Abby L. Harvey
GHG Monitor
11/13/2015
New-build coal plants can meet the Environmental Protection Agency’s New Source Performance Standards (NSPS) without the use of carbon capture and storage, the Electric Power Research Institute said in a report this week. “Yes, technology has been identified that would enable new coal power plants to operate so efficiently that a CO2 emission standard of 636 kg/MWh (1400 lb/ MWh) could be met without partial CCS,” the report says. However, EPRI added, “Among all of the options firing sub-bituminous coal considered in EPRI’s analysis … none with potential to meet the standard are commercially available, economically viable, and suitable for broad deployment.”
The NSPS requires that no new-build coal-fired power plant in the U.S. emit more than 1,400 pounds of CO2 per megawatt-hour of gross power produced. “Given the inability of state-of-the-art coal power plants to meet the NSPS, EPA has specified that partial implementation of CCS at future coal plants is the ‘best system of emission reduction’ to be used in achieving a CO2 emission rate at or below 636 kg/ MWh gross (1400 lb/MWh). EPA suggests that the standard could also be met by co-firing natural gas at coal plants,” the report explains.
A state-of-the-art ultra-supercritical (USC) plant on its own could not meet the EPA standard, the report says. “Even with steam temperatures exceeding 800°C (1500°F)—some 200°C (360°F) higher than those currently achievable—USC coal plants based on the conventional Rankine steam-electric cycle alone are not capable of meeting the standard,” according to EPRI. Such a plant running at 1,100 degrees Fahrenheit, a currently achievable level, would emit approximately 1,760 pounds of CO2 per megawatt-hour produced, well above the EPA standard.
However, EPRI found, “USC plants used in high-efficiency combined heat-and-power applications are capable of meeting the standard—but only at sites with ‘thermal hosts’ capable of using large volumes of steam.”
Throughout the report, it becomes clear that while technically achievable, the various ways to the 1,400 lb/MWh limit without CCS are all conditional. “Gasifying coal then firing the synthesis gas in a conventional combined-cycle configuration can meet the standard—but only for certain types of gasifiers, and only when the integrated plant is fueled by high-quality coal.”
Gasification appears to hold the greatest potential, the report suggests. “Assuming further technological progress, coal gasification provides multiple pathways for achieving the standard, including gasifiers integrated with solid oxide fuel cells; with combined cycle plants having firing temperatures for the combustion turbine approaching 1700°C (3100°F); or with novel cycle designs,” EPRI said.
