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Does New Source Review Contribute to Dirty Air?

By Larry Hands  

We recently worked with a company to obtain an air permit for a combined-cycle power plant. These combined-cycle plants use gas turbines that are inherently very clean. They are fueled with natural gas, a clean (but expensive) fuel and use dry-low NOx combustors. These pollution-prevention devices result in low oxides of nitrogen (NOx) emissions. In addition, the combined-cycle arrangement is very efficient, resulting in 50 percent more power produced per unit of energy when compared to a traditional coal-fired power plant. This is late 20th century technology, not late 19th century technology. Nevertheless, these turbines still need to compete with the old-technology coal plants.

An emission rate comparison in terms of pounds of emissions produced per megawatt hour of electricity generated (lbs/MWH) is presented below:


New Combined Cycle

Old Coal Fired

NOx, lbs/MWH



SO2, lbs/MWH



Particulate, lbs/MWH






 Under deregulation and “wheeling,” the market sets the price of power. Buyers don’t care whether the power comes from an old coal plant or a clean new plant. If environmental degradation is not included as a cost, a coal plant can generate power for a fraction of the cost of a clean combined-cycle plant.  

In years past, the EPA was concerned about particulate emissions from coal plants, then with sulfur dioxide emissions. Many of these plants have been retrofitted with upgraded control equipment. This year, the EPA wants to regulate these old plants again to limit the amount of NOx emitted.

Rather than adding another layer of bolt ons that commit us to 30 more years of burning coal, doesn’t it make sense to invest in new technology? How do we encourage this new technology? Does New Source Review and Best Available Control Technology (BACT) fit into this? How should regulators use their discretion to interpret BACT? Should they add cost and reduce the viability of this new technology, or should they interpret the regulations to fully take into account the impact of added control? 

Are there significant unintended consequences to adding controls on combined-cycle plants? Are secondary particulate formation, emissions of climate-change gases and additional emissions of biologically available nitrogen important? Is it possible that some existing power producers are using the BACT process to make the cost of combined cycle plants more expensive? By increasing the cost to competitors, are they extending the life of their old plants? Is the EPA being shortsighted to insist on adding controls to this already clean technology, thereby potentially inhibiting the investment in new power plants?

Regulators should make sure that their emission standards are technology enabling. Overly extreme emission standards may unintentionally raise barriers to better environmental quality.