Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=206968
Story Retrieval Date: 8/1/2014 12:46:16 AM CST
FutureGen Alliance is ready to retrofit a coal-fired power plant in Morgan County with carbon capture and storage.
After years of starts and stops, the project is the first of its kind in the country. Carbon capture and storage offer a future for “clean” coal, proponents say. The U.S. Department of Energy is committing $1 billion to the $1.3 billion project.
With the permitting process almost complete, the retrofit is scheduled to begin later this year, according to developers. It includes numerous safeguards to ensure that the risk of carbon dioxide leaks is extremely low.
FutureGen, now on its second life after investors deemed the original project too costly, is projected to capture nearly 90 percent of the 166-megawatt plant’s carbon dioxide emission. Planners reigned in the original price tag by partnering with Ameren Energy Resources to retrofit an existing Ameren power plant in Meredosia.
Once the retrofit is completed in 2015, a pipeline will transmit the captured carbon dioxide to a natural underground storage formation, nearly 30 miles from the actual plant.
“We specifically chose the storage site we have in Morgan County because it has an incredibly low level of seismic activity in that area,” says Ken Humphreys, FutureGen CEO.
A stable geographic location is a key component when deciding to build a plant equipped to use carbon capture and storage, or when deciding to retrofit a pre-existing plant to use carbon capture and storage, like the Morgan County plant.
That’s because carbon capture and storage relies on large, underground geologic formations to store all of this carbon dioxide. The one that FutureGen will use is the Mt. Simon sandstone formation.
Think of these formations as very, very large pockets in the earth, buried deep underground. The pipeline will run across Morgan County and down into a section of the Mt. Simon formation, where it will pump the captured carbon dioxide.
Large slates of naturally occurring, underground shale will act as a top to the subterranean pocket and seal the captured carbon dioxide below.
But environmental concerns remain.
“Not only are we unsure that the carbon dioxide is going to stay underground," but it’s energy intensive to capture, said Ben Schreiber, a representative from Friends of the Earth, an international environmental advocacy group based in Washington, D.C. “You’re burning more coal. It takes energy to capture the carbon dioxide.”
Sally Benson, a research professor in the Department of Energy Resources, part of the School of Earth Sciences at Stanford University, said this extra use of energy to capture the carbon dioxide is known as an energy penalty.
Currently, most electricity producing coal plants are about 40 percent efficient, according to Benson.
“If you put on a carbon capture unit, it goes down to something like 33 or 32 percent,” Benson said. “The hope is that over time, as people gain more experience with capture itself, the energy penalty would go down.”
For those concerned the natural formations would leak, Benson said these methods have been in use for quite some time.
“It’s a well-established technology they’ve been using since the 1970s,” Benson said. “The Mt. Simon formation is actually a really good formation for storing carbon dioxide — it’s been used for storing natural gas.”
She added that Mt. Simon also has an excellent shale seal.
And even if something like a natural disaster were to occur, Humphreys said the chance of this natural carbon dioxide container leaking should be pretty low.
“Catastrophic releases are essentially impossible, because the carbon dioxide is contained nearly a mile underground, and you have overlying shale,” Humphreys said.
He added that there’s also plenty of room down there, so there won’t be an incredible buildup of carbon dioxide any time soon.
There’s at least “a century of storage capacity available” in the basin, Humphreys said, so “the volume of carbon dioxide we’re storing relative to the surrounding geology is very small.”
As far as the pipeline itself goes, Humphreys said it’s engineered in such a way that makes it difficult for leaks to occur very frequently, if at all.
The pipeline is actually composed of two separate pipes: one larger, external pipe, and a smaller, internal pipe.
“The wellbore itself has a steel pipe and it is literally cemented on the outside,” Humphreys said. And then “there’s a small pipe in the center of the larger wellbore and the carbon dioxide is actually contained in that smaller, inner pipe, and it’s injected down into the geology.”
Additionally, filling the space between those inner and outer pipes is another safeguard that will give pipeline monitors a quick heads up if anything goes awry.
“You have saline water, which is under pressure, so that if you ever have a breach in your carbon dioxide injection tubing, which is going down the center, salt water will migrate into that inner tubing as opposed to the carbon dioxide migrating out,” Humphreys said.
So once site monitors notice a change in pressure, carbon dioxide pumping would be shut down by closing valves placed at intervals along the pipeline, making it relatively easy to go to the section of the pipe that’s leaking and make repairs.
Carbon dioxide emitted into the atmosphere as people burn fossil fuels for their cars, power plants, businesses and residences. The greenhouse gas is rising in the atmosphere where it traps heat and is contributing to global warming. FutureGen will test and research plans to make coal plants burn cleaner by collecting and storing carbon dioxide. The U.S. has a wealth of coal reserves.
The concern with a pipeline leak involves a burst of CO2 released at high concentrations. The major leakage concerns would be for workers repairing pipelines, Benson said.
“Carbon dioxide that comes out of a pipe really quickly, it gets really cold,” Benson said. “If there’s any moisture in the air, it freezes. It forms a cloud of carbon dioxide, and if you were right near that cloud, that could be very unsafe,” since, if the air has more than 10 percent carbon dioxide concentration, you could pass out.
Humphreys said the CO2 flow would be cut off to repair a pipeline, however.
Though environmental concerns shouldn’t be taken lightly, Benson emphasized the importance of developing this kind of technology.
“Whereas solar energy is really promising and wind is really promising, it’s going to take a while to have enough of these to provide what we need on a daily basis. It’s a good technology that doesn’t substitute for renewable energy.”