A long-running utility-scale pilot capturing CO2 from the flue gas of a 2,120 MW coal fired power plant in Wyoming is succeeding in capturing about a third of the carbon dioxide by mineralizing it in fly ash, according to a report at Energy Prospects.
It is no mere lab test. Dr KJ Reddy, a professor at the University of Wyoming School of Energy Resources, is the pioneer in taking highly alkaline ash from oil shale combustion to a more stable state to be more environmentally friendly, and his pioneering research, published over the last three decades in the Journal of Environmental Quality and the Environmental Science and Technology Journal, laid the groundwork for mineral carbonation studies by other scientists, engineers and researchers. These studies are the basis for Carbon Capture and Storage (CCS) technologies.
His new CCS process (SequesTech) has now run continuously for 7 years in a 2,120 MW coal plant, removing 25 to 30 percent of the CO2 from 300 to 500 standard cubic feet per minute of flue gas with a concentration of 11 to 12.5 percent CO2.
The process sequesters CO2 emissions in fly ash in the smokestacks of coal-fired power plants. Reddy’s three decades of research on speeding up the natural process of CO2 absorption by mineralization is the basis of the development.
He hopes his SequesTech process will be ready for commercial application “within a year or so.” He said the technology is estimated to cost $10 to $12 per ton of mineralized (sequestered) CO2.
“The ash, or fly ash, serves as a sink for the CO2,” Reddy said of his process, which runs flue gas through a fluidized bed reactor containing fly ash captured by a coal plant’s bag houses. “In turn, the CO2 fixes the toxic and heavy metals in the ash. This is a natural process, but very slow. So we needed to figure out how to speed it up.”
Unlike other carbon capture processes being considered, which would require additional energy to isolate, pressurize, transport and inject CO2 deep under ground, this uses no energy, other than to run the fans that blow the flue gas through the reactors. It also binds the carbon, making it safer than sequestration. The fly ash used to sequester the CO2 and other pollutants could also still be used safely in most traditional fly ash applications, such as gypsum.
Reddy’s SequesTech process is also capturing most of the SO2 and 80% of flue gas mercury as well – making this a potential game changer for climate protection – because regardless of how it quibbles over carbon, the coal industry already has to use some means to reduce its mercury and SO2. This kills 3 birds with one stone.
- CCS Demos Grinding to a Halt (cleantechnica.com)
- Energy Dept. spends $106M to put captured CO2 to use (green.venturebeat.com)
- DOE to Award $106M to Six CO2 Conversion Projects; $156M in Matching Private Funding (greencarcongress.com)
- Will the Car of the Future Be Made from Coal Ash? (scientificamerican.com)