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Fugitive emissions are leaks and other irregular releases of gases or
vapor In physics, a vapor (American English) or vapour (British English and Canadian English; see spelling differences) is a substance in the gas phase at a temperature lower than its critical temperature,R. H. Petrucci, W. S. Harwood, and F. G. Her ...
s from a pressurized containment – such as appliances, storage tanks, pipelines, wells, or other pieces of equipment – mostly from industrial activities. In addition to the economic cost of lost commodities, fugitive emissions contribute to local air pollution and may cause further environmental harm. Common industrial gases include refrigerants and
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon di ...
, while less common examples are perfluorocarbons,
sulfur hexafluoride Sulfur hexafluoride or sulphur hexafluoride ( British spelling) is an inorganic compound with the formula SF6. It is a colorless, odorless, non-flammable, and non-toxic gas. has an octahedral geometry, consisting of six fluorine atoms attached ...
, and
nitrogen trifluoride Nitrogen trifluoride () is an inorganic, colorless, non-flammable, toxic gas with a slightly musty odor. It finds increasing use within the manufacturing of flat-panel displays, photovoltaics, LEDs and other microelectronics. Nitrogen triflu ...
. Most occurrences of fugitive emissions are small, of no immediate impact, and difficult to detect. Nevertheless due to rapidly expanding activity, even the most strictly regulated gases have accumulated outside of industrial workings to reach measurable levels globally. Fugitive emissions include many poorly understood pathways by which the most potent and long-lived
ozone depleting substance Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone lay ...
s and greenhouse gases enter Earth's atmosphere. In particular, the build-up of a variety of man-made halogenated gases over the past several decades contributes more than 10% of the radiative forcing which drives global climate change as of year 2020. Moreover, the ongoing banking of small to large quantities of these gases within consumer appliances, industrial systems, and abandoned equipment throughout the world has all but guaranteed their future emissions for many years to come. Fugitive emissions of
CFCs Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propa ...
and HCFCs from legacy equipment and process uses have continued to hinder recovery of the stratospheric ozone layer in the years since most production was banned in accordance with the international Montreal Protocol. Similar legacy issues continue to be created at ever-increasing scale with the mining of fossil
hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or e ...
, including
gas venting Gas venting, more specifically known as natural-gas venting or methane venting, is the intentional and controlled release of gases containing alkane hydrocarbons - predominately methane - into earth's atmosphere. It is a widely used method fo ...
and
fugitive gas emissions Fugitive gas emissions are emissions of gas (typically natural gas, which contains methane) to atmosphere or groundwater which result from oil and gas or coal mining activity. In 2016, these emissions, when converted to their equivalent impact o ...
from coal mines, oil wells, and gas wells. Economically depleted mines and wells may be abandoned or poorly sealed, while properly decommissioned facilities may experience emission increases following equipment failures or earth disturbances. Satellite monitoring systems are beginning to be developed and deployed to aid identification of the largest emitters, sometimes known as super-emitters.


Emissions inventory

A detailed inventory of
greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and lar ...
from upstream
oil and gas A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels ...
activities in Canada for the year 2000 estimated that fugitive equipment leaks had a
global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time ...
equivalent to the release of 17 million metric tonnes of carbon dioxide, or 12 percent of all greenhouse gases emitted by the sector, while another report put fugitive emissions at 5.2% of world greenhouse emissions in 2013. Venting of natural gas, flaring, accidental releases and storage losses accounted for an additional 38 percent. Fugitive emissions present other risks and hazards. Emissions of volatile organic compounds such as
benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...
from oil refineries and
chemical plant A chemical plant is an industrial process plant that manufactures (or otherwise processes) chemicals, usually on a large scale. The general objective of a chemical plant is to create new material wealth via the chemical or biological transfor ...
s pose a long term health risk to workers and local communities. In situations where large amounts of flammable liquids and gases are contained under pressure, leaks also increase the risk of fire and explosion.


Pressurized equipment

Leaks from pressurized process equipment generally occur through
valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...
s, pipe connections, mechanical seals, or related equipment. Fugitive emissions also occur at evaporative sources such as waste water treatment ponds and storage tanks. Because of the huge number of potential leak sources at large industrial facilities and the difficulties in detecting and repairing some leaks, fugitive emissions can be a significant proportion of total emissions. Though the quantities of leaked gases may be small, gases that have serious health or environmental impacts can cause a significant problem.


Fenceline monitoring

Fenceline monitoring techniques involve the use of samplers and detectors positioned at the fenceline of a facility. Several types of devices are used to provide data on a facility's fugitive emissions, including passive samplers with
sorbent tube Sorbent tubes are the most widely used collection media for sampling hazardous gases and vapors in air, mostly as it relates to Industrial hygiene. They were developed by the US National Institute for Occupational Safety and Health (NIOSH) for ai ...
s, and "SPod" sensors that provide real-time data.


Detection and repair

To minimize and control leaks at process facilities operators carry out regular leak detection and repair activities. Routine inspections of process equipment with
gas detector A gas detector is a device that detects the presence of gases in an area, often as part of a safety system. A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave. This type of d ...
s can be used to identify leaks and estimate the leak rate in order to decide on appropriate corrective action. Proper routine maintenance of equipment reduces the likelihood of leaks. Because of the technical difficulties and costs of detecting and quantifying actual fugitive emissions at a site or facility, and the variability and intermittent nature of emission flow rates, bottom-up estimates based on standard emission factors are generally used for annual reporting purposes.


New technologies

New technologies are under development that could revolutionize the detection and monitoring of fugitive emissions. One technology, known as differential absorption
lidar Lidar (, also LIDAR, or LiDAR; sometimes LADAR) is a method for determining ranges (variable distance) by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. It can also be ...
(DIAL), can be used to remotely measure concentration profiles of hydrocarbons in the atmosphere up to several hundred meters from a facility. DIAL has been used for refinery surveys in Europe for over 15 years. A pilot study carried out in 2005 using DIAL found that actual emissions at a refinery were fifteen times higher than those previously reported using the emission factor approach. The fugitive emissions were equivalent to 0.17% of the refinery throughput. Portable gas leak imaging cameras are also a new technology that can be used to improve leak detection and repair, leading to reduced fugitive emissions. The cameras use infrared imaging technology to produce video images in which invisible gases escaping from leak sources can be clearly identified.


Types


Natural gas


See also

* Gas flare *
Greenhouse gas A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), methane ...
* Leaks * Volatile organic compound *
Fugitive gas emissions Fugitive gas emissions are emissions of gas (typically natural gas, which contains methane) to atmosphere or groundwater which result from oil and gas or coal mining activity. In 2016, these emissions, when converted to their equivalent impact o ...


References

{{Reflist


External links


2006 IPCC Guidelines for National Greenhouse Gas Inventories
(see Section 4.2). Air pollution Greenhouse gas emissions