Undersea volcanic rocks offer vast repository for greenhouse gas, says study

A group of scientists has used deep ocean-floor drilling and experiments to show that volcanic rocks off the West Coast and elsewhere might be used to securely imprison huge amounts of globe-warming carbon dioxide captured from power plants or other sources. In particular, they say that natural chemical reactions under 78,000 square kilometers (30,000 square miles) of ocean floor off California, Oregon, Washington and British Columbia could lock in as much as 150 years of U.S. CO2 production. The findings are published today in the Proceedings of the National Academy of Sciences.

Interest in so-called carbon sequestration is growing worldwide. However, no large-scale projects are yet off the ground, and other geological settings could be problematic. For instance, the petroleum industry has been pumping CO2 into voids left by old oil wells on a small scale, but some fear that these might eventually leak, putting gas back into the air and possibly endangering people nearby.

Lead author David Goldberg, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory, called the study "the first good evidence that this kind of carbon burial is feasible."

"We are convinced that the sub-ocean floor is a significant part of the solution to the global climate problem," said Goldberg. "Basalt reservoirs are understudied. They are immense, accessible and well sealed--a huge prize in the search for viable options." One of the main advantages, he said, is a chemical process between basalt and pumped-in CO2 that would convert the carbon into a solid mineral.

In their paper, Goldberg and his colleagues Taro Takahashi and Angela Slagle used previous deep-ocean drilling studies of the Juan de Fuca plate, some 100 miles off the Pacific coast, to chart a vast basalt formation that they say could be suitable for such pumping. Basalt, the basic stuff of the ocean floors, is hardened lava erupted from undersea fissures and volcanoes. In this region, much of it lies under some 2,700 meters (8,850 feet) of water, and 200 meters (650 feet) or more of overlying fine-grained sediment. Drilling by the Integrated Ocean Drilling Program has shown the rock is honeycombed with watery channels and pores that would provide room for pressurized CO2. The scientists have mapped out specific areas that they say are isolated from earthquakes, hydrothermal vents or other factors that might upset the system.

Ongoing experiments by Lamont scientists on land have shown that when CO2 is combined with basalt, the gas and components of the rock naturally react to create a solid carbonate—basically, chalk. Later this year, a separate team headed by Lamont geochemist Juerg Matter will begin pumping CO2 into a landbound basalt formation at a power plant near Reykjavik, Iceland—the first such large-scale demonstration. Basalts lie at or near the surfaces of other land areas including the northeast United States; the Caribbean; north and south Africa; and southeast Asia.

Goldberg says that undersea basalts, which are widespread, may be bigger, and better, than ones on land. At the depths studied, any CO2 that does not react with the rock will be heavier than seawater, and thus unable to rise. And in places like the Juan de Fuca, even if some did escape the rock, it would hit the overlying impermeable cap of clayey sediment.

Skeptics point out that getting the CO2 to such sites could be expensive and tricky. But Goldberg says the West Coast formations should be close enough to the land for delivery by pipelines or tankers. He called on government to study the details of how the idea might work, and whether it would be economically feasible. The United States currently spends about $40 million a year studying carbon sequestration, but nearly all of that goes to land-based research. "Forty million is about the opening-day box office for Finding Nemo," said Goldberg. We need policy change now, to energize research beyond our coastlines."

Source: The Earth Institute at Columbia University

Related stories:

Scientists Test 'Artificial Upwelling' to Learn More About Complex Ocean Ecosystem Behavior
(PhysOrg.com) -- A team of scientists is studying the complex ocean upwelling process by mimicking nature – pumping cold, nutrient-rich water from deep within the Pacific Ocean and releasing it into surface waters near Hawaii that lack the nitrogen and phosphorous necessary to support high biological production.
Climate change target may lead to 'dangerously misguided' policies
The pledge from G8 countries to cut global emissions by 50 per cent by 2050, in an effort to cut global warming to 2ºC, could lead to ‘dangerously misguided’ climate change adaptation policies, according to new research from The University of Manchester.
Viruses are hidden drivers of ocean's nutrient cycle
Scientists on Wednesday said they had discovered deep-sea viruses to be an unexpectedly potent driver of the so-called carbon cycle that sustains oceanic life and helps dampen global warming.
Why is Greenland covered in ice?
There have been many reports in the media about the effects of global warming on the Greenland ice-sheet, but there is still great uncertainty as to why there is an ice-sheet there at all.
Arctic sea ice drops to 2nd lowest level on record
(AP) -- Arctic Ocean sea ice has melted to the second lowest minimum since satellite observations began, according to scientists at the National Snow and Ice Data Center. Sea ice melt recorded on Monday exceeded the low recorded in 2005, which had held second place.
Carmakers falling short on EU emissions targets: report
Car makers are not doing enough to meet proposed EU targets for cutting carbon dioxide emissions, according to a report Tuesday, with some German and Japanese brands facing the biggest challenge to make the grade.
'Clock ticking' on global warming: UN climate chief
Time is running out in the fight against global warming, the UN's top climate change official warned as a new round of UN talks got started here Thursday.
Cockroach King reigns as pest-killers discuss climate change
More than 100 of Southeast Asia's hardiest bugs measured up this week in Bangkok, where experts met to discuss new ways of controlling the pests, which they say are a major contributor to global warming.

News discussion:

Space & Earth science news