POWER July 2017 - 10

THE BIG PICTURE: SO2 Success
Emissions of sulfur dioxide (SO2
) from the U.S. electric power sector have fallen a dramatic 86% since the 1970s, owing to
several factors such as the varying sulfur and heat content of coal, the heat rate of power generation, diminished generation
from coal, and the growing share of coal plants that use flue gas desulfurization (FGD) systems. Notably, since the
1970s when SO2
emission controls first became available, FGD costs have declined by nearly a third, and as of 2015 had
been installed on 60% of the nation's coal units. By comparison, fluidized bed combustion was installed on just 8% of
units, and only three plants in the U.S. employed integrated gasification combined cycle technology. Here's a look at how
the power sector's laudable environmental achievement came to be. Sources: EPA Criteria Pollutants National Tier 1
(1970-2016); " Environmental Quality and the U.S. Power Sector: Air Quality, Water Quality, Land Use and Environmental
Justice, " Oak Ridge National Laboratory (January 2017); Energy Information Administration
-Copy and artwork by Sonal Patel, a POWER associate editor
20
million tons
1970:
46%
17.5
million tons
1980:
51%
15
million tons
1990:
52%
12.5
million tons
2004-2014: Heat content declines
10
million tons
1995: Phase 1 of the
Acid Rain program
begins.
2000:
52%
7.5
million tons
2005: EPA develops Clean Air Interstate Rule
(CAIR), a cap-and-trade program to reduce
SO2 emissions beyond the Acid Rain Program.
CAIR and proposed alternatives have been
challenged in court, but they prompted 91
GW of coal-fired capacity to retrofit FGD
scrubbers.
5
million tons
2012:
2.5
million tons
2016:
30%
COAL'S SHARE OF TOTAL
U.S. GENERATION IN
THE GIVEN YEAR
1970s1980s
10
1990s
www.powermag.com
SO2
has a steep 26% decrease between
2014 and 2015, owing to low
utilization, and coal plants are retired
to comply with the federal Mercury
and Air Toxics rule.
2000s
2016:
30%
2010s
POWER | July 2017
37%
(Projected)
2007:
2010:
49%
45%
2012: Natural gas prices
decline sharply, and coal
generation starts to fall.
and heat rate increases slightly, owing
to greater production of higher sulfur
coal from Illinois Basin. However, coal
generation also generally declines, and
more FGD scrubbers are installed.
2000: Phase 2 of the
Acid Rain Program
begins.
1990: Clean Air Act
Amendments establish
national cap-and-trade
program for SO2
.
Increased coal generation,
lower heat content,
and higher heat rates
ramp up SO2 emissions.

http://www.powermag.com

POWER July 2017

Table of Contents for the Digital Edition of POWER July 2017

Contents
POWER July 2017 - Cover1
POWER July 2017 - Cover2
POWER July 2017 - Contents
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