May 2009
Summary of Greenhouse Gas Reporting Requirements for Landfills
ALERT: Your facility may be one of the 13,000 facilities in the US potentially impacted by EPA’s proposed greenhouse gas emissions regulations.
On March 10, 2009, the Environmental Protection Agency (EPA) proposed rule 40 CFR 98, which would require mandatory reporting of greenhouse gas (GHG) emissions from large sources in the United States. The proposed rule was published in the Federal Register on April 10, 2009, and the public comment period is open until June 9, 2009. The rule would require collecting and reporting comprehensive emissions data from certain facilities, suppliers of fossil fuels and industrial GHGs, manufacturers of vehicles and engines, and some facilities that emit 25,000 metric tons per year or more of GHGs. The purpose of this memorandum is to provide a brief overview of the proposed rule relative to the landfill industry.
General Provisions - 40 CFR Part 98
If enacted, the rule would require reporting of annual emissions of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6), hydrofluorocarbons (HFCs), perfluorochemicals (PFCs), and other fluorinated gases (e.g., nitrogen trifluoride, hydrofluorinated ethers [HFEs]). The proposed rule would apply to certain facilities that emit GHGs, including landfills that generate greater than 25,000 metric tons (tonnes) of carbon dioxide equivalents (CO2e) per year. The primary GHG emitted from landfills is methane (CH4).
Background - Landfills
The decomposition of waste in municipal and industrial landfills produces significant quantities of CH4. Methane gas is of concern as a GHG because it has a global warming potential (GWP) of 21. The GWP is a measure of a compound’s ability to trap heat relative to the effects of CO2. In other words, methane traps heat 21 times more efficiently than CO2. The EPA estimates that the 7,800 municipal solid waste (MSW) landfills in the United States emitted over 111 million metric tons (tonnes) of CO2e in 2006. Approximately 33 percent of these landfills account for 82 percent of total GHG emissions from MSW landfills, all of which generate greater than 25,000 tonnes CO2e annually. Commensurate with other reporting programs, EPA is proposing a generation threshold of 25,000 tonnes CO2e for MSW landfills that would be required to report under the proposed rule regardless of whether the gas is collected or destroyed. Under this reporting threshold, EPA estimates that 1,001 active and 1,550 closed MSW landfills would be required to report their 2010 GHG emissions.
In addition to MSW landfills, industrial landfills are considered to be major sources of GHGs as well. EPA estimates that industrial landfills at 180 pulp and paper facilities emitted 7.3 million tonnes CO2e in 2006. Additionally, landfills at 189 food processing facilities emitted 7.2 million tonnes CO2e in 2006. GHG emissions from industrial landfills would be reported only if the combined emissions from the facility meet the reporting requirements for the respective industry. For example, pulp and paper, food processing, and ethanol production facilities with on-site landfills would be required to report landfill emissions if the total GHG emissions emitted at the facility (including combustion sources, etc) are greater than 25,000 tonnes CO2e. However, on-site landfills at petroleum refineries would be accounted for regardless of the amount of CO2e emitted since all petroleum refineries would be required to report their GHG emissions.
Hazardous waste landfills and construction and demolition landfills are not included in the landfills source category under the proposed rule because they are not considered a significant source of GHG emissions.
Subpart HH – Landfills
The proposed rule defines MSW Landfills as:
“…an entire disposal facility in a contiguous geographical space where household waste is placed in or on land. An MSW landfill may also receive other types of RCRA Subtitle D Wastes (§257.2 of this chapter) such as commercial solid waste, nonhazardous sludge, conditionally exempt small quantity generator waste, and industrial solid waste. Portions of an MSW may be separated by access roads. As MSW landfill may be publicly or privately owned.”
40 CFR 98 Subpart HH would require municipal and industrial landfills to report both CH4 generation and emissions. This subpart also includes reporting requirements for industrial landfills but does not include hazardous waste landfills or construction and demolition landfills (as previously stated). Facilities would also report the CH4 destruction resulting from landfill gas collection and combustion systems, and CO2, CH4, and N2O emissions from stationary fuel combustion devices (includes supplemental fuels used for flaring). CO2 emissions resulting from the flaring and combustion of captured landfill gas are not included in the proposed rule and would not be required to be reported.
Monitoring of Emissions
The proposed rule lists three monitoring methods to estimate GHG emissions. These methods include:
- Modeling Method – Methane generated by the landfill is quantified using the Intergovernmental Panel on Climate Change’s (IPCC) First Order Decay Model (2006).
- Engineering Method – The flow rate and CH4 concentration of collected landfill gas are directly measured to determine the CH4 generated by the landfill.
- Direct Measurement – Methane generated by the landfill is quantified through direct measurement methods including flux chambers and optical remote sensing.
EPA determined that direct measurement techniques are typically expensive, provide only short-term measures of emissions, and often suffer from high uncertainty. As such, EPA is proposing a combination of monitoring methods, modeling, and engineering methods to determine CH4 emissions from landfills.
Estimating Modeled Methane Generation
Under the proposed rule, modeled methane generation would be required to be determined via the IPCC First Order Decay (FOD) Model. The FOD Model allows for two different calculation options. The first is a waste material-specific option, and the second is a bulk waste option.
Under the proposed rule, EPA would require that all industrial landfills employ the first calculation option to estimate modeled methane generation. Additionally, MSW landfills that have material-specific waste quantity data available would be required to use the first calculation option. However, where MSW landfills do not have waste material-specific data, the second calculation option would be used (bulk waste). The FOD Model’s equation is available in spreadsheet format at the EPA website: www.epa.gov/ttn/catc/products.html#software.
Estimating Methane Generation and Emissions
The modeled methane generation must be adjusted to account for the portion of CH4 that is oxidized by aerobic microorganisms in the landfill cover material prior to being released into the atmosphere. The methane generation is determined by application of a default oxidation fraction (0.1) to the modeled methane generation. For landfills without gas collection systems, the methane emissions are the same as the adjusted methane generation. For landfills with gas collection systems, the emissions are reduced by the amount of gas recovered while considering the destruction efficiency of the control system (default efficiency is 99 percent).
The methane recovered is determined via the engineering method of monitoring the recovered landfill gas flow rate and methane content. The flow rate and methane content of recovered landfill gas may be determined through continuous metering or monthly sampling. Monthly sampling involves the use of a gas flow meter and a gas composition meter. Data including the flow rate, CH4 concentration (%), temperature, and pressure are recorded. The data can then be used to calculate the quantity of methane recovered (mass/yr).
Under the proposed rule, landfills with gas collection systems may also use an alternative method for determining methane generation and methane emissions. The alternate method for determining the methane generation and emissions involves the use of the methane recovered, the collection efficiency of the system (taking into account system coverage, operation, and cover system materials [default is 75 percent]), the oxidation fraction (from landfill cover material), and the destruction efficiency of the control device (default of 99 percent).
GHGs to Report / Inventory
Under the proposed rule, the following information would be required to be reported:
- CH4 generation and CH4 emissions from landfills.
- CH4 destruction resulting from landfill gas collection and combustion systems.
- CO2, CH4, and N2O emissions from stationary fuel combustion devices. This includes emissions from the combustion of supplementary fuels used in flares. CO2 emissions resulting from the flaring and combustion of landfill gas are not to be reported or accounted for.
Since EPA is proposing a reporting threshold approach for landfills, an important question for small and medium-sized MSW/industrial landfills is whether or not their emissions fall below their respective reporting thresholds. The reporting threshold for MSW landfills would be 25,000 tonnes of generated CO2e annually. GHG emissions from on-site industrial landfills at food processing, ethanol, and pulp and paper facilities would be required to be reported if the facility’s total GHG emissions (including combustion sources, etc.) is 25,000 tonnes of CO2e annually or greater. For those facilities already required to report under the proposed rule (e.g., petroleum refineries), emissions associated with on-site landfills would be required to be reported regardless.
Recordkeeping / Reporting
If the rule is enacted, all affected landfills would begin monitoring GHG sources on January 1, 2010. Landfills would report all GHG emissions on March 31, 2011, for the 2010 reporting year. Each annual GHG report would be certified by the facility to be true, accurate, and complete. EPA would have the jurisdiction to perform selective random audits of all facilities in respective EPA regions. The rule would require QA/QC documentation and demonstrations on how each emission source is calculated. Facility record maintenance would be required for 5 years.
