POWER February 2011 - 72

COMMENTARY
Pre-Combustion Technologies:
A Key Environmental
Compliance Tool
By Jason Hayes
A
rizona Public Service's (APS) plan to close three older
coal-fueled units at the Four Corners Power Plant in New
Mexico and buy out Southern California Edison's 48% share
of the two remaining units is a creative means of surviving the
U.S. Environmental Protection Agency's (EPA) committed action
against coal-fueled generation.
The Impact of Mandatory Upgrades on Utilities' Bottom Lines
Hamstrung by the EPA's endless stream of regulatory revelations,
utilities are searching for reliable and affordable means
of producing power while escaping the imposition of billions in
regulatory-related upgrade costs. In this case, APS was facing a
$1 billion price tag to meet the EPA's demands for, among other
things, an 80% reduction in nitrogen oxide (NOx
) emissions. Required
upgrades would have tacked an additional 3% to 4% onto
the bills of each APS customer. With its new proposal, APS is now
looking at a $295 million outlay to buy the stake in Units 4 and
5 and an additional $290 million for emissions controls.
APS's proposal was made possible because Southern California
Edison is being forced out of coal-fueled generation by stringent
state regulations. So, what will be a loss for the people of California,
in terms of utility rates and power supply, could work in
favor of APS customers as they save more than a half billion dollars,
reduce emissions, and end up with more generation capacity
than when they started.
This type of switch may be effective for one utility and its
customers. However, APS's situation is unique, and as permitting
processes and regulations continue to place a bull's eye
on the development of new coal generation, other utilities will
likely lack the option to buy out a competitor's stake in adjacent
plants. So, utilities and rate payers will be saddled with the costs
of navigating the latest regulatory maze or be forced to close
facilities that regulations and unworkable New Source Review
rules are turning into " marginal plants. "
The Coal 2.0 Alliance: Promoting Pre-Combustion
Technologies
The members of one American Coal Council committee are offering
utilities another option. Their Coal 2.0 Alliance is focused
on advancing the development and use of pre-combustion and
coal preparation technologies by promoting awareness of their
benefits. Pre-combustion technologies produce engineered fuels
that result in increased plant efficiency as well as lower sulfur
dioxide (SO2
), NOx
, mercury, and carbon dioxide (CO2
) emissions
at plants that use them.
A number of processes are in commercial operation and under
development that treat coal prior to combustion, making
it a cleaner, more efficient fuel. Those processes involve coal
preparation (cleaning), upgrading (dewatering with heat and/or
microwaves), and treatment with additives to alter combustion
72
characteristics. The environmental benefits of these technologies
can be further enhanced if other combustion technologies
(oxy-coal combustion) or post-combustion technologies (fabric
filters, electrostatic precipitation, and scrubbers) are also used.
Depending on the specific technology employed and the feed
coal being used, the energy content of lower rank feedstock
coals can be increased from 30% to 200%. Higher energy content
equates to more efficient combustion, and studies conducted by
the Electric Power Research Institute and the Coal Utilization Research
Council indicate that for each 1% increase in combustion
efficiency there is a 2.5% reduction in CO2
can be reduced from 10% to 50%, and SO2
can be reduced 10% to 80%.
Direct emissions reductions are not the only benefits associated
with using pre-combustion technologies. They can also aid
in fuel sourcing decisions as increasing international demand
tightens some coal markets. They can enhance transportation
efficiencies, because reduced moisture content can equate to
a 30% decrease in load volumes and associated transportation
costs. Pre-combustion technologies also can be applied universally
for proposed new coal generation and in the existing fleet
without additional capital expenditures.
Utilities can rely on pre-combustion technologies to provide a
single, consistent fuel resource that has reduced risk of spontaneous
combustion, reduced mill demands, and improved combustion
characteristics. Those features lead to reduced outages from
slagging, reduced need for sootblowing, and reduced unburned
carbon loss.
New offerings from Coal 2.0 Alliance members will also aid in
meeting state renewable portfolio standards and provide the positive
aspects of biomass co-firing, including reduced greenhouse
gas emissions. Engineered fuels now offer coal and biomass briquettes/pellets
and coal " look alike " products that improve the
energy density and reduce the grindability and handling challenges
typically associated with biomass.
A Low-Cost Approach to Improving Environmental
Performance
Pre-combustion technologies represent an excellent low-capital
cost opportunity to significantly improve boiler performance and
reduce emissions. This is especially true in cases where utilities
are using fuels below boiler design specifications. Engineered fuels
provide the opportunity to improve on coal-our most abundant,
secure, and affordable fossil energy resource. By applying
these technologies along with combustion and post-combustion
stage technologies, our coal use will help to power us well into
the future. ■
-Jason Hayes, ME Des, is communications director for the
American Coal Council (www.americancoalcouncil.org).
www.powermag.com
POWER | February 2011
emissions from power
plants. At the same time, emissions of mercury can be reduced
from 15% to 90%, NOx
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POWER February 2011

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