environmental facts
WHAT'S A SCRUBBER?
Energy and economy are very common words in today's
conversations. There is a new word--"scrubber"--which
is becoming increasingly more common and, at the same
time controversial. The issue centers around the means
of controlling sulfur oxide emissions from plants
burning high-sulfur fuels, particularly coal-fired
electric generating units.
The U.S. Environmental Protection Agency, after
extensive public hearings, determined that scrubbers
were a practical solution to this problem. A number of
utilities have installed scrubber units and have worked
diligently to improve their effectiveness. The American
Electric Power System, on the other hand, is conducting an
advertising campaign attacking scrubbers as expensive,
unreliable and unnecessary. Understandably, the public
is perplexed by these charges. To help clear the air,
we have prepared this fact sheet which answers the most
common questions asked about scrubbers.
Ann L. Dore, Director
Office of Public Affairs (A-107)
What's a scrubber?
It's a chemical-mechanical system that washes ("scrubs")
sulfur oxides and particulates out of the stack gases going
up the. stacks of plants burning high-sulfur coal or oil.
Technically, these are flue gas desulfurization systems, or
FGD's for short, but "scrubber" is a handier tag to use.
Does EPA require the use of scrubbers?
No. EPA requires only that the national air quality
standards be met and that means controlling the emissions
coming out of smokestacks. Clean fuels and stack gas treat-
ment are equally acceptable.
How serious is the sulfur oxide problem?
A Federal Power Commission advisory committee recently
reported that failure to meet the air quality standards for
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY • WASHINGTON, D.C. 20460
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sulfur oxides could result each year in 6,000 premature deaths,
20 to 30 million needless days of aggravation for persons
suffering from heart and lung disorders, and 6 to 10 million
avoidable asthma attacks.
Are scrubbers the best way to handle the problem?
Considering the options, yes. The easiest solution, of
course, is to burn fuels with little or no sulfur but these
are precisely the fuels in shortest supply. Both natural
gas, our cleanest fuel, and low-sulfur oil are best reserved
for home and commercial heating since it is much easier to
control a relatively few large industrial pollution sources
than thousands of small sources. There is a lot of low-sulfur
coal available but most of it would have to come from strip
mines, which have severe environmental drawbacks. America's
greatest energy resource is deep-mined coal and most of it has
a high sulfur content. In order to make the most of this
energy resource without damaging human health, we need scrubbers
Can't the sulfur be removed before the coal is burned?
Yes, but present techniques are neither efficient nor
economi cal.
What about tall stacks? Wouldn't they disperse pollutants
over such a wide area that the impact on health would be
negligible?
EPA will not accept the permanent use of intermittent
control systems, such as tall stacks, which merely disperse
pollutants over a larger area or release them at varying times
rather than reducing or eliminating them. There isn't
enough information on pollution dispersion patterns to
enable us to know where these pollutants would go. Recent
evidence suggests that loading the atmosphere with sulfur
oxides causes a build-up of sulfates--a pollutant believed
to endanger human health even at low levels. In any event,
if thousands of plants were to resort to this tactic, their
overlapping pollution patterns would cancel out any benefits
which might be gained by dispersion. And if the method can
be used only by a few plants, who decides which ones get a
free ride on the environment and which ones must pay for
pollution control?
Who needs scrubbers?
Most of the sulfur pollutants get into the air from
electric generating plants. Out of about 1,000 existing
power plants, some 110 coal-fired plants require additional
controls to meet the health-protective standards for sulfur
oxi des .
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But do scrubbers work?
Yes. This is a relatively new technology and there
have been, and still are, bugs to be worked out. However,
over the past year we have had greatly improved performance
by many different operating units. Today a utility can
decide to install scrubber facilities with full confidence
that they can be made to operate effectively and reliably.
How effective are today's scrubbers?
We can reasonably expect 90 percent removal of sulfur
oxides. Anything better than that might cost more than it's
worth.
And reliability?
In 1974 units equipped with scrubbers were available
for utility service about 90 percent of the time. When you
consider that all generating units are shut down periodically
for routine maintenance and reductions in consumer demand,
90 percent availability is excellent.
Is it true that scrubbers will produce mountains of sludge?
No. Lime and limestone scrubbing systems do produce
large quantities of semi-solid sludge and this sludge must be
disposed of carefully so that there isn't any adverse impact
on the environment. But sludge disposal is not an insur-
mountable problem. Wet sludge can be hardened through
chemical reactions to form a dry, solid, largely inert
material which has several uses, the most important of which
is landfill. Numerous landfill sites are available in the
United States, especially in areas where there has been
strip mining. Where geographic location, space availability,
or other considerations make sludge disposal impractical,
alternative scrubber systems can be used. Regenerable
systems, such as magnesiumoxide and catalytic oxidation, do
not produce sludge. Instead, these systems regenerate the
scrubbing agent and produce such valuable materials as
elemental sulfur and sulfuric acid.
How many scrubbers do we have now?
By the end of 1974 twenty-two units will be in service.
Companies plan to start 10 more units in 1975, 12 units in
1976, and 19 units in 1977. Another 30 units will begin
operation in 1978 or 1979, or on dates not known today.
Forty-seven of these projected units are to be installed in
new plants and their start-up dates are tied to plant
construction.
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How much do scrubbers cost?
Cost varies depending on the type and size of the unit
but they are expensive. For example, Philadelphia Electric
Company will pay about $68 million to install scrubbers on
three of its generating units.
Can we afford such an expense at this time?
Unless we close the facility producing the pollution,
there is no way we can avoid paying substantial costs one
way or another. Even after taking pollution control costs
in account, using high sulfur coal can be far less expensive
than relying on imported low-sulfur oil. If high-sulfur
fuels are burned, our choice is between paying for pollution
control or for the consequences of breathing bad aii—illness
and shortened lives, higher medical bills, lost wages and
property damage. EPA research indicates that sulfur oxides
and particulates cause $11.2 billion a year in measurable
"damage, compared with annual costs of less than half that
amount to control it. EPA believes that it is better and
cheaper to pay for the ounce of prevention than the pound of
cure.
October 1974
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