Watchdog Report: About Revisions to the New Source Performance Standards for National Gas Turbines

The U.S. Environmental Protection Agency (EPA) earlier this month published a final rule that revises the New Source Performance Standards (NSPS) for natural gas-fired stationary combustion turbines. 

Such turbines are ubiquitous, including in southwestern Pennsylvania. 

They generate electricity at power plants (and, increasingly, data centers) and drive heavy mechanical equipment at industrial facilities (including natural gas compressor stations).

The NSPS are emission standards for new, modified, and reconstructed sources that apply nationwide and ensure that the pollution controls on such sources are (more or less) up to date when they are installed. 

Emission rates established by an NSPS are to be based on the use of the “best system of emission reduction” (BSER, remember that acronym!) as determined by EPA. 

The revisions to the NSPS for natural gas-fired stationary combustion turbines that were published last week are codified as Subpart KKKKa; they revise Subpart KKKK, which had been in effect since 2006.

Subpart KKKKa garnered an unusual amount of press coverage for an NSPS revision, even before it was published in final form. Why, you wonder? Because when EPA promulgated Subpart KKKKa it stated that it would not attempt to monetize any claimed health benefits from the reductions in emissions of oxides of nitrogen (NO_x), fine particulate matter (PM_2.5), and sulfur dioxide (SO₂) that will result from the revised standards as part of the impact analysis that it performed for the revisions. 

EPA failure to do so in this instance appeared to be a break from long-standing practice that endangers the health protections provided by the Clean Air Act. 

You can read about the issue in the New York Times, on NPR, and in the Associated Press.  On the other hand, EPA claimed that its decision not to include health benefits in its impact analysis is justified because estimates of such benefits are too speculative to serve as a basis for rulemaking under the Act. 

It bears mention that a 1973 decision by a federal Court of Appeals established that EPA is not required to perform a cost-benefit analysis when it promulgates or revises an NSPS.

What caught our interest about the articles covering Subpart KKKKa were their suggestions and claims that Subpart KKKKa’s revisions weakened emission standards for natural gas-fired stationary combustion turbines. 

It is rare for a revised NSPS to weaken emission standards.

And what we learned was that those suggestions and claims were – mostly – not true.

In fact, for most categories of natural gas-fired stationary combustion turbines Subpart KKKKa either retains existing NO_X emission limits or decreases them.  Notably, in establishing Subpart KKKKa’s emission limits, EPA determined that BSER for new, large, high-utilization turbines required the use of selective catalytic reduction (SCR); forcing the operators of turbines to install and operate SCR has been a longstanding goal of environmentalists. 

However, EPA rejected the notion that SCR was BSER for all other categories of turbines, based on either technical infeasibility (SCR often cannot be added on to modified turbines and is not as effective for turbines that do not operate in a steady state) or high cost per ton of NO_X emissions that SCR would be able to remove. 

For those other categories, EPA determined that BSER is combustion controls, based on NO_X emission rates guaranteed by the manufacturers of new turbines or the manufacturers of commercially available add-on combustion controls (for modified turbines). 

And so, what’s the result? This chart compares allowable NO_X emission limits under the old Subpart KKKK and new Subpart KKKKa and shows how NO_X emission limits for some categories of turbine decrease under Subpart KKKKa.

These decreases are notwithstanding EPA’s failures to credit the health benefits from projected emissions reductions under the revised rule and to require more than one category of turbine to use SCR:

Subpart KKKK NOX Emission Limit for Categories of Natural Gas-Fired Turbines (expressed in parts per million)	Subpart KKKKa NOX Emission Limit for Categories of Natural-Gas Fired Turbines(expressed in parts per million)
New/Large…………………………………15	New/Large/High Utilization………………..5
	New/Large/Low Utilization/High Efficiency…………………………………25
	New/Large/Low Utilization/Low Efficiency…………………………………..9
New/Medium………………………………25	New/Medium/High Utilization…………...15
	New/Medium/Low Utilization……………25
New/Small/Electric Generating……………42	New/Small………………………………...25
New/Small/Mechanical Drive…….………100
Modified/Large…………………………….15	Modified/Large/High Efficiency……….25
	Modified/Large/Low Efficiency………….15
Modified/Medium………………………….42	Modified/Medium……………………...…42
Modified/Small……………………………150	Modified/Small………………………….150

The new, higher limits on NO_X emissions from new and modified large high-efficiency turbines allowed under Subpart KKKKa and in boldface above are based on EPA’s finding that the “only commercially available combustion controls” for such turbines are guaranteed at 25 parts per million NO_X by their manufacturers. 

“How much credence does that finding deserve?” asked GASP’s Senior Attorney, John Baillie, “Not much.”

Baillie noted that in  2005, when Subpart KKKK was still a proposed rule, EPA wrote:

Many manufacturers guarantee NO_X emissions of 15 ppm … for large natural gas-fired turbines, and a few even guarantee NO_X levels at or below 9 ppm….  In addition, we have gathered a number of source tests which confirm that these turbines can achieve these levels without the use of add-on controls. Therefore, this emission limit may be achieved by most large natural gas combustion turbines without the use of add-on controls.

Stay tuned, there is a good chance all this ends up in court and if so, we’ll report on that. Also, we intend to determine just when EPA started quantifying projected health impacts from the emission reductions resulting from new regulations and write about it.