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American Electric Power
Issues in Electricity
Power generation
at AEP
AEP believes strongly in
the merits of fuel diversity
in generating electricity.
Today, natural gas-fueled
power plants account for
approximately 28 percent
of AEP's owned
generating capacity, while
coal represents
approximately 50 percent
and nuclear 6 percent.
The remaining capacity
comes from wind, hydro,
pumped storage and other
sources, including energy
efficiency. Since 2004,
AEP has added nearly
5,000 MW of natural gas
generating capacity to our
portfolio. Through 2026,
we project that new
generating capacity
additions to the fleet will
likely be natural gasfueled and renewable
(wind & solar).
Natural Gas
The recent increase in the generation of electricity by natural gas
power plants is largely due to an increase in the known supply of
natural gas resulting in lower forward-looking prices, increasing
focus on power plant carbon dioxide emissions and the relative
flexibility of siting, constructing and operating natural gas power
generation.
The increase in supply is a result of gas production from
unconventional sources, such as shale gas or tight gas, which is
trapped in deep impermeable rock or non-porous limestone and
sandstone. Natural gas has much lower emissions of sulfur dioxide
(SO2) and nitrogen oxides (NOx) as compared to coal. Carbon
dioxide (CO2) emissions are approximately 50 percent lower than
coal when burned to generate electricity. As a result, natural gas
power plants can be constructed and operated with fewer
environmental control systems than a coal-fueled plant with similar
output under current environmental regulations.
Simple-cycle plants typically built for “peaking” opportunities can be
constructed in roughly 18 to 30 months, while large combined cycle
plants (>500 MW) can be constructed in about 36 months.
Issues in Electricity
American Electric Power
Industry data indicates that new combined cycle gas plants can achieve average efficiencies of 50
percent and higher. New simple cycle
gas turbines and reciprocating internal
combustion engine technologies are
achieving efficiencies ranging from 35 –
44 percent and combined cycle plants
have efficiencies of 52 – 60 percent
compared to efficiencies of up to 46
percent for super critical coal plants and
50 percent for ultra-supercritical coal
plants.
Types of natural gas plants
There are three types of natural gas
plants currently utilized by AEP to
generate electricity: natural gas steam
generation, simple cycle and combined
cycle.
AEP’s Dresden Plant
Steam generation plants use natural gas to heat water and create steam that spins a turbine, just
as in a coal plant.
Simple cycle plants burn natural gas in a combustion turbine (similar to a jet engine) to produce
high-pressure, high-temperature gas, that is then used to spin the turbine. These plants have short
start-up times compared to other generating facilities and, therefore, are used during periods of
peak demand. They are relatively inefficient in their ability to convert heat into electricity so their
use is often limited to periods of high demand.
Combined cycle plants incorporate simple cycle combustion turbines and a heat recovery steam
generator (HRSG). Waste heat from combustion turbines is used to generate steam in the HRSG
to drive a steam turbine. The use of waste heat results in higher plant efficiency (50+ percent).
The combined cycle arrangement adds to the complexity of operation, but these plants can still be
very flexible for load-following, intermediate and baseload generation.