Le Monde | • Updated | By
California is in a state of emergency. For over two months, a massive gas leak affects the Los Angeles area. This major industrial accident, described as unprecedented disaster in California by experts, has forced thousands of residents to evacuate the area.
The leak is located at 2400 meters deep in a wellbore Natural gas, on the site of Aliso Canyon, which is one of the largest reservoirs in the United States, about fifty kilometers northwest of Los Angeles. The well is operated by Southern distribution company California Gas Co. (SoCal Gas).
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Between 30 and 58 tonnes of methane per hour
Since its discovery on October 23, the flight leaves spilling huge amounts of methane in permanently the atmosphere. The California Air Resources Board, the agency responsible for monitoring air quality in California, has calculated through measurements made by air, it releases between 30 and 58 tonnes of methane per hour, according to figures December 23.
“These periodic measurements provide emission rates when flights are operated and can vary considerably, especially depending on wind and weather conditions prevents the body. However, they may provide a rough estimate of the total amount of methane released into the atmosphere. “ The final figure will not release another three or four months, when the leak has been plugged. A long and complex operation, since the company must drill a parallel wells to divert the gas to be a natural reservoir, before condemning the failed well.
The US NGO Environmental Defense Fund has still risky to count the total amount of released methane into the atmosphere since late October, Updated live from the data of the California agency. These 79 000 tonnes of methane corresponding to the issuance of 6.7 million tonnes of carbon dioxide (CO 2 ), or 2.8 million m 3 burned and lost 12 million dollars of oil – according to calculations by the NGO base, for conversion, on figures from the Intergovernmental Panel on Climate Change, the US Agency for Protection Environment and rates on gas markets
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In addition to emissions, the California Air Resources Board also conducts real-time measurements of concentrations of this gas colorless, odorless, two sites of Porter Ranch, a suburb of Los Angeles where the well is leaking. Over the last seven days, concentrations reached a maximum of 25 parts per million (ppm), against 2 ppm normally in nature. “Higher than 10 ppm results suggest a considerable amount of excess methane. The highest measured level of methane in the community of Porter Ranch since the flight is 230 ppm, although such high levels were not recorded regularly “, says the agency.
The equivalent of 7 million cars
The impact on the climate is already considerable, according to the air quality monitoring agency, the leak increased 25% annual emissions of methane California. This chemical compound represents 9% of total emissions of greenhouse gas in the state, which amounted to 459 million tons than equivalent CO 2 in 2013.
Methane, which consists of 80% natural gas, is considered the second gas responsible for global warming, behind the CO 2 , but far ahead of nitrous oxide (N 2 O) and hydrofluorocarbons (HFCs). If it persists as long in the atmosphere as carbon dioxide, methane (CH 4 ) has a global warming potential 86 times that of CO 2 a 20-year horizon, and 34 times in 100 years, according to the latest IPCC report.
All of which leads to the NGO Environmental Defense Fund, the impact of the leak is the same in the short term than 7 million cars that run every day, or eight to nine coal plants. “SoCalGas recognizes the impact of this incident on the environment. I want to assure the public that we intend to mitigate the environmental impacts of the leak “, said, without elaborating, the company president, Dennis Arriola.
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