Gas leak
A gas leak refers to a leak of natural gas or another gaseous product from a pipeline or other containment into any area where the gas should not be present. Gas leaks can be hazardous to health as well as the environment. Even a small leak into a building or other confined space may gradually build up an explosive or lethal concentration of gas.[1] Natural gas leaks and the escape of refrigerant gas into the atmosphere are especially harmful, because of their global warming potential and ozone depletion potential.[2]
For other uses, see Leak (disambiguation).
Leaks of gases associated with industrial operations and equipment are also generally known as fugitive emissions. Natural gas leaks from fossil fuel extraction and use are known as fugitive gas emissions. Such unintended leaks should not be confused with similar intentional types of gas release, such as:
Gas leaks should also not be confused with "gas seepage" from the earth or oceans - either natural or due to human activity.
Fire and explosion safety[edit]
Pure natural gas is colorless and odorless, and is composed primarily of methane. Unpleasant scents in the form of traces of mercaptans are usually added, to assist in identifying leaks. This odor may be perceived as rotting eggs, or a faintly unpleasant skunk smell. Persons detecting the odor must evacuate the area and abstain from using open flames or operating electrical equipment, to reduce the risk of fire and explosion.
As a result of the Pipeline Safety Improvement Act[3] of 2002 passed in the United States, federal safety standards require companies providing natural gas to conduct safety inspections for gas leaks in homes and other buildings receiving natural gas. The gas company is required to inspect gas meters and inside gas piping from the point of entry into the building to the outlet side of the gas meter for gas leaks. This may require entry into private homes by the natural gas companies to check for hazardous conditions.
Harm to vegetation[edit]
Gas leaks can damage or kill plants.[4][5] In addition to leaks from natural gas pipes, methane and other gases migrating from landfill garbage disposal sites can also cause chlorosis and necrosis in grass, weeds, or trees.[6] In some cases, leaking gas may migrate as far as 100 feet (30 m) from the source of the leak to an affected tree.[7]
Harm to animals[edit]
Methane is an asphyxiant gas which can reduce the normal oxygen concentration in breathing air. Small animals and birds are also more sensitive to toxic gas like carbon monoxide that are sometimes present with natural gas. The expression "canary in a coal mine" derives from the historical practice of using a canary as an animal sentinel to detect dangerously high concentrations of naturally occurring coal gas.[8]
Greenhouse gas emissions[edit]
Methane, the primary constituent of natural gas, is up to 120 times as potent a greenhouse gas as carbon dioxide. Thus, the release of unburned natural gas produces much stronger effects than the carbon dioxide that would have been released if the gas had been burned as intended.[9]
In the United States, most state and federal agencies have adopted the Gas Piping and Technology Committee (GPTC) standards for grading natural gas leaks.
A Grade 1 leak is a leak that represents an existing or probable hazard to persons or property, and requires immediate repair or continuous action until the conditions are no longer hazardous.
Examples of a Grade 1 leak are:
A Grade 2 leak is a leak that is recognized as being non-hazardous at the time of detection, but justifies scheduled repair based on probable future hazard.
Examples of a Grade 2 Leak are:
A Grade 3 leak is non-hazardous at the time of detection and can be reasonably expected to remain non-hazardous.
Examples of a Grade 3 Leak are:
Studies[edit]
In 2012, Boston University professor Nathan Phillips and his students drove along all 785 miles (1,263 km) of Boston roads with a gas sensor, identifying 3300 leaks.[9] The Conservation Law Foundation produced a map showing around 4000 leaks reported to the Massachusetts Department of Public Utilities.[9] In July 2014, the Environmental Defense Fund released an interactive online map based on gas sensors attached to three mapping cars which already were being driven along Boston streets to update Google Earth Street View. This survey differed from the previous studies in that an estimate of leak severity was produced, rather than just leak detection. This map should help the gas utility to prioritize leak repairs, as well as raising public awareness of the problem.[9]
In 2017, Rhode Island released an estimated 15.7 million metric tons of greenhouse gases, about a third of which comes from leaks in natural gas pipes. This figure, published in 2019, was calculated based on an assumed leakage rate of 2.7% (as that is the rate of leakage in the nearby city of Boston). The study's authors estimated that fixing the leaks would incur an annual cost of $1.6 billion to $4 billion.[10]