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Department of the Environment
A History of Power Plant Controlsin Maryland
What Did We Learn? – Where do We go Next?
Part 3 – SO2 Issues
Healthy Air Act SO2 CapsHealthy Air Act caps reduced annual SO2 emissions
Issues With SO2 Emissions• The Healthy Air Act’s annual caps – and
company-wide averaging concepts - worked extremely well to cost-effectively reduce annual SO2 emissions – These reductions have helped Maryland come into
attainment for the fine particulate standard and meet the Regional Haze requirements of the Clean Air Act
• The new 1-hour SO2 standard demands an entirely different regulatory scheme– 1-hour emission limits instead of an annual cap
– Unit-by-unit controls instead of company-wide averaging
• Units that under-controlled as part of a company-wide averaging plan are struggling to meet the limits needed because of the new standard
• Short-term periods where the scrubbers are not being used (for example during boiler emergencies and CEM QA) are also a problem
Very Old Short-Term Emission Limits
• The HAA used annual caps to drive very significant annual emission reductions
• The short-term limits for SO2 in Maryland regulations date back to the 1990s
– They are clearly not appropriate for the new 1-hour SO2 standard
• All short-term limits for all units will need to be updated
Capacity Factor Trends
Over the past 5 yearswe’ve seen a dramatic drop inhow often Maryland coal plants
are called upon to generateenergy
Raven Power
• Brandon Shores - Units 1 and 2
• Wagner – Units 1, 2, 3 and 4
• C.P. Crane – Units 1 and 2
Wagner Power Station
Brandon Shores Unit 1
Brandon Shores Unit 2
Crane Unit 1
Crane Unit 2
Wagner Unit 2
Wagner Unit 3
Total
2012 Annual SO2 Tons 1,547 1,301 1,212 961 2,513 4,960 12,494
2010-2012 Annual SO2 Limit, Tons
7,041 7,347 2,000 2,149 1,618 3,252 23,407
2013-On Annual SO2 Limit, Tons
5,392 5,627 1,532 1,646 1,239 2,490 17,926
HAA set annual and ozone season caps and allowed “system-wide” averagingWith tougher ozone standard and focus on “peak days” – units
that “under-controlled” are now being re-evaluated
Raven System Wide Compliance with MD HAA
Units with red font use credits from units in black font to meet annual HAA Limit
This numbers shows Annual tons well
below annual limits
Raven Power – Brandon Shores
UnitCapacity
(MW)SOx Controls
Brandon 1(Coal)
700 FGD
Brandon 2(Coal)
700 FGD
• Built in 1984
• Boiler type – Units 1 & 2 are both walled fired coal units
manufactured by Babcock & Wilcox
• Installed two scrubbers (Fluidized Gas Desulfurization/FGD) in 2010 (about $875 million)
• Total capacity = 1,400 MW
Brandon Shores – Capacity Factors
Brandon Shores Unit 1
0%
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Brandon Shores 1 Brandon Shores 2Brandon Shores Unit 2
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Brandon Shores - 2010 1-Hour SO2 Emissions (lbs/hr)Unit #1
0
1000
2000
3000
4000
5000
6000
7000
1/1/10 3/2/10 5/1/10 6/30/10 8/29/10 10/28/10 12/27/10
SO
2 (l
bs/
hr)
Brandon Shores - Unit 1
Very low rates consistent with
FGD control efficiency
MDE Current Thinking:
Allowable rate of 300 to 500 lb/hr
Brandon Shores - Unit 2
Very low rates consistent with
FGD control efficiency
MDE Current Thinking:
Allowable rate of 300 to 500 lb/hr
UnitCapacity
(MW)SOx
Controls
Wagner 2(Coal)
136 None
Wagner 3(Coal)
359 None
Wagner Power Station• Built in 1959 - 1972
• Boiler types
– Units 2 & 3 are both wall fired coal units manufactured by Babcock & Wilcox
– Units 1 & 4 are both gas and oil wall fired units manufactured by Babcock & Wilcox
• No add-on control technology. Coal fired units at times have used lower sulfur coal as a control strategy
• Total Coal capacity = 495 MW
Wagner – Capacity Factors
Wagner Unit 2
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Wagner 2 Wagner 3Wagner Unit 3
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Can see considerable variability in rates
resulting from load and coal sulfur content
Wagner - Unit 2
MDE Current Thinking:
Allowable rate of 500 to 1000
lb/hr
Wagner – Unit 3
Lack of emission controls and the use of coal with
higher sulfur content result in the highest SO2 rates in Maryland and some of the
highest in the eastern United States
MDE Current Thinking: Lower end of current
emissions still too high. Allowable rate appears to be in the 500 to 1000
lb/hr range
UnitCapacity
(MW)SOx Controls
CP Crane 1(Coal) 200 PRB Coal
CP Crane 2(Coal) 200 PRB Coal
C.P. Crane• Built in 1963
• Boiler types– Units 1 & 2 are both coal fired cyclone units manufactured
by Babcock and Wilcox
• No add-on control technology. Uses Powder River Basin (PRB) low sulfur coal as a control strategy
• Total capacity = 400 MW
Capacity Factors at Crane• Dramatic reductions since 2001 to 2007 timeframe
• Units are simply not being called upon to run as much as they used to be called upon
Crane - Units 1 & 2
Clearly can see that lower rates can be achieved with low sulfur coal and careful attention to coal
blending activities
Can also see that there are routine emission spikes. Controlling
these spikes is critical for complying with a 1-
hour standard
MDE Current Thinking:
Allowable rate of 700 to 800 lb/hr
Coal Fired Units Old SO2 Limit (as lb/hr) Proposed SO2 Limits (1 hr avg)
Brandon Unit 1(Scrubber)
1.2 lbs/mmBtu(~ 9,600 lbs/hr)
300 to 500 lb/hr SO2
Brandon Unit 2(Scrubber)
1.2 lbs/mmBtu(~ 9,600 lbs/hr)
300 to 500 lb/hr SO2
Wagner Unit 2(None)
1 wt% Sulfur Coal(~3,355 lbs/hr)
500 to 1000 lb/hr SO2
Wagner Unit 3(None)
1 wt% Sulfur Coal(~4,567 lbs/hr)
500 to 1000 lb/hr SO2
Crane Unit 1(Use of PRB Coal)
3.5 lbs/mmBtu (24-hr Average)(~ 8,750 lbs/hr)
700 to 800 lb/hr SO2
Crane Unit 2(Use of PRB Coal)
3.5 lbs/mmBtu (24-hr Average)(~ 8,750 lbs/hr)
700 to 800 lb/hr SO2
Raven Power – Current MDE Thinking
Preliminary SO2 Modeling - Raven
• MDE and DNR have performed preliminary modeling for the coal fired units in the Raven Power system
• Sierra Club has also performed modeling of the Ravens units
• More refined modeling is underway
• Preliminary modeling indicates that MDE’s current thinking on short-term limits for the Raven coal fired units will model attainment for the 1-hour SO2 standard
NRG Energy Inc.
• Morgantown - Units 1 and 2
• Dickerson – Units 1, 2 and 3
• Chalk Point – Units 1 and 2
Morgantown Chalk PointDickerson
Morgantown Unit 1
Morgantown Unit 2
Chalk PtUnit 1
Chalk PtUnit 2
Dickerson Unit 1
Dickerson Unit 2
Dickerson Unit 3
Total
2012 Annual SO2 Tons 1,231 1,698 2,470 2,176 275 245 297 8,395
2010-2012 Annual SO2 Limit, Tons
6,108 6,066 3,403 3,568 1,616 1,770 1,678 24,209
2013-On Annual SO2 Limit, Tons
4,678 4,646 2,606 2,733 1,238 1,355 1,385 18,641
HAA set annual and ozone season caps and allowed “system-wide” averagingNRG added scubbers at all three of their plants. Because of this
The NRG units all contributed proportionally to system-wide compliance. There are no units that “under-controlled.
NRG System Wide Compliance with MD HAA
This numbers shows annual tons well
below annual limits
Each unit, individually, was well under the unit-specific
HAA cap for that unit
UnitCapacity
(MW)SO2
Controls
Morgantown 1 (coal)
640 FGD
Morgantown 2 (coal)
640 FGD
NRG – Morgantown• Built in 1967
• Boiler types – Units 1 & 2 are both tangential fired coal units
manufactured by Alstom
• Installed two scrubbers (FGD) in 2009 for approximately $715 million
• Total capacity = 1,280 MW coal
Morgantown – Capacity Factors
Morgantown Unit 1
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Morgantown 1 Morgantown 2
Morgantown Unit 2
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Morgantown – Unit 1
Much higher rates during bypass stack
operationVery low rates consistent with
FGD control efficiency
MDE Current Thinking: Allowable FGD rate of 700 to
800 lb/hr
During routine operation, emissions are controlled with an FGD and vent to a shorter “FGD” stack. During upset situations, emissions vent
to a much taller “bypass” stack
Morgantown – Unit 2
Much higher rates during bypass stack
operation Very low rates consistent with
FGD control efficiency
MDE Current Thinking: Allowable FGD rate of 700 to
800 lb/hr
During routine operation, emissions are controlled with an FGD and vent to a shorter “FGD” stack. During upset situations, emissions
vent to a much taller “bypass” stack
UnitCapacity
(MW)SO2
Controls
Both Units 1 & 2 vent through a
common FGD and a common 400 ft stack
710 FGD
NRG – Chalk Point• Built in 1964 & 1965
• Boiler types– Units 1 & 2 are both wall fired coal units
manufactured by Babcock and Wilcox
• Installed scrubber (FGD) in 2009 for approximately $475 million
• Total capacity = 710 MW coal
Chalk Point – Capacity FactorsChalk Point Units 1 & 2
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Chalk Point Units 1 & 2Both units vent to a common stack. During routine operation, emissions are
controlled with an FGD and vent to a shorter “FGD” stack. During upset situations, emissions vent to a much taller “bypass” stack
Very low rates consistent with
FGD control efficiency
Much higher rates during bypass stack
operations
MDE Current Thinking: Allowable FGD rate of 700 to
1000 lb/hr
NRG - Dickerson• Built in 1957, 1957, & 1960
• Boiler types– Units 1, 2, & 3 are all tangential fired coal units
manufactured by Combustion Engineering, Inc.
• Installed scrubber (FGD) in 2009 for approximately $475 million
• Total capacity = 573 MW coal
UnitCapacity
(MW)SO2
Controls
All three Units 1, 2 & 3 vent through a
common FGD and a common 400 ft stack
570 FGD
Dickerson – Capacity FactorsDickerson Units 1, 2, & 3
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Dickerson – Unit 1, 2 and 3All three units vent to a common stack. During routine operation, emissions are controlled
with an FGD and vent to a shorter “FGD” stack. During upset situations, emissions vent to a much taller “bypass” stack
Very low rates consistent with
FGD control efficiency
Much higher rates during bypass stack
operations
MDE Current Thinking: Allowable FGD rate of 700 to
1000 lb/hr
Coal Fired Units Old SO2 Limit (as lb/hr) Proposed SO2 Limits(1 hr Avg)
Chalk Point Unit 1&2(Scrubber, Common Stack)
1% Sulfur Coal(~ 10,433 lbs/hr)
700 to 1000 lb/hr
Morgantown Unit 1(Scrubber)
3.5 lbs/mmBtu(~ 22,628 lbs/hr)
700 to 800 lb/hr
Morgantown Unit 2(Scrubber)
3.5 lbs/mmBtu(~ 22,628 lbs/hr)
700 to 800 lb/hr
Dickerson Unit 1, 2, & 3(Scrubber, Common Stack)
2.8 lbs/mmBtu(~ 13,826 lbs/hr) 700 to 1000 lb/hr
Short-Term SO2 Limits
NRG– Current MDE Thinking
Preliminary SO2 Modeling - NRG
• MDE and DNR are in the process of performing preliminary modeling for the coal-fired units in the NRG system
• Sierra Club has also performed modeling of the NRG units
• Preliminary information indicates that MDE’s current thinking on short-term limits for the NRG coal-fired units will model attainment for the 1-hour SO2 standard when the FGDs are running
• MDE continues to analyze the NRG SO2 emissions that occur during bypass stack operation when emissions are vented through the taller stacks uncontrolled
AES Warrior Run• Built in 1999
• Boiler type– Coal-fired atmospheric circulating fluidized bed unit,
manufactured by ABB
• No add-on control technology. Uses fluidized bed technology as a SO2 control strategy
• Total capacity = 205 MW coal
UnitCapacity
(MW)SO2 Controls
Fluidized Bed Boiler
180 Fluidized bed
SO2 Mass Rate vs. Operating Hours
0
200
400
600
800
1000
1200
1400
0 5000 10000 15000 20000 25000 30000
Operating Hours 2010-2013
SO2 M
ass
Rat
e (l
b/hr
)
AES Warrior Run
Low rates consistent with inherently clean design of fluidized
bed boilers
MDE Current Thinking: No modeling has been completed for Warrior Run. Allowable rate
being analyzed
Next Steps – SO2• Significant additional modeling is underway
• Continue to analyze options for emission reductions at Crane and Wager 3
• Continue to work with EPA on the “Bypass Stack” issues at all three NRG Plants– Additional modeling of by-pass stack issues is
underway
• Continue to work on start-up/shut-down issues
• Continue to work with EPA and other states on the form of the short-term limits needed for the new SO2 standard– Lb/hr or lb/mmBtu with a short-term average
• Continue to work with stakeholders on proposed limits
• Continue to work with EPA on “early action” provisions of EPA’s draft guidance
• Suggest that early December or January 2014 meeting focus solely on short-term SO2 limits