The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject.(May 2007) |
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 gas concentration. [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]
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.
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.
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]
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]
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:
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]
In 2021, University of Geoscience(Beijing) affiliates Jian Rui Feng and Wen-men Gai, along with Chief Engineer of the Guangzhou Metro Group Co Ya-bin Yan, launched a case study modelling a subway within Guangzhou, China and potential evacuation plans and actions that could mitigate risk to personal against gas leaks via virtual computations [11] . This study found that the activation of air vents, the reduction number of initial people that needed to evacuate, and the increased ability for each person to identity the risk all reduced the risk that a gas leak would pose within the subway. [11]
This section needs expansion. You can help by adding to it. (July 2014) |
Legislation passed in 2014 [12] requires gas suppliers to make greater efforts to control some of the 20,000 documented leaks in the US state of Massachusetts. The new law requires grade 1 and 2 leaks to be repaired if the street above a gas pipe is dug up, and requires priority be given to leaks near schools. It provides a mechanism for increased revenue from ratepayers (up to 1.5% without further approval) to cover the cost of repairs and replacement of leak-prone materials (like cast iron and non-cathodically protected steel) on an accelerated basis. The law sets a target of 20 years for replacement of pipes made from leak-prone materials if feasible given the revenue cap; as of 2015 [update] , Columbia Gas of Massachusetts (formerly named "Bay State Gas"), Berkshire Gas, Liberty Utilities, National Grid, and Unitil say they will meet this target, but NSTAR says it will take 25 years to complete. [13] [14] Leaks, statistics on leak-prone materials, and financial statements are reported annually to the Department of Public Utilities, which also has responsibility for rate-setting.
Additional proposals not included in the law would have required grade 3 leaks to be repaired during road construction, and priority for leaks which are killing trees or which were near hospitals or churches. [15] [16]
An attorney for the Conservation Law Foundation stated that the leaks were worth $38.8 million in lost natural gas, which also contributes 4% of the state's greenhouse gas emissions. [16] A federal study prompted by US Senator Edward J. Markey concluded that Massachusetts consumers paid approximately $1.5 billion from 2000–2011 for gas which leaked and benefited no one. [15] Markey has also backed legislation that would implement similar requirements at the national level, along with financing provisions for repairs. [15] [ needs update ]
This section needs expansion. You can help by adding to it. (November 2013) |
Catastrophic gas leaks, such as the Bhopal disaster are well-recognized as problems, but the more-subtle effects of chronic low-level leaks have been slower to gain recognition.
This section needs expansion. You can help by adding to it. (November 2013) |
In work with dangerous gases (such as in a lab or industrial setting), a gas leak may require hazmat emergency response, especially if the leaked material is flammable, explosive, corrosive, or toxic. For instance, the transportation of natural gasses can be susceptible to gas leaks them with themselves have explosive properties, such as the Latvian natural gas system and its report on the classification and potential risks of gas leakage as well as actionable responses [17] . There is also the safety of the public to consider, such as analyzing technics to help ensure the safety and ease of evacuation plans.
Natural gas is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane (95%) in addition to various smaller amounts of other higher alkanes. Traces of carbon dioxide, nitrogen, hydrogen sulfide, and helium are also usually present. Methane is colorless and odorless, and the second largest greenhouse gas contributor to global climate change after carbon dioxide. Because natural gas is odorless, odorizers such as mercaptan are commonly added to it for safety so that leaks can be readily detected.
A pipeline is a system of pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than 2,175,000 miles (3,500,000 km) of pipeline in 120 countries around the world. The United States had 65%, Russia had 8%, and Canada had 3%, thus 76% of all pipeline were in these three countries. The main attribute to pollution from pipelines is caused by corrosion and leakage.
A trench is a type of excavation or depression in the ground that is generally deeper than it is wide, and narrow compared with its length.
A hydrostatic test is a way in which pressure vessels such as pipelines, plumbing, gas cylinders, boilers and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection, and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.
Cryogenic fuels are fuels that require storage at extremely low temperatures in order to maintain them in a liquid state. These fuels are used in machinery that operates in space where ordinary fuel cannot be used, due to the very low temperatures often encountered in space, and the absence of an environment that supports combustion. Cryogenic fuels most often constitute liquefied gases such as liquid hydrogen.
A gas stove is a stove that is fuelled by flammable gas such as natural gas, propane, butane, liquefied petroleum gas or syngas. Before the advent of gas, cooking stoves relied on solid fuels, such as coal or wood. The first gas stoves were developed in the 1820s and a gas stove factory was established in England in 1836. This new cooking technology had the advantage of being easily adjustable and could be turned off when not in use. The gas stove, however, did not become a commercial success until the 1880s, by which time supplies of piped gas were available in cities and large towns in Britain. The stoves became widespread on the European Continent and in the United States in the early 20th century.
A gas explosion is the ignition of a mixture of air and flammable gas, typically from a gas leak. In household accidents, the principal explosive gases are those used for heating or cooking purposes such as natural gas, methane, propane, butane. In industrial explosions, many other gases, like hydrogen, as well as evaporated (gaseous) gasoline or ethanol play an important role. Industrial gas explosions can be prevented with the use of intrinsic safety barriers to prevent ignition, or use of alternative energy.
Landfill gas is a mix of different gases created by the action of microorganisms within a landfill as they decompose organic waste, including for example, food waste and paper waste. Landfill gas is approximately forty to sixty percent methane, with the remainder being mostly carbon dioxide. Trace amounts of other volatile organic compounds (VOCs) comprise the remainder (<1%). These trace gases include a large array of species, mainly simple hydrocarbons.
A gas flare, alternatively known as a flare stack, flare boom, ground flare, or flare pit, is a gas combustion device used in places such as petroleum refineries, chemical plants and natural gas processing plants, oil or gas extraction sites having oil wells, gas wells, offshore oil and gas rigs and landfills.
Natural gas has been used almost as long as crude oil in Canada, but its commercial development was not as rapid. This is because of special properties of this energy commodity: it is a gas, and it frequently contains impurities. The technical challenges involved to first process and then pipe it to market are therefore considerable. Furthermore, the costs of pipeline building make the whole enterprise capital intensive, requiring both money and engineering expertise, and large enough markets to make the business profitable.
Fugitive emissions are leaks and other irregular releases of gases or vapors 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, while less common examples are perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride.
A liquefied natural gas (LNG) spill can happen during an accident or an intentional act. LNG is normally stored and transported in liquid form at a temperature of approximately −162 °C (−260 °F). If this cooled liquid is released from a storage facility, pipeline, or LNG transport ship, then it begins to warm. As LNG warms above its storage temperature, the liquid begins to vaporize. The resulting gas produced by this warming is typically methane, which is the major component of natural gas and one of the most potent and hazardous greenhouse gases.
Landfill gas utilization is a process of gathering, processing, and treating the methane or another gas emitted from decomposing garbage to produce electricity, heat, fuels, and various chemical compounds. After fossil fuel and agriculture, landfill gas is the third largest human generated source of methane. Compared to CO2, methane is 25 times more potent as a greenhouse gas. It is important not only to control its emission but, where conditions allow, use it to generate energy, thus offsetting the contribution of two major sources of greenhouse gases towards climate change.
There are many exemptions for fracking under United States federal law: the oil and gas industries are exempt or excluded from certain sections of a number of the major federal environmental laws. These laws range from protecting clean water and air, to preventing the release of toxic substances and chemicals into the environment: the Clean Air Act, Clean Water Act, Safe Drinking Water Act, National Environmental Policy Act, Resource Conservation and Recovery Act, Emergency Planning and Community Right-to-Know Act, and the Comprehensive Environmental Response, Compensation, and Liability Act, commonly known as Superfund.
The Aliso Canyon gas leak was a massive methane leak in the Santa Susana Mountains near the neighborhood of Porter Ranch in the city of Los Angeles, California. Discovered on October 23, 2015, gas was escaping from a well within the Aliso Canyon underground storage facility. This second-largest gas storage facility of its kind in the United States belongs to the Southern California Gas Company, a subsidiary of Sempra Energy. On January 6, 2016, Governor Jerry Brown issued a state of emergency. On February 11, the gas company reported that it had the leak under control. On February 18, state officials announced that the leak was permanently plugged.
The Cook Inlet natural gas leak began in December 2016 when a pipeline ruptured, resulting in an underwater methane leak beneath Turnagain Arm in Cook Inlet near Nikiski, Alaska.
Increasing methane emissions are a major contributor to the rising concentration of greenhouse gases in Earth's atmosphere, and are responsible for up to one-third of near-term global heating. During 2019, about 60% of methane released globally was from human activities, while natural sources contributed about 40%. Reducing methane emissions by capturing and utilizing the gas can produce simultaneous environmental and economic benefits.
Founded in 1989, Hilcorp is an American privately-held energy exploration and production company. The company is headquartered in Texas, with operations in nine different states. It has 3200 employees world-wide, and 1500 in Alaska.
A methane leak comes from an industrial facility or pipeline and means a significant natural gas leak: the term is used for a class of methane emissions. Satellite data enables the identification of super-emitter events that produce methane plumes. Over 1,000 methane leaks of this type were found worldwide in 2022. As with other gas leaks, a leak of methane is a safety hazard: coalbed methane in the form of fugitive gas emission has always been a danger to miners. Methane leaks also have a serious environmental impact. Natural gas can contain some ethane and other gases, but from both the safety and environmental point of view the methane content is the major factor.