Massachusetts haze plan counts on coal unit shutdowns

The U.S. Environmental Protection Agency proposes to approve a regional haze State Implementation Plan for the state of Massachusetts that would lock in emissions reductions at several power plants, including the Brayton Point and Salem Harbor coal units of Dominion Resources (NYSE: D).

EPA in a May 24 Federal Register notice said it is proposing approval of a revision to the Massachusetts SIP that addresses regional haze for the first planning period from 2008 through 2018. It was submitted by the Massachusetts Department of Environmental Protection (MassDEP) in December 2011. EPA is also proposing to approve a supplemental regional haze submittal from Feb. 17. EPA will be taking public comment on its proposed approval of these changes until June 25.

As allowed by the regional haze rule, Massachusetts opted to pursue source-by-source Best Available Retrofit Technology (BART) determinations for select sources and to demonstrate an “Alternative to BART” for other sources. Under the source-by-source category, MassDEP developed an individual BART determination for Wheelabrator-Saugus Units 1 and 2. Wheelabrator-Saugus is a municipal waste combustor which contains two mass burn incinerators with water wall boilers.

Other facilities fell under the BART alternative. That category offers permit restrictions for Mount Tom, Brayton Point and Salem Harbor that: disallow the use of SO2 Early Reduction Credits and federal Acid Rain Allowances; place an annual cap of 300 tons of SO2 for Salem Harbor Unit 2, and call for a shutdown of Units 3 and 4 beginning June 1, 2014; the retirement of the Somerset Power coal plant in 2010; institution of a low-sulfur fuel oil regulation, which would require electricity generating units (EGUs) that burn residual oil to limit the sulfur content to 0.5% by weight beginning July 1, 2014.

  • In May 2009, MassDEP issued an amended Emission Control Plan Final Approval for Mount Tom that prohibits the use of Early Reduction Credits (ERCs) and federal Acid Rain Allowances for compliance after June 1, 2014.
  • On Feb. 16, at Brayton Point’s request, MassDEP issued an Amended Emission Control Plan Draft Approval which prohibits the use of ERCs and federal Acid Rain Allowances for compliance after June 1, 2014.
  • On Feb. 17, at Salem Harbor’s request, MassDEP proposed an Amended Emission Control Plan that prohibits the use of ERCs and federal Acid Rain Allowances for compliance after June 1, 2014. The emission control plan also establishes an annual cap of 300 tons of SO2 for Salem Harbor 2 and the shutdown of Units 3 and 4 effective June 1, 2014. Under a consent decree, Salem Harbor Units 1 and 2 were removed from service as of Dec. 31, 2011. MassDEP’s proposed permit restrictions will make the emission reductions from Salem Harbor federally enforceable. As such these reductions are not required under the consent decree and are included in Massachusetts’ Alternative to BART.
  • Instead of complying with the new restrictions, the coal-fired Somerset Power plant ceased operating in 2010, and in June 2011, at Somerset Power’s request, MassDEP issued a letter that revoked all air approvals and permits for the facility and deemed all pending permit applications withdrawn.

MassDEP calculated that the Alternative to BART results in an estimated SO2 reduction of 54,986 tons from 2002 emissions (89,254 tons minus 34,268). This reduction is 4,234 tons (54,986 tons minus 50,752 tons) more than the calculated emission reduction from the BART benchmark.

New NOx limits also rely in part on coal shutdowns

The Massachusetts Alternative to BART for NOX relies on: new NOX emissions limits for certain EGUs; an annual cap of 276 tons of NOX for Salem Harbor Unit 1 and an annual cap of 50 tons of NOX for Unit 2, and a shutdown of Units 3 and 4 beginning June 1, 2014; the retirement of Somerset Power in 2010; and Reasonably Available Control Technology (RACT) for sources of NOX that establishes NOX emission standards for various sources, including EGUs.

A MassDEP existing regulation establishes a rolling 12-month average NOX emission rate of 1.5 lbs/MWh and a monthly average emission rate of 3 lbs/MWh. This applies to Brayton Point (Units 1-4), Canal Station (Units 1-2), Mount Tom (Unit 1), Mystic (Units 4, 5, 6, 7, 81, 82, 93 and 94), Salem Harbor (Units 1-4), and NRG Somerset (Unit 8).

On Feb. 17, at Salem Harbor’s request, MassDEP proposed an amended ECP approval that requires an annual cap of 276 tons of NOX for Salem Harbor Unit 1 and an annual cap of 50 tons of NOX for Unit 2, and a shutdown of Units 3 and 4 beginning June 1, 2014. While these units are subject to a consent decree that requires them to be removed from electric generation service, the consent decree does not prevent these units from operation other than electric generation service. Therefore, Massachusetts’ proposed amended ECP approval will result in an enforceable limitation on emissions from Salem Harbor in excess of currently required reductions.

A MassDEP existing regulation establishes NOX emission rates for various stationary sources, including EGUs. Cleary Flood Units 8 and 9 are subject to a NOX emission rate of 0.28 lbs MMBtu. Mystic Unit 7 is subject to a NOX emission rate of 0.25 lb/MMBtu. Mystic is also subject to this rule on a facility-wide basis. However, Mystic Unit 7 could exceed the set NOX rate of 1.5 lbs/MWh while the facility as a whole complies with the rate because the other units at Mystic are natural gas-fired with low NOX emissions, and therefore the established unit-specific NOX rate of 0.25 lbs/MMBtu is the controlling factor for Unit 7.

The BART benchmark results in a calculated emission reduction of 12,820 tons of NOX (20,034 tons minus 7,214 tons) from 2002 emissions. The Alternative to BART results in an emission reduction of 13,116 tons (26,455 tons minus 13,339 tons) from 2002 emissions.

For the third BART pollutant, particulate matter (PM), Massachusetts’ proposed Alternative to BART does not cover PM10 emissions. Collectively, the covered facilities emitted 1,531 tons of PM10 in 2002.Through installation of controls for other purposes, these facilities have significantly reduced PM emissions, so that in 2009 these facilities emitted a total of 109 tons of PM10.

SO2 controls installed at Brayton Point

Several of the Massachusetts EGUs already have installed SO2 controls or are planning additional SO2 controls to help them meet regulatory limits. Brayton Point has installed spray dryer absorbers on Units 1 and 2 and plans to operate a dry scrubber on Unit 3 starting in 2012. Mount Tom has installed a dry scrubber. Salem Harbor plans to shut down all units by 2014. Somerset Power shut down in 2010. Canal Station is using lower sulfur oil and will be subject to MassDEP’s proposed low sulfur oil regulation. SO2 emissions were reduced by 72% from 2002 to 2011 at the targeted units. Additional reductions will occur in the 2012–2014 timeframe as the Salem Harbor units retire and the Brayton Unit 3 scrubber becomes operational.

MassDEP believes that there will be further emissions reductions at the targeted units as a result of EPA’s recently issued Mercury and Air Toxics Standards (MATS) rule. MATS gives coal units with scrubbers a compliance option to meet an SO2 emissions rate of 0.2 lbs/MMBtu as an alternative to a hydrogen chloride emissions rate, which is more stringent than MassDEP’s annual SO2 emissions rate (3.0 lbs/MWh, which is roughly equivalent to 0.3 lbs/MMBtu). Brayton Point and Mt. Tom may choose this option for their coal units, thereby further reducing their permitted SO2 emissions, EPA noted.

To be subject to MATS in a given year, an EGU must fire coal or oil for more than 10% of the average annual heat input during the three previous consecutive calendar years, or for more than 15% of the annual heat input during any one of the three previous calendar years. This provision provides an incentive to Canal Unit 2, which can burn oil or natural gas, to limit the amount of oil it burns so that it is not subject to MATS, which would result in future SO2 emissions continuing to be lower than permitted emissions.

MATS also establishes work practices (versus emissions rates) for oil-fired units with an annual capacity factor of less than 8% of their maximum heat input. Canal Unit 1’s utilization was 1% in 2011, and thus has an incentive to remain below 8%, which would result in future SO2 emissions staying lower than its permitted emissions. Even without MATS, oil-fired combustion at Canal Units 1 and 2 is expected to be low well into the future because of the high cost of oil relative to natural gas. This cost differential is why Canal’s utilization currently is very low.

MassDEP conservatively projects SO2 emissions in 2018 would represent at least a 67% reduction compared to 2002 emissions. However, taking into account EPA’s MATS, including the SO2 compliance option and incentives for low utilization of oil-fired units, MassDEP believes there is a likelihood that SO2 emissions in 2018 will be up to 87% lower than 2002 emissions.

Brayton Point Unit 1-3 are fired by coal, while Unit 4 is fired by oil and natural gas. Salem Harbor Unit 4 is fired by oil, while Unit 3 is fired by (and the shut Units 1-2 were fired by) coal. Mount Tom, controlled by FirstLight Power Resources, is fired by coal.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.