Under the sea

In early July, Alberta’s government announced billions of dollars in funding for carbon sequestration, potentially trapping the province’s millions of tonnes of annual greenhouse emissions in abandoned oil wells or coal seams (4.9 MB PDF). One of the dangers in these kinds of projects, some say, is that the gas could leak, causing a disastrous dispersion of oxygen (“outgassing”) and, therefore, suffocating any animals or humans nearby. Sequestration projects’ costs, often government subsidized, are also a bone of contention.

But for landlocked prairie province like Alberta, there’s nowhere to go but into the ground when it comes to burying emissions. Likewise, most research money is currently being directed toward land-based storage. But for those with access to the ocean the options could go much, much deeper.

Researchers at Columbia University’s Lamont-Doherty Earth Observatory have published a paper titled “Carbon dioxide sequestration in deep-sea basalt” (1.6 MB PDF) suggesting that porous volcanic rocks off the coast of Vancouver Island could be used to contain gigatonnes of greenhouse gas, enough to offset almost 150 years of US CO2 emissions. These formations of basalt, 2,700 metres below sea level and about 160 kilometres away from shore, would be able to absorb the gas in their pores, eventually forming “solid carbonate.” Any gas not absorbed by the rock, say the researchers, would simply remain contained below water, which is lighter than the gas.

Unlike land-based sequestration, the undersea storage proposed in the paper still just conceptual. The paper notes that the next step would be a pilot project to test injection and the resulting effects on the surrounding water, as well as the viability of transporting billions of tonnes of CO2 out into the ocean. But as places like Alberta begin to look at storing their greenhouse gas emissions, often plugging emissions back into the same sites that produced the fuel releasing them, the sea may eventually be an attractive alternative.