guides TVAs production of reliable power
|As part of
TVAs hydro modernization process, an employee replaces a faulty
bushing in a turbine at the agencys Guntersville Hydropower
is something many people take for granted: flip a switch and the lights
come on. But behind every electric outlet lies a complex system of power
production facilities and the ecosystems in which they operate. These
may seem like two very different systems, but in fact theyre not.
In generating electric power, TVA treats them as a balanced, integrated
TVA derives power
from an array of sources: hydropower dams, nuclear plants, combustion
turbines, fossil plants, purchases from nearby utilities, and renewable
resources like wind and sunlight. Of those, hydropower provided the
Tennessee Valley with only about 9 billion kilowatt-hours of electricity
last year. TVA is working to increase the efficiency of its hydro units,
some of which still use equipment originally installed in the 1930s
chart for raw data.
In the early 1990s,
the agency embarked on a massive modernization project that has produced
a number of improvements in its facilities operation. During the
past few years, for instance, TVA upgraded some of the dams complex
mechanical controls by replacing bushings that required regular applications
of lubricating grease with greaseless ones. Unfortunately, the new bushings
proved unsatisfactory (they repeatedly caused friction and overheating,
with subsequent outages), but they are being replaced with low-volume
greased bushings that drastically reduce releases of grease into the
Nuclear power furnishes
a solid base of available energymore than 46 billion kilowatt-hours
in 2000and TVAs nuclear operations routinely set industry
records for safety and performance. Last year, in fact, nuclear units
run by TVA were ranked among the top 25 performers in the U.S. by Nucleonics
Week, an industry trade publication. And although nuclear power has
always aroused controversy, it helps to reduce the emissions caused
by fossil-fuel combustion. In the U.S. alone, according to the Nuclear
Energy Institute, nuclear power generation keeps 1.11 million metric
tons (1.22 million tons) of nitrogen oxide and 2.16 million metric tons
(2.38 million tons) of sulfur dioxide out of the air each year.
chart for raw data.
plants provide most of the electricity generated by TVAmore than
95 billion kilowatt-hours in 2000, or 63 percent of the agencys
total power production. TVA knows its emissions contribute to the regions
air quality issues through the release of relatively large quantities
of sulfur dioxide (SO2) and nitrogen oxide (NOx).
Thats why the agency has taken a number of stepssome exceeding
those required by lawto improve the performance of its fossil
plants and to lower emissions.
January 1, 2000, marked the beginning of Phase II of the Environmental
Protection Agencys acid-rain program, which is designed to reduce
SO2 and NOx emissions nationwide by 9 million
metric tons and 1.8 million metric tons (10 million tons and 2 million
tons) from 1980 levels, respectively. Although TVAs fossil plants
generated 6 percent more electricity in 2000 than in 1999, the agency
succeeded in reducing its SO2 emissions by more
than 6 percent and its NOx emissions by 20 percent. The SO2
reduction figure, however, did not meet TVAs target due to timing
and delays related to planned low-sulfur fuel switches, which underscores
the need to continue to improve performance in this area.
chart for raw data.
significant effort to reduce fossil-plant emissions in 2000 was its
installation of its first selective catalytic reduction (SCR) system
at Paradise Fossil Plant in Kentucky. An SCR system removes NOx by directing
a plants flue gas into an ammonia-injection reactor. In the presence
of a catalyst, the ammonia reacts with the NOx in the gas to form harmless
nitrogen gas and water vapor. TVA did have to overcome several start-up
and operational problems with its first SCR, one of which was an improper
sizing for an ammonia vaporizing system.
Using the experience
it gained at Paradise, the agency is now set to spend an estimated $850
million on the installation of 17 more SCRs by the spring of 2005, with
the goal of reducing NOx emissions during the summer ozone season by
70 to 75 percent. This step comes in addition to TVAs introduction
of low-NOx burners, overfire air controls, and boiler-optimization controls,
which are decreasing NOx emissions at other fossil plants across the
for raw data.
2000 figures reflect increases in fossil-power and combustion-turbine
chart for raw data.
In addition to
installing limestone scrubbers at three plants, TVA continued to reduce
SO2 emissions by burning low-sulfur coal. Occasionally
the coal was co-fired, or burned simultaneously, with natural biomass
materials to lower SO2 emissions even farther.
Eight new oil- or natural-gas-fired combustion turbines were installed
last year, and 20 others were modified to burn natural gas, which improves
efficiency, reduces SO2 and other emissions, and
plays an important part in meeting the Valleys growing demand
for power. TVA will install eight additional turbines by the summer
of 2001 to ensure that it can continue to supply the power needed during
peak periods while working toward its SO2-reduction
the release of CO2, a substance that is considered
to contribute to global warming, remains relatively unchecked. There
are currently no commercially viable retrofit technologies available
to lessen the release of CO2, and TVA anticipates
that its CO2 emissions will continue to rise in
coming years as demand for power increases.
is a big job. But TVA makes a concerted effort to ensure that the environmental
impact of its operations remains as small as possible.
is pleased to play a role in helping TVA improve the Tennessee Valleys
bigger environmental picturea picture in which the power needed
to keep our communities and our businesses humming is generated in an
environmentally sensitive manner. The catalysts we produce for TVAs
selective catalytic reduction systems not only help provide high-quality
jobs in the Valley but also contribute to a cleaner environment here.
Fred Maurer, President and CEO, Cormetech