|July 30, 2013|
Is there a fix for global warming under our feet?
|After nearly a decade of preparation, the experiment that started last week near the banks of the Columbia River seems almost anti-climactic.|
Four cylindrical tanks, each containing about 40 tons of carbon dioxide, sit tethered by pipes and tubes to a hole in the ground. There's a faint hum of machinery as a pump forces the liquefied gas down the well and into rocks more than half a mile below the surface.
The setup doesn't look like much, conceded project leader Peter McGrail, of the Pacific Northwest National Laboratory (PNNL). But it represents the first crack at finding out whether the vast basalt deposits of the Columbia Basin might someday serve as a geologic vault to lock up greenhouse gas emissions from power plants and other industrial sources.
"This is the only one in the world," McGrail said earlier this week at the experiment site. "Nobody else has injected (liquefied) CO2 into basalt."
The pumping started July 17 and will continue for about two weeks. The goal is to inject 1,000 tons of carbon dioxide --- about as much as an average coal-fired power plant emits every three hours. Then the well will be capped and monitored for more than year to make sure there's no leakage.
But it's not clear when --- or if --- the approach will ever be applied to help slow the rate of global climate change.
The project was conceived during the mid-2000s, a period McGrail wistfully refers to as the "heady days" of research on methods to capture carbon dioxide and store, or sequester, it underground.
The federal government seemed poised to restrict greenhouse gas emissions. With more than 100 coal-fired power plants on the drawing board in the United States, carbon sequestration appeared to offer a relatively simple way to reduce the amount of carbon dioxide flooding into the atmosphere.
"Those days are long gone," McGrail said with a shrug.
As the experiment finally gets under way, the prospects of federal climate change legislation have dimmed to the point of invisibility. At the same time, hydraulic fracturing of shale deposits in the Rocky Mountains and elsewhere has produced such a bounty of cheap natural gas that most proposed power plants have abandoned dirtier-burning coal in favor of cleaner-burning gas.
"That has dramatically changed the landscape," McGrail said. "The outlook for carbon sequestration isn't very bright at the moment."
Federal funding for carbon-storage research is falling and several utilities have scrapped plans for demonstration projects, said Judi Greenwald, of the Center for Climate and Energy Solutions, a nonpartisan think tank. Two proposed coal-based power plants in Washington that could have incorporated underground carbon storage were both canceled.
"Why would you invest all this money in the technology if you don't have to reduce CO2 emissions?" asked Greenwald.
She testified before the House Energy Subcommittee on Thursday, calling for continued research on carbon storage and tax incentives to encourage companies to adopt a variation on the approach. But the Obama administration's proposed 2014 budget would actually cut funding, Greenwald said.
Not a new idea
The $12 million PNNL project is part of a government-industry consortium called the Big Sky Carbon Sequestration Partnership. Six other regional consortiums across the country are also exploring carbon storage technology.
The idea of pumping carbon dioxide underground isn't new. The oil industry has been doing it for decades to force recalcitrant petroleum out of rocks.
One of North America's biggest carbon storage projects pumps carbon dioxide from a coal gasification plant in North Dakota to oil fields in Saskatchewan, where it is injected into wells to boost production and provide a test bed for storage technology.
Several other sequestration projects are operating around the world, mostly injecting gas into deposits of sandstone --- the same type of fine-grained rock where oil is often found.
The thing that's unique in Washington is basalt, McGrail explained, holding up two cylinders of the dark-colored rock. The Columbia Basin is underlain by layers up to three miles thick, the result of repeated outpourings from volcanic fissures.
One of McGrail's cylinders was shot through with small holes formed as gas bubbled out of the cooling lava millions of years ago. "This is the kind of stuff we're injecting CO2 into," he said. The liquefied gas flows into the pores, displacing groundwater.
The second cylinder was free of pores. "This is what sits on top," McGrail said. Thick layers of the impermeable cap rock act as a natural barrier to prevent carbon dioxide from leaking out.
But laboratory tests at PNNL have also shown that once carbon dioxide diffuses into the porous basalt, it is quickly converted to solid, carbonate minerals, which further lowers the risk of leaks. The main goal of the experiment is to see if the computer modeling and lab tests hold up in the real world.
"There's no substitute for doing a field study," McGrail said.
The best way to verify that the CO2 actually solidifies would be to drill cores from around the test site, something the researchers hope to do if they can scrape up the money.
A PNNL analysis estimated that basalt flows in the Northwest are commodious enough to hold 20 years' worth of U.S. power-plant emissions --- though it's unlikely carbon dioxide would ever be piped here from other parts of the country.
But the results from the Washington experiment will be relevant to basalt deposits elsewhere in the United States and in countries like India, where the growing appetite for energy is fueling a boom in power-plant construction and heat-trapping emissions.
Finding the right site
McGrail and his colleagues originally planned their experiment for 2007, but it wound up taking several years just to find a place to drill. Their first choice was the Hanford site, where the Department of Energy had spent $500 million studying basalt as a possible nuclear-waste repository. But with the current emphasis on cleanup, DOE didn't want the sequestration experiment on-site.
Next, the research project was linked with plans for a coal-gasification plant on property owned by the Port of Walla Walla. But residents objected and the project unraveled.
The experiment eventually found a home in an unlikely spot: On the grounds of the Boise Inc. paper mill at Wallula. The mill doesn't have any plans to capture and store its own carbon emissions, but is interested in tracking and helping advance the research, said spokesman Destry Henderson.
Washington's Ecology Department reviewed the plans and found no reason to be concerned about impacts on water quality, said regional director Grant Pfeifer. The injection zone is far below any wells, and the aquifer in the area is laced with so much iron, fluoride and other chemicals that it's not suitable for drinking or irrigation. The agency is also convinced that there's no chance of a gas leak big enough to be dangerous to people.
Geologists have raised concerns that large-scale carbon injection --- on the order of millions of tons --- could trigger small earthquakes. But the amounts involved in the PNNL experiment are so tiny that's not a worry, McGrail said.
The project is currently injecting about 40 tons of carbon dioxide a day. By the time they're done, the researchers will have gone through 25 of the big white tanks.
For a waste product that everyone wants to get rid of, carbon dioxide is not cheap, McGrail said. The experiment is using food-grade gas --- the type that's bubbled into carbonated beverage --- at a cost of about $100,000.