POWER May 2011 - 66

THE FUTURE OF COAL
Coal-Fired Generation Cost and
Performance Trends
Increasing regulatory requirements and a focus on reducing carbon emissions
in the U.S. have significantly reduced the number of new coal-fired plants
under development compared with past years. In addition, projected capital
costs for new coal-fired plants have risen sharply in the past year,
while those for natural gas combined-cycle and combustion turbines have
stayed relatively flat. In order to keep coal a viable energy source, many
countries, including the U.S., are seeking ways to improve plant efficiency
while reducing carbon emissions.
By Dale Probasco and Bob Ruhlman, Navigant
C
oal-fired generation, both existing
and proposed, is under heavy pressure
to " clean up its act " if it wants
to remain a viable fuel for power generation.
The latest U.S. Energy Information
Association (EIA) predictions of U.S.
electricity generation estimate that the
percentage of U.S. electricity generated by
the combustion of coal will decline by 2%,
from 45% to 43%, between 2009 and 2035
(Figure 1).
The EIA Annual Energy Outlook 2011
(AEO) reference case estimates that 21 GW
(supplied by approximately 30 to 35 new
units) will be added during this roughly 25year
period and that coal will remain the
dominant energy source in the absence of any
federally mandated policy to reduce carbon
emissions. Many industry observers consider
this a " best-case " scenario, as the continued
uncertainty over future emission regulations
continues to dampen interest in committing
to new coal-fired generation projects.
The AEO 2011 reference case also sees a
heavy reliance on the existing coal-fired fleet
to meet the nation's electricity demand in
future years. Undoubtedly, where possible,
plant owners will continue making investments
to improve the operating efficiency of
the existing fleet. A pleasant side benefit of
improved plant efficiency is a reduction in
carbon dioxide emissions. However, as new
generation comes online to meet the predicted
increase in electricity demand, less-efficient
older units that cannot be economically
modified to meet more stringent emission
requirements will likely be retired.
The Existing Coal-Fired Fleet
The current portfolio of coal-fired generation
in the U.S. was a shade over 338 GW of installed
nameplate capacity for 1,436 units at
66
the end of 2009, the last full year for which
EIA data is available. These units are generally
conventional pulverized coal (PC) plants
based on either subcritical (80% of the units)
or supercritical (20%) boiler technology.
In general, three conventional boiler
technologies are now available for new
construction:
■ Subcritical steam generators operate
at steam pressure less than the critical
point of water-3,208 pounds per
square inch (psi).
■ Conventional supercritical steam generators
operate with steam pressure greater
than 3,208 psi and steam temperatures
generally in the 1,000F to 1,050F range.
■ Ultrasupercritical (USC) steam generators,
the latest generation of advanced supercritical
design units, operate at steam
pressures greater than 3,208 psi and steam
temperatures greater than 1,100F.
Currently, no USC units are operating in
the U.S.; however, American Electric Power
is building a 600-MW USC unit, scheduled
for completion in late 2012, at the Turk site in
Arkansas. (See " Designing an Ultrasupercritical
Steam Turbine, " in the July 2009 issue or
in the archives at www.powermag.com.)
Follow the Data
The data source for our analysis of existing
coal-fired plant cost and performance
trends is Navigant's proprietary Generation
Knowledge Service, or GKS Fossil
database. Data from 459 coal units totaling
165 GW of capacity was studied for
the period 2005-2009. Non-fuel operations
and maintenance (NFOM) cost data
1. Electricity generation by fuel, 1990-2035. Data is shown as net electricity generation.
Sources: Historical data from EIA, Annual Energy Review 2009; projections from National
Energy Modeling System, run REF 2011, D120810C
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5
4
3
2
1
History
Projections
Coal
45%
10%
23%
Oil and other liquids
1990
2000
www.powermag.com
20%
1%
2009
Year
POWER | May 2011
2020
Renewables
Natural gas
Nuclear
14%
25%
17%
1%
2035
43%
Trillion kWh/yr

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POWER May 2011

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