In efforts to accelerate the development of commercially viable carbon capture and storage methods, the U.S. Department of Energy unveiled a new testing facility last week at the National Carbon Capture Center (NCCC) in Gaston, Alabama.
The Post-Combustion Carbon Capture Center (PC4), part of the larger NCCC established by the DOE in 2009, was commissioned to test and evaluate emerging carbon capture technologies for more cost-effective and energy efficient solutions.
Although employed by the oil and gas industries for years as a means of increasing oil and gas recovery rates, carbon capture technologies have only recently been explored on a larger scale for environmental purposes.
The current goal of carbon capture and storage technology is to reduce the amount of carbon dioxide emitted into the atmosphere through the combustion of fossil fuels, primarily by power plants. In doing so, scientists hope to curb the emission levels of this greenhouse gas significantly enough to mitigate the effects of global warming.
If enough carbon dioxide emitted from the combustion process can be captured and safely stored, scientists believe humans can lower atmospheric levels of CO2.
Existing carbon capture technologies, however, are too expensive and energy intensive to commercially implement.
“The cost of CO2 capture using current technology…is on the order of $150 per ton of carbon – much too high for carbon emissions reduction applications,” according to the DOE.
Furthermore, a cost analysis by SFA Pacific, Inc. showed that the implementation of current CO2 capture methods to an electricity generation process would cause a price increase of 2.5 cents to an average rate of 4 cents/kWh.
In order to develop an economically feasible solution, the testing facilities at the Gaston plant, operated by Southern Company and several partnering energy companies, are working to advance post-combustion carbon capture methods.
This involves trapping carbon dioxide after the fuel source (coal, natural gas, oil) has been combusted. Using an amine solvent, CO2 is absorbed from a stream of flue gases produced by the combustion process.
While the remaining flue gases are released into the atmosphere, the solvent – carrying the dissolved CO2 – travels to another area of the plant where it is then heated, releasing water vapour and leaving a concentrated stream of carbon dioxide.
This gas must then be compressed for transport to an isolated location in the energy intensive process known as carbon storage.
The biggest benefit to using post-combustion carbon capture, as opposed to pre-combustion or oxy-fuel combustion methods, is that this technology can be retrofitted to older power plants. A filter containing the amine solvent, which will absorb the CO2, can be installed in the chimneys and smokestacks of existing plants, rendering costly renovations unnecessary.
The Gaston test center will be evaluating the efficiency of various solvents, different methods of stripping CO2 from the solvents, and several ways to regenerate the solvents for reuse on an 880 MW pulverized coal plant.
“Initial testing at the PC4 began recently when researchers used a solvent called monoethanolamine (MEA) to capture CO2 from a slipstream of flue gas from the plant. To date, the MEA solvent has exceeded the expected 90 percent CO2 capture, and the unit is now in steady operation capturing about 10 tons of CO2 per day. Data from these initial tests will be used as a baseline to evaluate the performance of emerging CO2 capture technologies,” explained the DOE.
The NCCC posits that “clearly, major technology advancements are needed for commercial application of CO2 capture with conventional pulverized coal units,” citing high capital costs, the large footprint required for CO2 capture equipment, numerous operational concerns, and a high energy penalty for CO2 stripping and regeneration of solvents.
With the Obama administration continuing to stand behind clean coal as a viable alternative energy source, however, the DOE has called the plant opening “another step forward” in developing cost-effective solutions for carbon capture and storage methods.
Photo credit: arpa-e.energy.gov/ProgramsProjects/IMPACCT.aspx