POWER October 2010 - 36

TOP PLANTS
Dickerson Generating Station,
Dickerson, Maryland
Owner/operator: Mirant Corp.
Dickerson Generating Station, a 50-year-old facility servicing Maryland and Washington,
D.C., was recently upgraded with a flue gas desulfurization system and a
unique draft system that allows an electrostatic precipitator and a baghouse to
share flue gas cleanup chores on each unit. In addition, state-of-the-art equipment
monitoring and diagnostics keep plant reliability high for this baseload unit.
By Dr. Robert Peltier, PE
M
irant Corp. (Mirant) is the prototypical
independent power producer,
with a history that closely
parallels the triumphs and tragedies of
merchant generation. Originally formed
as Southern Energy Inc., a subsidiary of
Southern Company, it focused on global
investment opportunities in power generation.
Southern Energy was spun off from
Southern Company in 2000 and was subsequently
renamed Mirant. By the end of
2001, Mirant joined other merchant generators
facing financial hardships in the wake
of Enron's collapse and an overbuilding of
competitive generation. Chapter 11 bankruptcy
filing resulted in July 2003. Reorganized
with new management, Mirant
emerged as a profitable merchant power
competitor in 2006. The company divested
its foreign businesses in 2007 and has since
focused on producing and selling electricity
in key, densely populated U.S. regions.
Mirant's 11 U.S. generating stations,
nominally rated at 10,000 MW, are located
in the San Francisco; Washington, D.C.;
Boston; and New York City greater metropolitan
areas. Mirant's Mid-Atlantic fleet
36
consists of its Morgantown, Chalk Point,
and Dickerson Generating Stations in Maryland,
as well as its Potomac River Generating
Station in Virginia. All burn coal, natural
gas, or oil, or a combination of fuels.
Modernizing Maryland Plants
Dickerson Generating Station (DGS) is located
in Montgomery County, Md., on the
Potomac River. DGS has three coal-fired
190-MW units that were constructed in
1959, 1960, and 1962 and two 147-MW
combustion turbines constructed in 1992.
DGS was originally built by the Potomac
Electric Power Co. but was acquired in
2000 by Mirant. DGS is usually dispatched
as baseload generation by the PJM Interconnection
regional transmission organization.
Perhaps the principal challenge for merchant
generators that own coal-fired assets
is grappling with the incessant investment
required for environmental upgrades. The
Maryland Healthy Air Act (MHAA), effective
in 2006, set the air emissions rules of
the road for coal-fired plants in that state.
The MHAA, while based on the U.S. Environmental
Protection Agency's Clean
www.powermag.com
Courtesy: Mirant Corp
Air Interstate Rule and Clean Air Mercury
Rule, requires larger reductions in air
emissions that apply year-round, unlike
the seasonal NOx
rules in other states. The
Maryland Department of the Environment
expects to meet federal ambient air quality
standards for particulates and ozone by
requiring two-step reductions totaling 75%
for NOx
by 2012, 85% for SO2
by 2013, and
90% for mercury by 2013, all compared to
a 2002 baseline. The MHAA also closed
another loophole: Out-of-state emissions
allowances cannot be used to avoid the
capital investment required to meet these
air emissions requirements.
Savvy Shopper
Mirant has invested about $1.67 billion
over the past several years installing flue
gas desulfurization (FGD) systems, selective
catalytic reduction systems, and, in
some cases, switching to low-sulfur coal at
its three Maryland plants. The Shaw Group
Inc. finalized an engineering, procurement,
and construction contract with Mirant in
August 2007 to retrofit all three of Mirant's
Maryland coal plants (seven units) with
POWER | October 2010
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POWER October 2010

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