Maryland Department of the E

Michael Woodman/Tad Aburn

Stakeholder Meeting # 3

Draft Power Plant Regulations – February 

SO2 Regulatory Sup

Modeling

What Emission Rates Are Needed 

With the 1-Hour SO2 Standa
Topics Covered

• Background• Role of modeling in 1-hour SO2 

compliance

• Modeling completed by Maryland• Modeling completed by Sierra Club• Summary of results• Emission rates from the modeling
Background

• EPA guidance sets up a 

process that allows states to achieve early compliance with the 1-hour SO2 standard

– Can avoid being designated 

“nonattainment” altogether

• Must use models to establish 

emission limits for sources that guarantee that 1-hour standard will not be exceeded

• Not the usual process to 

comply with federal standards

– Appropriate because peak 1- 

hour SO2 levels are almost always associated with individual ... or closely located – stationary sources of SO2
The Model

• EPA has approved regulatory 

model that must be used to perform this kind of modeling

• The model use several 

different types of data

– Physical data from the source

• Stack height, exit velocity, exit 

temperatures, etc.

– Emissions data– Meteorological data– Topographical data
Who Has Modele

• Maryland has performed 

modeling for all of the Raven and NRG plants

– Modeling for Warrior Run is in 

the works

– The Maryland modeling was 

completed by MDE and the Department of Natural Resources (DNR) Power Plant Research Program (PPRP)

• Sierra Club has performed 

modeling for the Raven and NRG plants

• Raven and NRG may also be 

performing modeling to look at this issue
Model Set-Up

• MDE/PPRP

– AERMOD(v12345) Model– Raven Power:

• BWI Met data (2008-2012)• Essex Background (2010-2012)

– NRG Power

• Met Data (2008-2012)

– Washington National 

(Chalk Point & Morgantown)

– Dulles 

(Dickerson)

• Beltsville Background (2010-2012)

• Sierra Club

– Raven Pow

• AERM• BWI M• No Ba

– NRG Powe

• AERM• Met Da

– W

(

– D

(

– D

(

• Beltsv

Modeling Raven P

• Three of the Raven plants 

are located fairly close to each other

– Brandon Shores– Wagner– Crane

• This requires that all three of 

the plants be modeled together to insure that the potential concentrations in that area are modeled accurately
Crane Modeling Res

Sierra Club

“Stand Alone”

MDE/PPRP

“Stand Alone”

MDE/PPRP

“Cumulative”

Unit #1

Not Completed

1,501 lbs/hr 1,436 lbs/hr

Unit #2 1,501 lbs/hr 1,436 lbs/hr

Plant Total

(Units #1 & #2)

3,482 lbs/hr 3,002 lbs/hr

Modeled 

Concentration <196.2 ug/m3 195.6 ug/m3

Allowable Rates From the Mo
Wagner Modeling Re

Sierra Club

“Stand Alone”

MDE/PPRP

“Stand Alone”

MDE/PPRP

“Cumulative”

Unit #2

Not Completed

987 lbs/hr 493 lbs/hr

Unit #3

2,023 lbs/hr

1,011 lbs/hr

Plant Total

(Units #2 & #3)

3,115 lbs/hr 3,010 lbs/hr

Modeled 

Concentration <196.2 ug/m3 194.6 ug/m3

Allowable Rates From the Mo
Brandon Shores Modelin

Sierra Club

“Stand Alone”

MDE/PPRP

“Stand Alone”

MDE/PPRP

“Cumulative”

Unit #1

Not Completed

1,797 lbs/hr 1,026 lbs/hr

Unit #2 1,797 lbs/hr 1,026 lbs/hr

Plant Total

(Units #1 & #2)

2,182 lbs/hr 3,594 lbs/hr

Modeled 

Concentration 196 ug/m3 194 ug/m3

Allowable Rates From the M

Modeling NRG Ene

• In designing their scrubber 

systems, for all three of their plants, NRG vents to tall “bypass” stacks when the scrubber or the continuous emission monitors are being repaired or tested

– Emissions may also vent to the 

by-pass stacks during emergencies

• Because of this, the modeling 

must look at operations when the scrubbers are running and also when emissions vent to by-pass stacks
Chalk Point Modeling 

By-Pass Stack (729 feet) Results

Sierra Club MDE/PPRP

Facility 

Emissions

(Total of 2 units)

Not Completed 11,705.8 lbs/hr

Modeled 

Concentration

__ 196.0 ug/m3

Scrubber Stack (400 feet) Results

Sierra Club MDE/PPRP

Facility 

Emissions

(Total of 2 units)

2,300.2 2,430.9 lbs/hr

Modeled 

Concentration <196.2 ug/m3 195.6 ug/m3

Allowable Rates From the Mod

Lim

Scru

a

By-P

a
Morgantown Modeling 

By-Pass Stack (700 feet) Results

Sierra Club MDE/PPRP

Facility 

Emissions

(Total of 2 units)

Not Completed 7,551.6 lbs/hr

Modeled 

Concentration

__ 195.8 ug/m3

Scrubber Stack (400 feet) Results

Sierra Club MDE/PPRP

Facility 

Emissions

(Total of 2 units)

2,615.5 lbs/hr 3,126.2 lbs/hr

Modeled 

Concentration <196.2 ug/m3 195.0 ug/m3

Allowable Rates From the Mod

L

Sc

By
Dickerson Modeling R

By-Pass Stack (703 feet) Results

Sierra Club MDE/PPRP

Facility 

Emissions

(Total of 3 units)

Not Completed 8,909.8 lbs/hr

Modeled 

Concentration

__ 195.9 ug/m3

Scrubber Stack (400 feet) Results

Sierra Club MDE/PPRP

Facility 

Emissions

(Total of 3 units)

360 lbs/hr 1,043.3 lbs/hr

Modeled 

Concentration <196.2 ug/m3 195.6 ug/m3

__

Allowable Rates From the Mod

L

Sc

By