Carbon capture and storage technology seeks to reduce atmospheric concentrations of carbon dioxide from coal-burning power plants.
Scientific data correlating concentrated levels of greenhouse gases in the atmosphere to climate change precipitated the landmark Kyoto Protocol, which defined the framework for industrialized nations to curtail greenhouse gas emissions and provided a scheme of cap-and-trade. Carbon dioxide is a greenhouse gas released in abundance by coal-fired power plants that supply 50 percent of U.S. energy needs. This stark reality has motivated research into technologies aimed at capturing and storing carbon to mitigate its impact on global warming and climate change.
How Carbon Capture and Storage Works
Coal-burning power plants emit carbon dioxide and other pollutants during the combustion cycle. Newer Integrated Gasification Combined Cycle plants can effectively reduce carbon dioxide emissions. In an IGCC plant, coal is first gasified and converted into a synthetic gas to fuel a combustion turbine that drives an electrical generator. Extracting carbon dioxide, mercury and sulfur from the mixture refines the "syn" gas. In the second stage of the combined cycle, waste heat is utilized to power a steam generator to further increase electrical output. It is estimated that IGCC plants can eliminate 85 percent of carbon emissions through this method. Retrofitting existing power plants for carbon capture is more costly than IGCC, but can be achieved using pulverized coal and a chilled ammonia or amine technique to scrub carbon from stack gases. Carbon dioxide extracted by either method is compressed into a liquid under high pressure and injected into geologic repositories deep underground beneath impregnable cap rock, where it is sequestered.
DOE Carbon Capture and Storage Simulaton Initiative
In 2010, U.S. Energy Secretary, Steven Chu, announced $40 million in carbon capture and storage research grants. The target goal is a production-scale deployment of the technology within eight to ten years. Stimulus funds from the American Recovery and Reinvestment Act will underwrite the program, officially known as the Carbon Capture and Storage Simulation Initiative. Key to success is research to develop effective simulation models necessary to achieve economic feasibility. The initiative will further leverage the U.S. Department of Energy's National Risk Assessment Partnership program to create safe methods for long-term carbon dioxide storage.
Ameren Power Plant CCS Retrofit
A 200-megawatt power plant in Illinois became the recipient of a $1 billion grant in stimulus funds from the Obama administration in 2010, announced by Energy Secretary, Steven Chu, and Senator Dick Durbin. The grant money is being directed to demonstrate the feasibility of retrofitting the coal-fired Ameren plant with carbon-capture technology. Dubbed, FutureGen 2.0, the project replaces an earlier program to build a brand new clean-coal power plant from scratch and includes the construction of a new series of pipelines to transport captured carbon to a storage depot in Mattoon, Illinois.
ADM Carbon Storage Facility Grant
The Archer Daniels Midland Company was awarded a $99.2 million grant by the U.S. Department of Energy towards the cost of its $163.9 carbon sequestration facility in Decatur, Illinois. The facility is being designed with an annual capacity to capture one million tons of carbon dioxide from its ethanol operations for storage 7,000 feet underground. ADM will rely on research conducted by the Illinois State Geological Survey to determine if the natural geology of the Mount Simon Sandstone region can safely facilitate large-scale storage.
Carbon Storage Risks
The future of carbon capture and storage appears bright, yet assessment of the technology would be incomplete without addressing its potential risks and action plans to manage those risks. Key hazards identified by the Lawrence Berkeley National Laboratory are accidental leakage of carbon dioxide from pipelines and geological storage in potentially lethal concentrations to humans and animals, contamination of groundwater and underground fuel supplies and stress fractures in rock formations leading to seismic events due to the high injection pressures used.
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