Giant carbon storage bag on ocean floor might help to cut global emissions

Washington, Feb 19 : Researchers are pondering over the idea of a gigantic, inflatable, sausage-shaped bag, resting on the seabed of an ocean, which would be capable of storing 160 million tones of carbon dioxide, thus capturing almost 2.2 days of current global emissions.

One of the researchers who finds the idea feasible is from Dr. David Keith, an expert on carbon capture and sequestration.

Though the original idea of ocean storage was conceived several years ago by Dr. Michael Pilson, a chemical oceanographer at the University of Rhode Island, it really took off last year when Keith confirmed its feasibility with Dr. Andrew Palmer, an ocean engineer at Cambridge University.

According to Keith, this seemingly impossible idea for carbon storage solution can serve as a potentially useful complement to CO2 storage in geological formations, particularly for CO2 emanating from sources near deep oceans.

It may offer a viable solution because vast flat plains cover huge areas of the deep oceans. These abyssal plains have little life and are benign environments.

"If you stay away from the steep slopes from the continental shelves, they are a very quiet environment," said Keith.

For CO2 to be stored there, the gas must be captured from power and industrial point sources, compressed to liquid, and transported via pipelines that extend well beyond the ocean's continental shelves.

When the liquid CO2 is pumped into the deep ocean, the intense pressure and cold temperatures make it negatively buoyant.

"This negative buoyancy is the key," explained Keith. "It means the CO2 wants to leak downwards rather than moving up to the biosphere," he added.

The use of containment is necessary because CO2 will tend to dissolve in the ocean, which could adversely impact marine ecosystems.

"Fortunately, the cost of containment is quite minimal with this solution," said Keith.

He and his colleagues have calculated that the bags can be constructed of existing polymers for less than four cents per tonne of carbon.

The real costs lie in the capture of CO2 and its transport to the deep ocean.

"If we can drive those down, then ocean storage might be an important option for reducing CO2 emissions," said Keith.

ANI