What is the EPA 40 CFR Part 75 Regulation?
Learn about the Part 75 rule created by the U.S Environmental Protection Agency (EPA) to establish requirements for monitoring and recordkeeping of air pollutants emitted from electric generating units (EGU) in support of the Acid Rain Program (ARP).
A 40 CFR Part 75 Overview
The Part 75 rule found in Volume 40 of the Code of Federal Regulations (CFR) was created by the U.S Environmental Protection Agency (EPA) to establish requirements for monitoring and recordkeeping of air pollutants emitted from electric generating units (EGU) in support of EPA’s Acid Rain Program (ARP).
The Part 75 regulations consist of eight subparts based on the purpose and applicability of the regulation, requirements relevant to each pollutant, missing data procedures, certification and recertification requirements, and recordkeeping and reporting policies. Part 75 also includes ten appendices that highlight CEMS requirements and data calculation guidelines based on pollutant and fuel type.
An in-depth overview of 40 CFR Part 75 can be found in EPA’s Plain English Guide to the Part 75 Rule.
What Does 40 CFR Part 75 Do?
Part 75 was originally published in 1993 to provide support for the ARP which was instituted in 1990 under Congress’ Title IV of the Clean Air Act. The program regulates EGUs that burn fossil fuels and serve a generator greater than 25 megawatts. Part 75 requires these units to provide continuous emissions monitoring (CEM) and reporting of three pollutants:
- Sulfur dioxide (SO2)
- Carbon dioxide (CO2)
- Nitrous oxides (NOx)
The Acid Rain Program and Part 75
One of the main purposes of Part 75 is to support the ARP in requiring emission reductions of SO2 and NOx, the main precursors of acid rain. Acid rain is created when SO2 and NO2 react with water, oxygen, and other chemicals to form sulfuric and nitric acids. These acids combine with water and deposit in the form of acid rain, which is harmful to ecosystems and the environment.
Part 75 is referenced in several other core Acid Rain rules and also interfaces with parts of the New Source Performance Standards (NSPS) in 40 CFR Part 60. There are currently three active programs that require Part 75 monitoring:
- Acid Rain Program (Federal)
- Clean Air Interstate Rule (CAIR) (Federal)
The regulations within Part 75 also include requirements for continuous emissions monitoring (CEM) or opacity monitoring systems to ensure they are working properly. Specifications for these requirements are included in the appendices.
What are the 40 CFR Part 75 Subparts and Appendices?
The subparts of Part 75 are based on the purpose and applicability of the regulation, requirements relevant to each pollutant, missing data procedures, certification and recertification requirements, and recordkeeping and reporting policies.
EPA added Subpart H to Part 75 in 1998. This subpart was adopted due to growing concerns over hazards associated with NOx emissions, as NOx is a precursor to ozone and fine particulate matter formation.
The appendices of Part 75 break down specific requirements for CEMS and guidelines for calculating and estimating emissions data. Appendix D and E specify the methodology and protocol of emissions monitoring depending on the fuel type fired by an EGU (coal, gas, or oil).
Why is Continuous Monitoring Necessary?
SO2, NOx, and CO2 are monitored under a “cap and trade program” in which EPA (or a state regulatory agency in the case of CO2) limits the total annual/seasonal mass emissions of the pollutant and divides it into emission allowances that are allocated to sources over a period of time. Sources may buy and sell allowances from each other. To measure the total mass of emissions over time, the emissions must be monitored continuously. Part 75 provides a necessary measurement method by:
- ensuring that the emissions from all sources are consistently and accurately measured and reported,
- requiring a complete record of emission data to be produced for each unit in the program (i.e., data are obtained for every hour of unit operation), and
- verifying that emission caps are not exceeded, thereby ensuring that emissions are not underestimated and that emission reduction goals are being met.
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