Some European countries like Norway and Denmark are currently working on CO2 storage in the North Sea. CO2 capture and sequestration (CCS) is considered an important precursor to achieving global net-zero goals. Its high cost, however, deters countries from moving fast in that direction.
“CO2 sequestration in oceans will be beneficial for India as, according to a conservative estimate, the Bay of Bengal alone can be able to sequestrate several hundred giga tonnes of anthropogenic CO2 in oceans and marine sediments, which is equivalent to several years of total greenhouse gas (GHG) emission emitted by India,” said prof Jitendra Sangwai, department of chemical engineering at IIT Madras, who led the research.

The researchers through their scientific findings, published in several peer-reviewed journals including ACS Energy & Fuels, claimed that the stored carbon dioxide can create an eco-friendly ice-like substance called ‘gas hydrates’, one cubic meter of which can sequester approximately 150-170 cubic meters of CO2 under oceanic conditions beyond 500 meters of sea depth.
Beyond 2800 m sea depth, CO2 can be stored permanently in the form of liquid pools and solid hydrate. Once the CO2 is permanently stored as a gas hydrate, it does not allow for any reemission into the atmosphere owing to the gravitational and hydrate permeability barrier in the subsea sediments.
“There are different ways to sequester CO2 to reduce its impact on the environment. Using the ocean as a CO2 storage sink is an attractive proposition but storing CO2 directly into the ocean at shallow depth can harm marine life. Hence, CO2 needs to be stored permanently in the ocean in the form of liquid pools or solid hydrates beyond a certain depth,” said Yogendra Kumar Mishra, a research scholar at IIT Madras.
Asked about the next move, Mishra said, “IIT Madras is currently engaged in discussions with governmental and industrial entities to explore opportunities for research funding and collaboration for large-scale CO2 sequestration. The primary objective of large-scale CO2 sequestration is to facilitate the transition of carbon-intensive industries, such as power, steel, and other coal-based units, towards carbon neutrality.”
Scientists believe that the carbon capture and sequestration (CCS) technology offers a promising alternative to managing CO2 emissions and helping the world achieve its climate targets.
Since the world’s dependence on fossil fuels will continue for the foreseeable future till it finds the reliable source of energy to completely replace such carbon-emitting fuels, they think there is no other “attractive option” than oceans as it covers 2/3rd the surface of our earth.
Under the Paris Agreement on climate change, over 190 countries unanimously agreed in December 2015 to substantially reduce carbon emissions under countries’ nationally-determined voluntary pledges so that global warming can be restricted to 2 degree Celsius of temperature rise (from 1850-1900 level) by the end of the century. These countries also promised to make efforts to ensure the warming can be limited to 1.5 degree Celsius of rise to save the world from the disastrous consequences of climate change. These promises are, however, not on track and use of fossil fuels continues unabated.
The United Nations Environment Programme (UNEP) in its report last year flagged that the world is on track to produce 110% more fossil fuels (coal, oil, and gas) by 2030 than what the 1.5 degree Celsius warming threshold allows, and 69 per cent more than what it needs to limit the warming to 2 degrees C.
The increase in global production of fossil fuels comes despite 151 national governments having pledged to achieve net-zero emissions, mostly by mid-century. India has promised to do so by 2070 whereas China by 2060. Incidentally, most of the big fossil fuel-producing countries continue to provide significant policy and financial support for its production.
The UNEP report analysed 20 major fossil fuel-producing countries including India, in detail and noted that though the global coal, oil, and gas (key drivers of overall GHG emissions) demand will peak this decade, the countries plan put together would still lead to an increase in global coal production until 2030, and in global oil & gas production until at least 2050.
Under these circumstances, the CCS technology appears to be a solution provided it can be available to countries at affordable cost. Nevertheless, the solutions like massive afforestation drive and conservation of dense forests will always be the most sought after natural option to increase the carbon sink.