National Energy

Technology Laboratory

Ken Kern

Strategic Energy Analysis and Planning Division

National Energy Technology Lab, Pittsburgh, PA

June 16, 2015

Coal Baseload Asset Aging,

Evaluating Impacts on Capacity 

Factors

Workshop on Coal Fleet Aging and Performance, 

EIA Post-Conference Meeting, Renaissance Hotel, 

Washington D.C.
Generation by fuel

“As natural gas prices increase in the AEO2013 

Reference case, the utilization rate of coal-fired 

generators returns to previous historical levels and 

continues to rise, to an average of around 74 percent in 

2025 and 78 percent in 2040.”

AEO’13 - Issues in Focus (page 42)

(Coal Capacity Factor Assumption)
Baseload Generation (1998-2014)

A Dominant Factor in Power Generation... Critical to the Economy

Non-Baseload

(28%)

Coal

(59%)

Nuclear

NG (33%)

(8%) Other

(<1%)

Baseload

(72%)

Total Generation 

(56,182 BkWh) Baseload Generation

(40,190 BkWh)

From 1998-2014, coal and nuclear generation accounted for 91% of baseload generation

Source: Ventyx, Velocity Suite; Baseload is assumed to be generation with >65% capacity factor
Annual Energy Outlook 2015 Capacity Factors

AEO’15 

Reference 

case Coal 

c.f. at 75%

Source: AEO’15 page 25, based on a November 2014 NEMS run
Coal Units Capacity Factors in Age Bands

(1998-2014 Based on Age of Unit in Year of Data)

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80

0 to 10

11 to 20

21 to 30

31 to 40

41 to 50

51 to 60

61 to 70

71 and older

Average Capacity Factor %

Unit Age in Year of Data 

Age Bands

2014
Coal unit capacity factors drop off as they age

Data source and notes: Data from Ventyx's Energy Velocity. Unit age in each year was calculated then averaged

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

Average capacity factor (%)

Unit age in years

Average capacity factor by unit age for coal operations, 1998-2014

Approximation of actual industry capacity 

factor experience based on unit age

80%

60%

14%

T

o

d

a

y
0

10

20

30

40

50

60

70

80

90

0

2

4

6

8

10

12

14

16

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Capacity (GW)

Age

Coal Capacity and Unit Ages in 2040

Historic Age-based

Capacity Factor Trend 

(1998-2014)

AEO’15 AVERAGE Capacity Factor 2040

Historic AVERAGE Capacity Factor 

Existing Units (1998-2014)

75%

64%

AVERAGE Capacity Factor of coal 

units in 2040 based on ages and 

16 year past performance data

30%

Capacity 

Factor

(%)

References – Ventyx Velocity Suite (existing units and announced retirements, accessed 6/10/2015) - EIA AEO 2015 (Reference case forecasted additions); assume

units retire that would be older than 100 years of age in 2040.

Capacity-weighted average age 62

(average unit age 66)

80%

60%

14%

Overestimation of coal unit capacity factors can result in reliably issues and 

underestimation of replacement baseload capacity need
0

10

20

30

40

50

60

70

80

0

20

40

60

80

100

120

140

Capacity factor (%)

Total Capacity (GW)

Age groupings in 2040

Announced Retirement

Projected Retirement

Continued Operation

Average capacity factor in 2012

Age Distribution of Existing Coal Units by 2040

(AEO 2015 Reference Case)

Identity of Projected Retirement units using NETL methodology

75% average 

capacity factor 

goal in 2040

Will they serve 

baseload needs?

75% Capacity Factor

224 GW

88% of 

capacity

> 50 years
0

20

40

60

80

100

Average capacity factor 

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

(%)

Unit age in years

Average capacity factor by unit age for coal operations, 1998-2014

Potential Baseload Coal GW Equivalence Needed

Missing generation estimate 144 GW @80% average C.F. for new units to meet 2040 demand

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

201420152016201720182019202020212022202320242025202620272028202920302031203220332034203520362037203820392040

BkWh

EIA AEO’14 Generation

80%

60%

14%

144

GW

1,007 BkWh

109

GW

56

GW

31

GW 79

GW
Electricity Generation by Fuel, 1980-2040

billion kilowatthours

Coal

Petroleum

Nuclear

Natural Gas

Renewables

0

500

1000

1500

2000

2500

1980 1990 2000 2010 2020 2030 2040

Note: Includes generation from plants in both the electric power and end-use sectors.

Source: History: U.S. Energy Information Administration (EIA), Annual Energy Review; 

Projections: AEO 2015 Reference case

History 2012 Projections

Overview of AEO2014 Accelerated Power Plant 

Retirement Side Cases May 20, 2014

Coal Capacity Factor

Effect on kWh 

Expectations?

-1,000 

BkWh

of 

~5,000

BkWh

total

(-20%)
0

2

4

6

8

10

12

14

16

18

20

19501952195419561958196019621964196619681970197219741976197819801982198419861988199019921994199619982000200220042006200820102012

Net Summer Capacity Additions (GW)

Supercritical

Subcritical

Historic Coal-Fired Capacity Additions

Segmented by Subcritical and Supercritical (1950-2013)

Ventyx Velocity Suite Supercritical contains one ultra supercritical plant

Built

(what is shown on the graph)

Currently Not Retired

(as of 3/2014)

Boiler Type Capacity 

(GW)

# of Units Capacity 

(GW)

# of Units

Supercritical 94 138 (large units) 88 125 (large units)

Subcritical 241 1,490 217 (71%) 1,054

Additions

Retirements

Supercritical

Subcritical

Announced Retirements

Supercritical

Subcritical

50 

Years 

Old

in 2040

Will the Units of the ‘70s and ‘80s Age, Maintain and Operate Like those of the ‘50s and ‘60s?

?

50 Years 

Old

Today Basis for 

Age-based 

Operating

Experience

Concerns

High C.F.

Expected

Thru 2040
Supercritical Unit Capacity Factors

(by 10-year Age Band)

0

10

20

30

40

50

60

70

80

90

100

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

0 to 10

11 to 20

21 to 30

31 to 40

41 to 50

51 to 60

Units

14

0

3

39

65

3

124

Age Band in 2014

84%

52%

Average Capacity Factor %

Few supercritical units have surpassed 50 years old;

majority of units are beyond 40 years, with average age 62 in 2040
Supercritical vs Subcritical Capacity Factors

(41-50 Age Band)

0

10

20

30

40

50

60

70

80

90

100

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

41 to 50 - N

41 to 50 - Y

Subcritical

Supercritical

Average Capacity Factor %

No significant capacity factor advantage for supercritical units that have 

passed beyond 41 years of age (52% of all supercritical units)
0

5

10

15

20

25

0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 99

Capacity (GW)

Age of units by 2040

Coal & Nuclear Baseload Capacity Renewal

(by 2040)

Reference – Ventyx Velocity Suite (existing units and announced retirements

- EIA AEO 2016-2015 (forecasted additions)

End of 

AEO’06-’09 

forecast

2030

AEO 2006

AEO 2007

AEO 2008

AEO 2009

AEO 2010

AEO 2011

AEO 2012

AEO 2013

AEO new Coal

AEO new Nuclear

AEO 2014

Existing coal and nuclear fleet by 2040 Forecasted new coal and 

nuclear fleet to meet 

demand and replace aging 

fleet

Average coal unit age = 66

Average today’s nuclear unit age = 60

AEO 2015 adds

9 GW nuclear

1 GW coal
• The U.S. EPA says it will seek to ease permitting obligations that are expected to crop up 

for power plants required to make retrofits to meet the agency's climate rule for existing 

facilities, a top official with the agency said Feb. 9 at a conference in Washington, D.C. 

• At issue is the EPA's new source review program, which requires power plants to obtain 

permits prior to making modifications, such as boiler heat rate improvements to meet the 

climate rule. Industry groups say that it is an unduly onerous and "very complicated 

process" that causes "significant delays.“

• The EPA is "certainly comfortable acknowledging that we will need to address NSR [new 

source review]" 

• EPA faces an uphill battle, recalling that in a past case a federal appeals court ruled that 

an attempt to make changes to the new source review program was not in the agency's 

"statutory purview."

Constraints of the NSR Regulation

Affects Ability to Perform Major Maintenance

Result: “The state could also develop conditions for a source expected to trigger NSR that would limit the unit’s 

ability to move up in the dispatch enough to result in a significant net emissions increase that would trigger NSR.”

Per June 18, 2014 Federal Register for ESPS
• Past coal plant operating performance reflects declining 

capacity factors after age 50; uncertainties for meeting 

generation forecast by assuming high coal capacity factors

• Anticipation that supercritical coal plants will perform 

distinctly better with age, not supported by early evidence

• Industry practice, under positive economic conditions, is to 

replace the baseload asset base before reaching age 60

• A significant portion of the generation forecast relies on 

infrastructure performing well at unprecedented average age

• NSR recognized as a limiting regulatory issue for coal-plant 

major maintenance; resolvable by reducing capacity factor

• QER emphasized concern for aging U.S. energy asset base

Conclusions