Cement Manufacturers Association (CMA)

46 chemistry today. • Microalgae-based Carbon Capture: One of the greatest potentials of carbon sequestration by biological systems is well understood and natural process of photosynthesis mechanism the photosynthesis of algae which reduces carbon in the gas stream by converting it to biomass which can be carried out either by open pond or closed bioreactor system in presence of light. A controlled closed bioreactor with higher capacity will be more successful than the Open Pond system for cement flue gas. • Oxy combustion capture: There is no real capture of CO 2 . The fossil fuel itself is burnt in an oxygen-rich environment thus allowing for cleaner and fuller combustion of fossil fuels greatly reducing CO 2 and SO2 gases. The process doesn’t involve any membranes or absorbents and is thus significantly cost-effective for new plants but the cost increases if old plants are retrofitted. Some studies conclude that the overall cost of carbon capture is less in oxy- combustion capture. Another advantage is that almost pure 90% CO 2 can be directly compressed and stored without the need for any further purification. The challenges of this technology are primarily related to retrofitting an old plant which is caused by high temperature during combustion and air that leaks into the system. These factors negatively affect performance. Decarbonisation of Indian Cement Industry Several technologies are available and have been proposed for the separation of CO 2 from the flue gas from new and existing plants with retrofit capture units. Out of many few CO 2 capture technologies relevant to Indian cement plants, are suitable technology like oxy-combustion, biotic (algal) sequestration, amine-based absorption, and adsorbent- It is the only process that is industrially employed. Post-combustion capture is widely researched, and experimented with the adaptable method with various technology being used, a few of them is discussed below: • Solvent Waste Absorption: Amongst solvent-based post-combustion carbon capture (PCC), amine-based solvents are widely used. Monoethanolamide (MEA) is most widely used for its high CO 2 reactivity and high capture efficiency. • Adsorption-driven: Adsorption is a process of CO 2 capture by making it interact with a solid (Molecular sieves or Activated carbon or Chemical adsorbents) such as modifying low-cost carbons using Polyethyleneimine. In the last few decades, ionic solvents have had better adjournment than the other media. Ionic liquid provides several advantages over the other methods due to easy regeneration, low solvent loss and low environmental impact. • Membrane Separation: Membrane technology provides a promising pathway for sustainable CO 2 capture because of its unique features such as high energy efficiency, low ecological footprint, low capital and operational costs, and easy scalability. The potential advantage associated with membranes makes them attractive for CO 2 capture. • Mineralisation: The process of mineralisation is mineral carbonation where CO 2 is converted into stable carbonates for their storage, especially in areas that lack suitable geological formations. It is also a process of storage as opposed to the others that deal with only carbon capture and is more environmentally friendly than geologic sequestration. • Cryogenic Capture: Metal-organic framework (MOF) cryogenic capture involves lowering the temperature of flue gas. MOFs are the fastest-growing class of materials in