Fossil Fuel Power Plant Emissions
Over the years, a variety of filtering techniques have evolved to improve
the emissions from power plants. Large-scale power generation requires
the consumption of tremendous volumes of fuel. There is some advantage,
however, in producing so much power in one location. The advantage is
that advanced emissions control techniques can be implemented that are
not possible to use in smaller power generation applications.
The following is an overview of techniques used independently or in
conjunction with one another to help reduce power plant emissions.
• Baghouses. Particles are trapped on filters made of cloth, paper, or
similar materials. These particles are then shaken or blown from the
filters down into a collection hopper. Baghouses are used to control
air pollutants from power plants, as well as steel mills, foundries,
and other industrial furnaces. They can collect more than 98% of
the particulates.
• Electrostatic precipitators. By use of static electricity, these precipita-
tors attract particles in much the same way that static electricity in
clothing picks up small bits of dust and lint. See Figure 26-6.
• Wet scrubbers. Particulates, vapors, and gases are controlled by pass-
ing the gaseous stream of emissions through a liquid solution, or
“scrubber.” Scrubbers are used in coal-burning power plants, asphalt
and concrete plants, and a variety of other facilities that emit gases
that are highly soluble in water. Wet scrubbers are often used for
corrosive, acidic, or basic gas streams.
These techniques have vastly improved the quality of power plant emis-
sions. There is, however, still more work to be done. Fossil fuel pollutants
and the consumption of coal for power generation, in particular, remain
the principal causes of acid rain and the greenhouse effect.
Baghouse: A tech-
nique used to
reduce power plant
emissions in which
particles are
trapped on filters
made of cloth,
paper, or similar
materials. These
particles are then
shaken or blown
from the filters
down into a collec-
tion hopper.
Wet scrubber: A
technique used to
reduce power plant
emissions in which
particulates,
vapors, and gases
are controlled by
passing the
gaseous stream of
emissions through
a liquid solution.
Chapter 26
622
Figure 26-6. Electrostatic precipitators and other control devices help to
reduce the emissions of particulate matter and gases from pollution sources,
such as this steel mill. They are regarded as being 98–99% effective.
Electrostatic precipitators are often used instead of baghouses when the
particles are suspended in very hot gases, such as in emissions from power
plants, steel and paper mills, smelters, and cement plants.