Quiz: What You Don't Know About Carbon Capture
Illustration by Joe Zeff, National Geographic
You've heard about carbon capture and storage, but how much do you really know about the developing technology that seeks to reduce the greenhouse gas emissions of fossil fuels?
All of the following geological formations are viewed as potential sites for long-term storage of carbon dioxide EXCEPT:
- Deep saline aquifers
- Water table aquifers
- Unmineable coal seams
- Oil and gas reservoirs
Researchers see deep saline aquifers, unmineable coal seams and depleted oil and gas reservoirs as prime storage locations. But safe CO2 storage must be designed to avoid pollution of drinking water sources like shallow aquifers.
About how much of the flue gas leaving a coal-fired power plant is CO2?
- 2 percent
- 12 percent
- 20 percent
- 50 percent
About 10 to 15 percent of the flue gas is CO2. Capturing CO2 post-combustion (in the flue) requires the technology to separate it from a mixture that is 75 percent nitrogen; 8 to 10 percent water; and small amounts of oxygen, sulfur, and other contaminants like mercury.
CO2 also could be captured before combustion, avoiding the issue of separating CO2 from flue gas. What additional pre-combustion step does this require?
The current technology for pre-combustion carbon capture involves gasifying the fuel source, such as coal, by applying heat under pressure in the presence of steam and oxygen.
The physical and chemical absorption of CO2 can be achieved with all of the following EXCEPT:
- Cryogenic techniques
There are many techniques for capturing carbon, including solvents, cryogenic techniques, solid sorbents and membranes, but water alone won’t do the job.
Norwegian oil company Statoil’s Sleipner project in the North Sea is considered the world’s first demonstration of carbon capture and underground storage. When was it started?
Started in 1996, the Sleipner project sequesters about 1 million tons of CO2 per year in a saline formation 2,600 feet (800 meters) below the seabed. The CO2 occurs naturally in the natural gas produced at Sleipner, and must be removed before the fuel can be sold.
In the view of the International Energy Agency (IEA), what is the advantage that renewable energy has over carbon capture and storage technology in the greenhouse gas solutions marketplace as of 2012?
- It is a cleaner solution.
- There are more feasible locations for deployment.
- It can generate revenue.
- The technology is mature.
The IEA noted in a 2012 report that unlike renewable energy, carbon capture does not generate revenue unless there is a carbon price or a commercial market for captured CO2.
The Intergovernmental Panel on Climate Change estimated the world’s geological formations have a technical potential for how much storage of CO2, at current emissions rates from fossil fuel sources?
- About one year’s worth.
- About 10 years’ worth.
- About 30 years’ worth.
- About 60 years’ worth.
IPCC estimates about 2,000 billion metric tons (or gigatons) technical storage capacity. That’s about 60 times the current fossil fuel-related CO2 emissions, estimated at 35 billion metric tons in 2010.
For which kind of plant would the costs be the highest for adding carbon capture technology, according to a study by Massachusetts Institute of Technology researchers, supported by the U.S. government?
- Natural gas plants
- Pulverized coal plants
- Coal plants with integrated gasification
At combined cycle natural gas facilities, which are considered the most efficient electricity generation plants, the cost of adding carbon capture is the highest, because the concentration of carbon dioxide in the flue stack is so low—about 3 percent.
The British government in 2011 cancelled its first carbon capture project, a long-planned £1 billion facility at Longannet, in Fife. Costs were cited as a primary concern, but what was the other technical difficulty that the U.K. energy secretary raised about the plan?
- The efficiency of the carbon absorption system selected for the plant.
- The length of the pipeline needed to carry the CO2 to the North Sea oil fields for burial.
- The height of the smokestacks that would tower over the Fife coast.
- The stability of the underground reservoirs into which the CO2 would be buried.
U.K. Energy Secretary Chris Huhne blamed problems with the length of pipeline needed. Longannet is the U.K.’s second largest coal plant, and one of the nation’s biggest carbon polluters.
What will be the impact on the costs of climate change, if carbon capture and storage technology does not reach commercial viability, in the view of Sir Nicholas Stern, who is known for his analysis of climate change economics?
- It will be 50 percent cheaper to address climate change without CCS.
- It will be 10 percent cheaper to address climate change without CCS.
- The cost of mitigating climate change will increase 10 percent without CCS.
- The cost of mitigating climate change will increase 50 percent without CCS.
Stern has said a clear benefit of CCS is that the cost of mitigating climate change will be 10 percent higher by 2050 if CCS does not achieve commercial viability. He has called for stronger policy to develop the technology.
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