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May 22, 2009

On April 10, EPA published in the Federal Register its proposed rule that would establish a new reporting regime for greenhouse gas emissions in the U.S. The proposal excludes normal process emissions from the wastewater treatment facilities owned by public clean water agencies, but does have implications for wastewater treatment facilities that burn fossil fuels in certain quantities. The proposal’s stationary combustion source includes sewage sludge (biosolids) incinerators, boilers and other sources used by NACWA members. Based on NACWA’s analysis, the fuel usage by any one clean water agency facility would have to be very large for it to trigger the reporting requirements.

This Regulatory Alert builds on the summary information provided in Regulatory Alert 09-01 and provides additional details to determine whether your agency will be subject to reporting. The 60-day comment period for the rule closes on June 9, and NACWA is asking its members, especially those who may be impacted by the rule, to provide comments on the proposal by May 22.

Summary of GHG Reporting Rule

The rule, if finalized, will establish a new program to estimate and report greenhouse gas (GHG) emissions annually from a wide array of industrial and commercial sources in the U.S. If finalized, the accounting and reporting requirements would likely provide the basis for any regulatory or cap and trade program that EPA or Congress might establish. EPA’s proposal outlines in detail its rationale for the rule, what sectors must report, and how each facility should calculate whether it exceeds defined reporting thresholds.

While the rule specifically excludes from the wastewater treatment category normal biologically based process emissions typically generated by publicly owned treatment works (POTWs), the rule does require annual reporting of GHG emissions from stationary fuel combustion sources that burn fossil fuels, biogas, sewage sludge, and other fuels. Annual accounting and reporting is proposed to be required if a facility exceeds a defined threshold of 25,000 metric tons of CO₂ equivalents annually. Carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) are the defined GHGs to be reported, with the common reporting metric expressed in CO₂ “equivalents” (CO₂e) by normalizing N₂O and CH₄ emissions to equivalent tons of CO₂ based on defined global warming potential values.

The rule provides a series of equations and assumptions that must be used to determine whether emissions need to be reported. In many cases, quantifying the amounts of fuel oil, diesel fuel, natural gas and other fossil fuels combusted at a POTW each year will be sufficient to account for the GHGs emitted from these stationary sources. Combustion units used for emergency power generation would not be included and biogenic CO₂ emissions from the burning of biogas would not count toward the threshold.

Who Is Subject to the Annual Reporting Requirements?
All facilities emitting 25,000 metric tons of CO₂e or more annually in aggregate emissions from stationary combustion of non-biogenic fuels (anthropogenic) in any calendar year starting in 2010 will be required to submit annual reports. Stationary fuel combustion sources are “devices that combust solid, liquid, or gaseous fuel generally for the purposes of producing electricity, generating steam, or providing useful heat or energy for industrial, commercial, or institutional use, or reducing the volume of waste by removing combustible matter. Stationary fuel combustion sources include, but are not limited to, boilers, combustion turbines, engines, incinerators, vapor combustion units, and process heaters.”

How Do I Determine if my Facility Must Estimate and Report its Emissions?
Clean water agencies with any non-emergency stationary combustion units burning fossil fuels may be subject to reporting. The quantity of fossil fuels burned annually and the aggregate maximum rated heat input capacity of the combustion units at the facility will determine whether reporting is necessary.

In general, a facility would need to be burning more than the following quantities of fuels to be subject to reporting. These are rough estimates and NACWA members should still consider the rule’s applicability provisions if they are close to these figures.

The following steps will help clean water agencies with combustion units determine if they are subject to reporting.

1. If your facility has a combined aggregate maximum rated heat input capacity of greater than or equal to 30 mmBtu/hour, then you are required to estimate your emissions to determine whether your facility exceeds the annual 25,000 metric tons of CO2e threshold. This determination is made for each facility, not for your organization as a whole.
   
   Facilities that do not have an aggregate maximum rated heat input capacity of 30 mmBtu/hr or greater are not expected to exceed the CO2e threshold and are not required to estimate their emissions.
    
2. The threshold determination entails calculating the quantity of CO₂, CH₄, and N₂O generated from each combustion unit, multiplying by the appropriate emissions factors, and summing the total CO₂e emitted. A sample calculation is provided in number 3 below.

Sewage sludge (biosolids) and biogas (methane recovered from the digestion process) are considered biomass and the CO₂ emissions associated with burning these do not count toward the threshold determination. Only CO₂ emissions from the combustion of fossil fuels are counted toward the threshold. CH₄ and N₂0 emissions from the combustion of biomass, however, should be included in the threshold determination. If the threshold is exceeded and reporting is necessary, these biomass-related CO₂ emissions should then be reported separately.

Please refer to the following summary table for pollutants in the emissions threshold determination:
 

3. The following is an example calculation for a utility with a sewage sludge incinerator using natural gas as auxiliary fuel, a boiler used for heating, and other units combusting natural gas. Calculations similar to those for the boilers below would be required for other combustion units, including electric generation units.

EPA’s proposal contains a series of default heating values and emissions factors for the various solid, liquid and gaseous fuels that might be used in these combustion units. The example below uses English units and the corresponding heating values, emission and conversion factors. The equations also use factors to convert units of CH₄ or N₂0 emissions to CO₂ equivalents. These factors (1 for CO₂; 21 for CH₄; and 310 for N₂0) reflect the global warming potential of these gases – CH₄ is 21 times more potent than CO₂ as a GHG.

The basic equation for determining the CO₂e associated with the combustion of a particular fuel as outlined in the proposal is summarized below using metric units.

CO₂e = 0.001 (conversion factor from kg to metric tons) x Fuel Quantity (Standard Cubic Feet (scf) or Gallons) x High Heat Value (mmBtu/scf or mmBtu/gallon) x Emission Factor (kg CO₂, CH₄, or N₂O/mmBtu) x Global Warming Potential (1 for CO₂; 21 for CH₄; or 310 for N₂0)

NACWA has used the basic equation above to develop the example below using English units.

1. Sewage sludge incinerators require calculation of emissions from the auxiliary fuel and the biosolids (English Units):

1. GHG emissions associated with the burning of 50,000 mcf of natural gas in the incinerators:

CO₂ = 50,000 mcf x 120 lbs/mcf x 453 grams/lb x 1 metric ton / 1,000,000 grams x 1 (CO₂e conversion factor)
          =2,718 metric tons CO₂e

 

CH₄ = 50,000 mcf x 0.0023 lbs/mcf x 453 grams/lb x 1 metric ton / 1,000,000 grams x 21 (CO₂e conversion factor) 
          =1 metric tons CO₂e

 

N₂0 = 50,000 mcf x 0.0022 lbs/mcf x 453 grams/lb x 1 metric ton / 1,000,000 grams x 310 (CO₂e conversion factor) 
          =15 metric tons CO₂e

 

Total Incinerators – Natural Gas Component = 2,735 metric tons CO₂e

 
2. GHG emissions associated with the burning of 20,000 dry U.S. tons of sewage sludge (biosolids) annually:

CO₂ = The proposed rule states that CO₂ emissions from the combustion of biogenic fuels (like biosolids) shall be excluded from the threshold determination calculations. 
          = 0 metric tons CO₂e

 

CH₄ = Given the high exhuast gas temperatures in biosolids incinerators, CH₄ emissions were determine to be 0 
          = 0 metric tons CO₂e

 

N₂0 = EPA has established a default N₂0 emissions factor for biomass (including biosolids) of 4 grams/mmBtu

 

N₂0 = 20,000 dry U.S. tons (biosolids) x 2,000 lbs/U.S. ton x 0.70 (combustible content of the biosolids) x 10,000 Btu/dry lb (combustibles) x 1 mmBtu/1,000,000 Btu x 4 grams/mmBtu x 1 metric ton/1,000,000 grams x 310 (CO₂e conversion factor)
          = 298 metric tons CO₂e

 

Total Incinerators – Biosolids Component = 298 metric tons CO₂e

2. Package Boilers (English Units) – 100,000 mcf of natural gas annually

CO₂ = 100,000 mcf x 120 lbs/mcf x 453 grams/lb x 1 metric ton/1,000,000 grams x 1 (CO₂e conversion factor)
          =5,436 metric tons CO₂e

 

CH₄ = 100,000 mcf x 0.0023 lbs/mcf x 453 grams/lb x 1 metric ton/1,000,000 grams x 21 (CO₂e conversion factor)
          =2 metric tons CO₂e

 

N₂0 = 100,000 mcf x 0.0022 lbs/mcf x 453 grams/lb x 1 metric ton/1,000,000 grams x 310 (CO₂e conversion factor)
          =31 metric tons CO₂e

 

Total Package Boilers = 5,469 metric tons CO₂e

3. Other Units Utilizing Natural Gas (small boilers, unit heaters, hot water tanks, etc)

CO₂ = 25,000 mcf x 120 lbs/mcf x 453 grams/lb x 1 metric ton/1,000,000 grams x 1 (CO₂e conversion factor) 
          =1,359 metric tons CO₂e

 

CH4 = 25,000 mcf x 0.0023 lbs/mcf x 453 grams/lb x 1 metric ton/1,000,000 grams x 21 (CO₂e conversion factor) 
          = 1 metric tons CO₂e

 

N₂0 = 25,000 mcf x 0.0022 lbs/mcf x 453 grams/lb x 1 metric ton/1,000,000 grams x 310 (CO₂e conversion factor) 
          = 8 metric tons CO₂e

 

Total Other Units = 1,367 metric tons CO₂e

 

Combined total for all units = 9,868 metric tons CO₂e

Given that the total metric tons calculated for this facility does not exceed the 25,000 MT CO₂e threshold, reporting by this facility would not be required.

Wastewater Treatment

Process emissions from the actual treatment of wastewater are not reportable and are not included in the threshold at this time. EPA states that POTWs “are not included in this proposal because...emissions from POTWs do not exceed the thresholds considered under this rule” (Section V.II of the Preamble). The technical support document for the wastewater treatment category provides the methodology EPA used to make this determination. Using the Agency’s GHG inventory and data from the Clean Watersheds Needs Survey, EPA estimated how many POTWs would trip thresholds of 1,000; 5,000; 10,000; 25,000; and 100,000 metric tons of CO2e. It will be important to ensure that EPA’s methodology for evaluating GHG emissions from municipal wastewater treatment is accurate and defensible, and NACWA encourages its members to review the technical support document available on line at: www.regulations.gov (Docket ID No.: EPA-HQ-OAR-2008-0508-0035). EPA’s exclusion of POTW emissions at this point is based on the Intergovernmental Panel on Climate Change (IPCC) methodology of estimating N₂0 emissions, which is based on per capita loadings of ammonia into treatment plants. NACWA’s work under the Critical Issues Action Initiative and earlier Targeted Action Fund efforts has focused on ensuring that these IPCC estimates are accurate. Research is currently being conducted by the Water Environment Research Foundation (WERF) to develop N₂0 emissions factors based upon direct source testing, which could ultimately impact how emissions from wastewater treatment plants are estimated.

Reporting Requirements

Entities subject to reporting would begin collecting data on January 1, 2010 under the proposal. The first emissions report would be due on March 31, 2011, for emissions during 2010. Reports would be submitted annually. All reporting would be electronic and designated representatives would be required to sign using an electronic signature device. The report would include total annual GHG emissions in metric tons of CO2e and separately present annual mass GHG emissions for each source category by gas. This proposed federal program would not preempt other local, state or regional reporting requirements such as the California mandatory reporting rule.

NACWA Next Steps

NACWA attended an April 6-7 public meeting on the proposal and is working to develop comments on the proposal by the June 9 deadline. NACWA encourages its members to review the proposal and determine how it may affect your facility. Please contact Chris Hornback at This e-mail address is being protected from spambots. You need JavaScript enabled to view it if you have comments or would like to discuss how this may impact your utility.

^[1] These figures are rough estimates. For incinerators, the actual quantity of fuel combusted that will exceed the reporting threshold will be slightly less than these figures depending on the annual quantity of biosolids combusted.