An emergency action proposed by Maryland regulators on Friday will require 14 coal-fired units in the state to minimize nitrogen oxide (NOx) emissions every day during the 2015 summer ozone season, starting as soon as May 1. 

The rule submitted on April 17 by the Maryland Department of the Environment (MDE) to the Joint Committee on Administrative Executive and Legislative Review (ALER) would become effective as soon as ALER approves it.

It essentially requires that beginning on May 1, for each operating day during the ozone season (which ends on Sept. 30), owners of affected coal-fired power units should minimize NOx emissions by operating or optimizing the use of all installed pollution control technology and combustion controls.

Affected units include Raven Power’s Brandon Shores Units 1 and 2; C.P. Crane Units 1 and 2; and H.A. Wagner Units 2 and 3. They also include NRG Energy’s Chalk Point Units 1 and 2: Dickerson Units 1, 2, and 3; and Morgantown Units 1 and 2; as well as AES Corp.’s Warrior Run generating station.

Generators will also be required to demonstrate compliance with the action using documentation.

In Maryland, an emergency action remains in place for a period of up to 180 days to meet “pressing circumstances.” MDE in December 2014 submitted proposed a rule that would permanently require NOx reductions at coal plants.

The state admits that it has implemented strict rules to tamp down power plant emissions, including the Maryland Healthy Air Act, which it says is “the toughest power plant emissions law on the East Coast.”

That rule was developed to bring the state into attainment with the National Ambient Air Quality Standards for ozone and fine particulate matter by a federal deadline of 2010. It required cuts in NOx, sulfur dioxide, and mercury emissions from large coal plants, but it also required the state to become involved in the Regional Greenhouse Gas Initiative.

MDE acknowledges that power plants in the state have invested $2.5 billion in technology to comply with that rule.

It said in a statement on April 17, however, that its proposed emergency action is required because one or two days a year, two out of 20 air quality monitors in the monitoring network statewide are reading ozone values that exceed the current standard.

“Those monitors are in Cecil County and Prince George’s County, and they represent about 10% of Maryland’s population. Maryland has had no Code Red air quality days for ozone in either of the past two summers,” it said.

The state added that the reductions expected from the emergency action will allow Maryland to attain and maintain compliance with the current health-based federal standard for ozone pollution. “However,” it said, “continued reductions are necessary because the EPA is expected to propose a new, more stringent ozone standard this year. Maryland continues to seek emission reductions to ensure that progress made is not lost as the State begins the process of meeting the pending, more stringent standard.”

Meanwhile, the state will continue to collaborate with more than 25 states to reduce power plant emissions that cross state lines and cause ozone pollution. “About 70 percent of Maryland’s ozone pollution originates in upwind states,” it said.

Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)