Electric power plant emissions of sulfur dioxide and nitrogen oxides have fallen dramatically during an era when coal-fired generation has been cut nearly in half within the U.S.
It may seem like a “no kidding!” moment, but a new report by the federal Energy Information Administration showed that SO2 and NOx have declined 88 and 76 percent, respectively from 1997 to 2017. During the same period, coal-fired plants went from 50 percent of U.S. electricity generation to 30 percent, while gas-fired power and renewables filled in the gap.
Coal-fired generation produced 1,206 million MWh of electric power last year, 800 million MWh less than in 1997, according to the EIA. During the 20-year period, coal-fired power accounted for 90 percent of S02 emissions and 76 percent of the NOx emitted by power plants.
Yet efficiencies and more technologies made necessary by tighter environmental regulations have pushed down the rate of sulfur and NOx emissions by about 80 percent in coal-fired plants. Altogether, they produced 14.6 pounds of SO2 and 6.4 pounds of NOx per MWh of electricity generation in 1997, but only 2.4 and 1.5 pounds, respectively, in 2017. See a graphic representation of the decline below:
The Clean Air Act Amendments (CAAA) required several regulations that reduced emissions of SO2 and NOx. The Acid Rain Program imposed a cap on emissions of SO2 and NOx from coal and residual-fuel oil-fired power plants starting in 1995.
The main compliance approach by electric generators for Mercury and Air Toxics Standards (MATS), with an April 2015 initial deadline, was to install flue-gas desulfurization (scrubber) or dry sorbent injection equipment, both of which also remove SO2 and NOx in addition to the targeted air pollutants regulated under MATS.
In 2005, the Clean Air Interstate Rule (CAIR) addressed regional interstate transport of contributors to ground-level ozone (smog) by requiring 27 eastern states to file implementation plans to reduce SO2 and NOX emissions. CAIR was replaced by the Cross-State Air Pollution Rule (CSAPR) in 2015.
The 27 states regulated under CAIR accounted for more than 80 percent of both coal-fired electricity generation and national SO2 and NOx power sector emissions in 1997. The decline in emissions between 1997 and 2017 mostly occurred in these 27 states; Ohio, Pennsylvania, and Indiana saw the greatest decline in SO2 emissions between 1997 and 2017, while Ohio, Indiana, and Kentucky saw the greatest decline in NOx emissions.
Peabody Energy named its Clean Coal Leadership Award winners last week at the POWER-GEN International conference in Orlando. The winners included:
High-Efficiency Low-Emissions Leadership and Innovation
Huaibei Shenergy Power Generation Co., Ltd: The 1,350-megawatt ultra-supercritical coal-fueled generation unit is currently under construction in China with commission targeted for 2020, and is expected to be among the most efficient coal-fueled generating plants in the world.
High-Efficiency and Sustainability Leadership and Innovation
Nabha Power Limited: The 1,400-megawatt powerplant in Rajpura, Punjab achieved the best heat rate and auxiliary power consumption in India’s 660-MW class for FY 2017 – 2018 and has 100 percent dry fly ash utilization and zero liquid discharge.
Carbon Capture and Storage Pioneer
Wyoming Integrated Test Center: The test center is one of the few research and testing facilities at an operating coal-fueled generating plant and offers space for researchers to test CCUS technologies using 20 MW of coal-based flue gas. Additional research looks at taking carbon emissions from flue gas and turning it into a marketable commodity.