The Constitution of Air Pollution
October 2, 2014

Oil and gas operators (O&G) know that air pollution is an important matter to be concerned about every day.  Air quality rules affect operations, engineering, accounting, purchasing, and environmental and safety departments.  With the focus on hydraulic fracturing of wells and resultant air emissions from new well facilities, these air quality issues are expected to only get more regulatory scrutiny.  In fact, the EPA is currently looking at the potential to make the NSPS OOOO (Quad O) regulations more stringent in 2015. It is important to know about the constitution of air pollution and why you need vent gas management

Flare burning natural gas from production facility.

flare_shutterstock_173810612.jpg

 

Below is a brief summary of air pollution and processes that generate the different regulated air pollutants from O&G operations. 

Sources of Air Pollution

A definition of air pollution is the presence of contaminants or pollutant substances in the air that interfere with human health or welfare, or produce other harmful environmental effects.  Air pollution is generated by the following activities occurring during the drilling, production, transmission and distribution of O&G:   

  • Combustion of fossil fuels such as natural gas, diesel fuel and gasoline.  Diesel is the primary fuel for drilling.  Natural gas is mainly used for O&G production, processing and transmission. 
  • Venting of natural gas or liquid hydrocarbon vapors

Combustion emissions can result from internal combustion engines, line heaters, boilers, heater treaters, reboilers, flares, enclosed combustors and incinerators. 

Venting of natural gas can result from fugitive emissions (leaking components), oil and produced water storage tanks, glycol dehydrators, gas sweetening units, pressure safety devices, pneumatic devices, well unloading, casing head gas releases, venting from well completions, compressor seals and pipeline/facility blowdowns. 

Categories of Air Pollutants

The federal regulations (USEPA) that seek to minimize air pollution emissions have created four general categories of air pollution.  These categories include:

Some air pollutants fall into more than one category. 

Generally, O&G operations do not result in release of ozone depleting substances except for possible releases from auxiliary equipment (e.g., refrigerators, A/C units) and safety systems (e.g., fire suppression). 

Regulation of Air Pollution

Each air pollutant and/or air pollutant category will have its own unique federal, state or local air quality regulations affecting the processes and equipment that generate these pollutants.  Some states (e.g., Louisiana) use the term toxic air pollutant (TAP) for HAPs and have a HAP listing that may include pollutants not included in the federal HAP listing. 

There are many different local, state and federal regulations that affect stationary (permanent) facilities such as a production facilities and mobile sources (onsite <1 year) such as drilling rigs.  YES – IT IS AN ALPHABET SOUP. 

Always consult your state or local permitting agency to ensure compliance with air quality permitting rules and emission standards. 

For greenhouse gases (GHG), the USEPA requires annual reporting under 40 CFR 98 Subpart W for O&G.  As of October 2014, only very large sources of GHGs may be require control of GHG emissions.

For Criteria Pollutants and Hazardous Air Pollutants (HAPs), very strict federal regulations are in effect to control air emissions from stationary sources at O&G facilities.  The regulations are typically enforced by state agencies.  The regulatory mechanisms include:  

  • Air permits – permits that specify limits to air emissions, control methods, monitoring, testing, recordkeeping and reporting.  Typically, air permits are granted and enforced by state and local environmental agencies. Some states require a construction permit to obtained prior to construction and then will issue an operating permit; other states combine the construction and operating permit.  The use of General Permits for oil and gas operations is common in many states. 
  • New Source Performance Standards (NSPS) – standards that apply to specific processes and equipment to control Criteria Pollutants (or precursor such as VOC).  For example, the NSPS in 40 CFR 60 Subpart OOOO.  Check out the Texas Commission on Environmental Quality’s (TCEQ) great online NSPS rule summaries and links for more information. 
  • National Emission Standards for Hazardous Air Pollutants (NESHAPS) standards that apply to specific facilities, processes and equipment to control HAPs.  For example, glycol dehydrators are regulated in 40 CFR 63 Subpart HH and HHH.  Check out the TCEQ’s online NESHAPS rule summaries and links for more information. 

To help you understand some of the ABCs of air pollutants, refer to the table below. 

List of Primary Air Pollutants Regulated

Air Pollutant

Common Abbrev

EPA Pollutant Class

Primary Reason for Regulation of Air Pollutant

Major Process Causing the Pollutant

Main O&G Equipment Emitting the Pollutant

Carbon Dioxide

CO2

GHG

GHG with global warming potential of 1. 

Fuel Combustion

Engines

Methane

CH4

GHG

GHG with global warming potential of 25.

Nat. Gas Venting

All process vents and fugitive leaks

Nitrous Oxide

N2O

GHG

GHG with global warming potential of 310.

Fuel Combustion

Engines

Nitrogen Oxides

NOx

Criteria

Precursor to ozone and smog formation.

Fuel Combustion

Engines

Nitrogen Dioxide

NO2

Criteria

Respiratory irritant and precursor to smog.

Fuel Combustion

Engines

Ozone

O3

Criteria

Primary component of smog. Ozone created by sunlight acting on NOx and VOC in the air.

N/A

Not emitted by O&G operations.

Carbon Monoxide

CO

Criteria

Can cause harmful health effects by reducing oxygen delivery to the body's organs.

Fuel Combustion

Engines

Sulfur Dioxide

SO2

Criteria

Component of smog and PM.  Respiratory impacts to humans.

Fuel Combustion

Sour gas flaring/ combustion

Particulate Matter, PM2.5

PM2.5

Criteria

Soot/Particulate matter <2.5 microns aerodynamic diameter.  Respiratory and heart impacts to humans.

Fuel Combustion

Diesel Engines

Particulate Matter, PM10

PM10

Criteria

Soot/Particulate matter <10 microns aerodynamic diameter.  Respiratory and heart impacts to humans.

Fuel Combustion

Diesel Engines

Volatile Organic Compounds

VOC

Other  - VOC

Precursor to ozone and smog formation.  Propane plus (C3+) fraction of natural gas.

Nat. Gas Venting

Nat. Gas Venting and Tank Vapors

Hydrogen Sulfide

H2S

Other

Acutely toxic chemical.

Nat. Gas Venting

Sour gas venting

Acetaldehyde

N/A

HAP, VOC

Respiratory system irritation. 

Fuel Combustion

Engines

Formaldehyde

N/A

HAP, VOC

Carcinogen risk & blood disorders in humans. 

Fuel Combustion

Engines

Benzene

BTEX

HAP, VOC

Carcinogen risk. 

Nat. Gas Venting

Glycol Dehydrators

Toluene

HAP, VOC

Central nervous system dysfunction.

Nat. Gas Venting

Glycol Dehydrators

Ethylbenzene

HAP, VOC

Respiratory system irritation. 

Nat. Gas Venting

Glycol Dehydrators

Xylenes

HAP, VOC

Respiratory system irritation. 

Nat. Gas Venting

Glycol Dehydrators

N-hexane

n-C6

HAP, VOC

 CNS depression in humans.

Nat. Gas Venting

Glycol Dehydrators

2,2,4-trimethylpentane

N/A

HAP, VOC

Respiratory system irritation and CNS depression.

Nat. Gas Venting

Glycol Dehydrators

Note that most oil and gas venting sources have the potential to emit methane, VOCs and HAPs (e.g., n-hexane, BTEX) listed.  Oil and gas combustion sources can emit methane, VOCs and BTEX due to incomplete combustion of natural gas, gasoline and diesel fuel.

Emission Controls

Regulations and air permit requirements specify emission reductions for certain equipment, processes and facility types.  Review the facility’s air permit and specific NSPS and NESHAPS for requirements.  A detailed discussion of emission controls is not included in this topic. 

VOC Emissions and HAPs from Venting

Emissions from venting sources at O&G operations will use VRUs (vapor recovery units), flares and enclosed combustion units to control VOC emissions.  This is especially true for VOC venting from Quad O facilities. 

Some sources such as glycol dehydration units will use a condenser plus recovery by a VRU or combustion of non-condensable gases from the still column vent. 

Combustion Source Emission Controls

Depending on the type of engine, an internal combustion engine will use catalytic converters to control emissions of NOx, CO, VOCs and HAPs.  Some engines are designed to be inherently low emitters of NOx and CO emissions. 

Monitoring of Venting Sources

With the development of IR cameras that can “see” and record natural gas venting emissions and storage tank flaring, operators, regulators and the public are finding new ways to detect and fix leaks from oil and gas facilities.  The regulatory agencies are using new technology every day to find the leaks.  Operators are aware of this and are working to find better ways to prevent, detect and repair leaks in a timely manner. 

Concerned Air Pollution?

HY-BON is your expert at vent gas management.  We use our IQR Survey to help O&G operators find leaks, quantify storage tank emissions and rectify the emissions.  This helps a company with their GHG data management stay in compliance and can make the company money by recovering valuable product.  Let HY-BON take away some of your air pollution concerns so your facilities stay in compliance.