneTy
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