Page 106 - Fundamentals of Air Pollution

76 6. Sources of Air Pollution

for light, there was no television, and food was stored in a cellar, the
total of the air pollution generated by all the individual sources probably
exceeded that of the modern generating stations supplying today's energy.
It is easy for citizens to point out the utility as an air pollution source
without connecting their own use of the power to the pollution from the
utility. Figure 6-3 illustrates a modern electric power plant.
Utilities are in the business of converting energy from one form to another
and transporting that energy. If a large steam generating plant, producing
2000 MW, burns a million kilograms per hour of 4% ash coal, it must
somehow dispose of 40,000 kg of ash per hour. Some will be removed from
the furnaces by the ash-handling systems, but some will go up the stack
with the flue gases. If 50% of the ash enters the stack and the fly ash
collection system is 99% efficient, 200 kg of ash per hour will be emitted
to the atmosphere. For a typical generating plant, the gaseous emissions
would include 341,000 kg of oxides of sulfur per day and 185,000 kg of
oxides of nitrogen per day. If this is judged as excessive pollution, the
management decision can be to (1) purchase lower-ash or lower-sulfur coal,
(2) change the furnace so that more ash goes to the ash pit and less goes
up the stack, or (3) install more efficient air pollution control equipment.
In any case, the cost of operation will be increased and this increase will
be passed on to the consumer.
Another type of utility that is a serious air pollution source is the one
that handles the wastes of modern society. An overloaded, poorly designed,

Fig. 6-3. Coal-fired electric generating plant.