Indian Ocean, Bay of Bengal may serve as potential carbon storage sinks

IIT Madras researchers have identified the Indian Ocean and the Bay of Bengal as potential storage sinks for huge amount of carbon dioxide (CO2) that can be stored there permanently “in the form of liquid pools or solid hydrates beyond a certain depth” without harming the marine ecology — a move that can be an effective way to decarbonise India’s industrial clusters and help the country reach its 2070 net-zero goal.

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.

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.

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.