For 60 years, these two blights have brooded over the region even as more life-affirming activities like farming and recreation have expanded. Today, the area's population centers on the Tri-Cities - Richland, Pasco and Kennewick - which cluster where the Columbia River, flowing down from the north and skirting nuclear wasteland, swallows the Snake and Yakima rivers before taking a sharp westward turn to become the border between Washington and Oregon.
At one point, the Department of Energy considered injecting its millions of gallons of liquid nuclear waste deep into the Columbia basalt. During the search for an appropriate injection site, hundreds of core samples were drilled and archived. Those core samples have come in very handy for Pete McGrail as he conducts studies that may lead to another industrial use for an already hard-used land.
Regardless of geology, proper carbon sequestration requires a chamber or system of interconnected pores to accept an infusion of carbon dioxide, as well as a competent caprock above it, to keep the CO2 from escaping. Spent oil and gas formations and saline aquifers contained in sedimentary rock have usually been considered the most likely candidates for geosequestration; experts frequently point out that oil and gas have been safely held for millions of years in such formations.
The Columbia basalt is volcanic, rather than sedimentary, rock. But based on the Energy Department's core samples of the area and other research, McGrail believes the Columbia group has real sequestration potential.
Lava oozing out of a fissure can contain high volumes of trapped gas, such as sulfur dioxide and CO2. These gases will push toward the top of the flow to escape. As the lava begins to set, some of the gas is trapped in bubbles, which form the pores or vesicles that are the targets of CO2 injection. The more bubbles, the more surface area is available for the CO2 to make contact with basalt's minerals. The cylindrical cores McGrail has studied are about three inches in diameter and clearly show the boundaries between lava flows, interrupted periodically by thinner, small-grained layers from non-eruptive periods, when windblown soil, volcanic ash, and other materials drifted across the landscape.
Because the Columbia basalt is made up of many separate flows, it has numerous alternating porous and dense layers. McGrail thinks the former can absorb and transform large amounts of CO2 and the latter can serve as an effective caprock, aided by the occasional sedimentary layer that lies in between.
CO2 and basalt have attributes whose combination could be a marriage made in heaven. At depths below around 3,000 feet, CO2 becomes supercritical - that is, it turns into a liquid slightly less dense and much runnier than water. Injection pressure and the weight of the earth above it will force the CO2 to dissolve in groundwater residing in aquifers and distributed throughout the small cracks and holes in porous sections of basalt. As anyone familiar with Perrier can attest, dissolved CO2 makes water fizzy; this sparkling, mildly acidic "pore water" reacts with minerals in the basalt, principally calcium, and eventually breaks up CO2 molecules, sequestering their carbon in solid deposits of calcium carbonate, also known as limestone. Over long time periods, further reactions convert the available elements into even more stable types of rock, such as olivine.
When McGrail first started working on basalt sequestration, he thought it a wacky idea. Experience has since changed his mind, but other experts still question the details.
David Keith, a professor of chemical and petroleum engineering and economics at the University of Calgary, says bluntly, "I don't think (basalt) is that important. Saline (aquifer) capacity is gigantic. I think (basalt) doesn't matter for a long time. We're not going to run short for half a century even if we do this at a huge scale."
George Peridas, a science fellow with the Natural Resources Defense Council, supports geosequestration in general, saying that "with rigorous regulatory controls, we are confident that sequestration can work very well without endangering health or the environment." He thinks McGrail's research worthwhile, although he's not ready to treat it as "a high confidence scenario." Peridas is concerned that the columnar joins and other crack networks that allow CO2 to travel into porous areas of the basalt will also allow it to come back out. Monitoring may also be a problem. For example, Peridas says, when seismic signals are used to determine underground structures, "in the data you get back it's hard to distinguish between the CO2 and the rock itself."
Nick Riley, a geosequestration researcher for the British Geological Survey, says, "My take on this is that the (chemical) reactions are too slow. I also think it will be difficult to get the rock to receive the CO2 at the rates required." But McGrail has reason to differ. In unpublished lab experiments currently being prepared for peer review, McGrail and his team put small amounts of basalt into a vessel with CO2, heating and pressurizing the samples to levels representing conditions deep underground. The carbonate minerals, he says, formed in "weeks to months."
"We really did not expect this," McGrail says. "It was pretty close to serendipity."
Such rapid transformation is orders of magnitude faster than the rate of similar reactions in sedimentary rocks, which can take tens to thousands of years to fix injected carbon dioxide into solids. Since the trick is to keep the liquid CO2 buried long enough for the chain of chemical reactions to immobilize it, basalt's processing speed is one of its strongest assets in the carbon sequestration race.
A 2005 Intergovernmental Panel on Climate Change report on geosequestration estimates that the world's deep saline formations could handle over a trillion tons of CO2. The Columbia basalt, however, may only be able to absorb a hundred billion tons, and McGrail has an even more conservative estimate of 20-50 billion tons. Fossil fuel emissions are putting about 26 billion tons of CO2 into the atmosphere every year, and the figure is rising. So if the Columbia basalt were the planet's sole repository of captured CO2, it would likely fill up in a couple of years.
Still, McGrail points out, the Columbia basalt could hold centuries' worth of the CO2 produced in the region. The Northwest's long dependence on hydropower has made it a minor source of greenhouse gases so far. But the area's power mix is likely to change as population and power demand grow, and the region may have to one day rely on basalt sequestration, because it has relatively few saline aquifers or spent gas and oil wells for CO2 storage.
McGrail's work is part of the Big Sky Carbon Sequestration Partnership, a consortium led by Montana State University and drawing on researchers from all three of Idaho's universities, the U.S. Department of Energy's Idaho National Laboratory near Idaho Falls, and Battelle. The DOE and several private companies have given $17.9 million to the Big Sky partnership, which covers the eastern halves of Washington and Oregon, Idaho, Montana, Wyoming and South Dakota and is one of six regional programs covering the whole country. A map of the entire Big Sky region shows only 21 major industrial sources of CO2 within the Columbia basalt. But the area is surrounded by more than 100 major sources. And because the economics of energy and sequestration discourage long-range transport of CO2, the Columbia Plain may wind up hosting many new coal-fired power plants, sited there specifically to be close to sequestration opportunities.
(There may, of course, be state-to-state variations in permitting. Oregon "is opposed to [new] coal plants" for several reasons, including their release of mercury to the environment, says Dirk Dunning, an environmental engineer with the Oregon Department of Energy. John Stormon, a Washington Department of Ecology hydrogeologist, says that under new legislation, Washington will accept coal plants provided they "address and reduce their CO2 emissions.")
McGrail says he is unaware of any specific plans to build energy facilities that would sequester CO2 in basalt, but he does concede that geosequestration "will dramatically change the siting picture" for energy production. Electricity from coal-fired, CO2-sequestering plants in the Columbia basalt region could feed the power grid throughout the Western United States. Once again, it seems, the Northwest's massive intermountain desert may become the waste receptacle for interests beyond its borders. On the other hand, assuming the unintended consequences of basalt sequestration remain minor, the region is likely to benefit from the resulting jobs and economic growth.
But we're a long way from knowing how CO2 will behave in actual basalt formations, a state of ignorance that will be reduced by the outcome of McGrail's field test.