August 2015: Sulfur Dioxide in Indiana

Indiana is making tremendous progress in reducing sulfur dioxide emissions from coal fired utilities operating here, according to data we have been collecting since 1980. Indiana has unique monitoring requirements, and IDEM collects more SO2 data than most other states. SO2 is monitored near utilities, in addition to 10 continuous SO2 monitors that IDEM operates under federal requirements. (Most states operate the minimum number of monitors required by federal regulations.)

We have seen dramatic reductions of SO2 in the ambient air around six coal fired utilities in Indiana. These six sites have measured SO2 since 1980, and I used the current standard (the 99th percentile of one hour SO2 levels) to see how levels have changed over the years.

  • The site in Floyd County has dropped from a level of 291 parts per billion (ppb) in 1980 to a level of 44 ppb in 2014 (a decrease of 85%).
  • The site in Fountain County has dropped from a level of 319 ppb in 1980 to a level of 22 ppb in 2014 (a decrease of 93%).
  • The site in Jasper County has dropped from a level of 70 ppb in 1980 to a level of 25 ppb in 2014 (a decrease of 64%).
  • The site in Lake County has dropped from a level of 372 ppb in 1980 to a level of 20 ppb in 2014 (a decrease of 95%).
  • The site in LaPorte County has dropped from a level of 120 ppb in 1980 to a level of 15 ppb in 2014 (a decrease of 88%).
  • The site in Porter County has dropped from a level of 126 ppb in 1980 to a level of 27 ppb in 2014 (a decrease of 79%).

Table 1, below, shows yearly data for these six sites going back to 1980.

Reductions in SO2 emissions are equally as impressive. Table 2 shows SO2 emissions from coal fired power plants from 1980 up through 2014. In 1980, the total emission rate was 1,566,260 tons per year of SO2. By 2014, it was down to 290,664 tons per year (a decrease of 81%). In 1980, two separate plants, Clifty Creek and Gibson, put out more SO2 than all utilities put out in 2014.

We expect to see even more reductions in SO2 emissions in the next few years. The Wabash River plant is expected to close. It had approximately 27,000 tons of SO2 in 2014. The Gallagher plant is expected to close its two remaining coal fired units and switch to a natural gas generating facility. This source emitted approximately 1,500 tons of SO2 in 2014. IPL’s Eagle Valley facility, which is currently coal fired, will be replaced with a new natural gas generating facility. Eagle Valley emitted approximately 8,000 tons of SO2 in 2014. IPL plans to convert the Harding Street station from coal to natural gas. This facility emitted approximately 30,000 tons of SO2 in 2014.

The fact that we have nine townships in parts of five counties classified as non-attainment under the current SO2 standard does not mean we failed. Indiana has a long history of compliance with the previous SO2 standard. What may not be recognized is that the current one-hour standard for SO2 was adopted only a few years ago. We are achieving the new standard at many sites. One of the reasons some areas have non-attainment classifications under the more stringent standard is our requirement for monitors around utilities. Full compliance is expected within the coming two to three years.

Table 1: Measured SO2 Levels (ppb) – 99th Percentile – 1 Hour Values
Year Floyd
043-1004
Fountain
045-0001
Jasper
073-0002
Lake
089-2008
LaPorte
091-0005
Porter
127-0011
1980 291 319 70 372 120 126
1981 243 251 78 337 98 124
1982 235 224 48 322 54 105
1983 201 238 80 340 92 104
1984 263 285 74 45 113 136
1985 250 261 52 451 126 140
1986 258 271 54 179 113 112
1987 242 210 73 209 107 125
1988 210 290 72 152 98 190
1989 241 235 65 97 68 182
1990 188 244 71 234 55 145
1991 220 230 58 111 63 76
1992 153 220 66 232 45 66
1993 179 204 53 166 87 71
1994 135 196 53 166 58 67
1995 161 176 56 151 49 62
1996 153 177 51 111 51 57
1997 127 225 56 107 56 73
1998 130 187 52 191 44 70
1999 149 212 62 93 35 69
2000 163 104 74 105 32 62
2001 151 118 60 115 37 53
2002 119 114 44 53 33 57
2003 173 127 66 72 31 53
2004 174 125 44 39 31 59
2005 158 180 58 42 29 74
2006 177 169 64 36 27 55
2007 194 200 49 50 26 62
2008 138 236 61 37 29 82
2009 125 38 88 37 23 51
2010 123 26 39 34 30 62
2011 38 29 32 40 19 44
2012 32 30 33 28 21 36
2013 21 34 40 24 15 36
2014 44 22 25 20 15 27

Table 2: SO2 Emissions from Indiana Coal Fired Utilities (Tons Per Year)

  • 1980: 1,566,260
  • 1985: 1,406,766
  • 1986: 1,473,523
  • 1987: 1,413,122
  • 1988: 1,422,091
  • 1989: 1,507,640
  • 1990: 1,499,176
  • 1991: 1,338,157
  • 1992: 1,208,864
  • 1993: 1,037,977
  • 1994: 1,276,771
  • 1995: 894,566
  • 1996: 933,624
  • 1997: 979,403
  • 1998: 968,182
  • 1999: 941,855
  • 2000: 874,592
  • 2001: 795,392
  • 2002: 778,760
  • 2003: 804,666
  • 2004: 862,726
  • 2005: 870,710
  • 2006: 820,924
  • 2007: 714,497
  • 2008: 595,964
  • 2009: 413,714
  • 2010: 414,219
  • 2011: 371,961
  • 2012: 273,596
  • 2013: 268,195
  • 2014: 290,664