U.S. EPA Proposes Stronger Nitrogen Oxide Emission Standards for New Power Plants

The U.S. Environmental Protection Agency has proposed to strengthen standards for nitrogen oxide, or NOX, emissions from new gas-fired power plants, the first update in nearly 20 years. The standards would apply to most new, modified, and reconstructed fossil fuel-fired stationary combustion turbines, lowering exposure to hazardous air pollution for local communities.

Nitrogen oxide emissions have negative health impacts on nearby communities, and contribute to detrimental health effects. The proposed New Source Performance Standards, or NSPS, are built upon combustion controls and selective catalytic reduction, or SCR, a cost efficient and widely utilized additional control technology, which reduces emissions of NOx.

The NSPS for stationary combustion turbines includes standards of performance to limit emissions of NOx and sulfur dioxide, or SO2. EPA last revised the NSPS in 2006. The agency is proposing to retain existing limits for sulfur dioxide as it is well-controlled based on the long-term required use of low-sulfur natural gas and distillate fuels.  NOx emissions have declined by 87 percent between 1995 and 2022, while S02 emissions have dropped by 93 percent, according to the agency.

EPA estimates that the proposed rule will reduce NOx emissions by 198 tons in 2027 and 2,659 tons in 2032. The agency estimates the present value of net benefits to society at up to $340 million, with an equivalent value of up to $46.4 million per year. In order to enhance the NOx performance standards for new stationary combustion turbines, the agency is proposing to determine that combustion controls, in addition to post-combustion SCR, is the best system of emission reduction, or BSER, for most turbines. The agency is also proposing to lower the standard for affected sources based on the application of the BSER and to create more protective standards for new sources that plan to fire or co-fire hydrogen.

The agency will accept comments for 90 days after the proposal is published in the Federal Register.