a history of power plant controls in maryland what did we learn? – where do we go next?

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


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


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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

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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





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


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



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)



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)


Crane Unit 2(Use of PRB Coal)

3.5 lbs/mmBtu (24-hr Average)(~ 8,750 lbs/hr)


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


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


operation Very low rates consistent with



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




operations


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


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




operations


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)


700 to 800 lb/hr

Morgantown Unit 2(Scrubber)


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


UnitCapacity

(MW)SO2 Controls

Fluidized Bed Boiler

180 Fluidized bed

SO2 Mass Rate vs. Operating Hours

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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

a history of power plant controls in maryland what did we learn? – where do we go next?

Documents

annual tons

annual capunit

annual so2 emissions

wagner units

crane units

fired coal units

annual haa limitthis

boiler type units