Ocean Floor Could Be Greenhouse Gas "Dump," Scientists Say

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Under the Sea

Undersea storage is different, House says.

At depths below 8,900 feet (2,700 meters) the pressure is great enough that CO2 is compressed into a liquid that is denser than water. Therefore it can't bubble back to the surface.

But simply putting carbon dioxide on the surface of the seabed would wreak ecological havoc, House explains.

Not only would the carbon dioxide smother life on the ocean floor, but it would also react with seawater to form acid.

House proposes to bypass this problem by injecting the carbon dioxide into sediments below the seabed.

This would take advantage of the unique changes in temperature and pressure found beneath the deep ocean, he says.

About 1,000 feet (300 to 400 meters) deep in the sediment, the Earth is warm enough that the carbon dioxide will no longer be denser than the seawater in the rock's pores.

That's a good thing, House says, because as the gas percolates up through the waterlogged sediment, it will react with seawater to produce a type of ice called a hydrate.

This ice will block the pores in the sediments, House says, creating a cap that keeps additional carbon dioxide from moving upward.

"Enormous" Capacity

The seabed of the U.S.'s territorial waters alone has enough suitable sediments to hold thousands of years' worth of CO2 produced from fossil fuel use, House says.

"The storage capacity is enormous," he said.

The prospects are even greater for a country like Japan, where there are very few depleted gas fields or other land-based options for storing CO2.

"If Japan wanted to do something with their carbon dioxide, this might be their best option," House said.

But the technology would come with a big price tag.

House estimates that it would cost about U.S. $35 to $75 per ton of CO2—about the amount produced by burning two barrels of oil.

At the moment the new idea is a proposal, not a mature technology.

"This is one of those ideas that you have to try out to see if it works," said David Goodstein, vice provost of California Institute of Technology in Pasadena and author of Out of Gas: The End of the Age of Oil.

But that doesn't mean that innovative ideas for getting rid of carbon dioxide aren't important, he says.

"We are doing an uncontrolled experiment on the climate of the only planet we have," Goodstein said, regarding carbon dioxide emissions from fossil fuels. "That is very foolish."

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