Accelerating Net Zero

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ACCELERATING NET ZERO

hydrate based process. Currently, a large 30 litres demonstration of this

process is operational at IITM which has demonstrated a modular design

for separation of CO2 from a rich gas mixture with reasonable kinetics

which operates in continuous mode like a PSA approach. Talking about

PSA, IITM has done extensive work on carbon dioxide capture using

MoF/ZIF, activated carbon-based adsorbents, Zeolite materials etc. for

adsorption of CO2 rich and CO2 lean gas mixtures. Further, solid materials

which chemically binds to CO2 has also been studied in detail for direct air

capture application. An end to end solution for direct air capture has been

demonstrated and an operational pilot plan exist in the campus.

As discussed above, captured carbon dioxide needs to be either

utilized or sequestrated. CO2 utilization is a very rich research field,

and IITM has developed quiet a number of such processes where at

laboratory scale CO2 to methanol, formic acid, methane and other higher

hydrocarbon through carbon -carbon coupling has been demonstrated.

CO2 utilization processes have difficulty in scale-up and IITM is looking

forward to demonstrate such processes at large scale, however, this

is still on going. However, a significant work on fundamental science

and demonstration of CO2 sequestration demonstrations have been

done at IITM. Carbon dioxide sequestration is defined as storage of

anthropogenic CO2 in geological formations either permanently or for

geologically significant time periods. Depleted oil and gas reservoirs,

saline aquifers, unmineable coal beds and deep-sea beds are geological

formations that can be used for long-term CO2 sequestration. India has a

complex and diverse geology. Much of the geology of present-day India is

a result of volcanic eruptions dating back to prehistoric eras. The Indian

subcontinent is mantled with the remnants of at least five continental

flood basalt provinces that occurred between the middle Proterozoic to

the late Cretaceous-early Tertiary eras. The geographical land area of

India can be divided into three parts: The Deccan Trap (youngest of the

five continental flood basalt provinces), Gondwana and Vindhayan. The

Deccan Trap is acknowledged to be one of the largest volcanic features

on Earth. It presently occupies around half a million square kilometers

of western and central India and southernmost. Such sediments are

also prominently found under the sea-bed and could be a rich source of

CO2 sequestration. An alternative solution exist in the form of injecting

CO2 in either gaseous or liquid form 100-500 m beneath the seabed and

sequester it in the form of clathrate hydrates within the bounds of

the gas hydrate stability zone (GHSZ). CO2 storage in the form of solid

hydrates under the sea-bed is promising, as 1 m3 of CO2 hydrate can store

120–160 m3 of CO2 gas at STP. Studies like, effects of water salinity and

clay on CO2 hydrate formation to comprehend the effect of electrolyte and

capillary effects on the interlayer pores have been studied in laboratory

scale at IIT Madras. These studies have also helped in determining

the appropriate CO2 injection depth for hydrate formation in such

unconsolidated sediments in the deep sea. Further, IITM researchers

have investigated different kinetic promoters with porous silica gel, silica

sand, pumice stone etc. to concluded that certain additives could improve

the efficiency of such sequestration by influencing the induction time and

in improving the degree of hydrate formation. A pilot scale demonstrator

for CO2 sequestration was developed at IIT Madras which is equipped

with mild fracking setup, injection wells (both vertical and horizontal)

for liquid/gaseous CO2 injections. This unit not only the measures the

rate and quantity of CO2 sequestrated at conditions similar to sub-

sea environment, it also could study the stability of sequestered CO2.

Multiple options for efficient CO2 sequestration was demonstrated and It

was also identified that the sequestered CO2 could be stable upto 10-12 oC

rise in sub-sea temperature.

FIGURE 1. Demonstration of a multi-bed reactor for CO2 capture using Gas-Hydrates Formation and Dissociation Cycle

FIGURE 2. Demonstration of point source CO2 capture in a mobile container unit

The Deccan Trap

(youngest of the five

continental flood

basalt provinces),

Gondwana and

Vindhayan. The

Deccan Trap is

acknowledged to be

one of the largest

volcanic features on

Earth. It presently

occupies around

half a million square

kilometers of western

and central India and

southernmost

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