Extreme problems call for extreme solutions and, with atmospheric damage on the rise from our ever-increasing CO2 emissions, it’s no wonder scientists and researchers are looking for new and unique ways to sequester this potentially dangerous gas. David Goldberg, director of Borehole Research at Lamont-Doherty Earth Observatory of Colombia University says that he has a solution: put the emissions under the ocean. More specifically, trap the unwanted CO2 in hardened lava erupted from undersea volcanoes and fissures, also known as basalt. 

It’s no joke-there’s even a method to the madness. The process involves pumping liquid CO2 into basalt resting under 8,850 ft. of sea water. To do this, the CO2 is first transported to the ocean floor, then it’s pumped down another 650 ft. or so of sediment. Finally, it’s injected into the open pores of basalt, causing it to dissolve in the sea water and create a chemical reaction. 

Goldberg says the process would simply accelerate the natural weathering that already happens to basalt in the ocean. “The reason we want it to happen is because when the chemical reaction occurs, the result is a chalk, iron, calcium or magnesium carbonate that are filling solids. These are permanent in the sense that they are filling what was open pore space with rock,” he says. 

Research into this reaction occurring on dry land has been going on for years. The difference between land and ocean, says Goldberg and his team of researchers, is that on land it’s still possible for CO2 gas to leak back into the atmosphere after the reaction. This isn’t the case underwater. “Going under the ocean is the particular advantage here,” Goldberg says. “The two biggest advantages are the size of storage and the security.” 

Of course, there are pros and cons to every new experiment, and this case is no different. 

THE PROS

The Juan de Fuca tectonic plate, off the coast of the Pacific Northwest, is where the first sequestration of CO2 could take place. The plate can store up to 150 years worth of U.S. greenhouse gas at today’s levels. That comes out to 1.7 gigatons annually. 

“This is a very attractive piece of the ocean,” Goldberg says, “because it’s very open in terms of inter-crack and open voids within the crust that allow active fluid to flow, so the injection would be easy.”

Security helps too-the operation would have a number of trapping mechanisms that could simultaneously keep the liquid CO2 in place while the chemistry reaction has time to work its magic. 

Basalt, an openly active reservoir, is blanketed by very fine grains of sediments that cover the ocean floor. This is key in the process. 

“We chose the thickness of some 200 meters over an area that we thought would have a good capping safety margin,” Goldberg says. “The sediments will cap the fluids into the basalt and they will remain there as long as necessary to be until the chemical process occurs.”

In the event of a leak through the sediment, Goldberg and his research team are relying on the ocean’s depth and temperature to prevent serious damage from occurring. At greater ocean depths, CO2 liquid is under enough pressure that it becomes denser than sea water. This causes it to sink in the sediment and create another layer, rather than percolate up into the ocean. Secondly, Gerber explains, “If the CO2 percolates up into the cold water, it would form what’s known as a hydrate, where it basically freezes in place and forms little ice crystals. A sponge would absorb the crystals. It’s as secure as anything proposed.” 

THE CONS 

So what are the downsides? The cost of shipping the CO2 to its final ocean destination, in addition to drilling expenses, are unknown at this point of research, but scientists can predict that it’s going to be very expensive. While nearly $40 million is spent in the United States each year on the research of carbon sequestration, almost all of it goes to land-based research. 

“It’s not going to be the easiest, least expensive, simplest approach,” Goldberg admits. “The infrastructure that would need to be built out into the ocean a few hundred miles is not the cheapest way to do it.” 

Although researchers are looking for other areas in oceans all over the world to store the carbon, transportation will remain a big issue until these alternative areas are discovered. Seventy percent of the ocean floor is made up of basalt, after all, but not necessarily the right kind- it may be under too much sediment to reach, too young or too old. 

In spite of this, Goldberg and his team seem to be doing all they can to find the resources needed. “We are looking for areas that have the right nature of basalt areas. There are other ones around the globe. They’re not evenly distributed, but they’re widespread. We are looking into that.”

CARBON SEQUESTRATION ON LAND 

While research of carbon sequestration in the ocean is ongoing, land is and will be a place to store CO2 until the needed finances are available and further tests administered. Much of the other reservoirs that will be used are existing oil and gas wells. These wells will be re-filled with carbon dioxide and what is left will be trapped on land much the same way as in the ocean. The advantage is that these wells, pipelines and reservoirs are already established. 

One disadvantage: A depleted oil and gas area has a lot of wells that don’t have permanent seals, which can and does lead to leaking and other damages. 

“I think if we go this route as a society, the basalt will be needed because the size of the CO2 problem is just so immense,” Goldberg says. “We’ll need all the ideas we’ve got.”