Southern California Methane Leak
In 2010, an explosion on an oil platform in the Gulf of Mexico left an open pipeline near the ocean floor gushing oil for months. A tiny bit of that oil made it to the surface and into nearby beaches, but because most of the leak was kilometers beneath the ocean’s surface, it was barely seen until a webcam was placed in the ocean near the recovery effort. Even though the oil wasn't making it to the surface, it still had the power to damage marine ecosystems, some of which have yet to recover.
Something similar is happening right now near Los Angeles.
In mid-October, a large natural gas leak formed at the Aliso Canyon Natural Gas Storage Facility, an underground reservoir that holds gas in the urban area. The gas leak has proven unstoppable since it formed, and it has caused the evacuation of several hundred families in the community.
Methane is a particularly pernicious pollutant. It is transparent to light in the visible wavelengths and therefore it can’t be seen, and on its own it has no odor so it can’t be smelled. However, it is explosive when mixed with oxygen and so if a leak forms in someone’s home, that leak can remain undetected until it becomes explosive and potentially deadly.
To avoid this scenario, natural gas companies purchase methane and mix it with a chemical known as mercaptan in large storage facilities; that chemical provides the odor you’ve noticed if you’ve ever smelled a natural gas leak. The Aliso Canyon facility is this sort of storage facility.
The Los Angeles basin is one of the richest hydrocarbon reservoirs in the United States; in the early decades of the 20th century there were huge wells bored into the entire basin to extract oil and natural gas. The Aliso Canyon gas storage facility takes advantage of one of these oil fields; it is built atop a now-empty oil reservoir where the geology naturally held the oil in place until it was tapped. That sedimentary reservoir sits at a depth of about 2500 meters below the surface, beyond where anything other than drilling equipment can easily reach.
During normal operations, the facility receives delivery of natural gas from the surrounding area, mixes in the mercaptan, pumps the gas down to this natural geologic container, then pumps the gas out to ship throughout the Los Angeles basin. However, in early October, one of the pipes that pumps gas down into the reservoir ruptured, opening a flow path for gas to escape the pressurized reservoir below.
The gas has since been leaking from this broken pipe, working its way upwards through the ground from the leak site. Once it reaches the surface, it leaks into the air and since it is already mixed with the mercaptan, people in the area are hit by the gas odor. Residents have reported breathing and health problems associated with this leak since it began, but it is unknown how much of those health problems could be due to the odor or how much could be due to anything else. In high enough quantities it is an asphyxiant that denies your body oxygen, but in smaller quantities there are no known health effects. In fact, most people are regularly exposed to some methane, whether it is leaking out of the ground naturally or being released through some industrial operation. However, there are few studies regarding continuous exposure to methane over many months and natural gas leaking directly from the ground could have other trace components in it that would otherwise readily burn off; several studies have shown increased rates of respiratory illness in areas surrounding large natural gas operations with the exact cause of those illnesses still not constrained.
The amount of methane leaked already from this site is enormous. The volume being released from this pipe is estimated to be ~1/4 of the total methane emissions of the state of California, including all industrial and agricultural sources. It probably already shows up in satellite data, although I don’t have that available yet. Because human eyes can’t see it, the area’s population can’t see the plume, but infrared cameras can detect light wavelengths that do interact with methane. The Environmental Defense Fund flew a couple flights in December at this site using the appropriate cameras to image the plume. A still frame of that plume is shown in this post; more complete video is available over at our blog: http://tmblr.co/Zyv2Js1_rw5gK and http://tmblr.co/Zyv2Js1_s0Zuz.
In addition to the other issues, methane is also a potent greenhouse gas, much stronger than carbon dioxide. In small doses, like those released in the ocean or in swamps from decaying organic matter, methane can be used as an energy source by organisms, preventing it from reaching the atmosphere, but a huge plume like this is a direct pipeline of methane up to the atmosphere. The estimates of the California Air Resources Board suggest that this one leak is having the same climate impact as 7 million cars.
Because the ruptured pipe is deep underground, efforts to contain the leak so far have failed. Initial plans involved pumping heavy fluids down the pipe to block it, but methane is extremely low density and so even when fluids were pumped down, the gas was able to continue escaping upwards. The final plan is therefore going to require digging a relief well to reach the ruptured pipe and seal it at a different spot; this digging will take several more months to complete. Until then, this invisible geyser of methane will continue pouring into the skies near Los Angeles.
People directly affected by this leak are already filing lawsuits, and it is possible that an end result could be closure of this facility. However, storage facilities like this are common around the world; you literally can’t run an energy system using natural gas without a place to store the gas, and geologic storage is cheaper and more reliable than storing gas above ground. There’s a good chance you have a storage facility like this one within a short drive of wherever you live; in 2008 there were over 400 of them in the U.S. alone. Southern California Gas operates 4 of these facilities; the Aliso Canyon site is the largest.
-JBB
Image credits: Earthworks, EDF https://flic.kr/p/BWWgYw http://bit.ly/1OXdbYZ
References/more info: http://1.usa.gov/1YQ0LqT http://1.usa.gov/1Ufax4D http://www.eia.gov/naturalgas/storage/basics/ http://www2.socalgas.com/safety/aliso-canyon/ http://reut.rs/1lLYQqQ http://bit.ly/1mKSMjh